PT83292B - LAMINATED BARRIER FOR THE RETENTION OF ESSENTIAL OILS AND AROMAS; PROCESS FOR YOUR MANUFACTURE AND CONTAINERS SO OBTAINED - Google Patents

Abstract

Shelf-stable citrus beverage package comprises a 1-piece folded blank lined with glycol-modified PET (GMPET) and contg. a citrus beverage comprising levels of peel oil and l-ascorbic acid approaching those of an equiv. amt. of beverage stored in a glass container. The substrate for the blank is paper, paperboard, fireboard or bleached kraft paper, and the carton has rectangular crossection with fold-in top and bottom closures. Pref. a layer of oxygen barrier material is situated between the substrate and the GMPET. Pref. the outside of the carton is also coated with GMPET. Pref. the GMPET i's uncrystallised. Other substrates may be used in place of the paper blank, e.g. metal foil, ABS, SAN, PVC, polystyrene, polycarbonate, polyethylene, polypropylene, etc.

Description

The present invention relates to barrier laminates, a process for making them and the containers thus obtained. More particularly, the present invention relates to barrier laminates useful in the manufacture of containers and cartons that substantially resist the absorption of essential oils and aromatic components that are present in various drinks contained therein.

In recent years, manufacturers of fruit juices and the consumer public have made some criticisms regarding normal polyethylene-coated cardboard containers, currently used in the market, because of their tendency to absorb several essential oils and aromatic components. that are present in most fruit and citrus drinks. Specifically, these essential oils and aromatic compounds diffuse easily through the inner casing and polieti ethylene are absorbed by both the polyethylene and the card substrate significantly impairing the taste and quality of the _T fruit juice. In addition, oxygen easily penetrates into the container and oxidizes various flavor components that are present in the juice, decreased

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thus, the possible duration of storage of the product and also adversely affecting the taste of the juice. A more detailed description of the problems associated with the use of polyethylene-coated cardboard boxes for packaging citrus-derived drinks is made in United States Patent No. 9429660, which is incorporated by reference in this specification.

A well-known attempt to solve the aforementioned problem was to manufacture containers from a mine that has an intermediate layer of metal foil, usually aluminum. An example of a cardboard / aluminum foil / polyethylene laminate is described and mentioned in United States Patent N93-365 111 which is hereby incorporated by reference. As described therein, the intermediate layer of aluminum foil provides a good barrier that prevents oxygen from entering the container. In addition, the sheet inhibits the drink's essential oils from being absorbed by the cardboard base. However, as expected, it has been found that the polyethylene layer in contact with the beverage continues to easily absorb an unacceptable amount of essential oils and flavoring components from the beverage.

Another attempt to resolve the above mentioned problem of retention of essential oils and flavoring components found in various packaged citrus drinks is referred to in United States Patent N94 513 036 which was issued on April 23, 1985. The barrier laminate described therein comprises, from the outer surface to the inner surface, a cardboard substrate, a propylene polymer web applied to it and an olefin polymer web covering the propylene polymer web. Preferably, the cardboard layer is also coated on its outer surface with a heat-sealable olefin polymer web. Unfortunately, it was found that this laminate only provides a marginal improvement in the retention of essential oils and

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flavoring components in relation to other prior art laminates and containers made from them.

It is also known in the art to use a polyester, such as PET (polyethylene terephthalate), which has excellent aroma barrier properties, in the formation of blow molded bottles to contain drinks made of fruit juices. However, the technique does not refer to any laminate that comprises a substrate such as cardboard that has a layer of polyester such as PET directly attached and that can be used to manufacture a sealed beverage box or container. However, some success has been achieved by indirectly laminating PET to cardboard for use in other applications. For example, United States Patent N94 455 184 describes a method for coextruding a layer of PET, with an intermediate layer of adhesive, to a cardboard substrate. The resulting laminate is useful for building. construction of trays with a small depth that can go into the oven, being well known in the technique that it is extremely difficult to fix by heat, PET to PET, as would be the case when trying to manufacture a cardboard box, with an edge top to powder, coated internally with PET, as described in United States Patent N93 120 333. The greatest difficulty in manufacturing this hot-sealed packaging resides in the high temperatures (about 2609C = 5009F) necessary to fix PET to PET by heat . In fact, at these extreme temperatures, the common card fades markedly and even begins to burn. To make matters even worse, Christian PET liza when it is cooled from such a temperature necessary to create a PET / PET heat seal, thus making it virtually impossible to obtain commercially reliable liquid-tight seals.

Recently, a new polyester resin, generally known as PET-G (glycol modified polyethylene terephthalate), was introduced on the market. While recognizing good clarity, barrier properties and processabi

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quality of this resin, the industry has not realized until today that, unlike PET, PET-G can be laminated on substrates such as cardboard without the need to use intermediate layers of adhesive or pre-treat the substrate with special materials or processes. It is of significant importance that, unlike PET layers, PET-G layers can be heat sealed to each other using conventional heat sealing techniques and equipment. Consequently, the present invention relates to a wide range of laminates that are extremely useful in the manufacture of economical cartons and containers, which not only perform an excellent function in preserving and maintaining the volatile flavoring components found in the drink in them contained, but also have commercially acceptable liquid-tight seals.

In light of the above, a main objective of the present invention is to provide several economic barrier laminates that are useful in the manufacture of containers that have superior retention and preservation properties of essential oils and flavoring components that are present in the various liquids. contained therein, the said laminates comprising a base substrate such as cardboard and an inner layer of heat-sealable PET-G in contact with the drink. In other particularly preferred embodiments, laminates also include intermediate layers of oxygen barrier materials such as aluminum foil, PET, nylon, polyvinylidene chloride (PVDC) and ethylene / vinyl alcohol cup (EVAL).

Another main objective of the present invention is to provide economical containers that are constructed from the aforementioned upper barrier laminates, to achieve the retention of essential oils and flavoring components that are present in many liquids.

Another object of the present invention is to provide a barrier laminate blank which comprises a substrate

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which has an inner layer of PET-G that is in contact with the product, which can be easily folded and heat sealed in a conventional manner to form an economical, liquid-tight cardboard box that substantially preserves essential oils and flavoring components present in the beverage contained therein.

It is yet another object of the present invention to provide a process for the manufacture of upper barrier laminates such as PET-G / carton / PET-G and PET-G / PET / carton / PET ~ G which are useful for the manufacture of packaging , heat sealed in a conventional manner, to store various drinks containing essential oils and flavoring components.

As used in the following summary, the standardized description of the present invention, the expressions essential oils and flavoring components are intended to include the detectable components that are present in many drinks and that have a direct impact on the taste of these drinks, which, in the case of orange juice it includes oil from the peel (of which d-limonene is an important component).

The present invention provides a number of barrier laminates that are useful for the manufacture of containers and cartons for storing various drinks, particularly citrus fruit drinks, which contain essential oils and flavoring components. A common example, which all barrier laminates according to the present invention have, is an inner surface that is in contact with the beverage, consisting of a thin layer or PET-G film. As an example of a particularly preferred embodiment, the barrier laminate comprises a cardboard substrate that has a thin layer of polyethylene terephthalate (PET-G) directly attached to the interior surface of the card in contact with the liquid and its outer surface. Other examples of suitable substrates include paper, foil, acrylonitrile-bu tadiene-styrene (ABS), styrene-acrylonitrile (SAN), polyvinyl chloride (PVC), polystyrene (PS), polycarbonate (PC),

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polyethylene (PE) and polypropylene (PP). In other particularly preferred embodiments of the present invention, the barrier layer comprises a substrate, an intermediate oxygen barrier such as polyvinylidene chloride (PVDCj, ethylene-vinyl alcohol copolymer (EVAL), nylon, PET or aluminum foil; and a thin layer of PET-G as the surface of the container in contact with the drink.

The barrier laminates described above are particularly suitable for the construction of various types of sealed cartons, a well-known example of which is the carton with angled top and the blank for them described in the United States Patent. N93 120 333 which is incorporated in the present specification as a reference. Another particularly suitable beverage container in which these barrier laminates can be used is the Hypa-S container, which is a semi-rigid container available from Bosch Packaging Machinery, a devision of Robert Bosch Techical Products Corporation, Piscataway, NJ, United States of America. Other containers, cartons and packages that can be made of barrier laminates in accordance with the present invention include those described in United States Patent N93 795 359 which was issued on March 5, 1974 to Tetrapak International AB, Lund, Sweden, and United States Patent N93 977 591, which was granted on August 31, 1976 to AB Ziristor, Lund, Sweden, which are incorporated in this specification by reference. Still other containers, cartons and the like that can be made of barrier laminates according to the present invention in / include Tetra PakA- ⁷ , Combi Blocs ⁷ and sheet fiber cans, currently widely used in the packaging industry. frozen orange juice concentrate.

Various methods of making these barrier laminates and boxes and containers obtained from wounds are also described.

Although the specification ends in the claims

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that particularly and distinctly claim the present invention, it is believed that the present invention will be better understood by reading the following description in which reference is made to the following drawings in which: Figure 1 is a straight section view of a shape of making a barrier laminate according to the present invention;

Figure 2 is a cross-sectional view of a particularly preferred barrier laminate according to the present invention;

Figure 3 is a cross-sectional view of a machine for making a barrier laminate according to the present invention; and Figure 4 is a cross-sectional view of another barrier laminate, particularly preferred according to the present invention.

Figure 1 is a cross-sectional view of an upper laminate 10 according to the present invention. In Figure 1, laminate 10 comprises a substrate material 12 such as cardboard that has a thin layer 14 of glycol-modified polyethylene terephthalate (PET-G) attached to it. It is of particular importance that the PET-G layer is directly attached to the card substrate 12 without the need for an intermediate adhesive layer. It is also of importance that the card substrate 12 does not need to have special characteristics such as having been coated with a primer or having undergone a special treatment such as a corona discharge. For example, the card substrate 12 may comprise normal bleached kraft paper which is well known in the art of container making.

Figure 3 illustrates a machine that was used in the manufacture of the barrier laminate represented in Figure 1. In Figure 3, a film 14 with 30.5 cmx 30.5 cmx 0.051 mm (12 x 12 x 2.0 thousandths) was placed ) PET-G, which was obtained from Van Leer Plastics, Houston, Texas, United States of

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America and it is identified as Product N9 42002, directly on the upper surface of a substrate 12 of cardboard with 30.5 cm x 30.5 cm x 0.61 mm (12 x 12 x 0.024) that was

obtained from the International Paper Company, Stamford, Connec titut, United States of America and substantially identical to that used in the manufacture of its standardized cardboard box with polyethylene-coated top edge. Subsequently, substrate 12 and PET-G film 14 were placed between an upper press plate generally designated 20 comprising an aluminum foil 22 with a thickness of 0.72 mm (0.030) and a sheet of separation material 24 of fluorinated plastic and a bottom press plate generally designated 30 comprising from top to bottom a sheet of separation material 32 of fluorinated plastic, a sheet with the thickness of 0.46 mm (0.018) of cardboard 34, a mat silicone rubber 36 with a thickness of 0.79mm (1/32), another sheet of cardboard 3 with a thickness of 0.46mm (0.018), another silicone rubber mat 36 with a thickness of 0 , 79mm (1/32) and a lower aluminum sheet 38 with a thickness of 0.76mm (0.030). The resulting sandwich was then placed in a conventional heated press having the upper plate 40 heated to approximately 1219C (2509F) and a lower plate 42 at room temperature. The sandwich was applied with a force of fifty (50) tons (approximately 49 kg / cm = 700 psi) for approximately 30 seconds. The press was deactivated and the card substrate coated with PET-G was removed. Particularly significant was the fact that PET-G attaches extremely well to the card without the need to use an intermediate adhesive layer between the PET-G and the card and without having to pre-treat the card with, for example, an electrical discharge . In fact, when it was manually separated from aluminum, the PET-G film was covered with adhered cardboard fibers, thus indicating that the PET-G / card bond was significantly stronger than the bond that they hold together. individual card fibers.

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Figure 2 is a cross-sectional view of a particularly preferred laminate which is useful in the construction of heat-sealed containers and boxes. In Figure 2 the barrier laminate 50 comprises a cardboard substrate 52 which has a thin layer 54 of PET-G attached to the surface of the laminate which contacts the liquid when laminate 50 is transformed into a container or packaging. The barrier laminate 50 also has another thin layer 56 of PET-G which is applied to the outer surface of the card substrate 52 following substantially the same method of application as described above in a single-phase, two-phase process. This externally and internally laminated laminate is particularly suitable for making blank sheets of cardboard which are intended to be folded to form a packaging box and heat sealed in areas where the inner and outer surfaces of the packaging overlap to each other, such as the side seam of the package, the bottom panels and the top panels. An example is a wedge-top package described in United States Patent N93 120 333 which is also incorporated in this specification by reference. .

Surprisingly, it was found that, in the manufacture of packaging from the barrier laminate described in this specification, raw plate forming, folding and sealing techniques well known to those skilled in the manufacture of packaging with a top could be employed wedge. It was particularly surprising to find that, unlike PET layers, PET-G layers easily adhere to each other after they have undergone a conventional heat sealing operation using modest temperatures and pressures, while at the same time having po provides seals impermeable to commercially acceptable liquids. For example, one was cut. barrier laminate comprising PET-G / paper card / PET-G in order to obtain a blank plate with a wedge top, by means of a ~ 2 die and ordinary presses at a pressure of 4.2 Kg / cm relative (60

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psig). Then, the raw sheet was bent in order to obtain a tube of rectangular section with heat sealing the side seam with a sealing device at 1219C (2509F) and a pressure of 4.2 Kg / cm relative (60 psig) for approximately 30 seconds. Then, the bottom flaps were heat sealed with a bottom heat sealing device at 1359C (2759F) and

4.2 kg / cm relative (60 psig) for approximately one minute. The package was then filled with orange juice and then the upper flaps of the package were heat sealed with the sealing device currently used in the industry. Of particular significance was the fact that, unlike PET / PET heat seals, PET-G / PET-G heat seals were liquid-tight and extremely reliable. In part, this is believed to be due to the fact that PET crystallizes when it is cooled from the temperature required to create a hot seal (about 2609C = 5009F) while PET-G practically does not crystallize when cooled to a temperature of twin saddle at about 13 59C (2739F).

Although it has been found that a packaging or container with a layer of PET-G as a surface in contact with the drink, inhibits the permeation of essential oils and flavoring components through them, it has also been found that PET-G is somewhat deficient to prevent oxygen from entering the package or container. As mentioned earlier in the present specification, oxygen oxidizes various components that are found in many drinks, thus causing a change in taste. One solution to this problem is to include an intermediate oxygen barrier layer between the laminate substrate and the PET-G layer that is in contact with the beverage. For example, an intermediate layer of PET between the laminate substrate and the bed of PET-G of the laminate that contacts the liquid provides an excellent barrier against oxygen. This laminate

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barrier is illustrated in Figure 4. In Figure 4, the barrier laminate 60 comprises a substrate 62 such as cardboard which has a layer 64 of PET-G attached directly to it. Laminate 60 has a PET intermediate layer 66 adhered to the internal surface of substrate 62 by means of an adhesive layer 68 such as that described in United States Patent No. 4,455,184 which is incorporated by reference in this specification. Finally, the barrier laminate 60 has an inner layer of PET-G in contact with the beverage, directly connected to the intermediate PET layer 66 through the simultaneous application of heat and pressure.

Other examples of intermediate oxygen barrier materials that can replace the PET 68 intermediate layer of Figure 4 include aluminum foil, PVDC, EVAL and nylon. In some cases, it is also necessary to include bonding resins between the laminate substrate (such as as card) and those intermediate oxygen barrier layers. In general, the resins in this bonding layer are polyolefin-based interlaminating bonding agents used to adhere unaffordable layers to structures obtained by coextrusion or laminates. In addition to bonding different polymer layers, bonding resins are also used to bond polymers to metals (sheets), wood and paper plywood. These materials are either coextruded between other polylilers or coated by extrusion on other substrates before being combined to form composite structures by applying heat and pressure. Coextrusion applications include cast film and sheet, film supplied and extrusion blow molded bottles.

Typical bonding resins include DuPont's CXA resins and the PLEXAR family of resins sold by the Northern Petrochemical Company (Norchem). CXA resins are multifunctional polymers based on an ethylene structure. They include terpolymers, ethylene and vinyl acetate polymers and other types of modified polyolefins.

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PLEXAR resins are produced from modified LDPE, MDPE, HDPE, PP and EVA copolymers.

The choice of bonding resin for a particular application depends on several factors such as the chemical nature of the materials to be bonded, the melting viscosities of the other resins to be treated by coextrusion, the processing temperatures of the material, the type of process used and the type of processing equipment. The bonding resins offered by the suppliers identified above cover a wide range of melt indexes and are capable of bonding numerous base materials used in packaging applications as indicated in an article entitled What Can Be Coextruded? The Sky's The Limit published on pages 78-80 of the September 1980 issue of Modern Plastics magazine which is incorporated in this specification as a reference.

To illustrate the superior quality of PET-G coated and filled cartons according to the above described method in the retention of peel oil, which is considered to be one of the essential oils found in orange juice, an aging study was carried out on orange juice which was stored in cartons made of a barrier laminate according to the present invention. Various packages and containers of the prior art were also tested for comparison. The filled packs were stored at 4.4 ° C (409F) for a period of thirty-five days after which the orange juice was analyzed to determine the percentage of loss of essential oil from the peel. The results are shown in the following TABLE 1.

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TABLE 1% of oil loss from shell

Box A

Box B

Box C

Box D

Bottle E

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<5

Box A

Box B

Box C

Box D

Bottle E

- Normal polyethylene / cardboard / polyethylene box

- Polypropylene / cardboard / polypropylene box

- Polyethylene / cardboard / polyethylene / aluminum foil / polyethylene box

- Box according to the present invention of PET-G / cardboard / PET-G

- glass (control)

All cartons and bottles were 1/4 gallon in size except for package B which was 1/2 gallon in capacity.

The way to proceed practically followed to measure the% of oil loss from the peel is described in detail in Scott, Clifford and M.K. yeldhuis, Rapid Estimate of

Recoverable Oil in Citrus Juices by Bromate Titration,

Journal of the Association of 'Agricultural Chemists, Volume 49 N93,628 - 633 (1966) which is incorporated in the present specification as a reference.

The above comparison shows that packages made of a barrier laminate according to the present invention are clearly superior to other prior art packages in retaining oil from the shell. In reality, the packaging made of a barrier laminate in accordance with the present invention approximates the capacity of the oil to peel off the peel by glass.

Although several embodiments of the present invention have been described and illustrated particularly

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It is obvious to technicians in the field that changes and modifications of various kinds can be made in them without departing from the spirit and scope of the invention. In addition, although the foregoing description of the present invention has generally been devoted to the manufacture of an upper barrier laminate to make containers that retain a substantial amount of essential oils and flavoring components that are present in the fruit juices contained therein, the present The invention can be applied with equal ease to any container or package intended to contain other drinks and products that have essential components similarly difficult to retain. Accordingly, it is intended that the following claims cover those changes, modifications and other areas of application that are within the scope of the present invention.

Deposit of the first application for the credit was made in the United States of the invention described above

Claims (11)

I ^a '- Barrier laminate useful for the manufacture of a sealed container that has an improved retention of essential oils and flavoring components that are present in a liquid contained therein, characterized by the fact that said barrier laminate comprises a substrate material having an inner surface and an outer surface and a layer of glycol modified polyethylene terephthalate attached to said interior surface of said substrate material, said layer of glycol modified polyethylene terephthalate being the surface of the said sealed container which is in contact with the liquid. 2 ^a '- Barrier laminate according to claim 1, housing -1410 • 25 57457 Case 3442 _s ΓΓΗϊτπ posuir terised in that an intermediate layer of oxygen barrier materials between the substrate material and which is connected to the layer of polyethylene terephthalate glycol modified. Barrier laminate according to claim 2, characterized in that the intermediate layer of oxygen barrier material is polyvinylidene chloride, ethylene / vinyl alcohol copolymer, nylon, polyethylene terephthalate or metal foil. Barrier laminate according to any of the preceding claims, characterized in that it has a layer of polyethylene terephthalate modified with glycol attached to the outer surface of the substrate. Barrier laminate according to any of the preceding claims, characterized in that the substrate material is paper, cardboard, polyvinyl chloride, polyethylene terephthalate, polystyrene, polyethylene, polypropylene or ethylene / vinyl acetate copolymer. 6 ^a '- A process for manufacturing a laminated barrier according to any of claims 1 to 5, characte ized in that contacting a terephthalate film of polyethylene modified with glycol directly with the inner surface of a web of substrate material, thus forming a laminate and applying heat and pressure to said laminate in order to form said barrier laminate. 7 ^a '- Process according eat claim 6, wherein placing a film second terephthalic lato polyethylene modified with glycol in direct contact with the outer surface of the substrate material web thereby forming a laminate of two faces and heat and pressure are applied to said two-sided laminate in order to form the barrier laminate. 8 ^to * - Process for preparing a barrier according to any of claims 1 to 5, characterized in that - Case 3 442 of coating the inner surface of a substrate material with an adhesive fixing layer; placing a film of a material that forms an intermediate barrier to oxygen in contact with the said adhesive fixing layer; and attaching a glycol modified polyethylene terephthalate film to said film of a material that forms an intermediate oxygen barrier, thereby forming said barrier laminate. 9 ^and '- container that has a better retention - essential oils and flavoring components that are present in a liquid contained therein, characterized in that it comprises a body portion having an upper edge and a lower edge; an upper end panel connected to said upper edge of said body part; and a lower end panel connected to said lower edge of said body part, said body part being made of a barrier laminate according to any of the preceding claims. 10 '- Container that has improved retention of essential oils and flavoring components that are present in a liquid contained therein, said container being made from a single piece of folding laminate blank sheet and comprising: four wall panels sides forming a tubular body with a generally rectangular cross-section having inwardly foldable upper and lower closures, characterized in that the single-piece folding laminate blank comprises a laminate according to any of claims 1 to 5. 11 ^a * - Process for the manufacture of sealed containers, according to claim 10, from a blank sheet of foldable laminate constituting a single piece having an inner surface in contact with the liquid, said container having four panels that constitute the respective side walls and which form a tubular body with a generally rectangular cross-section and having super-161 closures 57457 Case 3'442 upper and lower folding inwards and presenting the container reference improved retention characteristics of essential oils and flavoring components that are present in a liquid contained therein, a process characterized by the fact that a layer of polyethyl terephthalate is bonded in modified with glycol to the inner surface and the outer surface of a one-piece, folding blank which constitutes the substrate material, forming the aforementioned single-piece folding blank which has a surface in contact with the liquid and folding said foldable blank to form said tubular body; and still for sealing by heat action the said laminated raw sheet, foldable, of a single piece of cardboard, in order to form the said sealed container.