CA1285364C

CA1285364C - Method of forming thermoplastic headed tubular containers

Info

Publication number: CA1285364C
Application number: CA 540040
Authority: CA
Inventors: George P. Whitaker; George H. Holoubek; Harland E. Harms
Original assignee: Courtaulds Packaging Inc
Current assignee: Courtaulds Packaging Inc
Priority date: 1986-06-18
Filing date: 1987-06-18
Publication date: 1991-07-02
Anticipated expiration: 2008-07-02
Also published as: GB2191730B; SE8702547L; NO872564D0; SE8702547D0; GB8714207D0; NO872564L; GB2191730A

Abstract

Abstract of the Disclosure A method of forming a head on a thermoplastic container wherein a molten disc seals a tubular element and, while the disc is still in a moldable state, the disc is formed into a head using either a fluid pressure, a vacuum, or both. A
sealing head on an internal sealing mandrel has a first shoulder thereabout which is complementary with a second shoulder about a mold cavity, which trap the periphery of the disc and the head is formed in a configuration conforming to the mold cavity fluid pressure injected through the internal sealing mandrel, through a vacuum pulled through the mold form containing the cavity, or by use of both said fluid pressure and said vacuum.

Description

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The present invention relates to a method of forming thermoplastic tubular containers and, more specifically, to a method for forming a head on a tubular sleeve to provide a neck portion of a thermoplastic tubular container.

This application is related to co-pending Canada application Serial No. 536,141 filed May 1, 1987, and entitled ~Method For Producing Tubular Plastic Containers", in the names of George H.
Holoubek, John J. Rhoades, and George P. Whitaker, assigned to the present assignee.

Thermoplastic tubular containers, especially collapsible or squeezable containers, have continued to take over an increasing share of the container market from metallic tubes. Such thermoplastic tubular containers are extensively used in packaging of cosmetics, medicinal preparations, shampoos and other products. With the increased development of multilayer or laminated tubes having oxygen barrier properties, that resist oxygen permeation, ~urther increases in packaging of pharmaceutical products and of foodstuffs in thermoplastic tubes are occurring.

An advantageous method for forming such containers involves the extruding of a hollow tube and then cutting the tube to desired lengths and forming a head or neck portion to close one end of the resulting tube. The other end is retained in an open condition for filling the container with the goods to be packaged, followed by sealing of the open end to provide an integral sealed tubular container.

A known method for forming collapsible plastic tubes with neck portions, known as the "Downs" process, is described in U.S.
3,047, 910. As described therein, thermoplastic tubular containers are fabricated by placing a thermoplastic tubular member, or hollow tube, into a forming collar and forcing a cut, 1~5~

molten disc into an open end of the tubular member. The latent heat of the molten disc is sufficient to weld the peripheral edye of the disc to the inner wall of the tubular member and thus form an end closure for the tubular container. As described, pressure is exerted through the interior of the tubular container to the sealed end closure to shape the latter to a desired contour. The preferred means for applying pressure to the sealed end closure is through the use of a mandrel that is inserted through the open end of the tubular member. Air pressure, or vacuum, are not suggested for forming the contour of the sealed end closure, although it is suggested that air under suitable pressure or a reciprocable flat end mandrel may be admitted interiorly of the tubing to assure that a flat end closure is not distorted upon cooling and remains desirably flat.

While the above-described process has been suitable for forming headed portions or necks on collapsible tubular containers, complicated tooling is required to force the plastic dlsc to conform to a mold cavity, necessitating high tooling costs and subsequent upkeep. Also, with the use of compression molding of the headed portions, massive hydraulic equipment is used, adding to capital cost and maintenance costs. In addition, relatively thick discs are needed where compression molding is used which increases costs and adds to scrap produced. Not only are cost considerations prevalent with the use of such a process, ~ut the process is limited with respect to the type or shape of head produced by such a compression molding system. Such a process is not, for example, readily adaptable to formation of heads on tubes where the heads have multiple orifices or complex/head configurationsO

one modification of the above-described process for use in forming multi-layer or laminated collapsible thermoplastic tubular containers is described in U.S. 3,962,006. In that process, a laminated film is used to form a thermoplastic sleeve ..

~285~6~L

having an impermeable layer and a molten disc also having an impermeable layer is welded to the interior wall of the laminated thermoplastic sleeve. A pressing operation is used to form a head member on the tube, the pressing operation using a female mold and a core which interiorly supports the laminated thermoplastic sleeve.

The present invention provides an improved method for forming a thermoplastic tubular container whereby a head can be readily formed which has a predetermined complex head configuration.

The present invention also provides a method for forming a thermoplastic tubular container that uses a molten disc to seal the end of a tubular sleeve but does not require the massive hydraulics presently used to compression mold a head on the tube.

The present invention also provides a method for forming a thermoplastic tubular container that uses a molten disc to seal the end of the tubular sleeve which enables the use of a thinner shoulder, relative to compression molded heads, thus increasing manufacturing speed, lowering material costs, and reducing scrap.

A method for forming a thermoplastic tubular container, wherein a molten plastic disc is secured within the confines of an open end of a hollow tubular element, with the latent head of the molten disc welding the disc to the inner wall of the hollow tubular element to seal the same, includes the use of an internal sealing mandrel to seal only a shoulder thereof, and then forming the thermoplastic disc, while still in a moldable state, to a mold configuration. The internal sealing mandrel, having a sealing head on the end thereof, is inserted into the other open end of the hollow tubular member, the sealing head having a first shoulder which traps the periphery of the disc between said first shoulder and a second shoulder about the periphery of a mold ~L28~i3~9~
cavity. Pressure on tha sealing mandrel is applied only to form a seal of thermoplastic material between the first and second shoulders, and forming of the thermoplastic disc, while in a moldable state and while only the seal of thermoplastic is in contac~ with the sealing head, is effected by either applying a fluid pressure against the surface o-f the thermoplastic disc confronting the sealing head, or applying a vacuum to the surface of the thermoplastic disc opposit~ the surface thereof confronting the sealing head, or both. So fonming of the disc, while in a moldable state, causes the disc to conform to the predetermined shape of a mold cavity to form a closed end wall on the tubular container having said predetermined shape.

Thus according to one aspect thereof the present invention provides a method of forming a thermoplastic tubular container wherein a molten plastic disc is secured within the confines of an open end of a hollow tubular element and allowing the latent heat of the molten plastic disc to weld the peripheral edge of the disc to the inner circumferential wall of the tubular element to seal the same, the improvement wherein: An internal sealing mandrel, having means for in~ecting a fluid therethrough, is inserted into the other end of the hollow tubular member, the internal sealing mandrel having a sealing head on the end thereof, the sealing head having a first shoulder thereabout;
positioning the hollow tubular element and disc within a mold cavity defining a predetermined shape, with a second shoulder about the periphery of the mold cavity complementary with said first shoulder; applying pressure on said sealing head to trap the periphery of said thermoplastic disc only to form a seal of thermoplastic material between said first and second shoulders, such that only the portion of the thermoplastic disc not sealed between said shoulders is subject to forming into the predetermined shape of said mold cavity; and forming said portion of said thermoplastic disc, not trapped between the complementary first and second shoulders, by injecting a fluid through said fluid injecting means of said internal sealing mandrel against the surface of said disc confronting said intQrnal sealing mandrel, while the same is in a moldable state, and while said periphery of said thermoplastic disc is in contact with said sealing head, to cause the same to conform in shape to the predet~rmined shape of said mold cavity to form a closed end wall on said thermoplastic tu~ular container having said predetermin~d shape. Suitably said means for injecting fluid through said internal sealing mandrel comprises an internal sealing mandrel having a sealing head with an axial passageway therethrough, and means communicating with said passageway to inject fluid therethrough. Desirably said fluid is pressurized air. Suitably said forming of said thermoplastic disc is effected by injecting a fluid through said internal sealing mandrel, a vacuum is applied to the surface of said disc oppQsits the surface confronting said internal sealing mandrel. Desirably said fluid is injected through said internal sealing mandrel at a pressure of between about 5 to 140 pounds per square inch and said vacuum is in an amount of betw~en 10 to 30 inches. Preferably sald fluid is air.

In one embodiment of the present invention said hollow tubular element and said disc comprise a laminate of a plurality of layers of material. Suitably at least one of said layers is a barrier material. Desirably said barrier material is comprised of an oxygen imperrneable material.

In another aspect thereof the present invention provides in a method of forming a thermo~lastic tubular container wherein a molten plastic disc is secured within the confines of an open end of a hollow tubular element and allowing the latent heat of the molten plastic disc to weld the peripheral edge of the disc to the inner circumferential wall of the tubular element to seal the same, the improvement wherein: an internal sealing mandrel is inserted into the other end of the hollow tubular memberr the internal ~ ;2 853~L

sealing mandrel having a sealing head on the endthereof,the sealing head having a first shoulder thereabout; positioning the hollow tubular element and disc within a mold cavity defining a predetermined shape, with a second shoulder about the periphery of the mold cavity complementary with said first shoulder;
applying pressure on said sealing head to trap the periphery of said thermoplastic disc only to form a seal of thermoplastic material between said first and second shoulders, such that only the portion of the thermoplastic disc not sealed between said shoulders is subject to forming into the predetermined shape of said mold cavity; and forming said portion of said thermoplastic disc, not trapped between the complementary first and second shoulders, by applying a vacuum to the surface of said disc opposite the surface confronting said internal sealing mandrel, while the same is in a moldable state, and while said periphery of said thermoplastic disc is in contact with said sealing head, to cause the same to conform in shape to the predetermined shape of said mold cavity to form a closed end wall on said thermoplastic container having said predetermined shape.
Suitably said vacuum is in an amount of be-tween about 10 to 30 inches.

In a further aspect of the invention a method of forming a thermoplastic tubular container wherein a molten plastic disc is secured within the confines of an open end of a hollow tubular element and allowing the latent heat of the molten plastic disc to weld the peripheral edge of the disc to the inner circumferential wall of the tubular element to seal the same, the improvement wherein: an internal sealing mandrel is inserted into the other end of the hollow tubular member, the internal sealing mandrel having a sealing head on the end thereof, the sealing head having a first shoulder thereabout; posi.tioning the hollow tubular element and disc within a mold cavity defining a predetermined shape, with a second shoulder about the periphery of the mold cavity complementary with said first shoulder;

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applying pressure on said sealing head to trap the periphery of said thermoplastic disc only to form a seal of thermoplastic material between said first and second shoulders, such that only the portion of the thermoplastic disc not sealed between said shoulders is subject to forming into the predettermined shape of said mold cavity; and applying a fluid pressure aga1nst the surfacet of said disc confronting said internal sealing mandrel, while at the same time applying a vacuum to the surface of said disc opposite the surface confronting said internal sealing lo mandrel, while the disc is in a moldable state, and while said perlphery of said thermoplastic disc is in contact with said sealing head, to cause said portion of said thermoplastic disc, not trapped between the complementary first and second shoulders, to conform in shape to the predetermined shape of said mold cavity to form a closed end wall on said thermoplastic tubular container having said predetermined shape.

The present invention will be further illustrated by way of the accompanying drawings in which:
Figure 1, containing figures lA through lF, illustrate the conventional process for formation of a head on a tubular element by an internal forming mandrel, such as described in U.S.
3,0~7,910;
Figure 2 shows a sealing mandrel useable in the present method within a hollow tubular element having one end, closed with a disc, positioned ad~acent a mold cavity;

Figure 3 illustrates the application of pressure to the sealing mandrel with insertion of the lower portion of the hollow tubular element and the moldable disc within the mold cavity and application of fluid pressure therein to form a head;

- 5b -~t Figure 4 shows a sealing mandrel within a hollow tubular element having an end, closed with a disc, positioned adjacent a mold cavity for use with application of a vacuum to form a head, Figure 5 illustrates the application of pressure to the sealing mandrel with insertion of the lower portion hollow tubular element and the moldable disc with tne mold cavity and application of a vacuum to form a head;

Figure 6 shows a sealing mandrel usable in the present method within a hollow tubular element, having one end closed with a disc~ positioned above a mold cavity prior to application of both fluid pressure and vacuum to form a head;

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j ~Lgure 7 illu~t~tes the applIcatIon of pressure to ¦the sea1in~ m~ndrel with insertion of the lower portion of t.h~
h~llow tubulAr el0men~ and the mold~ble di6c within ~he mold l cavity and the appl~cation of both fluld pre~sure and vac~um ¦ thereto to form ~ head;
Fi8ure ~ shows a tubula~ ele~ent ~nd disc posi~Ioned adjacent a mold cavity ~or fnrmnt~on ~f ~ ~ul~us head;
~ igu~e ~ illustrates ths applicatlon o~ fluid p~essure l to ~orm a bul~o~s he~d;
¦Fi~ure 10 illus~rates a eont~in~r having ~ bulbous he~d, formable by the present me~hod;
~i~ure ll ~llustrate~ the applicatLun o~ ~luid pre~sure ~o form an ~ppllcaeor-type t~e~d a~cording to ~he pr~sen~ method; , ~igure 12 ill~strates a c~ntainer having an applicato~
head, f~rm~ble by t~e present method9 Figure 13 illus~ra~es the ~plic~tion of rluld pre~-sure to form a novelty he~d in the ~hape o~ ~ clown's head ~ccordin~ to ~he p~esent method;
Figu~e 14 illustrates a ~ont~iner hAving ~ novelty head, such as a clown's head~ formable by the p~esent method;
Fig~re 15 illustr~tes t~e Application of fluid pres~ure to form ~ twi~t-of~ head ac~ordin~ to the present method; and : 25 Fi~ure 16 Illustr~tes ~ ~ont~iner h~ving A ~wist-off hea~ or~a~1e by ~he present met~o~.
~t~
The present met~od is ~n improvemen~ Dv~r conventional processes ~or formin~ a head ~r closed ~nd ~Ub~lhr container, JuN~ iæ7 TUE 15:33 ID: PtIW ~NDI<P~H TEL NO: 412 281 18c1 ~ P09 I

¦and enables the fo~-na~ion of un~onvention~l heads of vario~s ¦ shapes. A.s i~ known, conventional p~ocesse~, such ~s the "~o~ns"
pro~Qss described in U.S. 3,047,910 use ~he latent he~t of a l molten the~oplastic dlsc to seal the per~phery of the disc to the inner clrcumferential wall of a tube ~o close the end ~hereof. Figures 1~ throu~h lF illus~rate such a conventional process. As illustrated therein, ~ hollow tubular element 1, or ~leeve, of ~ ther~oplastic m~terL~l is formed) such ~s by l ext~uding a tube o~ rmoplastic m~terial and cutti~g desired lengths~ as illustr~ed in Figure lA. The hollow tubular element i5 then conveyed to a punch st~tion (~i~ure lB), havlng punrhes 3, while suppor~ed on ~ formin~ mandrel 5 that has a support membe~ 7, ~e~d portion ~, ~nd protruslon 11 ther~on~ The l ~upported holLow tubular elemcnt is posit~oned above a molten l strLp or fllm 13 of a ~hermoplas~ic materi~l suppor~ed on a ~ase 15. Upon aCtiV~tiQn a~ the pu~ch station, the punch 3, sucb as : by lowerin~ ~he sa~e as lndic~ted by the arrow in Fi~ure i~, mec~anic~lly cuts through the molten thermoplastic strLp 13~
forming #nd pickln~ up ~ circular ~lu~ or disc 17~ The molten ~hermoplastic disc 17 is then in con~act ~ith ~he bottom e~e of the hollo~ tubul~r element 1, where the l~tent h~ad ~rom the disc 17 ~hen p~rtlally melts t~e ma~lng edge of the hollow tub~lflr element 1~ formlng a natural ~eld lg be~ween the perip~eral ed~e 21 of the dlsc i7 and inner circ~mferenti~l w~11 Z5 73 o~ the tubulAr element 1 to seal t~ s~me (Figure lP1, to pro~ide a preform 25 for sub.sequent ~orming. The preform 25 (~i~ure 1~) is then transpor~ed to ~ molding s~tlon where hydraulic pressure i~ ap~lied ~o the ormin~ mandrel in a mold fo~. As illust~a~ed in Fig~re lE, the preform ~5 supported by ~2~

forming mandrel 5, is positioned above a mold form 27 having a cavity 29, with walls 31 thereabout. The mandrel 5, upon pressure being applied thereto, as indicated by the arrow (Figure 1) compresses the molten disc 17 against the walls 31 of the cavity 29 in the mold form 27, forciny the thermoplastic to conform to a head 33 in the shape of the mold space between the forming mandrel head 9 and the protrusion 11 and the walls 31 of the mold cavity 29. The external tooling is constantly cooled so that, as the formed disc 17 is compressed into the desired shape, the thermoplastic "sets up", thus permanently forming the shape of the thermoplastic tube head.

This prior art process, as illustrated in Figure 1 has been very successful in formlng thermoplastic tubular containers, but contains some drawbacks. The forming mandrel must be capable of forcing the thermoplastic disc into the required shape and thus limits the shapes that can be produced. Tooling costs and subsequent upkeep costs are high, while manufacturing speeds are not as high as are desirable. Massive hydraulic systems are also required in order to provide the compression forces necessary to mold the head. In addition, exotic shaped heads or novelty shaped heads are not readily produced using such a compression type forming mandrel.

By use of the present method, these disadvantages are removed. The present method uses either fluid pressure, vacuum, or a combination of fluid pressure and vacuum to form heads on tubes where an internal sealing mandrel is used only to provide a seal about the periphery of the head formed.

Referring now to Figures 2 and 3, one embodiment of the present process is illustrated wherein fluid pressure alone JU~ 16-i~7 TUE 1~,:34 ID: PMW Rl`ID K PEiH TEL NO: 41~ 2~1 1821 #048 Pll ~ ~Z~353~

is used to form ~ head. A hollow tubular el~ment or sleeve 1 has a rnolten ~is~ 17, with the peripheral edge 21 thereof welded to the inn~r clrcumferen~ial wall 23 of t~le hollow tubul~,r mem~er, and ~n internal sealing mandrel 35 i~ Inser~ed ~herein, ~he intern~l se~ling m~ndrel 35 having a sealing head 37 on ~he end th~reo~ said se~lin~ he~d havin~ a first shoulder 39 about th~
~;urfaee thereof con~rontlng s~id disc, and ~ conduit 41 thereon which communic~es wlth ~ pAss~eway 43 that ext~n~s thro~lg~ the sealing heatl 37. The hollo~ tub~llar element 1, wit~ t~e disc 17 still in ~ mol~ahle s~a~e, is positione~ adjacent ~ rnold form 27 which may be ~n integr~l Imit or formed of mating sections 27 and 27i~ havin~ a ::avity ~9, wl~h w~lls 31 About ~he cavity~
with one sectlorl h5 of the wall 31 ~lavlng a se~ond shoulder 47 thqt i9 complemen~ary with the first shoulder 39 on the se~lin~S
head 37 o~ the sealing mand~el 3~. A source of pressurized fluid, such as ~ir 4~ is provide~ which cc~mm~nica~es ~ith the ~on{luit 41 of the s~aling m~ndrel throu~h lin~ 51. ~n forming c)f a head 53 s as illustrated in Fi&ure 3, the holLow tubular element 1 with disc 17 in a moldable st~te9 i~i positloned within the mold ca~i~y 2~ of mold ~o~m ~7~ und pressiure is applied~ as indicute~ by the das~led arrow, to the sealing head 35 only ~o form a seal o~ thermoplastic material, indica~ed at 55, be~ween the first shoulder 39 on the sealing he~d and the eomplemen~ary second shoul~er 47 o the mold ca~ity wall. After formation vf ~he seal of ~hermoplastic material 55$ air ~rom the source 49 is lnjec$ed throug~ t~e con~ui~ 41 o~ the sealing mandrel 35 whic~
forees ~e por~ion o~ the thermoplastic disc ~urrounded by sealed por~ion 55, while s~ill in a moldable state, into cont~ct wlth the exposed wsll 31 of ~he mold ~or~, such ~Yi the threuded _~_ JIJN~ ;S7 TUE i5:35 ID: PMW I~ND K PGH TEL I`10: 412 2æl 1821 ~048 PlZ

~28S364 ¦form illus~ra~ed~ to form the head of the t~be produced~ The ¦lnjection of ~he air agains~ the ~her~oplas~ic dis~ thus cause~
the por~ion ~ereof, whloh is not between the co~plementary ! flrst and seeond sealing shoul~ers 3~ and 47 to c~nform In shnpe S ¦ ~o the predetermined shape, such as the cylindrical thread-llke shape illustrated~ to form a closed end wall on the thermo-¦ plastic ~ub~lar container o~ a predetermined shape.
Ano~her embodiment of the present method is illus-l trated in Fl~ures 4 and 5, whereln a vacuum is applied to the dlsc 7 while in ~ mold~ble æea~el rather than the fluld pres~re ~ppl~c~tlon embodlment of Fi~ures 2 and 3. A$ illusera~ed, a sealing mandrel 57, sim:la~ to sealin~ mandrel 35 is provlde~, except ~hat the conduit or ~xtension may be a ~olld rod-llke elemen~ 59 h~ving a sealin~ head ~1 on the ~nd the~eof. The seal~ ng head 61 has ~ firs~ ~houlder 63 ~hereon about ~he s~rf~e ~hereof confron~ing the diec 17. The hollow ~bula~
element 1, with the di.s~ ~7 still in ~ m~ld~ble state, is positloned ad~acent a ~old fo~m 65, whic~ may be ~n lntegral unl~ or for~ed of mating sec~ions ~5a ~nd 65b, that has a cavl~y 2~ 67 therein wlth walls 6~ abou~ the cavlty, an~ one seetion 71 of ~he wall 69 ~a~ing a second shoul~er 73 ~hat is complemen~ary with the first shou~er 63 on the sealin~ he~d 61 of the seall~g mandrel S7. The~ nold form 65, in ~he area surroun~ed 4y the second sho~lder 73 thereof, has a plurality of apertu~es 75 t~erein whlch extend from ~he wall ~9 of t~e cavity 67 to the exterior ~ur~ace 77 of th~ mold ~orm 65. A source of vac~um 7 15 pro~ide~ which com~unic~te~ with t~e plurality o~ ~pe~tu~es 75 by means of line 8~ ~nd br~nch line5 83. In formin~ oi the ¦ head 53 usin~ v~u~m, AS illustrated ;n ~i~ur~ 5~ ~h~ hollow ll -10-~L285~64 tubular element 1 with moldable disc 17 is positioned within the mold cavity 67, and pressure is applied, as indicated by the dashed arrow, to the sealing head 61 only to form a seal of thermoplastic material, indicated as 85, between the first shoulder 63 on the sealing head and the complementary second shoulder 73 of the mold cavity wall. After formation of the seal of thermoplastic material 85, a vacuum is applied from source 7g and through line 81, branch lines 83, and apertures 75, which draws the portion of the moldable thermoplastic disc, surrounded by sealed portion 85, into contact with the exposed wall 69 of the mold form, such as the thread form illustrated, to form the head of the tube produced. The application of the vacuum causes the portion of the disc that is not between the complementary first and second sealing shoulders 63 and 73 to conform in shap to the predetermined shape, to form a closed end wall on the thermoplastic tubular container.

In the embodiment of the present invention illustrated in Figures 6 and 7, the application of fluid pressure, such as air, in combination with the application of a vacuum, to form a head are used. A hollow tubular element 1, with the disc 17 welded to the inner circumferential wall thereof, has an internal sealing mandrel 35 inserted therein, the sealing mandrel having a sealing head 37 on the end thereof. The sealing mandrel has a first shoulder 39 about the surface confronting the disc, and conduit 41 therein communicating with passageway 43 that extends through the sealing head 3. A source of air 49 communicates through line Sl with conduit 41.

The hollow tubular element on sealing mandrel 35 is positioned adjacent a mold form 65 having a cavity 67, with ~2853G4 walls 69 about the cavity. The sealing head 37 has a first shoulder 39 about the surface thereof confronting the disc, while the wall 69 of cavity 67 in the mold form 65 has a second shoulder 73 that is complementary with the said first shoulder 39. The area of mold form 65 surrounded by second shoulder 73 has a plurality of aper-tures 75 therein, extending from wall 69 to the exterior surface 77 thereof, and a source of vacuum 79 communicates with said apertures 75 through line 81 and branch lines 83.

Figure 7 illustrates formation of a threaded head using both fluid pressure and vacuum. The hollow tubular element 1, with disc 17 still in a moldable state, is positioned in mold cavity 67, and pressure applied, as indicated by the dashed arrow, to the sealing line 37 only to form a seal 87 of thermoplastic material between first shoulder 39 on the sealing head 37 and the complementary second shoulder 73 in the mold form 65. After the seal 87 is formed, vacuum ls applied through line 81, branch lines 83, and apertures 73 to the surface 89 of the disc faciny the mold cavity wall 69, while at the same time, air from source 49 is in~ected through the conduit 41 of the sealing mandrel 35 against the surface 91 of the disc facing the sealing head 37. Application o~ both vacuum to one side of the disc surrounded by shoulder 73 and fluid pressure to the other side of the disc surrounded by shoulder 39 forces that exposed area of the disc to conform to the shape, such as the threaded head shape illustrated.

As aforedescribed, the application of a fluid pressure, application of a vacuum, or both are made while the ., , - , ~, JUN~ æ7 TUE 15:37 ICI: PMW fll`ll:` K PGH TEL NO: 41~! 2~31 1821 #04æ P15 I ~ 3S3~i4 ¦thermop~ ic dl6c is stilL in a moldable sta~e. The the~mo-¦plastic m~teri~l of the dl~c is no longer In a p~rely molten staee or above lts melting point after the l~ten~ heak ~hereof l has welded the disc to the tubular ele~ent wall, but ~ust s~ill ¦ be above the ~lass ~ransition ~emperature of ths thermoplastic ¦ so tha~ the disç is soft an~ flexible ~nd moldable to the deslred shape.
When ~he applicatlon of pressure is used ~o for~ the l head, pressures between abou~ 5 to 140 pounds pe~ squ~re lnch l are used. When a vac~um is applied to fo~m the head, a ~cuum o about 10 to 30 i~c~e~ are used. The ~hermoplastio tub~lar l container formed according ~o the present method will norm~lly : ¦ have a ~bula~ wall section of between ~hout 0.010 to 0.040 inch :: in wall thickness, while the head port~on ormed thereon w~llhs~e a thickne~s of abou~ 0.010 tG 0.080 inch in wall thickness.
The presen~ method is also usable to for~ thermo-plastic contalners of lamina~ed or layer~d thermoplastic maeerials. SLIC~ la~inates comprise layers o~ ~ the~moplastic m~terlal an~ a barrier layer suc~ as aluminum ~oil, o~ ~he llke, or lay~rs vf varient plastlc ~a~eria~s w~ieh may be ~o-ex~ruded in layers to form a multi-layer thermopLastlc materl~l. In formatlon of such lamin~ted tubula~ therm~plasti~ containers, the tubular wall section and plast~ dlsc are formed fro~
laminated plastic materlal and then sealed to~ether an~ molded as woul~ be a thermoplasti~ ~ub~lar ~ontainer of a single thermoplas~lc material. Such a l~minate oi~ three layers, in the disc and hollow ~ubular el~ment ~ would, for example have Inner ~nd o~er l~yers of a materi~l such as polyethylene, or other thermoplastic; while An lnterme~i~te l~yer) such a~ an oxy~en .

JUl`i-16 i'~'7 TUE 15:~ ID: PMW hl~lD K PGH TEL N0: 412 ~ 21 #04~ P16 2 ~ ~ 3 ~ ~

l-npermeable layer, would be o~ a polyamide su~ as nylon, or ethylene polyvl~yl ~lcohol, or the llke- Or, a flve l~yer ~mpol~c c~uld be us~ ha~in~ successive layers of an outer l thermopl~stlc resin, a~hesl~e, ln~erme~iate impermeable laye~, ¦ adhesive, and an inner ther~oplastic ~esin. The ~hermoplastlc resin ~an colnprise polyeth~lene, polypropylene, a polyester such AS polyetllylene t~rephthalate, or ~he like, while the i~er-medlate i~permeable layer can ~omprise an oxygen i~permeable l materinl such as nylon, ethylene poly~inyl alcohol, polyvinyl-l idene chlori~e, or the like, wi~h the tw~ adheslv~ laycrs supplied c~ bon~ the intermediate layer ~o each of ~he inne~ and l outer layers.
¦ The productlon of ~arious embodimen~s of ~omplex heada l that may be formed accordin~ to the present ~e~thod~ and not lS l readily by the original Down's process, ls illustrated in Fi~res 8 through 16.
Fi~ure6 8 ~hrough 10 ill~str~te for~ation of a bulb-like head on a hollow ~bular eleme~ Figure 8 ~llus~ates a hollow tu~ular element 1, with A welded di~ 17 secured ~here~o~ and Wi~ the sealing mandrel removed, positioned adjacen~ a mold form 27, ~ormed of m~table mold form sec~lon~
~7~ and 27b. ~he mold cavi~y ~9 ;s in ~he for~ o~ a spherlcal ravity. Fi~uPe 9 ill~strates the application of ~luid pressure from the sealing mandrel 35, through conduit 41 t~at communa-cates with passa~eway 43 in the sealing head 37, to form the disc, while in a moldable ~ta~e~ into eonformity with the walls 31 of the mold cav~ ty 2g, ~o form a bulbous head 93 on the end of tl-e hollow tubular e~ement ae illustrated ln ~i~ure 10. Such a ~ulbous head would no~ readily ~ formed uslng a formlng 353~

mandrel since the same would not be able ko pass the constrictive portion 95 between the tubular element 1 and the bulbous head 93.

Figures 11 and 12 illustrate formation of another complex head embodiment according to the present method that is in the form of an applicator head for application of ointments or the like, over a larger area than would be provided by a single tube outlet. The applicator head 97 has a plurality of protrusions 99 through which orifices would be formed such that the contents of the finished and packed tube would be ex~dable through the plurality of apertures over a large surface area.

Figures 13 and 14 illustrate formation of a novelty type head 101, in the shape of a clown's head, with a constricted portion 103 forming a neck for the clown and wlth a cap 105, later applied, covering the orifice (not shown) for dispersing the product being in the form of a hat for the clown.

Figures 15 and 16 illustrate formation of a twist-off or ampoule-like head 107 for a hollow tubular element, where a very narrow constriction 109 is provided between the body of the tubular contour 111 and a gripable head portlon 113. By grasping the gripable head portion 113 and twisting the same, a break at constrictive portion 109 would occur, with access to the contents of the body 111 of the tubular contalner effected.

It should be noted that in Figures 8 through 16, the application of fluid pressure is illustrated, while equally effective would be the application of vacuum through a mold form, as previously described, as well as application of both fluid pressure and vacuum, as also previously described herein in accordance with the present method.

JUI`I-16-'13~ TUE 15~ P;1W f~ilD K PGH TEL l~m: 4i2 Zæ1 1æ21 ~ 48 P18 I f~
~3~ii3~L

The pr~sent rnethod enable~ ~he produc~ion of complex head desi~ns ~hat arç not: readily prod~ced usin~ compreæsion moldln~ iAS ef~ecte~l Ln the prior art, wlll enable ~he use of a l ~:hinner disc in the format~on of he~.~s on tubul~r elem~nts, and s ¦ provides an efflci~nt and ~aonc~mical meAni for formlng he~ds vn thermoplastic ~ubes.

Claims

1. In a method of forming a thermoplastic tubular container wherein a molten plastic disc is secured within the confines of an open end of a hollow tubular element and allowing the latent heat of the molten plastic disc to weld the peripheral edge of the disc to the inner circumferential wall of the tubular element to seal the same, the improvement wherein: an internal sealing mandrel, having means for injecting a fluid therethrough, is inserted into the other end of the hollow tubular member, the internal sealing mandrel having a sealing head on the end thereof, the sealing head having a first shoulder thereabout;
positioning the hollow tubular element and disc within a mold cavity defining a predetermined shape, with a second shoulder about the periphery of the mold cavity complementary with said first shoulder; applying pressure on said sealing head to trap the periphery of said thermoplastic disc only to form a seal of thermoplastic material between said first and second shoulders, such that only the portion of the thermoplastic disc not sealed between said shoulders is subject to forming into the predetermined shape of said mold cavity; and forming said portion of said thermoplastic disc, not trapped between the complementary first and second shoulders, by injecting a fluid through said fluid injecting means of said internal sealing mandrel against the surface of said disc confronting said internal sealing mandrel, while the same is in a moldable state, and while said periphery of said thermoplastic disc is in contact with said sealing head, to cause the same to conform in shape to the predetermined shape of said mold cavity to form a closed end wall on said thermoplastic tubular container having said predetermined shape.

2. The method as defined in Claim 1 wherein said means for injecting fluid through said internal sealing mandrel comprises an internal sealing mandrel having a sealing head with an axial passageway therethrough, and means communicating with said passageway to inject fluid therethrough.

3. The method as defined in Claim 2 wherein said fluid is pressurized air.

4. The method as defined in Claim 2 wherein, while said forming of said thermoplastic disc is effected by injecting a fluid through said internal sealing mandrel, a vacuum is applied to the surface of said disc opposite the surface confronting said internal sealing mandrel.

5. In a method of forming a thermoplastic tubular container wherein a molten plastic disc is secured within the confines of an open end of a hollow tubular element and allowing the latent heat of the molten plastic disc to weld the peripheral edge of the disc to the inner circumferential wall of the tubular element to seal the same, the improvement wherein: an internal sealing mandrel is inserted into the other end of the hollow tubular member, the internal sealing mandrel having a sealing head on the end thereof, the sealing head having a first shoulder thereabout;
positioning the hollow tubular element and disc within a mold cavity defining a predetermined shape, with a second shoulder about the periphery of the mold cavity complementary with said first shoulder; applying pressure on said sealing head to trap the periphery of said thermoplastic disc only to form a seal of thermoplastic material between said first and second shoulders, such that only the portion of the thermoplastic disc not sealed between said shoulder is subject to forming into the predetermined shape of said mold cavity; and forming said portion of said thermoplastic disc, not trapped between the complementary first and second shoulders, by applying a vacuum to the surface of said disc opposite the surface confronting said internal sealing mandrel, while the same is in a moldable state, and while said periphery of said thermoplastic disc is in contact with said sealing head, to cause the same to conform in shape to the predetermined shape of said mold cavity to form a closed end wall on said thermoplastic container having said predetermined shape.

6. The method as defined in Claim 5, wherein said vacuum is in an amount of between about 10 to 30 inches.

7. The method as defined in Claim 1 wherein said fluid is air at a pressure of between about 5 to 140 pounds per square inch.

8. The method as defined in Claim 4 wherein said fluid is injected through said internal sealing mandrel at a pressure of between about 5 to 140 pounds per square inch and said vacuum is in an amount of between 10 to 30 inches.

9. The method as defined in Claim 8 wherein said fluid is air.

10. The method as defined in Claim 1 wherein said hollow tubular element and said disc comprise a laminate of a plurality of layers of material.

11. The method as defined in Claim 10 where at least one of said layers is a barrier material.

12. The method as defined in Claim 11 wherein said barrier material is comprised of an oxygen impermeable material.

13. In a method of forming a thermoplastic tubular container wherein a molten plastic disc is secured within the confines of an open end of a hollow tubular element and allowing the latent heat of the molten plastic disc to weld the peripheral edge of the disc to the inner circumferential wall of the tubular element to seal the same, the improvement wherein: an internal sealing mandrel is inserted into the other end of the hollow tubular member, the internal sealing mandrel having a sealing head on the end thereof, the sealing head having a first shoulder thereabout;

positioning the hollow tubular element and disc within a mold cavity defining a predetermined shape, with a second shoulder about the periphery of the mold cavity complementary with said first shoulder; applying pressure on said ceiling head to trap the periphery of said thermoplastic disc only to form a seal of thermoplastic material between said first and second shoulders, such that only the portion of the thermoplastic disc not sealed between said shoulders is subject to forming into the predetermined shape of said mold cavity; and applying a fluid pressure against the surface of said disc confronting said internal sealing mandrel, while at the same time applying a vacuum to the surface of said disc opposite the surface confronting said internal sealing mandrel, while the disc is in a moldable state, and while said periphery of said thermoplastic disc is in contact with said sealing head, to cause said portion of said thermoplastic disc, not trapped between the complementary first and second shoulders, to conform in shape to the predetermined shape of said mold cavity to form a closed end wall on said thermoplastic tubular container having said predetermined shape.

14. The method as defined in Claim 13 wherein said hollow tubular element and said disc comprises a laminate of a plurality of layers of material.

15. The method as defined in Claim 14 where at least one of said layers is a barrier material.

16. The method as defined in Claim 15 wherein said barrier material is comprised of an oxygen impermeable material.