CA1296677C - Packaging - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
This invention relates to packaging. The invention provides a self-supporting tray-like product container (especially for food) comprising an inner dished part receiving said product in a first well, and an outer dished part having a second well into which the first well is entrant, the inner and outer parts contacting and being joined to each other at their respective peripheral edge portions otherwise with their wells in all-round mutually-spaced relation. The spacing provides thermal and/or shock insulation and allows the inner and outer parts to be made of different materials especially ones having different thermal deformation resistances which allows use of the package in either of a conventional or microwave oven or both according to the materials chosen.
The invention also provides a method and machine for making the container, including means for thermoforming the inner and outer dished parts, means for uniting one within the other, and means for filling with product and applying and sealing a cover in place.

Description

The present i~vention relates ts~ packa~3:ing, and ha~ app~ic~tion ~o ~;e~ supportirl~c product contain~rs, often o~ tra.y-like type.
crea.sing at~ention ~s b~ing paid to the packaging o~ ~ood procluc~s for 6ale to con~umer~ to ~nsure t:hat the food reache~ the consumer in the best po~sible cs~ndition. That h~s l~d to vacuum paclcing, and more resen~ly to coll~roll~d or modl~ied a-~lnospher~
pack~in~ ~ T~ere i~ al ~o ~n increa~ing demandL Por ~uch pa¢ka~;ed food to b~ supplie~ in ~el~ upp~rting tray-llke container~; In which the ~ood can b~ heated-up or cooked in either o~ converltion~l or ~ics~owave o~n~;~
lS Clearly, ma~erial~ used should nvt c~ theme;elv~.~ o:r otherwise lead to ~ontami.n~tion o-f :~ood prodllcts therein. Als~, mat~rials whlch e~sh~bi-~ suitahl~
~hysical ri~idity ~nd the~ a~ y ten~ ~o be cli~ lcult for con~entional diI:~e:renti~l pressure thermoXormin~, and often clo noi provide su~f:icient ~rrier, at least ~or ~ontrol. led or motllPied atmosphere , .4 p~c~aglng. Ac~ordingly, pro~ucin~ containerf~ which meet all the desired re~uireme~ts i~ par-ticular~y difficult at re~sonable cost, if not impossibleO The pre~ent invention aim~ t least irl ~iome pr~:~er~ed embodir~e~tæ, to help ov~r~ome Ithe abo~re mentioD~d dl~:Eiculties ~or Iood pac~sa~ln~.
In packaging in general J not necessarily l Lmlted to Iood proc,uct~3, there ~g o~ten a requireme:n'c ior - a~ording ~hock or lmpac1~ l~e~i~t~nce and/or ~ibration protect~on, and embodiment~; o;~ the in~ention c~n be use~ul ~o tk~Lt end.
~ccorc.ing to one ~spe~t o~ the preser~t inv,. ntion there is provided a 6el~-~uppor-tin~ pre~erably tray-l ike product container c~mprisi~g an inner ~i~hed part Iormed with a peripher;~l edge p~rtion there~bout and ~ iirst w~ eceiving said produ~, and an outer dished part ~ormed wi th a p~-~lphe~l ed~ portion thereab~ut and ~ sec~nd well intc~ which ~aid ~irst well 1~ entrarlt, the inner ancl ~u~er pal t~: co~t,~cting ~nd . il b~?in~ jolrlecl to ea~h other a~ t,heir re~p~c~ive peripheral e~dge por-tions, o~herwi~e with their well~ :ln round mLltUa 1 1 y -spaced re :l at lon, Use~ul therma:L and/or~.~hoc~ or impac~ insulation can resul~ from that ~paced r~lation ~v~ th ~n in~ul~ing/~ushionln~ fluid, usually a ga~ at or ne~r normal ~1;mo~pheric pres~ure ~nd of~erl wit;h alr, betw~en the inner aTld ou~er parts, which can be o~

di~Perent m~ter~als c~nt~ibuting also ~o eco~o~y o~
~ manu~a~ture. Pref~rahly, th~ peripheral edge portlons : o~ the inner ~nd out~r part~, which may ~e as ~lan~es~
lipR or a~u~ent ~u~ces, a~e join~d to~ether by a G ~ontinuou~ ~eal ~hereabaut.
Acco~d~n~ to another aspect o~ th~s inventio~, ~here is provided a n~thod o~ produci:ng a : sel~-supportin~ produc~ cont~iner~ comp~ising the steps o~ ~rmin~ a ~irst part having ~ p~ripher~l edge portion thereabout and a product~receiving well~
~ormin~ ~ second part having ~ peripheral edge portion thereabout ~nd a well accommod~ing ~he product-rec~!iving wèll in all-round mutually-sp~ed relatlon, ~c.d uniting -the ~irst and sec~nd par~ t lS their p~ripheral edge port.:Lon~ with ~he ~lr~-t p~rt inner ~nd th~ ~econd part ou~er relati~e to the c4nt~iner as a whole J pre~ra~ly w~th ~n Ln~ ting/c~ushioni~K ~luid therebetw~en.
Accorclin~ to ~ ~urther aspect G~ thl~ Lnv~nt~on, there is pxovlded apparatu~ ~or mak~ suppor~ing product c~ntainers, compr:i~in~ mean~ ~or f~rming ~ir~t ~nd ~econ~ par-ts each wlth peripheral edge portions ~herea~out ~nd re~eiving wells, the rec~ivin~ Y1ell of the fir~t part bein~ ~or product and the recei~ing well o~' the ~econ~ p~rt a~com~no~atin~ the - product-re~ivin~ well oi the first pal~ in ~ round ~utually-space~ rel~ n, arld mean~ ~vr ~olrliQg khe ~irst arld second p~rt~ at their peri~h~ral edge portion~, pr.e:~erably wi~h an in~3ulating/cu~3hionlng ~lul~ therehetween.
S The ~ ner and 4ut,er p~rts ca~ be mad.e, ~s~Ly by di~feren~ pressure aided th~rmoforlning ~ ~he~t material, as open-top containers or traye, e~ch ha~ing a b~se and upstandin~ ~ide walls e~tending the:re~rom and out-t~rned to ~orm re~pective periph~r~ ngiQg~
F4~1n~ may b~ do~e separatçl~ and the p~rt~ brou~ht : to~ther a~erwa~ds, or ~ub~tantially sim~ltan~vusly ~nd oppositely with the well o~ the inner part the~
illverted into the wel l o$ the otber part ~
Using di~Iererlt materials, the outer part c~n be : .
. 15 o~ a relatively inexpensive m~erial mainly to provide desired ph~,ical properties, includin~ rigidlty ~ the container, even ~s a board or pape~-b~sed materia.l, . whlls~ the inner 6~in i~ v~ a ~on-contaminati~ bar~ie~
m~terial, e.g. ln allowi~g a c~ntrolled/mor~lPied ~0 atmo~phere to be eskablishecl in the ~!ead ~pa~e abov~ a ~ood produc-t. Thermal d~ormatlon re~ n~,es c~n be di~fer~nt, whether for mi~rowavirlg ~requ~rlng ~i~her ~uch ~esi~tan~e (say 120 d~grees C) for the inne~ p~r~
than ~or the ou~er part ~say 50 to Ç0 de~rees ~, or Z5 ~o~ conventional o~en coo~ng requiIin~ higher ~uch re~iatance lor the outer p~r~ ~s~y 200~0 de~r-es C) .

; .. ~

than for the inner part (say 120 degre0s C)r Physically strong and rigid outer parts allow inner parts to be of ~lexible material. However, the opposite is feasible, say for conventional o~en use, i.e. where the inner part is physically supporting and the outer part is physically weaker, even flexible, but of high thermal distortion resistance as applies to polycarbonate. Generally, thic~ness of material o~
each part can be kept to a sensible minimum, also reducing costs. Clearly, flexibility of either part can contribute to shock/impactlvibration resistance.
There will normally be a cover for a product container hereoP, generally extending over its inner part, conveniently sealed thereto, often preferably continuously about the container.
Such cover may be of sheet, say a web or ~ilm, and cooperation with the inner partl can give close restraint of product then ef~ectively trapped as well as suspended by the inner part in the outer part. An alternative is to use two uncovered containers hereof in confronting relation. Suitable connection or securement can include hinging together at effectively common edge portions.
The inner and outer parts can be fused or sealed together at the same time as a cover web is applied.

Where a controlled or modified atmosphere is cal~ed Ior, a suitably impermeable material will be used for the cover web. It may be advantageous t at least ~or food products, if the cover web has a peelable fixing to the inner part,say for "cook-in" packs to allow openi~g up a corner, for escape of steam during cooking, and/or for easy removal after cooking. Seal strength can also provide a safety mechanism9 by breaking if excessive pressure builds up in unpuctured packs.
Peeling of a cover web can be aided if loose at a corner o~ the pack whereat inner and outer parts are sealed together. Cutting or heavy scoring o~ the inner ~ and outer parts, at a corner or along an edge, can also : ' aid Gover web removal, i.e. in "crack-peel" manner.
Continuous production can be b~ thermoiorming two ':
sheets or webs in one machine, but pre~ormed parts could be used, or a combination. Feasibly, product can be loaded into the inner part alone and a top web ~0 sealed over before inserting the loaded inner part into the outer part.
In one suitable apparatus, web materials ~or inner and outer parts are held together, at least up to sealing thereto of a cover, conveniently by a chain conveyor which grips opposite overlying edge portions.

~ ., Covering webs impermeable to gas, vapour, aroma ~r : flavouring are generally pre~erred ~or ~ood packs, and may be of clear or opaque or printed material, normally polymeric.
In connection with applying and/or sealing the covering web, the inner part may be gas flushed, or gas introduced where a controlled or modified atmosphere is called for in the head space between the inner part and the covering web, and at least the inner part may exhibit controlled permeation properties, say where the space between the inner and outer parts also contains an atmosphere helpful in conjunction with or relative to the head space atmosphere.
Speci~ic implementation of the present invention will now be described, by way oP example, with re~erence to the accompanying drawings; in which:-Figuxe 1 is a broken away perspective view of a container for food according to the present invention;
Figure 2 is a schematic sectional view of the con-tainer;
Figure 3 is a diagrammatic illustration showing the various parts of a ~achine and illustrating the s-tages in a method of producing a ~ood package;
Figure 4 is a simplified sectional view through a container providing protection against physical damage D~ j 7 ~' . 8 to product therewithin;
Figure 5 is a schematic view o~ the process o~
forming a container with material of in~er and outer parts brought together before formation; .-Figure 6 is a schematic view of another system forming filled containers; and .. Figure 7 illustrates diagrammatically provisions for allowing passage of gas to and from both sides of inner parts; and Figure 8 illustrates reversal o~ inner parts within the thermoforming station.
A container for food, generally indicated at 1, has inner and outer parts 3 and 57 respectlvely, the inner part 3 having wells 13 accommoda-ted substantially within a well space 11 o~ the outer part 5. The parts are in the ~orm of open-top trays, as illus-trated and each has a peripheral flange 7, g. The ~lange 7 o~ the inner part 3 overlaps and contacts the flange 9 of the outer part 5 so as to support the part 3. The wells 13 are then accommodated within the outer part well space 11 and spaced therefrom all-round in -that space 11.
Different materials are usual for the parts 3 and 5.
~ One of the parts 3 and 5, which can be preformed :: ~ to shape, can be physlcally robust, basically : 25 substantially rigid and form-sus-taining in ovens, and ~he othçr can be physi~ally weaker, even ~lexibl~, altho~gh ~hat is b~ no means e~,enti~l~ It i~, however, pre~erred ~h~t th~ inn~r p~t have ; character~stic~ ~g~in's~ ~ontamination and l~s o~
S de~ired atm~sphere, say an ~nti-cont~minant ma~eri~l imper~eable ~o co~trolled/mcdi~ied atmo~pheres. We ~re particularly interested ln the use o~
plastl~s/polymeric ma~erials ~ha~ c~n be ~haped by the technique~ o~ thermo~orming usin~ erential pressure~.
The ~ap all-round be~ween th~ two par~s 3 and 5 can be particularly advant~.geous as a thermal barrier in~ulat~on feature, or as a ~hock/i~pact protection.
In Fi~ure 1, the inn~r past 3 has two wells 13, al~hough ~ sin~le well m~y be more usual ~aF3 ~h~wn dotted in Figu~e 2).
~ n one application, suitable ~vr use in a mi~rowave o~eD I ~he inrler par-t 3 i~ ~ormed o~
~ lexible ~b o~ material which 'is capab`i.e o~
ZO wi~ths~t~ndin~ the cooking ~e~.peratures ~nerated in ~oo~
products, typically up to 120 ~egree~ C. A suitable mat~rial ls a ¢oextruded multilayer ~ .rn 0~
polyethylena/~dhe~ivzfnylonf~dhe~ive/poly~thylene~ with a thicknes~ o~ 5ay 50-100 rnicrons. The out~r par~ 5 ~5 can he m~de o~ a ~ateri~l w~ich has a lower re~stance to ~h~rmal dis~ortio~, ~hich may be as low as 50 or , 60 d~gr~e~ C. ~ ~ulta~le ma-~erial ~s a multilayer b~se ¦ web oi ~t~r~ne/~dhe~lve/polye~hylen~ extruded tv~e~her ' ~ay with ~ ~eb ~hicknes6 ~ 500 mi~ron~.
In prs~c~c~, the temperatur~ o-E th~ outer p~rt 5 . is ~sually sUch ~hat i~ ca~ ~e h~ld in kh~ h~nd com~or~a~ly, even whil~t the inner ~ki~ contalns produ~t at boiling point i.eO in ex¢ess o~ 100 degre~
C.
Use of a hi~h gr~det r~la~ivel~ expensive, b~rrler material te,g. non-~ontamin~nt and ga~
imperme~ble~ for ~he inne~ par~ 3 need not contribute ~gni~icant.ly to phy~ical robu~ness, thou~h the outer : p~rt 5 can ~o so, and be o~ ~ mu~h le~$ expe~sl~e mate~ial ~vho~e non-~onta~niIlan~ ~ature i3 1~
importan~ nd May even be g~ permeable. The barrier m~t,erial ~h~ld act to block ~ny o~ ~s, ~la~our, aroma and vapour p~rmeation.
In ancrther ~mbodi~ent, ~or u~e in a co~ventional 20 oven, the outer part ~ is o~ a m~-~erlal which will withs-tand ~verl-shel~ ~ontac-t-temperatures of 200-22~
~ d~grees C, ~vhil~t the ~ap 11 allows the inner pa~t 3 to .~ b~ mad~ of a materi~l which needs only to withstand the temper~ure of the ~ood, typically 120 de~ree~ C 3ince ~5 the ~ood ~cts as a h~at ~ink. In this case, for econo~y, it, rnay be preferred to ~orm the inner p~rt 3 from a physically strong or robust material, and:to have the outer part 5 o~ a weaker, even flexible, material. A suitable material for the inner part is a polypropylene/adhesive/nylon/adhesive/polypropylene laminate, say of 500 microns thickness. A suitable material for -the outer part is a thin ~lexible polycarbonate/sealant web with a thickness of 50-100 microns. Gas pressure between the inner and outer parts can inflate a flexible outer part and assure spacing it from the inner part, typically by heat generated in the cooking process expanding gas in the gap 11, so ensuring spacing of inner and outer parts.
It can be advantageous for shapes o~ the par-ts and amount of gas within the gap 11 -to be such that the outer part in~lates just suf~iciently on heating.
Ridges or dimples in the inner part can be employed, say relative to a plain outer part.
In producing a packaged food product, usually there will be sealing of the inner and outer parts 3, 5 together continuously about their peripheral flangings 7, 9, whether before or at sealing on of a top cover ; 20.
In one method of manufacture, see Figure 3, two webs of material 51, 52 are fed into respective thermoforming uni-ts 55, 57 to form inner parts 59 from web 51 and outer parts 61 from web 52~ Typically, each thermo~orming unit 5S, 57 comprises a heater 56 to heat up a web urged against it and render the web deformable, and a ~ould 58 to which hea~ed web is indexed and where differential pressure urges it into contact with the mould 58. The formed shape will be retained on cooling. The plate 56 and mould 5B may move up and down during indexing of the web. After thermoforming, the two formed webs are brought together at a combining stage 63 so that inner parts 59 are inserted into respective outer parts 61 of tray-like form.
The assembled parts then pass to a product loadin~ station 64. Conveyance may be by pairs o~
chain conveyors or the like (not illustrated) engaging overlying edge flanges o~ the two ~ormed webs.
conveyor with spring loaded side-engagers for grlpping edges of the web 52 can also pick up the web 51 at the station 63, and may serve to pull both webs of~ and through thermoforming, etc. However, a separate conveyor section may be employed for transporting the web of the inner part through its thermoforming unit.
The product loading station is ~ollowed by a ~ sealing station applying a covering web 65 unwound from - 25 a reel 67 over the open top of the container. This is i7~7 likewise preferably drawn through by said first conveyor. ~echanical means can be used to hold the covering web and two parts as required whilst the compartment accommodating the product, at least if food, is gas flushed where desired before sealing of the covering we~ in position, usually by heat. All required evacuation and gas flushing is preferably done at the sealing station. Thus, unwanted distortion o~
the inner parts can be assured by reduction of pressure in the space between the inner and outer parts.
Flushing of that space could use different gases from those for the product compartment. Figure 7 illustrates diagrammatically provisions for allowing evacuation to both sides of the inner skin 3 and/or for introduc-tion of any desired atmosphere prior to final sealing, for which purpose the webs of the inner and outer skins are pierced so as to align with respec-tive passages represented by respective larrows X and Y
leading to spaces above and below the inner part. Webs are then severed to give complete packages 71.
Spaced skin containers made as herein described can be useful for products other than food, whether as packaging for transportation~ including shock/vibration resistance, or for display, say using transparent material at least for covers.

,~ , - ' ' 7~

~ . Figure 4 shows a spaced skin container 90 that suspends and restrains a product or iproduc-ts 92, 94 with a considerable degree o~ protection ~rom impact shock and/or vibration. That may be done by a contacti~g cover web or, as illustrated by a ~lam-shell type container with top and bottom components 96, 98 ~ formed as above and hinged along one edge 99~ The top is shown hinged apart in dotted outline at A. Each component has an outer part 100, usuall'y this would be made of a relatively rigid material, and an inner part ; 102 both possibly transparent.
The two components 96, 98 can be separate spaced skin containers brough-t together and secured in any convenient way. Alternatively, a continuous series of alternating components 9Z, 94 can be severed in end-to-end pairs. Multiple ~ormation with the components side-by-side can also be,praduced and, at least then, adjacent ~ormations ~or top and bottom can readily be ~ormed with dif~eren-t desired well shapes.
Figure 5 shows simultaneous formation of inner and outer parts from webs 130, 132 ~ed together ,into a ~orming machine 134 in overlying relation, preferably with slight sepa.ration into which pressurised gas may be fed. The webs are moved simultaneously to a heating and forming station 110 where both webs are heated, then the webs are indexed and thermoformed. There are two moulds, one (llZ) for the outer we~, conveniently as a female mould9 a~d the other (114) also as a female mould ~or the inner web. Pressure applied be,tween the webs, such as from pipe 115, can help the webs to conform to the shape of the respective moulds, usually in conjunction with vacuum applied to interiors o~ the moulds. The webs preferably cool on contact with surfaces of the moulds.
Bringing the overlying peripheral edge portions of the webs together, say after initial shaping o~
inner and outer parts, whilst still in the mould, can serve in joining the two webs at their edges. Where a ~lexible material is used for the inner part, it can be inverted after ~ormation, shown at 121, either by application of pressure (mechanical or ~luid) or at introducing product~
Perhaps preferably, such inversioln can be done in the mould by the introduction o~ pressure between the part 120 and its mould 114, see dashed,arrow in Figure 5, and Figure 8 where the inner part is shown solid at 120 in the forming position, and chain dotted at 120 in its reversed position ready for introducing o~ product.
Gas pressure input by way of passageway 121 can serve to invert the part.

' The so-formed spaced~skin component then moves to successive stations in the ~achine (unless producing ; simple product container parts for later filling), see ; filling station 123, to~ web applying and sealing station 125, and severing station 127. Any desired atmosphere may be established in the final package, whether in the head space above the product or between the inner and outer skins. The inner,and outer parts can be apertured to allow evacuation and/or gas flushing and/or atmosphere introduction as illustrated with reference to Figure 7.
Figure 6 shows a further alternative for ~;~ manufacture. There, the inner and outer parts are brought together a~ter the inner par-t has been Rilled, even, as shown, after the ~illed inner part has been covered. The outer part can then be sealed to the filled inner part at station 1400 Inner part web thermoforming is shown at 141 progressing to a ~illing station at 142 with a covering web then being sealed to the filled container at 143. The Pilled conta-iner may be gas flushed prior to final sealing. This is followed by brlnging together with the thermoformed outer part 150, pre~erably after the filled inner part is severed from its web, indeed the filling may take place completely separately e.g~ at a remote location Xrom the ;Einal ~om~ination with th~ outer web.
Alte~na~ively, po3itioning and ~ealin~ o~ the co~er c~n k~ done a~ter brin~ing tog~her the ~illed inner part with the outer par-t ~u that on0 s~l in~ ~p~r~kion can 5 su~ice to ~eal all three we~. The other ~tatio~s c~n be ~s ~escribe~ previou~ly.
8y use o~ suitable web ~ormation~ the top web can pro~lde a peelabIe seal wlth the inner web. More e~pe~ially, with all three ~eb~ ~ealed to~ether, we propose to c:ut ~hrou~h the inner and auter we~s, ~y across a ~o~ner ~lange o~ t,he packa~e, to provide cra~k-peel ~y~tem.
In the foregolng, we de~cribe use o~ a ~rrier material ~c,r the i~n~r part, and re~er ~o i~ being 15 ~hosen ~or lts impermeabili-ty, It will be appr~olated ~hat many, i~ not all, ~o-ca].led ~mpermeabl~ m~ rial~
do possess some permea~ility, even i~ very low.
.~vreover, lt i~ ~ore~een that ad~antag~ can ~rise from ~ u~ing a innqr pa.rt material tha~ has ~n intentionAl ~ 20 ~ de~ired per~e~bili~ty, ~or ex~ple in ex~ange o~ ~a.~e~
khrough the inner part.
~ oreover, contain~rs h~reo~ c~n ~e sh~pe~d a~
desired, including deeper, ~ay ~or drlnk~ or #OUp~
etc., even tria~gular ~ay ~or sand~iches etc. Presence 25 o~ ~ ~luiclt ~sually ~ ~s but possibly ~ liqllid, between the inner and outer parts i~ a sl~ni~lcan~
aspect of inventio~ contributin~ to advant~geous combinations o~ heat ln~ulatio~ and phy~ical cushioning, especially ~or ~icrowavable ~ood product~

Claims (21)

1. A self supporting product container comprising an inner dished part formed with a peripheral edge portion thereabout and a first well for receiving said product, and an outer dished part formed with a peripheral edge portion thereabout and a second well into which said first well is entrant, the inner and outer parts contacting and being joined to each other at their respective peripheral edge portions, otherwise with their wells in all-round mutually-spaced relation and wherein the inner and outer dished parts are made each from different thermoformable plastic material, said materials being selected such that one dished part has a higher resistance to thermal deformation than the other.

2. A self supporting product container as claimed in claim 1, in which the peripheral edge portions of the inner and outer parts are joined together by a continuous seal thereabout.

3. A self supporting container as claimed in claim 1 in which the space between the inner and outer parts is occupied by a fluid with insulating/cushioning properties.

4. A container as claimed in claim 1 further comprising a cover for the product-receiving well.

5. A container as claimed in claim 4 in which the cover is separable by build up of pressure in the product receiving well.

6. A container as claimed in claim 4, in which the cover is a web or film sealed over the peripheral edge portion of the inner part.

7. A container as claimed in claim 6, in which the cover and the product-receiving well cooperate for close restraint of product.

8. A container as claimed in claim 1 having desired atmosphere in at least the product-receiving well.

9. A container as claimed in claim 1, for food, in which its constituent materials are microwavable and the outer part affords physical supporting properties, and the inner part affords non-contaminating barrier properties and has higher thermal deformation resistance than the outer part.

10. A container as claimed in claim 1, for food, in which the inner and outer parts have thermal deformation resistance properties permitting use of the container in a conventional oven for cooking purposes, the thermal deformation resistance of the outer part being higher than that of the inner part.

11. A method of producing the self-supporting product container of any one of claims 1 to 10, comprising the steps of forming a first part having a peripheral edge portion thereabout and a product-receiving well, forming a second part having a peripheral edge portion thereabout and a well to accommodate the product-receiving well in all-round mutually-spaced relation, and uniting the first and second parts at their peripheral edge portions with the first part inner and the second part outer relative to the container as a whole.

12. A method as claimed in claim 11, in which the first and second parts are formed from sheet materials and brought together at a joining station.

13. A method as claimed in claim 11, in which the first and second parts are formed form sheet materials in a differential-pressure thermoforming station substantially simultaneously and opposite each other, the well of the first part being subsequently invented.

14. A method as claimed in claim 11, further comprising the step of applying a sealed cover over the first part after loading its product-receiving well with product.

15. A method as claimed in claim 14, further comprising the step of introducing a desired atmosphere into the product-receiving well.

16. Apparatus to make the self-supporting product containers of any one of claims 1 to 10, comprising means for forming first and second parts each with peripheral edge portions thereabout and receiving wells, the receiving well of the first part being for product and the receiving well of the second part accommodating the product-receiving well of the first part in all-round mutually-spaced relation, and means for joining the first and second parts at their peripheral edge portions.

17. Apparatus as claimed in claim 16, comprising separate forming stations for the first and second parts and a joining station where they are brought together.

18. Apparatus as claimed in claim 16, comprising a single forming station having opposed forming chambers for forming the first and second parts substantially simultaneously in opposite directions, and means for inverting the well of the first part.

19. Apparatus as claimed in claim 16, further comprising means for applying a sealing cover over the first part after loading product into its product-receiving well.

20. Apparatus as claimed in claim 19, comprising a sealing station including said means for applying a sealing cover and means for communicating separately with the wells of the first and second parts.

21