CA1157623A

CA1157623A - Cushioning dunnage product, apparatus and method

Info

Publication number: CA1157623A
Application number: CA000362140A
Authority: CA
Inventors: Gary W. Ottaviano
Original assignee: Ranpak Corp
Current assignee: Ranpak Corp
Priority date: 1980-10-20
Filing date: 1980-10-20
Publication date: 1983-11-29

Abstract

CUSHIONING DUNNAGE PRODUCT, APPARATUS AND METHOD
Abstract of the Disclosure A method and apparatus for the production of air cell cushioning dunnage material, for protective cushioning purposes in packaging or other purposes, with the air cell product possess-ing substantial strength, and the ability to retain its original thickness under load. The method and apparatus are such that the apparatus can be halted in its operation without injurious effects to the dunnage product being produced, and can be restarted to again commence production of the cushioning dunnage product. The apparatus and method utilize flexible thermoplastic sheets or film of material, to produce the air cell product, with the plas-tic sheets being preferably formed of a composite of an interme-diate stratum of relatively high density high melting point plas-tic, and exterior stratums of relatively low density, low melting point thermoplastic bonded to the intermediate stratum. Various other embodiments of flexible air cell sheeting are also disclosed.

Description

` - - liS7623 CUS~IIONING DUNNAGE PRODUCT, ~PPARAI'US AND ME~HOD
S~ecification This invention relates to an improved method and ap-paratus for the production of air cell ~heeting material formed of flexible plastic sheet or film, and an improved cushioning dun-nage product and other air cell products, produced therefrom, and more particularly relates to an apparatus and method which enable~ -the operation of the apparatus to be expeditiously performed, and . including the ability to interrupt the operation, without effect-ing the workability of the apparatus and/or method when the latter are reinitiated after termination of the interruption, and which .~ results in a product of high strength, possessing the ability to retain its originally formed thicknes~ over a relatively long per-iod of time and under load, without losing any substantial amount of air from the air cells of the produced product.
Backqround of the Invention It is well known in the prior-art to produce an air .~ . cell cushioning dunnage product utilizing flexible plastic sheet . ~aterial and embossing one of the sheets,~and applying a laminat--~ 20 ing or cover sheet thereto, for sealing formation of the air cells, s with the product being utilized in cushioning applications. U.S.
: patent 3,416,984 dated December 17, 1968 and entitled Method and Apparatus For Making Cellular Material From Thermoplastic Sheets ~ ` i8 an example of such prior art.
: In ~uch patent, a heat sealable pla~tic sheet i8 heated to bring it.~ outer ~urface to a temperature in the vicinity of the fusion or melting temperature thereof, and is embossed on a vacuum drum, with the other surface of the embossed ~heet being . ' , ;

i '3 maintained at about the ~usion temperature of the plastic, ancl then the laminating sheet is applied to the embossed sheet while the latter is on the er~ossing drum, with the surface of the lam-lnat:ing sheet whlch is to contact the embossed sheet being at a temperature above the fusion temperature thereof, so that when the laminating sheet is applied to the embossed sheet, the contact-ing surfaces will equalize at a temperature at least equal to the fusion temperature, thus adhering or sealing the films together.
U.S. patent 3,392,0~1 discloses a multi-laminate cus~,-ioning product ~ormed of a plurali~y of layer~ of material includ-ing a high density plastic layer and a lower denslty low melting point plastlc layer, with the high density plastic layer being selected from the group consisting of polyvinylidene chlorlde and polyethylene, and the low density plastic layer being selected from the group consisting of polyethylene, polypropylene and polyethylene terepllthalate.
Moreover, tnere are consi~erable other patents in the air cell cushioning dunnage field, such as for instance Australian patent 160,551 published October 29, 1953, and U.S. patents 3,018,015; 3,142,599; 3,231,454; 3,28~,793; 3,349,990; 3,577,305;
3,389,534; 3,~23,0~5; 3,575,7~1; 3,616,155; 3,785,899; 3,817.,~0~;
3,837,990; 3,831,991; 3,868,056; 4,076,872 and 4,096,306.
`~ . The prior art air cell products do not possess the strength of the product of the present invention, and-the prior art methods and apparatus are not generally of the type which can be readily and conveniently interrupted in operation and then re-started, without having considerable undesirable effects upon t~e resultant product, on tlle stock material utillzed to produce the product, arld/or on the me~chanism or apparatus per se.

. . .

: -2-,., . ~ ~ . .
.:, ' ' Obiects of the Invention An ob;ect of the inventlon is to provide a novel method for the production of air cell flexible sheeting material, for use, for instance, in protective packaging applications, as well as in other applications. ~-A further object of the invention is to provide a novel apparatus for the production of thermoplastic air cell material.
Summary of the Invention The present invention provides a novel method and an apparatus for the production of air cell flexible thermo-plastlc sheeting material, having high strength and high resistance to loss of air from the cells, and an apparatus and method which provides for expeditious production of an air cell cushioning dunnage product.
~ As a specific embodiment, the present invention .~ provides, a method of manufacturing air cell cushioning dunnage material from a plurality of flexible thermoplastic . sheet~, each of the sheets comprising a composite of a stratum of high density, high melting polnt material generally impervious to the passage of gas therethrough and another stratum bonded to the first me~tioned stratum with .
the other stratum being formed of low density, low melting . point thermoplastic, and with the first mentioned stratum : be~ng of a higher density, higher melting point material as compared to the other stratum, comprising the steps of i~ heating a first of the sheets to a temperature above the melting point temperature of the other stratum but below the melting polnt temperature of the first mentioned .,`' , .
.;~ ' ' ~L5~3 stratum to provide for hot embossment of the sheet, embossing the heated first sheet by feeding it onto a rotating forming drum having a plurality of recesses therein and forming the air cells in the recesses on the forming drum by vacuum, heating a second sheet of the thermoplastic above the meltlng point of the other stratum of the second sheet, cooling the embossed sheet while on the rotating drum to a temperature below the melting point temperature of the other stratum by maintaining the drwm at a predetermined temperature below the first mentioned temperature, and so as to cool the embossed sheet by means of the drum to a temperature approaching the softening temperature of the other stratum thereof, and then applying ; the second heated sheet to the first sheet after completion of the embossing and the cooling, whereby the residue heat in the second sheet causes a melting of the confronting surface of the other stratum of the cooled embossed sheet .
sufficiently to cause a bonding together of the other stratums of the first and second sheets at the areas of 20 engagement while on the drum so as to seal the air cells in the product, and then removing the cushloning product from the forming drum.
As a further specific embodiment, the present invention provides an apparatus for producing air cell cushioning dunnage from flexible thermoplastic sheet stock, `. each sheet of w~ich comprises a composite of a stratum of . .~., ~j high density high melting point thermoplastic material generally impervious to the passage of air therethrough, and another stratum formed of relatively low density, low } ~ .
-3a-f ~ `
,,'.
~, ~ ~23 melting point thermoplastic material, with the first mentioned stratum being of a higher density, higher melting point material as compared to that of the other stratum, comprising a rotatable forming drum having a plurality of recesses formed therein for vacuum formlng the a1r cells in a first sheet of the thermoplastic material fed onto ~ the drum, the drum including means for cooling the drum to a predetermined temperature, and a series of spaced rollers spaced with respect to the forming drum, the series of rollers having means providing for heating the first sheet c; prior to its being fed onto the drum,Oto a temperature above the melting point of the other stratum of the first sheet but below the melting point temperature of the first . .
`~ mentioned stratum, and a second series of rollers spaced from the first series and having means adapted to heat a . second sheet of the thermoplastic stock material to a ~ temperature above the melting point of the other stratum .~ of the second sheet, and means coacting with the second series for applying the second sheet to the first sheet on the drum to seal the air cells, with the first series and the second series of rollers being so arranged with respect to the circumference of the drum that said applying means is spaced from the point of application of the first sheet ` to the drum sufficiently that the drum during rotation . thereof can cool the first sheet to a temperature approach-,i;
ing the softening point temperature of the first sheet prior .. to application of the second sheet thereto.
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3b-;' ' ., Other objects and advantages of the invention will be appar~nt from the following de~cription taken in conjunction with the accompanying drawings wherein, Brief Description of the Drawinqs FIGURE 1 is a top plan fragmentary view of a section of the cu~hioning dunnage material as produced by the method and apparatus.
FIGURE 2 is a sectional view taken generally along the plane of line 2-2 of FIGURE 1, looking in the direction of the 10 arrows.
FIGURE 3 is a fragmentary, perspective view of the cu~h-ioning dunnage material.
FIGURE 4 is an enlarged, vertical sectional view taken through one of the flexible plastic sheets utilized in the produc-tion of the product, illustrating the layers or stratums of plas-tic materials utilized in a ~heet or film of plastic stock mater-ial.
FIGURE S is a diagrammatic, end elevational view show-ing a strip of the product of the invention as rolled into cylin-drical form for ready transportation and/o~ storage.
FIGURE 6 i~ an enlarged, ver~ical sectional view of one of the air cell~ of the produced product, showing the stratum~
; or defining layers of the plastic sheet~ utilized to produce the - product.
FIGURE 7 i~ a side elevational, generally diagrammatic view of an apparatus utilizable in producing the product of the invention and in performing the method of producing the product.

~.' , FIGURE 8 i9 a diagrammatic, top plan view of a mechan-ism for mounting a plurality of the rolls of produced product of ' -; -4-~1~;j7~23 selected widths, and connecting such widths of product together by heat sealing confronting edges thereof, to produce a roll of product having a width of generally the s~m of the widths of the original individual rolls.
FIGURE 9 is a diagrammatic, side elevational view of the FIGURE 8 mechanism.
FIGURE 10 is an enlarged, vertical sectional view taken generally along line 10-10 of FIGURE 8 looking in the direction of the arrows and illustrating details of the heat sealing rollers of the mechanism of FIGURES 8 and 9.
FIGURES 11 to 26 (FIGURE 26 being located on sheet -3 of the drawings) are fragmentary illustrations of various other embodiments of air cell flexible plastic sheeting pro-ducts which may be produced on the mechanism of FIGURE 7 and utilizing the method of the invention, with such air cell products including means along the margins of the produced air cell product for stiffening the edges and/or providing a convenient arrangement for connecting the latter to confront-ing air cell sheeting, to selectively form, for instance, -envelopes of the flexible air cell material.
Description of Preferred Embodiments Referring now again to FIGURE 1, there is illustrated a plan view of a cushioning product 10 provided in accordance with the invention. The product is formed of two sheets 12 and 14 of flexible plastic material, with one of the sheets (i.e. 12) having been embossed to define relatively closely spaced cells 16 which are adapted to con-tain air which is entrapped by the laminating or cover sheet 14. Sheets 12 and 14 are heat sealed to one another at spaced areas 17 (FIGURE 2). Ps can be best seen in FIGURE
1, the cells 16 are prefera~ly arranged in rows (e.g. ~, B, . .

C, D) which are preferably staggered with re~pect to one another and with respect to the ~ide edge 18 of the strip of dunnage, with there being preferably provided along each ~ide edge of the formed strip of cushioning dunnage a sub~tantial width areD 20 prior to commencement of the row~ of air cells 16. The width of area 20 commencing at edge 18 and extending to the confronting periphery of the clo~e~t air cell, may be in the range of from about .125 to about 1 inch, but prefexably i9 in the range of from about .35 to .5 inch for a two foot wide strip of dunnage.
Each of the air cells 16 is of general dome ~haped con-figuration, a~ ~hown, and is, in the embodiment illustrated, fill-ed with air, which provides a cu~hioning effect when the product 10 is utilized for instance in packaging around a product, ~o as to cushion the product from vibration and/ox shock damage. Re-ferring now to FIGURE 2, each of the air cells 16 illu~trated i8 preferably approximately 5/16 to 1/2 inch high by approximately 1-3~ inches in diameter, with air filling the respective air cell and maintaining the walls of the air cell in the generally domed configuration illu~trated. However, variou~ heights and diame-ters of cells may be provided.
Referring now to FIGURE 4, each of the sheets 12 and 14 u~ed in formation o~ the product may be and preferably i9, formed of an intermediate stratum 22 of the flexible nylon and ext~rior stratums 24 of polyethylene. The sheet of film i~ pref-~rably made by a known ca~t coextru~io~ method, with the inter-mediate nylon ~tratum being of a relatively high donsity relative-ly high melting point (e.g. 490F) material substantially imper-,viou~ to the passage of gase~ therethrough, while the poly~thyl-ene stratums are formed of relatively low density polyethylene ~7~3 plastic having a relatively low melting point (e.g. 230 F.). The nylon content can be lO~o ~O~o 30% of the overall thickness of the structure and the exterior polyethylene layers 24 generally equally divide the balance of the thickness of the sheet material.
The overall thickness o~ the sheet material may vary from say for instance 1 and 1/2 mils to approximately 8 mils, but it is preferable that for use as a cushioning dunnage product, the embossed or domed sheet 12 be between approximately 2 to 8 mils thickness, while the laminating or base cover sheet 14 be between approximately 1.5 to 4 mils thickness, preferably being of a lesser thickness as compared to the embossed sheet 12, but a~ least being of no greater thickness. The stock sheet of film has an impact strength of from approximately 310 to 300 grams, and a tensile strength in pounds per square inch of ~rom 3400 to approximately 6200, depending on the percentage of nylon in the sheet. A sheet with the higher percentage of nylon, such as for 30% nylon, has the greater tensile strength. The exterior stratums 24 of the sheet will commence to become tacky or "so~t" at approxima-tely 16~ F. and will melt, as aforementioned, at approxima*ely 230 F. ~ ;
In the sheet stock material illustrated, the nylon ]ayer 22 is bonded to the exterior heat sealable layers 24 by a binder coating 26, the thickness of each of whicll in the embodiment shown represents about 5~ of the overall thickness of the sheet stock.
Moreover, each of the exterior polyethylene layers 24 preferably comprises an inner section 24a of combined low density virgin and recycled polyethylene and a relatively thin (e.g. 5% o~ the overall sheet thickness) outer section 24b of low density virgin polyethylene bonded together. The thickness of the intermediate stratum 22 is less than one third the overall thickness of the plastic sheet, and preferably is less than one third the thickness of each of the exterior stratums 24.

23 "

m is multi-layer composite plastic sheet utilized in the production of the cushioning dunnage product of the invention is available in commercial form from the Crown Zellerbach Corporation of Texas, and two preferable types are identified by it as "Crown Zeelon 305" (trademark) composite film and "Crown Zeelon 355" (trademark) composite film.
FIGURE 5 illustrates a roll of the embossed cushion-ing dunnage product as produced on the machine of FIGURE 7, and disposed or rotated into roll form about a hollow core 27.
The cushioning product utilizlng the aforedescribed stock film provides gas barrier characteristics rated at no greater than approximately 10 to 12 c.c. per 100 square inches per 24 hours at one atmosphere at 72F.
FIGURE 7 illustrates diagrammatically, an apparatus for producing the cushioning product of the invention. In the embodiment illustrated the apparatus comprises a frame 30 on which may be rotatably mounted a supply roll 32 of the poly-ethylene-nylon-polyethylene flexible plastic sheet or film ma-terial F, for rotation about a generally horizontal axis 34.
The stock sheet materlal F ls pulled off roll 32 and passes about a preferably stationary, generally horizontally orlented shaft 36 whlch is preferably coated with a layer of some fric-tion reducing anti-adhesion material, such as for instance polytetrafluorethylene, otherwise known as "Teflon" (trademark).
m e sheet passes beneath shaft 36 and then passes over a heating roller 28 which is preferably non-driven (l.e. idler) about axis 38a on frame 30, but which roller should be maintain-ed rotatable and movable with the film F at a surface speed at least not to exceed the speed of travel of the film. Roller 38 is preferably coated with a heat resistant anti-adhesion coating .

7~ ~3 and is preferably heated to a temperature of between approximately 180 to 200 F. by any suitable means, such as for instance, by thermostatic controlled electric heating means of known type, em-bodied therein. Passage of the plastic sheet around the idler roller 38 causes it to be preheated to a temperature within the heat range of the idler roller o~ approximately 180 D to 200 F.
The web o~ sheet material F then passes down around roller 40 (which is preferably an idler) which again is heated pre~erably to a temperature range of between approximately 180 -200 F. Roller 40 should be maintained rotatable and movable with the film F at a surface speed at least not to exceed the speed of travel of the film. If roller 40 is driven, it preferably is at a speed just slightly greater than the speed of roller 38.
Roller 40 is, as illustrated, preferably of a larger diameter as compared to roll 38 and is rotatable about axis 40a on framework 30, in a generally similar manner as roll 38. Roller~0 is preferably surface coated with heat resistant anti-adhesion material in a similar manner as roller 38.
From roller 40, the web Or plastic sheet moves about ao preferably non-heated idler roller 44 which again is preferably sur~ace coated with a layer of anti-sticking heat resistant material, such as the aforementioned "Teflon". The sheet may be traveling at a rate of approximately 52 feet per minute, and therefore the temperature of the sheet is generally maintained even though it passes over non-heated roller 44, such sheet being maintained relatively close to the aforementioned 180-200 F.

temperature.
From idler roller 44, the sheet passes about heated roller 46 which preferably is at a temperature of between approximate-ly 220-270F., roller 46 pre~erably being an idler roller. The sheet then passes about closely spaced rollers 48, 50, 52, 54, all of which are heated, and all of which, together with roller _ g 46, preferably have an exterior surface coating thereon of heat resistant anti-adhesion material, such as the afore-mentioned "Teflon". Roller 48 is preferably at a temperature of between approximately 220-270F. Roller 50 is preferably at a temperature of between approximately 230-290F. Roller 52 is preferably at a temperature of between approximately 240-320F., while roller 54 is preferably at a temperature between approximately 260-375F.
All of the rollers 48, 50, 52 and 54 are power driven, are of approximately the same size, and are driven at the same speed. As the web of plastic sheet material passes about these rollers, the polyethylene stratums are melted and turned into substantially liquid form as carried by the nylon intermediate stratum of the sheet.
From roller 54, the sheet material is immediately ap- `
plied to an embossing drum 56, many types of which are known in the art. Embossment of the plastic film or sheet on the emboss-ing drum 56 is preferably accompllshed by a vacuum means (e.g.
producing a vacuum of 5-7 inches of mercury) communicating with each individual depression 58, located on the surface of the em-bossing drum. m e depressions 58 are conventionally connected by passages connecting with a vacuum manifold in the embossing drum 56 and coupled to a controlled source of vacuum. m e form-ing drum 56 may be conveniently made of aluminum, with the sur-face thereof being preferably coated with a layer of adhesion preventing material, such as the aforementioned "Teflon" so that the preheated plastic sheet will not adhere to the surface of the forming drum 56 during the embossing operation. Although the drawings show a generally dome shaped defining surface of the depressions 58, as well as the exterior surface of the finished .~

product (as shown in FIGURE 6), it will be understood that the size, configuration and distribution of the embossments may be modified as desired so as to provide for different purposes or requirements. However, the dome shaped configuration illus-tratecl is preferred for the embossed air cells.
The drum is preferably maintained at a temperature of between approximately 150-15SF. Any suitable means can be uti-lized to maintain the temperature of the drum 56, with water be-ing suitable, since it more expeditiously and economically en-ables maintenance of a more precise and controlled temperature,which is utili~ed in cooling the embossed film or sheet FE on the drum, as will be hereinafter described~ Interior passages may provide for circulation of the water.
It will be seen from FIGURE 7 that in the embodiment illustrated, the pre-heated plastic sheet or film F is preferably applied to the forming drum 56 near the latter's lowermost under-side position, and is embossed as the drum rotates. At approxi-mately 160 circumferential degrees on the drum (in the embodi-mentillustrated) from theinitial point of application of the sheet F to the embossing drum 56, a laminating or cover sheet L
is applied. Accordingly, since the embossing drum i9 at a tem-perature of between approximately 150-155F, and the embossed sheet FE is at a much higher temperature, cooling of the embossed sheet FE on the drum occurs as the drum rotates from position point 60 where the sheet F is first applied thereto, to the posi-tion 62 where the laminating or cover sheet L is applied to the cooled embossed sheet. Accordingly, the embossed sheet FE at point 62 is at a temperature of approximately 170-180F., the drum having cooled the embossed plastic sheet down to a temperature well below the melting temperature of the polyethylene exterior layers 24, and to a temperature approaching the softening or'`tacky"

, temperature o~ the layers 24 (e.g. 160F) which is the tempera-ture at which the polyethylene commences to change from a crys-talline structure to an amorphus structure or vice versa.
The supply o~ laminating sheet L is preferably mounted on a roll 64 rotatably mounted about an axis 66 on upper frame 68 of the apparatus. Sheet L may be of a multi-stratum structure similarly to that aforediscussed for embossin~ sheet F, and generally similar to that shown in FIG~RE ~ Oe the application drawings. However, it will be understood that the thickness of ~0 laminating sheet L, is preferably thinner than the thickness of embossing sheet F. In this connection, i`f the embossing sheet F
is 2 mils in thickness, the laminating sheet L will be preferably 1.5 mil thickness.
From roll 64, the laminating sheet is pulled off to pass around non-heated, non-rotatable, rod 68 and then upwardly to pass onto heated preferably idler roller 70 which is preferably heated to a temperature within a range of approximately 180 to 200'F. similarly to a~orediscussed roller 40 which coacts with the embossing sheet F. Roller 40 should be m~intained rotatable and 0 movable wlth film L, and at a surrace speed at least not to exceed the speed of travel of the film L.
From roll 70, the laminating sheet passes around in-creased diameter roller 72 which is preferably heated to a simi-lar temperature ti.e. 180-200'F) with roller 72 likewise being preferably an idler roll, but maintained rotatable and movable with the film, and at a speed at leaæt not to exceed the speed of the film. The laminating sheet L then engages non-heated but driven roller 74 which is power driven by preferably conventional electrical motor means. Rollers 70, 72 and 74 as well as afore-mentioned rod 68, are preferably coated with a layer of anti-stick-ing material such as Teflon, ln a similar arrangement and for the same purpose as in the other coated rollers.

7~ 3 --From roller 74, the laminating sheet passes about heated roller 76 which preferably is at a temperature within a range of approximately 220-270F, thus raising the temperature of the laminating film as it passes about substantially a major extent of the circumference of roller 76. As can be ~een, the laminating sheet preferably passes around about at least 240 of the total circumference of roller 76.
From roller 76 the laminating sheet L passes about roll~r 78 which is preferably at a temperature within the range of 230 to 290F. This temperature is at least as great as the melting temperature of the polyethylene exterior layer~ on the laminating sheet L and thu~ in~ure that the polyethylene layers on the laminating sheet will be substantially liquid on the in-termediate nylon layer, when the laminating sheet i9 applied to the embossed sheet on drum 56 at point 62 tFIGURE 7).
From roller 78, the laminating sheet L passes about roller 80 which is preferably maintained at a temperature of ap-proximately 330F, thus raising the laminating sheet tempera~ure well above the melting temperature of the polyethylene layers of the laminating sheet, and from roller 8~ the sheet passes about a substantial portion of the exterior periphery of rolle~
81 which again is preferably maintained at a temperature of ap-proximately 330F. All of rollers74 through 81 are power driven at the same speed and preferably have coverings of anti-~ticking mate~ al thereon. Rollers 74 through 81 are driven at the same speed as aforementioned rollers 48 through 54, tmay be geared to the same source of power) and which speed is slightly slower than the ~peed of rotatably driving of the forming drum 56. As an example, the speed of the heating rollers 48-54 and 74-81~ may .

6 ~3 be approximately 52.17 lineal ft. per minute while that of the forming drum 56 may be 52.24 lineal ft. per minute.
From roller 81 the laminating sheet is directed to-ward the periphery of the embossing or forming drum 56 where the pressure engagement of the laminating sheet L with the exterior or confronting surface of the embossed sheet FE is accomplished at point or line 62 by means of generally linearly movable nip roller ~2. Roller 82 is preferably at a temperature of approx-imately 300 to 320F., includes a resilient layer of for in-stance silicone rubber, which in turn is "Teflon coated", and ismovable to and from engagement with the exterior of the laminat-ing sheet L as by means of the pair of spaced double acting air cylinders 84 disposed on each end of the rotary axis 82a of the roller 82, and coacting therewith so as to direct the nip roller 82 toward line engagement of the laminating sheet with the em-bossed sheet upon actuation of motor units 84.
Motor units 84 are preferably pivoted as at 84a to a support portion of the apparatus frame thus providing for rela-tive pivotal movement of the motor units with respect to the supporting frame. Motor unlts 84 preferably provide a total pressure of approximately 16-17 pounds force on the rotatable axle of roller 82, (approximately .7 pounds per lineal inch for a 2 foot long roller 82) although a lesser pressure, and as ~or instance, 5 pounds would result in an adequate bonding of the laminating sheet L to the embossed sheet FE; however 16-20 pounds pressure is preferred, with there being an upper limit of approximately 35 pounds total pressure. Roller 82 is approximately the same length as drum 56. Since the laminating sheet as it is applied to the embossed sheet is at a temperature of approximately 330F., well abo~e the melting temperature of , 6~3 the polyethylene stratums, a positive fusion or heat seal bond occuxs between the laminating sheet and the embossed sheet, with the laminating sheet passing heat to the con-fronting polyethylene layer on the embossed sheet, so as to cause melting of the confronting polyethylene layer on the em-bossed sheet and together with the pressure and heat applied by roller 82 providing for a secure bond between the laminating and embossed sheet layers. It will be understood that the lami-nating sheet I. and roller 82 raises the confronting layer 24b of the cooler embossed sheet from a temperature approaching its softening temperature (due to the cooling action of the drum) to its melting temperature, thus bonding together layer 24b of the embossed sheet FE and the adjacent melted layer 24 of the laminatlng sheet. It is believed that the underlying non-virgin polyethylene layer 24a of the embossed sheet does not melt, with substantially only layer 24b melting due to heat transfer from hot laminating sheet L`.
The sealed cushioning dunnage product is then moved about the surface of the embossing drum from the point of en-gagement of the laminatlng sheet with the embossed sheet, tothe anti-stick coated, driven roller 88 which preferably is at a temperature of approximately 100F., and thus the cushioning dunnage product, further cooled by the drum is stripped off the forming drum 56 and directed to another location such as for instance to rotatable accumulator 90, where it can be disposed in rolled form and as is illustrated for instance in FIGURE 5 of the drawings, for convenient handling and/or storage thereof.
By maintainin~ the "strip-off" roller 88 at the indicated tem-perature, wrinkles in the finished product are aided in being prevented. Roller 88 and accumulator 90 are driven at the same ~ 3 surface speed as drum 56. A cutter unit 92 of any suitable type may be provided for severing an accumulated roll of air : .
cell product from the producing apparatus. m e produced procluct illustrated in FIGURES 1-6 has a "clear" or "see through" appearance, which enhances its desirability and saleability. This "clear" or "see through" characteristic is at least in part, due to the cooling of the embossed film on the drum to approaching its softening temperature or heat :
softening point as it is identified in the art, and just prior to application of the laminating sheet thereto.
.~

, S!,` ' -~5a-.

Referring now specifically again to FIGURE 7, there is shown an alternate path in dashed lines, for movement of the laminating sheet, by the provision of an additional idler roll-er ~4 which is rotatable about a horizontal axis, and which is preferably coated with a layer of anti-adhering material, such as the aforementioned "Teflon". The laminating sheet can pass about roller 94 prior to passing about roller 74, thus provid-ing for an additional drying time of a coating applied to the laminating sheet L as by means of a spray head 95 (FIGURE 7) adjustably supported on frame 68. Such coating could be, for instance, an anti-static coating sprayable in liquid form onto sheet L as it passes from stock roll 64 around shaft 68 and roller 70.
This anti-static material is a commercially available item and can be purchased under the trademark "Staticide General Purpose", obtainable from Analetical Chemical Laboratories of Elk Groove Village, Illinois 60007. This material provides for rapid dissipation of any electrical static charges which may occur and which may be detrimental in the use of the product.
Spray head 95' may likewise apply a coating, such as the afoxementioned anti-static materlal, to the embossing sheet F, with the latter passing about an idler roller, such as roller ~4, to provide drying time, prior to passing to the heating roll-ers 46 thru 54 and as illustrated in dashed lines in FIGURE 7.
In any event, it will be seen that both sheets, sheet F to be embossed, and the laminating or cover sheet L,are gener-ally simultaneously passed about groups of heating rollers which have generally increasing temperatures, to progressively increase the temperature of the sheet material, with the la~inating sheet L being applied under pressure to the confronting surface of the ~ --16--~S7623 embos~ed ~heet well above the melting temperature of the poly~
ethylene ~tratum of the ~heet while at the time that the embossed sheet has been cooled by the forming drum to a temperature well below the melting temperature of the polyethylene and i8 at a temperature approaching the softening temperature of the latter.
Thi8 enable~ good control of the embo~sed ~heet, and the mainten-ance of the film clarity of the tran~parent air cell product, but yet provides or a po~itive sealing of the laminating sheet L to the embo~sed ~heet FE, thus maintaining the integrity of the air cells, and the excellent cushioning characteristics of the product.
The cushioning dunnage product aforedescribed meets and in certain instances, surpas~e~ the Federal Specifications entitled Cushioning Material, Flexible Cellular, Plastic Film For Packaging Applications, of the Federal General Services Ad-ministration, and identified as PPP-C-795A dated Decem er 2, 1970.
In addition, it has been found that the produced air cell product aforedescribed has very good "creep resistance", and that the creep resistance of the air cell product with a greater height of air cell (e.g. 1/2 inch high) is greater (has a greater resiatance to creep) as compared to an air cell product with a les~er cell he~ght (e.g. 5/16 inch high) utilizing the sAmO thick-ne~s of film stock material, even though the greater height air cell product demands or results in a qreater thinning or drawing of the film during the embossing operation to form the air coll~.
In any event, the resi~tance to creep or loss of air from the cells, under load, i~ extremely good for the formed air cell pro-duct of the invention, irrespective of the cell height, but a~
,afore~aid is even better for the greater air cell heights of pro-duct.

7Gi~3 Referring again to FIGURE 7, an arrangement is illus-trated for selectively applying a liner ~heet or strip S to the laminating or cover sheet L prior to the latter'~ being applied to the embos~ed sheet FE on the drum at application point or sta-tion 62. The liner strip may be supplied from a supply source, such a~ a roll of the liner (not ~hown) rotatably mounted, and adapted to be pulled off therefrom over idler roller 96, from which the liner strip S passe~ between retractable nip rollers 96a and 96b coacting respectively with aforementioned heating rollers 70 and 72, whereby the liner strip i~ heat bonded to the laminating strip or sheet L. Liner S may be any suitable mater-ial, such as for instance Kraft paper, or foil, or flexible pla~-tic foam such as for instance, polypropylene foam, or the like.
Nip roller~ 96a, 96b are preferably heated (but may not be) as by means of electric heating elements embodied therein, similarly to the heating rollers, and apply suitable pressure l:o the liner S in ~uperimposed relation to sheet L, to cause adher-ence therebetween. Such a liner covered air cell product can be u ed in the production of air cell envelope~ or pouches, as will be hereinafter discussed in greater deail.. Reciprocal, flùid pow-ered motor units 97, pivotally mounted a~ at 97a, may be ussd to project and retract the nip rollers 96a, 96b.
Referring now to FIGURES 8 through 10, there i8 di~clo~-ed diagrammatically, a mechanism 98 identi$ied as a width ext~nd-er mschanism, for connecting together along side edge margins thsre-of a plurality of the strip~ of air cell product produc~d on the apparatus of FIGURE 7, or providing for the expeditious and 9e-lective increasing of the width of strip of air cell material.
Such extender mechanism, in the embodiment illustrated, includes heat-pressure means 100, for heat bonding together confronting side edge margin~ of a plurality of the strips of air cell pro-duct. Such strips Sl, S2 of air cell pxoduct may be of the type illustrated for instance, in FIGURES 1 to 6, including ~ide mar-gin areas 20, and which have been wound into roll form as illus-trated in FIGURE 5, and mounted vertically for rotational move-ment (in the embodiment illustrated on rotatable platforms and axles 101, lOla) and which provide for ready pulling of the strips Sl, S2 of air cell material simultaneou~ly off the rolls thereof and pas~ing it through the heat-pressure means 100, to seal the confronting and abutting marginal edges 20 (FIGU~E 10) together.
Meanq 100 may include movahle jaw portions or supports 102, 104 coupled to reciprocal double acting, fluid powered mot-ox units 106, for urging the jaw portions 102, 104 toward one -P
another to cause sealing bonding engagement between the abutting margins of the vertically oriented strips Sl, S2 of air cell ma-terial.
In this embodiment, the heat-pressure sealing means in-cludes a plurality of opposing idler roller members 108 mounted on the respective jaw, with such roller ~embers formed for in-stance of yieldable heat resiqtant material, ~uch as silicone rubber coated with an anti-adhe~ion material, such as ~Teflon", and maintained for in~tance, at a temperature of 450F., 80 that -`
when the jaw~ are moved toward one another, the roller~ 108 are rollingly engaged in pressurized relation with tho interposed marginal sections 20 of the vertically oriented air cell product.
The applied heat and pressure causes a melting of the confront-ing layers of polyethylene (as~uming that the air cell product `~
iB made of the film stock having the composite structure afore- ~s di~cussed in connection with FIGURES 1 through 6) to cau~e heat .~

7`~iiZ3 sealing of the ~trip~ Sl, S2 together at their marginal edge~.
110 designates a heating means for the rollers which in this case i~ illustrated a~ being infrared heaters and associated re-flect:or means, mounted in jaws 102, 104.
The strips Sl, S2 of air cell material may be passed through the width extender mechanism 98 at ~peeds of, for instance, 100 lineal feet per minute, with the connected strips, after be-ing connected by the heat sealing means 100, being folded or spread outwardly from the lower edges thereof, and as illuqtrated in FIGU~ES 8 and 9, and wound on powered roller 112, which may be driven by any suitable means, such as for instance, by electric motor and a~sociated clutch means 113.
Vertical guides 114, 116 may be provided for guiding the movement of the strips Sl, S2 of thermoplastic air cell ma-terial through and from the heat-pressure connecting means 100, with quch guides, in the embodiment illu~trated, being laterally spaced pairs of vertical columns. Thus, it will be ~een that with the width mechanism 98, different widths of air cell mater-ial can be produced, attached aq at 117, along a generally cen-tral lengthwise running flange or web, which may utilize only aportion of the width of margin on each of the produced air cell stripq Sl and S2.
Referring now to FIGURES 12 through 24, there i9 illu~-trated various other embodiments of air cell products formed from air cell ~heeting produceable on the apparatus of FIGURE 7 and which may be of the general type of sheeting illustrated for in-~tance in FIGURES 1-6. FIGURES 11 and 12 which are respectively fragmentary ~ide elevational and top plan views, illu~trate an air cell product 119 having a reinforcing wire or line 120 running ~576~;23 along at least one marginal edge of the produced air cell pro-duct, with the edge 18 having been folded about the wire or line and heat ~ealed as at 122. Line 120 may be formed of any suit-able material, such as for in~tance plastic, or metal, or other suitable material~, such a~ cordage, and the edge 18 may be heat sealed down about line 120 continuously or intermittently, to trap the member 120 in encompa~ed relation by a portion of the marginal edge of the air cell product 119.
FIGURE 13 illustrate~ a similar arrangement of folding over the marginal edge and heat sealing the ~ame to tho confront-ing portion of the marginal edge area, and a~ at 124, but wh~rein no wire or line 120 is embodied therewith, such overlapped heat sealed Rection 125 strengthening and rigidifying the edge of the air cell product 126.
FIGURES 14 and 15 disclo~e respectively fragmentary ele-vational and top plan view~ of an air cell product 128 which em-bodies a ribbon 130 running lengthwise of the strip of air cell material with the ribbon 130 being adhered to the di~tal edge 18 of the air cell strip. Ribbon 130 may or may not be heat ~ealable, ~0 but preferably is and may be attached by he~t sealing pre~sure to the ribbon and adjacent marginal edge of the product.
FIGURE 16 discloses a somewhat similar product 128' wherein a ribbon 130 of material is disposed both on the upper and lower surfaces of the marginal edge of the air cell product, and is secured thereto, while FIGURE 17 disclo~e~ an air cell - product 128'' wherein the ribbon 130 is secured only to tho under-side of the marginal edge of the air cell product.
, FIGURES 18 and 19 disclosff fragmentary elevational and top plan views of an air cell product 132, in which a wiro or lin~

' ~i7~Z3 120 has been combined with a ribbon 130 oI the types of FIGURES 14 through 17, and oriented along the marginal edge of the product, to rigidify the marginal edges as well as providing a convenient arrangement for suspending the air cell product from a support.
FIGURES 20 and 21 disclose various other embodiments wherein FIGURE 20 discloses a product arrangement 132' with the combined wire and ribbon 1~0, 130, disposed at the distal edge of the margin of the air cell product, while FIGURE 21 discloses an embodiment wherein the combined wire or line 120 and ribbon 130 are disposed on the underside of the air cell product 132''.
FIGURES 22 and 23 disclose respectively a fragmentary, exploded elevational view and a top plan view, of an air cell pro-duct 133 wherein joiner strips 134, 134a which include respectively a lengthwise running male projection 136 and a complementary fe-male recess 138, are secured to at least one marginal edge of a respective sheet 139, 139a of the air cell product, for receiving in the female recess and in snap fastened or engaged holding rela-tion, the male portion 136 of confronting joiner strlp 134, for releasibly holding the distal edges of the air cell sheeting together in assembled relation. Joiner strips 134, 134a may be formed of for instance heat sealable plastic, and provide for rapid opening and closing of such connected air cell sheeting members 139, 139a. The other edges of the sheeting members may be connected by permanently heat sealing the same as at 1~0. Such an arrangement could be conveniently utilized in the formation oi' envelopes or other like receptacle packaging, to thus provide a product where the air cells 1~ project inwardly toward one another (or outwardly away from one another if tho air cells are arranged exteriorly) in a receptacle type environment. All or only certain of the marginal edge of the formed envelope member could be provided with .

1~i7623 the releasable joiner mechanixm 13~ ga with the non-openabl~
marginal edges being able to be heat sealed together in perman-ent secured relation.
FIGUR~ 2~ is a fragmentary secti.onal view wherein a separate ~joine~r member :l~2 1'ormed Or suitable material, such as pla.stic, is provi.ded with oppo~ing recesses l4~, l44a, for re-ceiving therein an en:Larged, male pro~jection, marginal edg~ l~l(i of an air cell ~heet, such a.s f'or instance the arrangement shown in FIGURE 20, -thus rel.easibly connecting together adjacent sheet~-~
of the air cell sheeting. Joiner me~ber 142 could run the fulllength of the connectcd air cell sheets 132', or spaced members 142 could be used, spaced leng-thwise along the juncture of sheet~i 132'.
FIGURE 25 illustrates an air cell sheeting product wherein a stiffening member 120 is entrapped between the heat bonded margin areas 20 O:r sheets 1.2 and 14, while FIGURE 26 il-lustrates a joiner arrangement similar to FIGURE 2~, except that the joiner member l42' of suitable material such às p~,tic, com-prises male projections 1~8, 1~8a adapl;ed to be received in Sl?-

2~ cured relation in female members 1~9> l~9a, heat bonded to mLIr-ginal edge portions of the respective air cell sheeting, to at-tach the latter together along side edges~thèreof.
From the foregoing description and accompanying draw-ings it will be seen that the invention provides a novel method and apparatus for the production of transparent air cell material, such as for instance air cell cushioning dunna~e material, with the product comprising an embossed layer of flexible plastic sheet and a cover layer of flexible plastic sheet secured together by heat-pressure bonding, and defining a plurality of spaced closed air cells therebetween, with each of the sheet layers including means generally impervious to passage o:f gases therethrough and providing substantial strength and tear and puncture resistance, ~S~623 and with the air cell product having side edge margins of pre-dete!rmined width running lengthwise of the air cell material, with the sheets being bonded together along such side edge mar-gins and intermediate the air cells with such marginal edges beirlg free of any air cells, thereby providing a defined strip of the air cell product. The laminating sheet in the method of the invention is heated to a temperature well above the melting temperature of the exterior stratum of the sheet and is applied to the embossed sheet which at the moment of application of the laminating sheet thereto has been cooled bythe embossing drum to a temperature well below the melting temperature, and to a temperature approaching the softening point temperature of the exterior stratum, with the laminating sheet being sufficiently hot so that the heat thereof when applied to the embossed sheet will cause melting of the confronting surface of the em-bossed sheet, and with applied pressure and heat provides an expeditious heat sealed bond between the sheets. The method and apparatus are such that the machine can be halted in its operation without producing injurious effects or problems to the m~chine and/or the air cell product being formed, and can be restarted to again commence production of the air cell product.
The terms and expressions which have been used are used a~ terms of de~cription, and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifi-cations are possible within the scope of the invention claimed.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a method of manufacturing air cell cushion-ing dunnage material from a plurality of flexible thermo-plastic sheets, each of said sheets comprising a composite of a stratum of high density, high melting point material general-ly impervious to the passage of gas therethrough and another stratum bonded to the first mentioned stratum with said other stratum being formed of low density, low melting point thermo-plastic, and with said first mentioned stratum being of a higher density, higher melting point material as compared to said other stratum, comprising the steps of heating a first of the sheets to a temperature above the melting point temper-ature of the other stratum but below the melting point temper-ature of the first mentioned stratum to provide for hot em-bossment of the sheet, embossing said heated first sheet by feeding it onto a rotating forming drum having a plurality of recesses therein and forming the air cells in the recesses on said forming drum by vacuum, heating a second sheet of the thermoplastic above the melting point of the other stratum of the second sheet, cooling the embossed sheet while on said rotating drum to a temperature below said melting point temperature of said other stratum by maintaining said drum at a predetermined temperature below the first mentioned temperature, and so as to cool said embossed sheet by means of said drum to a temperature approaching the softening temperature of said other stratum thereof, and then applying said second heated sheet to said first sheet after completion of said embossing and said cooling, whereby the residue heat in said second sheet causes a melting of the confront-ing surface of said other stratum of the cooled embossed sheet sufficiently to cause a bonding together of said other stratums of the said first and second sheets at the areas of engagement while on the drum so as to seal the air cells in said product, and then removing the cushioning product from the forming drum.

2. A method in accordance with claim 1 including the step of utilizing a heated roller to apply both pressure and further heat to said second sheet to urge it into posi-tive adhering contact with the embossed sheet on the forming drum.

3. A method in accordance with claim 1 including the step of applying anti-static material to at least one of said sheets prior to its being applied to the other on the forming drum.

4. A method in accordance with claim 1 wherein the first sheet is progressively heated to a temperature above the melting point of its other stratum by means of heated roller means engaging the first sheet prior to appli-cation of the latter to the forming drum, and including the step of driving said roller means at a slower speed as compared to the speed of driving the forming drum.

5. A method in accordance with claim 1 including the step of applying a liner sheet to the second sheet and securing the same together by means of pressure prior to application thereof to the embossed sheet on the forming drum.

6. A method in accordance with claim 2 wherein said applied pressure is between approximately 0.21 to 1.46 pounds per lineal inch and is applied by means of a rotatable heated roller approximately two feet long engag-ing said second sheet along generally line contact extend-ing transverse of said first sheet on said drum, and urging said second sheet into adhering contact with said cooled embossed sheet on the forming drum.

7. A method in accordance with claim 2 including subsequent removal of said utilized pressure on the second sheet.

8. In a method of manufacturing air cell cushion-ing dunnage material from flexible plastic sheet, with each of the sheets comprising a composite of an intermediate stratum of high density thermoplastic material generally impervious to the passage of gas therethrough and exterior stratums bonded to the intermediate stratum with the exterior stratums being formed of low density low melting point thermoplastic, with said intermediate stratum being of a high density, higher melting point material as compared to that of the exterior stratums, comprising the steps of heating a first of the composite sheets to a temperature above the melting point temperature of the exterior stratums but below the melting point temperature of the intermediate stratum, embossing said heated first sheet by feeding it onto a rotating forming drum having a plurality of recesses therein and forming the air cells in the recesses on said forming drum by vacuum, heating a second composite sheet of the plastic above the melting point of the exterior stratums of said second sheet, cooling by means of said drum the embossed sheet while on said rotating drum to a temperature below said melting point temperature of said exterior stratums and to a temperature approaching the softening temperature of the exterior stratums, and then applying said second sheet to said first cooled sheet after the latter has been cooled to said temperature approaching said soften-ing temperature whereby the residue heat in said second sheet causes a melting of the confronting exterior stratum of the cooled embossed sheet sufficiently to cause a bonding of the said first and second sheets at the areas of engage-ment while on the drum so as to seal the air cells in said product, and then removing the cushioning product from the forming drum.

9. A method in accordance with claim 8 wherein the first sheet is heated to a temperature in the range of 260°-375°F. just prior to its being applied to the forming drum, and the second sheet is heated to a temperature of approximately 330°F. just prior to its being applied to the embossed sheet on the forming drum.

10. A method in accordance with claim 8 including the step of utilizing pressure on the second sheet to urge it into positive adhering contact with the embossed sheet on the forming drum.

11. A method in accordance with claim 8 wherein the first sheet is progressively heated to a temperature of between approximately 260°-375°F. by means of heated roller means prior to application to the forming drum, the first of which roller means is at a temperature of approximately 180°-200°F.

12. A method in accordance with claim 8 including the step of applying anti-static material to at least one of said sheets prior to its being applied to the other on the forming drum.

13. A method in accordance with claim 8 wherein the first sheet is progressively heated to a temperature of between approximately 260°-375°F. by means of heated roller means engaging the first sheet prior to application of the latter to the forming drum, and including the step of driving said roller means at a slower speed as compared to the speed of driving the forming drum.

14. A method in accordance with claim 8 including the step of applying a liner sheet to the second sheet and securing the same together by means of pressure prior to application thereof to the embossed sheet on the forming drum.

15. A method in accordance with claim 8 wherein the first sheet is initially passed about a roller maintained at a temperature of approximately 180°-200°F. and of a pre-determined diameter, and then is passed around another roller maintained at a temperature in the range of approximately 180°-200°F. with the second roller being of a greater diameter as compared to that of the first roller, and then passing the first sheet about a further roller which is non-heated, then passing the first sheet about a further roller which is maintained at a temperature of between approximately 220°-270°F., then about a further driven roller which is maintained at a temperature of between approximately 220°-270°F. and then about a further driven roller which is maintained at a temperature of between approximately 230°-290°F., then about a further driven roller which is maintained at a temperature of between approximately 240°-320°F., then about a further driven roller which is maintained at a temperature of between approximately 260°-375°F., and then is applied to the forming drum which is maintained at a temperature of between approximately 150°-155°F.

16. A method in accordance with claim 8 wherein said exterior stratums are polyethylene, said first sheet being heated to a temperature in the range of 260°-375°F.
just prior to its being applied to the forming drum for embossment thereof, the second sheet being heated to a temperature of approximately 330°F. just prior to its being applied to the cooled embossed sheet on the forming drum, said cooled embossed sheet being at a temperature of between approximately 170°-180°F. prior to application of the heated second sheet thereto, and including the step of applying pressure on the second sheet to urge it into positive ad-hering contact with the cooled embossed sheet upon said application of the heated second sheet to the cooled embossed sheet.

17. A method in accordance with claim 9 wherein the embossed sheet on the forming drum is cooled to a tem-perature of between approximately 170°-180°F. prior to application of the second sheet thereto.

18. A method in accordance with claim 10 wherein said applied pressure is between approximately 0.21 to 1.46 pounds per lineal inch, and is applied along generally line contact transverse of said second sheet by means of a rotatable heated roller approximately 2 feet long urging said second sheet into adhering contact with said embossed sheet on the forming drum along said line contact.

19. A method in accordance with claim 10 including subsequent removal of said utilized pressure on the second sheet.

20. A method in accordance with claim 14 wherein said liner sheet is formed of paper.

21. A method in accordance with claim 14 wherein said liner sheet is formed of foil.

22. A method in accordance with claim 14 wherein said liner sheet is formed of flexible foam.

23. A method in accordance with claim 16 wherein the forming drum is maintained at a temperature of between approximately 150°-155°F. to accomplish said cooling of the embossed sheet, and including the step of further cooling the adhered first and second sheets on the rotating drum prior to removing the cushioning product therefrom.

24. In an apparatus for producing air cell cushion-ing dunnage from flexible thermoplastic sheet stock each sheet of which comprises a composite of a stratum of high density high melting point thermoplastic material generally impervious to the passage of air therethrough, and another stratum formed of low density, low melting point thermoplastic material, with the first mentioned stratum being of a higher density, higher melting point material as compared to that of said other stratum, comprising a rotatable forming drum having a plurality of recesses formed therein for vacuum forming the air cells in a first sheet of the thermoplastic material fed onto the drum,with said other stratum of said first sheet facing outwardly of said drum, said drum including means for cooling the drum to a predetermined temperature, and a series of spaced rollers spaced with respect to said forming drum, said series of rollers having means providing for heating the first sheet prior to its being fed onto said drum, to a tem-perature above the melting point of said other stratum of the first sheet but below the melting point temperature of said first mentioned stratum, and a second series of rollers spaced from said first series and having means adapted to heat a second sheet of the thermoplastic stock material to a tempera-ture above the melting point of the other stratum of the second sheet, but below the melting point of the first mentioned stratum of the second sheet, and means coacting with said second series for applying the second sheet with said other stratum thereof facing said other stratum of said first sheet, to the first sheet on said drum during rotation of the latter, to seal the air cells, with said first series and said second series of rollers and said applying means being so arranged with respect to the circumference of said drum that said applying means is spaced from the point of application of the first sheet to the drum sufficiently that said drum during rotation thereof can cool the first sheet to a temperature approaching the softening point temperature of the other stratum of the first sheet prior to application of the heated second sheet thereto.

25. An apparatus in accordance with claim 24 wherein each of said rollers are coated with a layer of heat resistant anti-adhesion material.

26. An apparatus in accordance with claim 24 in-cluding means thereon for rotatably mounting thereon supply rolls of the plastic stock material.

27. An apparatus in accordance with claim 24 in-cluding means coacting with said drum for stripping produced air cell dunnage therefrom.

28. An apparatus in accordance with claim 24 wherein said first and said second roller series are rotat-ably mounted and including means for driving said first roller series at a slower peripheral speed as compared to the driven peripheral speed of said forming drum.

29. An apparatus in accordance with claim 24 wherein said applying means includes means movably mounting the applying means relative to the forming drum whereby the applying means is operable for movement into and out of engagement with said forming drum.

30. An apparatus in accordance with claim 24 including in combination therewith width extender means for connecting together along side edge margins thereof a plurality of strips of cushioning dunnage from the cushioning dunnage producing apparatus, to increase the width of strip of cushioning dunnage.

31. An apparatus in accordance with claim 29 wherein said applying means comprises a rotatable idler roller including means for heating said roller to a pre-determined temperature, said idler roller being of a length at least great as the width of the second sheet and adapted for pressure engagement with said drum.

32. The combination in accordance with claim 30 wherein said extender means comprises a plurality of heat-pressure means for heat bonding together confronting side edge margins of a plurality of the strips of dunnage from the dun-nage producing apparatus.

33. The combination in accordance with claim 30 including means coacting with said width extender means for storing the extended width strip of dunnage in compact form as it comes off said width extender means.

34. In an apparatus for producing air cell sheet-ing from a plurality of sheets of flexible thermoplastic stock, each of said sheets comprising a composite of a stratum of high density, high melting point thermoplastic material generally impervious to the passage of gas therethrough and another stratum bonded to the first mentioned stratum with said other stratum being formed of low density, low melting point thermoplastic, and with said first mentioned stratum being of a higher density, higher melting point material as compared to said other stratum, said apparatus comprising a rotatable forming drum having a plurality of recesses formed therein for vacuum forming the air cells in a first sheet of the thermoplastic stock material fed onto the drum,with said other stratum of said first sheet facing outwardly of said drum, said drum including means for maintaining the drum at a predetermined cooling temperature, and a plurality of series of spaced heat applying roller means coacting with the forming drum, one series of said roller means having means providing for heating the first sheet to a temperature above the melting point of the other stratum of the first sheet but below the melting point temperature of the first mentioned stratum, prior to its being fed onto said drum during rotation of the latter and at a predetermined application station adjacent the periphery of said drum, and another of said series of heating rollers spaced from said first series and having means adapted to heat a second sheet of the thermoplastic stock material to a temperature above the melting point of the other stratum of the second sheet, but below the melting point of the first mentioned stratum of the second sheet, means coacting with said second roller series for pressurized application of the heated second sheet with the first sheet, with said other stratum of the second sheet facing said other stratum of the first sheet, the last mentioned means being so arranged with respect to the circumference of said drum and being suffi-ciently spaced circumferentially from said application station that said drum is operable to cool the embossed sheet on said drum during rotation of the latter to a temperature approach-ing the softening point temperature of the other stratum of the first sheet prior to application by said last mentioned means of the second sheet to the first sheet.

35. In an apparatus for producing air cell cushion-ing dunnage from flexible thermoplastic sheet stock, each sheet of which comprises a composite of an intermediate stratum of high density high melting point thermoplastic material generally impervious to the passage of air there-through, and exterior stratums formed of low density, low melting point thermoplastic material, with said intermediate stratum being of a higher density, higher melting point material as compared to that of the exterior stratums, comprising a rotatably driven forming drum having a plurality of recesses formed thereon for vacuum forming the air cells in a first sheet of the thermoplastic material fed onto the drum, said drum including means for maintaining the drum at a predetermined cooling temperature, and a series of spaced rotatably driven rollers spaced with respect to said forming drum, said series of rollers having means providing for heat-ing the first sheet prior to its being fed onto said drum, to a temperature above the melting point of the exterior stratums of the first sheet but below the melting point temperature of the intermediate stratum, and a second series of driven rollers spaced from said first series and having means adapted to heat a second sheet of the thermoplastic stock material to a temperature above the melting point of the exterior stratums of the second sheet, but below the melting point of the inter-mediate stratum of the second sheet, and means coacting with said second series for applying the second sheet to the first sheet on said drum during rotation of the latter to seal the air cells, said first roller series and said second series and said applying means being so arranged with respect to the circumference of said drum that the latter during rotation thereof is operable to cool the first sheet to a temperature approaching the softening point temperature of the exterior stratums of the first sheet prior to application by said applying means of the second sheet to the first sheet, and means for driving said first roller series at a slower speed as compared to the driven speed of said forming drum.

36. In an apparatus for producing air cell cushion-ing dunnage from flexible thermoplastic sheet stock, each sheet of which comprises a composite of an intermediate stratum of high density high melting point thermoplastic material generally impervious to the passage of air there-through, and exterior stratums formed of low density, low melting point thermoplastic material, with said intermediate stratum being of a higher density, higher melting point material as compared to the exterior stratums, comprising a rotatably driven forming drum having a plurality of recesses formed thereon for vacuum forming the air cells in a first sheet of the plastic material fed onto the drum, and a series of spaced rotatably driven rollers spaced with respect to said forming drum, said series of rollers having means pro-viding for heating the first sheet prior to its being fed onto said drum, to a temperature above the melting point of the exterior stratums of the first sheet but below the melting point temperature of the intermediate stratum, and a second series of rollers spaced from said first series and having means adapted to heat a second sheet of the thermoplastic stock material to a temperature above the melting point of the exterior stratums of the second sheet but below the melting point temperature of the intermediate stratum thereof, means coacting with said second series for applying the second sheet to the first sheet on said drum during rotation of the latter to seal the air cells, and said applying means including heating means and means movably mounting the applying means relative to the forming drum whereby the applying means is operable for movement into and out of pressurized engagement with said forming drum, said applying means being so spaced from the point of application of the first sheet to the drum that said drum during rotation thereof is operable to cool the first sheet to a temperature approaching the softening point temperature of the exterior stratums of the first sheet prior to applica-tion by said applying means of the second sheet to the first sheet on said drum.

37. An apparatus in accordance with claim 34 wherein said first roller series and said drum are rotatably driven, and including means for driving said first roller series at a slower speed as compared to the driven speed of said forming drum.

38. An apparatus in accordance with claim 34 wherein said last mentioned means includes means movably mounting said last mentioned means relative to the forming drum whereby said last mentioned means is operable for move-ment into and out of engagement with said forming drum.

39. An apparatus in accordance with claim 35 wherein said applying means comprises a rotatable idler roller including means for heating said roller to a predetermined temperature, said idler roller being of a length at least as great as the width of the second sheet and adapted for pres-sure engagement with said drum.

40. An apparatus in accordance with claim 34 wherein said last mentioned means is spaced circumferentially of said drum from said application station a distance at least as great as the radius of said drum.

41. An apparatus in accordance with claim 34 wherein said last mentioned means is spaced circumferentially of said drum from said application station approximately 160 circum-ferential degrees.