CA1039666A - Enclosures for baking - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Pouches and the like for use in cooking are formed from two webs of identical or dissimilar thermally stable materials bonded by an infusible adhesive.

Description

Back round of the Invention g The present invention relates to enclosures in tubular member form useful in the cooking of foods. More particularly, the invention relates to bags and pouches useful in cooXing applications. The tubular members of the invention suitably comprise thermally stable materials such as polyester films, nylon, metallic foils adhered with an infusible resin.
In recent years, the packaging industry has pro- -moted extensive use of pouches for packaging articles to be subject to conditions such as high and low temperatures, as, for example, packaging frozen food products and products to be cooked.
One modern procedure for making such pouches is to join the walls of a plastic film material together by a heat sealing process. This procedure requires that the film be of a physical character which will permit sealing by the application of heat and pressure. Webs which do not have heat sealing characteristics have not been considered suit-able for making tubular members, bags and the like. For example, the application of a coating to a surface to allow the walls of a bag to be joined at its edges by a heat sealing process, ;-increased the cost thereof. Another problem encountered in present methods of making pouches is that the time required for increasing the temperature of the material sufficiently to ~ ~'''''

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~03g666 heat seal webs together, restr~cted the output rate. Another difficulty has been that many heat sealable materials such as polyethylene are incapable of withstanding ordinary cooking temperatures in the range of 300F. and higher.
The present invention discloses plural walled members having unique properties permitting them to be used as enclosure mediums for foods or other articles to be cooked, baked or subjected to cooking temperatures. Surpris-ingly, a plural walled member is also taught that is particularly useful for cooking purposes comprising a wall of a thermally conductive material such as a metallic foil and a transparent wall which permits visual inspection of the article contained within.
The plural walled member of the present invention comprises at least one web of material interconnected by an adhesive at at least a first marginal edge of said web to form said member. It has also been found that a plural walled member having at least two webs of material one of said webs being non-heat sealable is useful in the present invention. The webs are adhesively interconnected along at least two opposing edges with an adhesive. The pre-ferred adhesive of this invention is infusible at relatively elevated temper-atures such as cooking temperatures from about 300F. to about 450F. The adhesive must also be free of toxic or harmful materials not consonant with its use with foods.
In particular, the present invention provides a plural walled member for enclosing food to be cooked, said member comprising as its sole structural elements two overlying webs of film material, each of said webs being ther-mally stable at cooking temperatures from about 300F to about 450F, the first of said webs being transparent to permit visual inspection of the con-tents of said member, the second of said webs being a metallic foil, at least one of said webs having an adhesive area generally along only two opposite side edges, said adhesive being infusible at temperatures from about 300F to about 450F, whereby said webs are interconnected along opposite con~ronting edges to form a sleeve to enclose food during a cooking or baking process.

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In order to offer greater convenience to the consumer the article of this invention ma~ often be found in pouch or bag form for a bake or roast in the bag application. Pouches having utility in this invention as an enclosure - `
mcdium for food to be cooked suitably corprise two webs of film material ;~ ~, ` "

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~039666 selected which may be selected from groups consisting of non-heat sealable materials or heat sealable materials. The film material are preferably thermally stable resins such as polyester resin or nylon and metallic foils such as aluminum foil. Polyethylene terephthalate (Mylar*) has been found to be particularly suitable for use as a web material in the instant invention.
Pouche~ from the foregoing material may be formed by adhering opposing edges of said webs with a suitable adhesive. It has been found that adhesives useful for securing the films of this invention are saturated polyester resins that are modified with non-drying alkyds and are C$055-linked with polyisocyanates, which imparts greater temperature resistance.
Typical examples of the polyisocyanates are tolylene diisocyanate, triphenyl methane 4,4'4" triisocyanate, and the like. The aromatic polyisocyanates are preferable for manufacturing the infusible adhesives of the invention.
Representative saturated polyesters are reaction products of, for example, trimethylolpropane, adipic acid and phthalic anhydride, propylene glycol and sebacic acid, and ethylene glycol (from 10 to 90 mol percent) propylene glycol (10 to 90 mol percent) and azelaic acid, in which the molecular ratio of hydroxyl compound to acid is greater than 1:1 to form polyester polyhydroxyls having primary terminal hydroxyl end groups available for reaction with isocyanates to form urethane linkages.
The adhesive useful in forming the plural walled memebers or ~ -pouches of the invention generally has an average molecular weight range in ;-~
the order of about 1000 to about 5000.
EXAMPLE I
A layer of a polyester urethane adhesive having a * TRADE MARK

- A -thickness o~ about 1 mil is app]ied to a polye~hy]~lle ter~-phthala~e we}~ 1~ inches wide alony three side edges there~f.
The adhesive may be made from the reaction product of a diisocyanate cross-linked with a combination of a saturated polyestcr and a castor oil modified phtalic anyhydride-glycerol resin wherein the ratio of polyester to isocyanate is about 3 parts polyester to about 2 parts isocyanate.
The polyethylene terephthalate web is then adhere~
to a second polyethylene terephalate web by passing said webs through a pair of cooperating contact pressure rollers to form a pouch.
EXAI~PLE II
- A pouch comprising webs of polyethylene terephalzte and prepared in accordance with this invention was filled wi~h a beef chuck roast and then closed by means of tie. The roast was cooked in an oven at 400 F. fox 1 hour. Therea~ter the meat was removed from the pouch which exhibited no leakage or other failure. -The cooked beef exhibited an excellent tender texture and fine flavor.
It has also been found that enclosures made of dis- -similar materials wherein one of the materials is a metallic foil offers unique advantages for cooking applications. For example a plural walled member having one web of a transparent heat stable material such as polyethylene terephthalate and a second web of an aluminum foil offers several advantageous features when compared to enclosures made of film materials.
A plural wàlled member having an aluminum foil web may be sealed without the use of ties and the like in view of the fold and dead se~l properties of the aluminum. The use of a self-sealing bag relieves the consumer of the necessity of .. ::
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. -1~39~;66 tyin~ the cnd or cnds of a bag and also avoids po~r~tial leakage problcms ~then a ba~ is not propcr]y tied.
~ hc use of aluminum foil or othcr metal foils also o~er improved heat distribution for ~he article within the enclosure. In addition a bag or the like having a foil web will resist burning or flaming to a greater extent than a bag having only plastic film walls.
The transparent web o the enclosure provides visi-~0 bility of the contents. This allo~s for visual inspection ofthe conents of articles made in accordance with this invention.
EY~LE III
A beef chuck roast is placed in a plural walleG
member comprising a web of Mylar and a web of aluminum foil sealed with the adhesive of Example I. The bag is sealed by means of the fold and dead seal properties of the alur,inur.
foil and the meat is then cooked in an oven at 400 F, for about 1 hour.
In a taste test the roast cooked in an enclosure made as in Example III has a generally more pleasing taste than a roast cooked and browned rore than a simultaneously cooked roast in a bag made solely of plastic film.
In addition to the infusible polyester urethane adhesive material previously mentioned other polyester isocya-nate adhesives can be used. One useful adhesive is a resin manufactured and sold by the E. I. Du Pont de Nemours & Co.
as Du Pont resin~No.~ 46982.
In order to effect an adequate seal bet~een web members the infusible adhesive resin should be applied in a thickness of at least about 0.2 mils. More suitably the : , ' ,`' ~, ,~

~1~)39666 adhesive layer should be from about 0.6 mils in thickness to about 0.9 mils in thickness. Various methods of manu-facture may be used in making the enclosures of this invention. Enclosures can be manufactured which are essentially webs of material in endless sleeve form.
Ribbons of these sleeves can be pack~ged so that the consumer can tear off a convenient size for the particular article to be inserted. Alternatively, the sleeves may be scored to provide a master ribbon of individual enclo-sures such as pouches.
It will be observed that variations and modifi- ;;
cations may be effected without departing from the spirit and scope of the novel concept of the invention. It is, of course, intended to cover by the appended claims all ~-such modifications as fall within the scope of the invention.

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Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A plural walled member for enclosing food to be cooked, said member comprising as its sole structural elements two overlying webs of film material, each of said webs being thermally stable at cooking temperatures from about 300°F to about 450°F, the first of said webs being transparent to permit visual inspection of the contents of said member, the second of said webs being a metallic foil, at least one of said webs have-ing an adhesive area generally along only two opposite side edges, said adhesive being infusible at temperatures from about 300°F to about 450°F, whereby said webs are interconnected along opposite confronting edges to form a sleeve to enclose food during a cooking or baking process.

2. The plural walled member of claim 1, in which said infusible adhesive resin is a polyisocyanate adhesive having an average molecular weight of about 1000 to about 5000.

3. The plural walled member of claim 1, in which said infusible adhesive resin comprises a polyester isocyanate resin having a ratio of polyester groups to isocyanate groups of about 3 to 2.

4. The plural walled member of claim 1, in which said infusible adhesive resin comprises an isocyanate cross-linked with a combination of a saturated polyester and a caster oil modified phthalic anhydride-glycerol resin wherein the ratio of polyester to isocyanate is about 3 parts polyester to about 2 parts isocyanate and said resin has an average molecular weight of about 1000 to about 5000.

5. The plural walled member of claim 1, in which the first web is selected from the group consisting of polyester film and nylon.

6. The plural walled member of claim 1, in which said polyester film comprises polyethylene terephthalate.