JPH03162424A - Film structure provided with a pattern and its manufacture - Google Patents

Abstract

PURPOSE: To provide a structure which gives a cook-in package which minimizes the loss of protein or moisture when cooked together with the contents and allows the contents to be taken out without causing sticking to the inner wall by subjecting the surface of a plastic to corona discharge treatment to form a discontinuous pattern.

CONSTITUTION: This structure is a plastic web which has one side subjected to corona discharge treatment to form a discontinuous pattern thereon and has adjacent untreated areas on the side. A plastic web 23 is fed from a feed roll 21 to a treating zone, is brought into contact with a part (generally a wrapping angle of 100-230° being suitable) of the outer surface of a roll 31 having a desired pattern formed thereon, is selectively subjected to corona discharge treatment with a corona field generated by a treating bar 46, and is wound up with a winding-up roll 26. For example, the pattern of the outer surface comprises regularly repeated rhombic zones demarcated by ridges 36, 37 upheaved spirally.

COPYRIGHT: (C)1991,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides surface-treated plastic web members (
(including membranes and laminates), and in particular to such structures in which a pattern is produced in a portion of the surface, which is achieved as a direct result of a charge treatment.

In order to increase the yield of meat products in cook-in packaging, tuck-out of fluids from the meat (cook-o
It has been recognized to date that flexible plastic containers having an inner wall portion that conforms to the meat product placed therein and that adheres to the meat during cook-in are used to minimize and even virtually prevent ut). It's here. The container itself may be a filler container or similar container that initially compresses the meat tightly against the walls of a somewhat resilient container member such as a casing, which means that the container used is Displays heat shrinkage characteristics that indicate capacity for shrinkage, allowing the container in a sealed form to closely conform to the meat placed within it, resulting in changes in the shape of the meat during the cook-in process. It is compensated by the shrinkage properties of the container during cooking.

For example, U.S. Pat. No. 4,411,919 to Thompson describes the cook-in of packaged meat using highly irradiated meat attached to the interior surface of a container made of a polymeric olefin, while U.S. Pat.
U.S. Patent No. 4,606,922 to Meat Cooker
They advocate the use of a layer of irradiated ionomer as the material that adheres to the inner surface of the container.

Cook-in packaging methods for attaching such meat exhibit certain disadvantages, especially in certain use environments. One problem is that when meat packaging utilizes meat with skin, such as turkey or other poultry meat, the meat that adheres to the inside surface can aggressively adhere to the skin, so that following cook-in, Upon removal of the packaging from the meat, the skin is torn from the cooked meat, producing the undesirable result of separation. Thus, even if fluid release or cook-in problems were overcome, the separation of the skin from the meat would be commercially disadvantageous.

Another cook-in packaging technique involving plastic containers
One problem is that it is difficult to correlate the amount of irradiation, corona treatment, or even ozonation applied uniformly to a plastic surface depending on the degree of adhesion of meat or other high-protein materials, and it is clearly not currently possible in some cases. Inherent in the possible environment. In other words, the degree and scope of flesh adhesion are currently
It does not appear to be possible to adjust by the amount of uniform surface treatment previously applied to the area of the surface of the intended cook-in container that is to be used for meat processing (preferably without emissions).

Another problem with cook-in packaging technology is that the uniform surface treatment of the intended inner surface of the cook-in container, which is treated to improve the capacity of the high-protein food to which it adheres, is It is important to note that heat sealing to a similarly treated surface of plastic would reduce the ability of the treated surface to adhere, even though the composition of the cooked-in plastic being filled This is because it is common for the container to be sealed before being subjected to cooking temperatures by heat-sealing together parts of the adjacent internal wall surface. Unless some container seal is formed, which occurs at about 200'F in cooking beef, the container seal tends to open during cooking, producing undesirable results.

When parts of the internal surface are treated by corona discharge, gamma radiation, ozone, etc., slight changes occur in the treated surface. The chemical nature of this change is unknown, but it is believed to represent at least some oxidized surfaces (possibly partially oxidized surfaces) that are assembled and heat-sealed;
The resulting seal tends to be weaker than the corresponding seal created between untreated surfaces. This result therefore has implications when the inner wall of the container is to be attached to such food products, e.g. to achieve release-free cook-in product packaging.
Presents problems in supplying containers for cook-in of meat and other high protein foods.

There is a need in the art for new and improved meat adhering surfaces for use in containers intended for use in the field of cook-in meat packaging.

More particularly, the present invention relates to plastic materials patternwise treated separately (selectively) with corona discharge, and methods of making and using the same, as well as products resulting therefrom.

In one aspect, the invention provides a plastic web for one
The plastic web is subjected to a selective pattern of corona discharge treatment such that one surface layer is patterned. This pattern is characterized by selective corona discharge treatment in certain areas. Preferably, the pattern has relatively small repeating units. One preferred pattern has a pattern unit in which the central area is treated but the edges and surrounding areas are substantially untreated.

This aspect of the invention further includes a method of achieving such a selectively patterned corona discharge treatment.

In another aspect, the invention is a container structure adapted for cook-in packaging to which meat (or other high-protein foods) is attached, whereby the cooking of such foods is made from meat or other high-protein ingredients. The present invention relates to said container structure which can be achieved with virtually no outflow of fluid (i.e. without release). The container may be non-formable or formable.

In another aspect, the invention provides a method for preparing packaged meat (or other high protein foods) when cooked within the package, and where emissions are minimized or eliminated, and where such foods adhere to internal container walls or the like. It relates to said packaged meat (and other high protein foods) which can be removed from the packaging without loss.

In another aspect, the invention provides a method for contacting heat-sealable untreated plastic materials, particularly when the contact surfaces are each constructed of substantially the same plastic material and are adapted to form an inner wall portion of a container. to obtain an improved heat seal between surfaces that For example, in the case of prior art plastic containers in which the container is conveniently hermetically closed by heat-sealing portions of the container's uniformly corona discharge treated internal surface together in the mouth or lip area. especially when the sealed container is subjected to increased temperatures, high shrinkage rates, and in some cases pressure increases sufficient to allow cook-in when the sealed container is filled with high protein food. It is common to experience problems with seal weakening. The parts of such internal surfaces that are so sealed together have heretofore been uniformly treated, such as by corona discharge, which alters and improves the internal surface properties with respect to the adhesion capacity of proteins (eg meat, etc.). As indicated above, such prior art treatments can lead to seal loss during cooking compared to the corresponding bond strength achieved between corresponding untreated but sealed surfaces. This is because the sealing bond created between surfaces sealed by

However, unlike the prior art, the respective contact surfaces that are heat sealed together are identical or similar surfaces that have been selectively surface treated with corona discharge according to the invention, for example in combination with a selective treatment pattern. An improved heat seal is obtained which exhibits improved overall bond strength when each constructed of plastic material. Variations in the selective surface treatment (corresponding to the treatment pattern) result in untreated areas of one surface being intermittently along the length of the elongated sealing region created by heat sealing, and non-treated areas of the adjacent contact surface. The change is such that it lines up with the treatment area. The shape in combination with the treated pattern can be used to enhance the increased bond strength achieved in the heat-sealed region.

In another aspect, the invention provides for high protein ingredients such as meat (including poultry and fish), eggs, cheese, etc. to be cooked in a sealed plastic container, and a portion of the interior surface of such container This allows for the creation of improved packaging in a form that is adhered to high protein materials such as. According to the invention, such an inner surface portion of the cook-in container:
It consists of a layer of plastic material that has been selectively surface treated, such as by corona discharge, to combine with the desired treatment pattern. Such a container is opened after cooking,
and when the wall section of the container is separated from the protein-rich material, the destruction (change) of the treated area with respect to the untreated area is similar to that of prior art containers whose inner walls were uniformly treated, such as by corona discharge. It has been found that this results in the destruction of less protein-rich material than would normally be expected to be present, as well as the separation of such protein-rich material from the main body.

Thus, when separation or delamination of the cooked-in high protein material from adjoining wall portions of the container to which it adheres is achieved, the non-uniform deposition pattern will cause the non-protein high material to separate and, in fact, This results in depletion of the main body of high protein material. Clearly, highly treated areas with selective treatment patterns are visually separated by untreated areas or only slightly treated areas. This fragmentation is in fact selectively treated, unlike the situation existing in the prior art where uniformly treated surfaces appear to substantially promote undue separation and depletion of the cooked-in high protein material. It acts as a mechanism to promote maximum release of protein-rich material from the textured surface areas.

The present invention thus overcomes the disadvantages associated with uniformly adhering meat (high protein) packaging materials, and provides improvements that allow for the separation of high protein foods cooked therein with minimal loss from such foods. Allows for the provision of cook-in meat (high protein) containers with sealed seals.

Other additional objectives, intentions, features, advantages, embodiments, applications, and the like will be apparent to those skilled in the art and teachings of the invention when considered in conjunction with the accompanying drawings.

Referring to FIG. It is generally designated by the number 20 in the figure. In the apparatus 20, a feed roll 21 is journaled for rotational movement on an axis 22 such that a web 23 is conveyed from the feed roll 21 to a processing zone 24 and thence ultimately to a conventional power train. 28 (not shown in detail), which is placed on a driven shaft 27 which is driven in rotation by a winding roll 28 (not shown in detail). A plurality of tension guiding rollers 29 are provided for regulating the passage of web 23 through processing zone 24 .

In the processing zone 24, the web 23 comes into contact with a portion of the circumferential surface of the roll 31, the portion or area to be wrapped being indicated generally by the numeral 32 for convenience. Preferably, as shown, such contact portion 32 spans approximately 180° of the circumferential surface 34 of roll 31. Wrap angles in the range of about 100" to 230 degrees are generally believed to be useful, although wrap angles may be larger or smaller without departing from the spirit and scope of the present invention. Generally, wrap angles are set so that the web is The angle must be sufficient to eliminate undesirable backside treatment of the web being processed in its area contacting the roll. A wrap angle as supplied is better than that achieved using a smaller wrap angle. Applicator roll 31 is provided with a power head (not shown) such that the speed of its outer periphery matches the running speed of web 23. Alternatively, if desired, the applicator roll 31 can be driven by tension on the web 23 at its outer peripheral surface portion 32.

The outer circumferential surface 34 of the roll 31 in the illustrated embodiment is made of steel and is pre-scorched with the desired pattern. The current choice is to use a roll 31 with a pattern on the surface 34 characterized by a regular repetition of a repeating design over the length and circumference of the roll 31. In the presently preferred embodiment, as shown in FIGS. 1 and 2, the design takes on a lenticular or diamond pattern, with the edges of the individual diamonds extending over the outer circumferential surface 34 of the roll 31. are formed by raised ridges or bars that span the spirals, one set of individual ridges spanning the generally clockwise spiral in this figure, while another set of individual ridges 37 generally span the individual spirals. It spans perpendicular to the ridge 36, but in a counterclockwise direction (as viewed from the end 38 of the applicator roll 31 as shown in FIG. 1, for example). The respective diamond-shaped regions 39 thus formed between each pair of intersecting ridges 36 and 37 are depressed relative to the protruding outer circumferential surface of the respective ridges 36 and 37.

For example, in the embodiment shown in FIG.
generally triangular in shape tapered to 4
side walls 40, so that each region 39 is now pyramid-shaped or porous.

Those skilled in the art will appreciate that such a sidewall 40 for a given area 39
in the shape of the pattern imparted to achieve or enhance a particular desired shape of treatment effect in the treated web member 23 such that the treated web member 23 has a treated patterned surface produced by the practice of the present invention. I think I'll admit that it's made.

In view of making the selectively textured surface treated web of the present invention, the general design of the pattern is not believed to be exact;
Rather, the exact design of a given web is, to some extent,
It is a matter of personal preference as well as cost. For example, area 3
The shape of the diamond pattern structure shown in Figures 1 and 2 with 9 is similar to that of an aniline printing machine in which the color or coating is transferred from a fountain roll to a plate or coating roll without the use of a doctor blade. The shape of the structure is similar to that used in combination with steel engraved applicator rolls, as most commonly used to add light and medium color or coatings to. Such roles are available, for example, at Modern Hillside, New Jersey.
Engraving and Machine Company (M
odernEngraving and Machine
e Company). In such rolls, the depth of the pyramid shape is, for example, about 0.05 to 0.05 mm. 0009 inches (approximately 1.27 to 0.009 inches)
02286 mm). The width across the surface of the ridges 36 or 37 can vary from a knife edge to a flat condition, with such widths ranging for example from about 0.
．． 001~0. 05 inch (approximately 0.0254~1
．． 27 mm). Other designs, dimensions, depths, etc. are believed to be useful and are within the spirit and scope of the invention.

For example, a star-shaped or circular pattern may be used on surface 34.

In another example, the design shown in FIG. 3 can be used for web processing. Such a design is also conveniently combined with a steel applicator roll 3l. In this case, the plurality of ridges 42 are arranged in a spiral manner across a portion of the outer circumferential surface of the applicator roll, leaving depressions 43 of triangular cross section between successive ridges 42. Conveniently, this three-stroke helical cell structure is similar in shape to the knurling structure combined with the applicator rolls used to bulk apply colors and coatings to machines using doctor blades. , such rolls are also available from Modern Engraving and Machine Company. For example, the maximum depth of such a pattern is approximately 0. 01~0. The width of the ridge is as described above if desired, although it can be approximately 0.009 inch (approximately 0.254 to 0.2285 mm).

Alternatively, instead of the engraved steel applicator roll 31,
Applicator rollers with a peripheral surface of silicone rubber or a surface of elastomeric hardened plastic can be advantageously used. Such surfaces can be patterned by laser etching methods known in the art.

Alternatively, instead of the engraved steel applicator roll 3l, an applicator roll with a continuous outer circumferential surface can be used. This outer peripheral surface is wrapped in a spiral shape with a plastic tape member made of polyethylene terephthalate or the like (the side edges are in contact with each other). The tape member is die-cut before being so wrapped to incorporate the desired coating pattern therein. Tape thickness is approximately 5-20 mils (approximately 0.15-0.6
millimeters), although a range of lO to 20 mils (about 0.3-0.6 millimeters) is currently preferred.

In the embodiment shown in FIGS. 1 and 2, the web 23
The entire web 23 contacts the ridges 36 and 37 as it moves over the peripheral portion 32 of the roll 31, so that 100% of one side of the web 23 contacts the peripheral surface portion of the roll 3l.

Extending longitudinally across the roll 31, but extending laterally across the web 23, is a treatment bar that is also close to but perpendicular to exposed adjacent surface portions of the web 23. They are placed in space so that they are separated and related to each other. The bar 46 is also positioned such that it is in the central region of the contact portion 23 where the web 23 contacts the outer circumferential surface 34 of the roll 31. The processing bar 46 conveniently
This is a commercially available form for corona discharge treatment of plastic films, laminates, etc. When the roll 31 has a steel engraved peripheral surface 34, a suitable treatment bar 46 is manufactured by Enercon Co.
in ceramic form, such as those available from Mpany. When the roll 31 has a plastic surface, such as one that is corroded by a laser, it is possible to
Electron discharge type treatment bars 46, such as those available from manufacturers such as Pillar, are conveniently used. As those skilled in the art will appreciate, electronic discharge equipment is generally less expensive than ceramic processing equipment, and therefore, for cost reasons, processing rolls with plastic or elastic (rubber) outer circumferential surfaces are chosen in the practice of the present invention. It may be used in

the width of the corona field generated by the treatment bar 46, the amount of energy combined with the corona, the extent of wrapping of the web 23 around the peripheral surface 34, the running speed of the web 23, the design of the pattern on the surface 34 of the roll 31 and depth,
As well as various other process variables, as those skilled in the art will readily appreciate, may affect the extent and type of corona discharge treatment achieved on a given web 23. However, because of the pattern associated with the peripheral surface 34 of the roll 31, the corona discharge treatment is selective, so that, for example, in the case of the design shapes shown in FIGS. This results in a corona treated web product resulting in an area of web 23 overlying depressions 39. The raised areas 36 and 37 in contact with the web 23 result in an untreated area of the web 23 adjacent to a particularly corona-treated discrete area in the web 23 (resulting from the web overlying the corresponding depressed area 43). ).

Thus, the web 23 processed using the apparatus of FIG.
has, for example, a treated pattern that substantially corresponds to the pattern or design shown in FIG. 4, and such pattern or design can be revealed by dyne measurement or the like. For example, dyne measurements can be accomplished using dyne measurement techniques and dyne measurement solutions commercially available from Pillar Company of Milwaukee, Wis.

As those skilled in the art will appreciate, any convenient measurement method can be used to confirm or recognize the pattern or even the presence of treated areas on the web 23.

For example, the treated web 47 shown in FIG.
It is shown as a two layer co-extruded laminate, identified as layer 49 and layer 49, respectively. Any convenient composition of resin may be used in each layer 48 and 49. For example, when treated web 47 is to be used in cook-in meat packaging, layer 48 is comprised of a melt-extrudable ionomeric polymer, polyethylene, or the like. Ionomeric polymers are available, for example, from E.I. under the trademark "Surlyn J.
DuPont & Denemers & Company (
E. I. Dupont and DeNemours
Zinc or sodium ionomers may be commercially available from John & Co., Ltd.

The thickness of web 47 is approximately 3 to 10 mils (approximately 0.076
2-0. 254 millimeters) or as desired, the thickness of layer 49 may be approximately 1 to 7 mils (approximately 0.0254 millimeters) along with the thickness of layer 48 to achieve the desired total thickness or as desired. ~0.1728 mm). Either or both of layer 47 or layer 48 can be selectively treated to incorporate the treated pattern as shown herein.

Generally, web 23 is a polymeric (plastic) material as desired.
It may consist of one or more layers. Suitable polymers with surfaces known to exhibit improved adhesive properties after corona treatment are preferred, such as polyesters, polyolefins (particularly polyethylene and polypropylene), polyamides (for combinations of elastomers and polyolefins). 1).

FIG. 5 shows an example of a three-layer coextruded non-formed membrane structure, designated as a whole by the numeral 80, with the individual layers represented by the numerals 81, 82 and 83, respectively. There is. The layer 8l consists in this case of an ionomeric polymer based, for example, on a zinc salt of an ethylene/methacrylic acid copolymer.

The layer 83 is in this case made of, for example, linear low density polyethylene (
LLDPE).

LLDPE is commercially available from a variety of manufacturers, such as from EI DuPont under the trademark "Sclair J."

Layer 82' in this case consists, for example, of ethylene/methacnolic acid polymer (EAA or EMAA). In fact, layer 82 consists of zinc ionomer layer 81 and LLDPE layer 83.
Acts as a bonding layer between

As will be recognized by those skilled in the art, ethylene/methacrylic acid copolymers are available from a variety of manufacturers, e.g.
It is available from EI DuPont under the trademark ucrel) J.

In membrane 80, the thickness of each of the individual layers 81, 82 and 83 may vary considerably without departing from the spirit and scope of the invention.

The co-extruded membrane 80 in a preferred embodiment of the invention comprises:
The membrane is first extruded into a tube and then thermally blown with the tubular membrane moving up the column using conventional equipment of the type previously used for thermal blowing techniques such as single layer polyethylene membranes. Included. During heat blowing, the three-layer coextruded tube is elongated and expanded in diameter to achieve double-sided orientation.

The finished blow tube is then neatly crushed using nip rollers, and then the crushed tube is cut into strips and rolled onto storage rolls. Each resulting sheet or film is then processed using apparatus 20 as shown and described with respect to FIG. Either layer 81 or layer 83 can face treatment bar 46 as the web moves over roll 31. The so treated and slit membrane is then wound onto a take-up roll.

The resulting selectively treated layer 83 is particularly suitable for the attachment of meat (and other high protein ingredients) such as turkey, beef, ham, cheese, eggs, etc. The same is true. The current trend is for layer 83 to be used for turkey (boneless or equivalent) and layer 81 for ham. Layer 80 is the cooking temperature (usually about 185~
It has the capacity to heat shrink at 200°F.

To prepare a formable web structure using selectively treated membrane 80, a preformed layer 84 of, for example, a cast selective polyamide with low crystallinity and highly amorphous structure is obtained. . Such polyamide membranes are commercially available, and current trends include E. I. DuPont of Canada under the trademark rEN972J or Allied Che
A polyamide membrane commercially available as Polyamide No. 1539 from Micals) is used. Layer 8 if possible
The thickness of 4 is preferably about 2 to 6 mils (about 0.05 to 0.15 millimeters), although thinner or thicker membranes may be used if desired. Layer 84 has the capacity to heat shrink at cooking temperatures (typically about 185-200 degrees F.).

To bond membrane 84 to either side of membrane 80,
A layer of adhesive is used between membrane 84 and membrane 80. One suitable adhesive is E. I. Trademark R5 from DuPont
A polyester adhesive such as that sold as 6065J.

In the formable web embodiment illustrated in FIG. 6 and designated generally by the numeral 86, layer 81 is thus bonded to one side of membrane 84 through layer 87 of adhesive. How about polyester adhesive? Night body kiya. It is preferred that the carrier be applied as a solution or powder to the polyamide N84 or to one of the layers 81 or 83, after which the carrier is evaporated leaving a thin layer of polyester adhesive. The respective layers are then combined into a composite laminate with the aid of heat and pressure to achieve the desired formable web structure 86.

The total thickness of such web 86 is approximately 4 mils (approximately 0.5 mils).
1 mm) thicker and approximately 11 mils (approximately 0.28
mm).

To provide a laminate structure suitable for use as a non-formed lid material, a web 88 as illustrated in FIG. 8 is provided. Web structure 88 has three layers: an outer layer 89, an inner layer 91, and an intermediate layer 92. In the illustrated embodiment, outer layer 89 is preferably comprised of polyamide, which resembles a polymer in structure and physical properties similar to the polyamide comprising membrane 84. Intermediate layer 92 is a polyester adhesive that is preferably similar in function and composition to the polyester adhesive used for layer 87 described above.

Inner layer 91 may be comprised of a zinc ionomer similar to the zinc ionomer used in layer 81 described above, or alternatively may be comprised of linear low density polyethylene similar to the linear low density polyethylene described above with respect to layer 83. When layer 83 is exposed, ie, is made to include the inner surface of a formable web structure such as structure 86, layer 91 is LLDPE, preferably matching the composition of the LLDPH used for layer 83.

However, if layer 81 is the inner surface of a formable web structure (not shown), then layers 81 and 83 are the sixth layer.
When placed in the opposite relationship to the respective positions shown in the figure,
Layer 92 is comprised of a zinc ionomer having a composition desirably comparable to the composition of the zinc ionomer used in layer 81.

Formable webs such as 86 are conveniently manufactured into rolls and in this form are conveniently fed to cook-in meat processors and the like. Such users may create their own plates, such as serving plates 93, from the web 86, which may need to be shaped and, depending on the construction used for the formable web, optionally include selectively processed layers 8l. What is necessary is to make the inner surface of the plate made of or 83. In some shaping operations, the shaper typically uses some of his own shaping equipment and procedures.

It is standard and desirable that the molding equipment and molding conditions associated with the production of the dishes utilize low temperatures, typically well below the normal thermoforming temperatures known in thermoforming technology; Nevertheless, such temperature is increased to a temperature high enough to soften the web structure 86 and allow some stretching. Forming equipment is standard and preferred in the form of what is known in the art as a "plug assist" thermoforming equipment. After forming, such as pan 93, the pan is separated from the mold or molding equipment. , quenched, and ready for filling and carving with meat or other high protein material. Dish 93 is then filled with high protein material and sealed with web 88. During the forming operation, web 86 is actually The entire procedure is commonly referred to in the trade as "cold forming".

The side of web 88 that is sealed to the edge of dish 93 is selectively processed in accordance with the present invention as shown in FIG. 1 and described above.

Thus, the inner layer 91 is made of zinc ionomer or LLDP.
Such a layer, whether or not made of E, is heat blown and then exposed to an extruded tube facing a patterned roller and subjected to a corona discharge using, for example, a device of the general configuration as shown in FIG. , thereby creating a membrane 9l having a pattern that is desirably similar or even identical to the pattern associated with the exposed external surface of membrane 80 in laminate 86, as will be appreciated by those skilled in the art.

When continuously heated to cooking temperature during the cooking time,
Dishes such as dish 93 tend to shrink or effectively "recover", and the maximum possible amount of dimensional shrinkage at such temperatures depends on the degree of elongation achieved in the dish molding, the size and construction of the dish. , etc., as would be recognized by those skilled in the art. It is a shaped, filled and sealed container, such as container 94 shown in FIG. 7, which is heat sealed with lid material 88 without releasing or losing meat juices during cook-in. It is this capacity for heat shrinkage of the dish 93 combined with the capacity of the inner wall portion of the dish 93 to adhere to the meat (or other high protein material) being cooked therein, which primarily allows the cook-in to be accomplished.

Thus, for example, when meat (or other high protein material) is filled into container 94 as described above, sealed therein, and cooked therein, a well-sealed cook-in with virtually no emissions can be achieved. product is obtained. Also, since the shape of the pattern is combined with the inner wall portion of the container 94, when the meat is removed and separated from the container 94, no unpleasant loss of meat due to meat adhesion to the inner wall portion of the container 94 occurs.

9, 10 and 11 show numeral 96, made from a membrane or web structure having an overall thickness of about 4 mils, treated in accordance with the present invention.
Figure 2 shows unformed containers identified by 97 and 98, respectively.

Container 96 is in the nature of a casing having an inner wall portion comprised of selectively treated layers according to the invention. The casing 96 is shown filled with a high protein food such as sausage, ham, poultry, etc. and sealed. Typically, the container 96 is sealed at its opposite ends, and the seal is reinforced with a lace loop 99 or the like. A single layer plastic material such as polyethylene is used for the casing 96;
Multiple structures can be used if desired as known by those skilled in the art. The currently preferred single-ply material is polyethylene which is hot extruded into a tube, blown and then processed into collapsed form using apparatus 20 (FIG. 1).

One form of container 97 is shown here that is conventionally made with conventional forming and filling equipment. Although a plastic membrane or web material similar to that used for container 96 can be used, it is desirable to use a material for container 97 that has a slightly greater heat shrinkage capacity during the cook-in operation.

The container structure 98 is a C-shaped container with an opening on one side. Such containers 98 are adapted for preassembly with intermediate storage prior to filling. For example, container 98 is assembled by a container manufacturer and then sent to a food processor for filling, sealing, and cook-in. Preferably, container 98 has heat shrinkage characteristics comparable to those associated with containers such as 97.

As is apparent from the foregoing specification, the invention is susceptible to various modifications and variations that may particularly differ from those disclosed in the foregoing specification and description. For this reason, it is fully understood that all of the foregoing is intended to be illustrative only and shall not be construed as a limitation on the invention other than as indicated and defined in the appended claims. should be understood.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of one embodiment of an apparatus adapted to produce selected patterns of corona discharge treated web members; FIG. 2 is an enlarged view showing a portion of the forming rolls used in the apparatus of FIG. FIG. 3 is a diagram similar to FIG. 2 but showing a different pattern of the forming roll; FIG. FIG. 5 is a perspective view in enlarged form illustrating the properties of a web member treated with the apparatus of FIG. FIG. 6 shows an embodiment of a three-layer coextruded laminate having a surface pattern of
FIG. 5 is an enlarged vertical cross-sectional view of one embodiment of a formable web structure of the present invention utilizing the separately processed coextruded membranes of FIG. 5 in combination with two membrane members; FIG. , FIG. 7 is an illustration of one embodiment of a container structure of the present invention in which the dish portion is made from the web structure of FIG. 6;
Figure 9 shows, in partially enlarged vertical section, one embodiment of a non-formed web structure suitable for use as a crutch for a memorial service. The illustration includes a (filled) selected corona discharge treated web member according to the present invention.
A perspective view of one embodiment of a non-formed container structure, FIG. 10, and a view similar to FIG. 9 showing another such container structure, FIG. 1 is a perspective view of an unfilled container structure of the form shown; FIG. Explanation of symbols: 20 - web production device; 21 - supply roll; 23 - web; 24 - processing zone; 26 - take-up roll

Claims (14)

[Claims] (1) A plastic web in which one surface layer has been subjected to a patterned corona discharge treatment such that the surface of such surface layer has discrete patterned areas therein,
A web characterized in that it comprises corona discharge treated areas separated by adjacent untreated surface areas and separating treated areas. (2) such untreated surface areas in said pattern extend generally continuously and linearly across such surface layer;
The web according to claim 1, characterized in that: 3. The web of claim 1, further comprising: (3) a single layer of plastic material. 4. The web of claim 1, comprising at least two laminate layers, each layer consisting of a different plastic material bonded to each adjacent layer. (5) The plastic web according to claim 1, comprising a repeating design in which discontinuous patterns occur regularly. 6. A plastic web according to claim 1, characterized in that the treated area is bounded by an untreated area to provide a heat-sealing edge of the package created by the web. (7) A method for selectively corona discharge treating a plastic web, comprising: (a) continually advancing said web through a treatment zone; and (b) placed across one side of such web. (c) continuously passing an opposing surface portion of such web in said treatment zone on a peripheral surface portion of a roll member; contact·
the contacting and supporting step, wherein the peripheral surface portion rotates at a speed equal to the advancement speed of the web, and the peripheral surface portion has a pattern of raised and lowered areas formed therein; , whereby the web is selectively treated with its corona discharge area overlying the lowered area. (8) The raised area extends generally continuously in a straight line above such layer, and the lowered areas are discontinuous between the raised areas. The method described in Section 5. (9) A cook-in container of high protein material having an inner wall surface consisting of a high protein material deposited layer of plastic material subjected to corona discharge treatment with a pattern such that a portion of the wall surface is corona discharge treated. (b) selectively contacting and depositing the cooked high protein material in such treated area; and (c) separating a minimal portion of the high protein material from the main body of said container. and facilitating the release of such inner walls from high protein materials cooked within such container. 10. The container of claim 7, wherein the container is filled with a high protein material and sealed. 11. The container of claim 8, wherein the high protein material is cooked within the container. (12) A method for improving the yield of high protein material in cook-in packaging, comprising: (a) filling a cook-in container with the high protein material to be cooked; (a) the filling step, wherein the container is adaptable around the inner wall surface, the container having an inner surface that adheres to the high protein material during cooking, and wherein the inner surface is provided with a selective pattern of corona treatment areas; (b) conforming the container around the high protein material and sealing the container, thereby providing a packaged product; and (c) cooking the packaged product. (d) removing the container from the finished cooked meat, thereby depositing the cooked high protein material on the internal surface; said removing step in which substantially all of said material is emitted from said internal surface. (13) The method according to claim 10, wherein the container is heat-shrinkable. 14. The method of claim 5, wherein the contacting interaction between said peripheral surface portion and said web is such that said back side treatment of said web is avoided.