Laminated structures

Abstract

Provided are sheets comprising at least three polymer layers, wherein each of the outer layers comprises a mixture of polylactic acid (PLA) and polycaprolactone (PCL) and each form from about 2.5% to about 20% of the total thickness of the sheet and wherein a core layer forms from about 60% to about 95% of the total thickness of the sheet; and to laminated structures comprising such sheets. Also provided are laminated structures comprising at least 3 biodegradable polymer sheets: a) first sheet comprising cellulose or a derivative thereof; b) a second sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PCL and combinations thereof; and c) a third sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PHA, PCL, PBAT and combinations thereof, wherein the second sheet is located between the first sheet and the third sheet

Description

[0001] LAMINATED STRUCTURES

[0002] FIELD OF THE INVENTION

[0003] The present invention, in at least some embodiments, is directed to biodegradable sheets comprising at least three polymer layers, wherein each of the outer layers comprises a mixture of polylactic acid (PLA) and polycaprolactone (PCL) and each form from about 2.5% to about 20% of the total thickness of the sheet and wherein a core layer forms from about 60% to about 95% of the total thickness of the sheet; and to laminated structures comprising such sheets. Further embodiments are directed to laminated structures comprising at least 3 biodegradable polymer sheets: a) first sheet comprising cellulose or a derivative thereof; b) a second sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PCL and combinations thereof; and c) a third sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PHA, PCL, PBAT and combinations thereof, wherein said second sheet is located between said first sheet and said third sheet.

[0004] BACKGROUND OF THE INVENTION

[0005] The use of biodegradable materials has increased over the past years due to the environmentally beneficial properties of such materials. Such materials are now commonly used in the manufacture of a wide range of products, including various types of plastic bags and other forms of packaging. In response to the demand for more environmentally friendly packaging materials, a number of biodegradable polymers have been developed.

[0006] Examples of such polymers include polyvinyl alcohol (PVOH), polylactic acid (PLA), polyhydroxyalkanoates (PHA), polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and polyhydroxybutyrate-hydroxyvalerate copolymer (PHBV), and poly (epsilon-caprolactone) (PCL).

[0007] Each of the foregoing biopolymers has unique properties, benefits and weaknesses. For example, PHB and PLA tend to be strong but are also quite rigid or even brittle. This makes them poor candidates when flexible sheets are desired, such as for use in making wraps, bags and other packaging materials requiring good bend and folding capability.

[0008] On the other hand, biopolymers, such as polybutylene adipate terephthalate (PBAT), are many times more flexible than the biopolymers discussed above and have relatively low melting points, so that they tend to be self-adhering and unstable when newly processed and / or exposed to heat. Further, due to the limited number of biodegradable polymers, it is often difficult, or even impossible, to identify a single polymer or copolymer that meets all, or even most, of the desired performance criteria for a given application. For these and other reasons, biodegradable polymers are not as widely used in the area of food packaging materials, particularly in the field of liquid receptacles, as desired for ecological reasons.

[0009] Existing biodegradable sheets either do not include barrier layers or include amounts and types of barrier layers that cause the sheets to be generally highly permeable to gases, having both a high oxygen transmission rate and a high water vapor transmission rate, and thus they cannot serve as long term food or drink receptacles.

[0010] Furthermore, it is frequently required to apply a metallized coating to an outer layer of a multilayered biodegradable structure for which a highly effective barrier for oxygen and moisture is required. Such metallized structures may be used in the preparation of packaging for various products, including foods, beverages and toiletry products.

[0011] When the packaging is used for certain products which are acidic in nature and are wet and / or oily, migration of acidic ions from the product result in corrosion of the metallized coating and loss of weight of the product.

[0012] Background art includes PCT Publication Nos. WO 2011 / 158240, WO 2013 / 088443, WO 2013 / 186778, WO 2015 / 059709, WO 2016 / 067285, WO 2016 / 174665 and WO 2016 / 207888 to the present applicant.

[0013] There remains a need for biodegradable sheets for packaging, which are devoid of at least some of the disadvantages of the prior art.

[0014] SUMMARY OF THE INVENTION

[0015] According to an aspect of some embodiments of the present invention, there is provided a biodegradable sheet comprising at least a first polymer layer, a second polymer layer and a third polymer layer, wherein said third polymer layer is situated between said first polymer layer and said third polymer layer, wherein each of said first layer and said third polymer layer comprises a mixture of polylactic acid (PLA) and polycaprolactone (PCL), wherein each of said first polymer layer and said third polymer layer forms from about 2.5% to about 20% of the total thickness of the sheet; and wherein said second polymer layer forms from about 60% to about 95% of the total thickness of the sheet.

[0016] According to a further aspect of some embodiments of the present invention, there is provided a laminated structure comprising a first biodegradable sheet comprising cellulose or a derivative thereof; at least a second biodegradable sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PCL or a combination thereof; and at least a third biodegradable sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PHA, PCL, PBAT or a combination thereof, wherein said second biodegradable sheet is located between said first biodegradable sheet and said third biodegradable sheet.

[0017] The present inventors have surprisingly found that when a biodegradable sheet or biodegradable laminated structure in accordance with the principles of the present invention is used in the preparation of a packaging for acidic, liquid products, reduced or negligible corrosion of the metallized biodegradable polymer sheet and loss of weight of the product occurs.

[0018] BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Some embodiments of the invention are described herein with reference to the accompanying figures. The description, together with the figures, makes apparent to a person having ordinary skill in the art how some embodiments of the invention may be practiced. The figures are for the purpose of illustrative discussion and no attempt is made to show structural details of an embodiment in more detail than is necessary for a fundamental understanding of the invention. For the sake of clarity, some objects depicted in the figures are not to scale.

[0020] In the Figures:

[0021] FIG. 1 is a schematic representation of a biodegradable polymer sheet comprising three biodegradable polymer layers, in accordance with the principles of the present invention;

[0022] FIG. 2 is a schematic representation of a laminated structure comprising three biodegradable polymer sheets, in accordance with the principles of the present invention;

[0023] FIGS. 3-7 are line graphs showing weight loss of ketchup with time from sachets prepared from laminated structures in accordance with the principles of the present invention and from comparative structures;

[0024] FIG. 8 is a line graph showing weight loss of strawberry jam with time from a sachet prepared from a laminated structure in accordance with the principles of the present invention;

[0025] FIG. 9 is a line graph showing weight loss of mustard with time from a sachet prepared from a laminated structure in accordance with the principles of the present invention; and

[0026] FIG. 10 is a line graph showing weight loss of apple puree with time from a sachet prepared from a laminated structure in accordance with the principles of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] Definitions

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. In case of conflict, the specification, including definitions, takes precedence.

[0029] The term “biodegradable” as used herein is to be understood to include a polymer, polymer mixture, or polymer-containing sheet that degrades through the action of living organisms in air, water or any combinations thereof within 1 year. Biodegradable polyester degradation is initially by hydrolysis, to eventually break the polymer into short oligomers, and later by microbial degradation, or microbial digestion. Biodegradable material may break down under a variety of conditions, for example under aerobic or anaerobic conditions, in compost, in soil or in water (such as sea, rivers or other waterways).

[0030] Material which may be degraded in compost is referred to as compostable. Hence, as used herein, the term “compostable” refers to a polymer, polymer mixture, or polymer-containing sheet which is degraded by biological processes under aerobic conditions to yield carbon dioxide, water, inorganic compounds and biomass and leaves no visible, distinguishable or toxic residues. Composting of such materials may require a commercial composting facility or the material may be home compostable.

[0031] As used herein, the term “home compostable” refers to a polymer, polymer mixture, or polymer-containing sheet which is compostable in a home composting container, i.e. at significantly lower temperatures and in the absence of set conditions as compared to those provided in a commercial composting facility. Home composting is usually carried out in significantly smaller volumes than those used for commercial composting, and do not include an industrial shredding process.

[0032] The term “sheet” as used herein is to be understood as having its customary meanings as used in the thermoplastic and packaging arts and includes the term “film”. Such sheets may have any suitable thickness, may be of a single polymer layer or of multiple polymer layers. Such sheets may be manufactured using any suitable method including blown film extrusion and cast film extrusion.

[0033] As used herein, the term “laminated structure” (also referred to as “structure” or “laminate”) refers to a structure comprising at least two sheets which are then adhered one to the other using a suitable adhesive (such as water-based adhesive) or using hot melt adhesion of a tie layer. As used herein, the term “tie layer” refers to a layer of polymer resin which can adhere to an adjacent polymer layer under co-extrusion conditions, optionally providing adhesion between two poorly adhering polymer layers or sheets. According to some embodiments, the tie layer has a thickness in the range of from about 12 to about 30 microns.

[0034] As used herein, the term “core sheet” of a biodegradable laminated structure comprising an odd number of sheets refers to the innermost sheet of the structure, such that an equal number of sheets (an outer sheet and at least one inner sheet) is positioned on each side of the core sheet.

[0035] As used herein, the term “contact sheet” of a biodegradable laminated structure refers to a sheet which, when the structure is used to form a wrapping or package, constitutes the inner surface of the wrapping or package, such that the contact sheet may contact material or items contained within the wrapping or package.

[0036] As used herein, the term “outer sheet” of a biodegradable laminated structure refers to a sheet which, when the sheet is used to form a wrapping or package, is the sheet furthest from the contact sheet, and is intended to include a sheet to which a coating is optionally applied.

[0037] As used herein, reference to a specified percentage (w / w) of a polymer layer is intended to refer to the percentage of the specified polymer in a polymer mixture from which the polymer layer is formed. The layer may further comprise a minor amount (no greater than about 10% (w / w) of the total composition of the layer) additives such as slip, anti-block, anti-oxidant and the like.

[0038] It is to be noted that, as used herein, the singular forms “a”, “an” and “the” include plural forms unless the content clearly dictates otherwise. Where aspects or embodiments are described in terms of Markush groups or other grouping of alternatives, those skilled in the art will recognize that the invention is also thereby described in terms of any individual member or subgroup of members of the group.

[0039] As used herein, when a numerical value is preceded by the term "about", the term "about" is intended to indicate + / -10%.

[0040] As used herein, the terms “comprising”, “including”, "having" and grammatical variants thereof are to be taken as specifying the stated features, integers, steps or components but do not preclude the addition of one or more additional features, integers, steps, components or groups thereof. These terms encompass the terms "consisting of" and "consisting essentially of".

[0041] In some embodiments, the biodegradable sheet as disclosed herein is used to prepare a biodegradable package, such as a bag or pouch, for example for containing therein an ingestible substance such as a food, drink or medicine, which may be a solid, semi-solid or liquid substance; or for containing therein a non-ingestible substance such as an item of clothing, a toiletry or cosmetic material or the like. For example, in some embodiments, the biodegradable package is prepared by heat sealing of two or more parts of the same sheet or two or more separate sheets.

[0042] As known to a person having ordinary skill in the art, some of the polymers discussed herein have one or more names or spelling thereof. For example, poly(caprolactone) and polycaprolactone are synonymous and the terms are used interchangeably. Similarly, polylactic acid and poly (lactic acid) are synonymous.

[0043] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

[0044] Many modifications and variations are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention can be practiced otherwise than as specifically described.

[0045] The specific embodiments listed below exemplify aspects of the teachings herein and are not to be construed as limiting.

[0046] Throughout this application, various publications, including United States Patents, are referenced by author and year and patents by number. The disclosures of these publications and patents and patent applications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains.

[0047] Citation of any document herein is not intended as an admission that such document is pertinent prior art or considered material to the patentability of any claim of the present disclosure. Any statement as to content or a date of any document is based on the information available to applicant at the time of filing and does not constitute an admission as to the correctness of such a statement.

[0048] According to an aspect of some embodiments of the present invention there is provided a biodegradable sheet comprising at least a first polymer layer, a second polymer layer and a third polymer layer, wherein the third polymer layer is situated between the first polymer layer and the third polymer layer, wherein each of the first layer and the third polymer layer comprises a mixture of polylactic acid (PLA) and polycaprolactone (PCL), wherein each of the first polymer layer and the third polymer layer forms from about 2.5% to about 20% of the total thickness of the sheet; and wherein the second polymer layer forms from about 60% to about 95% of the total thickness of the sheet.

[0049] According to some embodiments, the third polymer layer comprises a mixture of PLA and PCL.

[0050] According to some embodiments, each of the first polymer layer, the second polymer layer and the third polymer layer comprises PLA at a concentration of from about 50% (w / w) to about 90% (w / w) (such as about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt% or about 90 wt% PLA) and PCL at a concentration of from about 10% (w / w) to about 50% (w / w) (such as about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt% or about 50 wt% PCL).

[0051] According to some embodiments, each of the first polymer layer, the second polymer layer and the third polymer layer each comprise PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w).

[0052] According to some embodiments, each of the first polymer layer, and the second polymer comprises PLA at a concentration of from about 50% (w / w) to about 90% (w / w) (such as about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt% or about 90 wt% PLA) and PCL at a concentration of from about 10% (w / w) to about 50% (w / w) (such as about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt% or about 50 wt% PCL); and the third polymer layer comprises poly(butylene succinate -co-adipate) (PBSA).

[0053] According to some embodiments, each of the first polymer layer and the second polymer layer comprises PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w).

[0054] According to one such embodiment, the third polymer layer comprises about 100% (w / w) PBSA.

[0055] Alternatively, according to some embodiments the third polymer layer comprises a mixture of PBSA and PLA. According to some such embodiments, the third polymer layer comprises PBSA at a concentration of from about 50% (w / w) to about 90% (w / w) (such as about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt% or about 90 wt% PBSA), and PLA at a concentration of from about 10% (w / w) to about 50% (w / w) ((such as about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt% or about 50 wt% PLA).

[0056] According to some such embodiments, the third polymer layer comprises PBSA at a concentration of about 85% (w / w) and PLA at a concentration of about 15% (w / w).

[0057] According to one such embodiment, each of the first polymer layer and the second polymer layer comprises PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w) and the third polymer layer comprises PBSA at a concentration of about 85% (w / w) and PLA at a concentration of about 15% (w / w).

[0058] According to some embodiments, a thickness of the first polymer layer is substantially equal to a thickness of the third polymer layer.

[0059] According to some embodiments, each of the first polymer layer and the third polymer layer individually forms up to about 20% of the total thickness of the sheet. The sheet may be produced using biaxial orientation or cast extrusion.

[0060] According to some embodiments, a thickness of the first polymer layer is different from a thickness of the third polymer layer, such as differing by about 10%, about 15%, about 20% or about 30%. According to some such embodiments, such a sheet is produced by cast extrusion. According to some embodiments, the second polymer layer forms from about 80% to about 95% of the total thickness of the sheet and each of the first polymer layer and the third polymer layer together form from about 5% to about 20% of the total thickness of the sheet. The sheet may be produced using biaxial orientation or cast extrusion.

[0061] According to any of the embodiments disclosed herein, the biodegradable sheet further comprises a metallized layer provided on the first polymer layer, such as a layer comprising aluminum or an oxide thereof. According to some such embodiments, the biodegradable sheet further comprises an outer coating on the metalized layer.

[0062] According to some embodiments, the biodegradable sheets as disclosed herein show less shrinkage with time as compared to known sheets.

[0063] According to a further aspect of some embodiments of the present invention, there is provided a laminated structure comprising as a first biodegradable sheet the biodegradable sheet as disclosed herein, further comprising at least a second biodegradable sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PCL or a combination thereof, and at least a third biodegradable sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PHA, PCL, PBAT or a combination thereof, wherein the second biodegradable sheet is located between the first biodegradable sheet and the third biodegradable sheet.

[0064] According to a further aspect of some embodiments of the present invention, there is provided a laminated structure comprising a first biodegradable sheet comprising cellulose or a derivative thereof; at least a second biodegradable sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PCL or a combination thereof; and at least a third biodegradable sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PHA, PCL, PBAT or a combination thereof, wherein the second biodegradable sheet is located between the first biodegradable sheet and the third biodegradable sheet.

[0065] According to some embodiments of the laminated structure, the second sheet comprises at least three layers, wherein a first layer comprises a mixture of PBSA and PLA, a third layer comprises a mixture of PLA and PCL, and a second layer is located between the first layer and the third layer.

[0066] According to some embodiments, the first layer of the second sheet comprises PBSA at a concentration of from about 50% (w / w) to about 90% (w / w) (such as about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt% or about 90 wt% PBSA) and PLA at a concentration of from about 10% (w / w) to about 50% (w / w), (such as about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt% or about 50 wt% PLA).

[0067] According to some embodiments, the first layer of the second sheet comprises PBSA at a concentration of about 85% (w / w) and PLA at a concentration of about 15% (w / w).

[0068] According to some embodiments, the third layer of the second sheet comprises a mixture of PLA and PCL. According to some such embodiments, the third layer of said second sheet comprises PLA at a concentration of from about 50% (w / w) to about 90% (w / w) (such as about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt% or about 90 wt% PLA) and PCL at a concentration of from about 10% (w / w) to about 50% (w / w) (such as about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt% or about 50 wt% PCL).

[0069] According to some embodiments of the laminated structure, the second sheet comprises at least three layers, wherein a first layer and a second layer each comprise a mixture of PLA and PCL. According to some such embodiments, each of the first layer and the third layer of the second sheet comprises PLA at a concentration of from about 50% (w / w) to about 90% (w / w) (such as about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt% or about 90 wt% PLA) and PCL at a concentration of from about 10% (w / w) to about 50% (w / w) (such as about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt% or about 50 wt% PCL). According to some such embodiments, each of the first layer of the second sheet and the second layer of the second sheet comprise PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w).

[0070] According to some embodiments, the third layer of the second sheet comprises PBSA at a concentration of from about 50% (w / w) to about 90% (w / w) and PLA at a concentration of from about 10% (w / w) to about 50% (w / w). According to some such embodiments, the third layer of the second sheet comprises about 85% (w / w) PBSA and about 15% (w / w) PLA.

[0071] According to some embodiments, the third layer of the second sheet comprises about 100% (w / w) PBSA.

[0072] According to some embodiments, each of the first polymer layer, the second polymer layer and the third polymer layer each comprise PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w).

[0073] According to some embodiments, the second biodegradable polymer sheet further comprises an acid scavenger and / or an acid absorber.

[0074] According to some such embodiments, the acid scavenger is a metal oxide (such as magnesium oxide, calcium oxide or zinc oxide); a metal salt of a carboxylic acid (such as calcium, zinc or sodium stearate).

[0075] According to some embodiments, the acid scavenger is selected from the group consisting of chitosan and hydrotalcite.

[0076] According to some embodiments, the acid absorber comprises carbon black.

[0077] According to some embodiments, the second layer of the second sheet comprises polybutylene adipate terephthalate (PBAT). According to some such embodiments, the second layer of the second sheet comprises about 100% (w / w) PBAT.

[0078] According to some embodiments, the second layer of the second sheet of the laminated structure further comprises a metallized coating layer.

[0079] According to some embodiments, the third sheet of the laminated structure comprises at least a first polymer layer, a second polymer layer and a third polymer layer, wherein the third polymer layer is situated between the first polymer layer and the third polymer layer, wherein each of the first layer and the second polymer layer comprises a mixture of polylactic acid (PLA) and polycaprolactone (PCL), wherein each of the first polymer layer and the third polymer layer forms from about 2.5% to about 20% (such as about 2.5%, about 5%, about 10%, about 15% or about 20%) of the total thickness of the sheet; and wherein the second polymer layer forms from about 60% to about 95% (such as about 60%, about 65%, about 70%, about 75%, about 80%, about 85% or about 90%) of the total thickness of the sheet.

[0080] According to some embodiments, each of the first polymer layer of said third sheet and said second polymer layer of said third sheet comprise PLA at a concentration of from about 50% (w / w) to about 90% (w / w) (such as about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt% or about 90 wt% PLA), and PCL at a concentration of from about 10% (w / w) to about 50% (w / w) (such as about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt% or about 50 wt% PCL) and the third polymer layer of the third sheet comprises poly(butylene succinate-co-adipate) (PBSA).

[0081] According to some embodiments, each of the first polymer layer of the third sheet and the second polymer layer of the third sheet comprises PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w).

[0082] According to some embodiments, the third polymer layer of the third sheet comprises 100% (w / w) PBSA.

[0083] According to some embodiments, the third polymer layer of the third sheet comprises a mixture of PBSA and PLA.

[0084] According to some embodiments, the third polymer layer of said third sheet comprises PBSA at a concentration of from about 50% (w / w) to about 90% (w / w) (such as about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt% or about 90 wt% PBSA), and PLA at a concentration of from about 10% (w / w) to about 50% (w / w) (such as about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt% or about 50 wt% PLA).

[0085] According to some embodiments, the third polymer layer of the third sheet comprises PBSA at a concentration of about 85% (w / w) and PLA at a concentration of about 15% (w / w).

[0086] According to some embodiments, the third sheet comprises at least three layers, wherein a first layer comprises a mixture of PBSA and PLA, a third layer comprises a mixture of PLA and PCL, and a second layer is located between said first layer and said third layer.

[0087] According to some embodiments, the first layer of the third sheet comprises PBSA at a concentration of from about 50% (w / w) to about 90% (w / w) (such as about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt% or about 90 wt% PBSA), and PLA at a concentration of from about 10% (w / w) to about 50% (w / w) (such as about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt% or about 50 wt% PLA). According to some such embodiments, the first layer of said third sheet comprises PBSA at a concentration of about 85% (w / w) and PL A at a concentration of about 15% (w / w).

[0088] According to some embodiments, the third layer of the third sheet comprises a mixture of PLA and PCL.

[0089] According to some embodiments, the third layer of the third sheet comprises PLA at a concentration of from about 50% (w / w) to about 90% (w / w) (such as about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt% or about 90 wt% PLA) and PCL at a concentration of from about 10% (w / w) to about 50% (w / w) (such as about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt% or about 50 wt% PCL).

[0090] According to some embodiments, the third layer of the third sheet comprises PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 15% (w / w).

[0091] According to some embodiments, the second layer of the third sheet comprises 100% (w / w) PBAT.

[0092] According to some embodiments, the third sheet comprises PLA, PHA or a combination thereof.

[0093] According to some embodiments, the third sheet comprises a mixture of PLA and PHA.

[0094] According to some embodiments, the third sheet comprises from about 30% (w / w) to about 100% (w / w) PLA (such as about 30%, about 35 wt%, about 40 wt%, about 45 wt%, about 50 wt%, about 55wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt%, about 90 wt%, about 95 wt%, or about 100 wt% PLA). According to some such embodiments, the third sheet of the laminated structure comprises PHA at a concentration of about 45 (w / w) and PLA at a concentration of about 55% (w / w). According to some alternative embodiments, the third sheet of the laminated structure comprises PHA at a concentration of about 30 (w / w) and PLA at a concentration of about 70% (w / w).

[0095] According to some embodiments, the third sheet comprises about 100% (w / w) PLA. According to some embodiments, the third sheet comprises about 100% (w / w) PHA. According to some embodiments, the laminated structure further comprises a metallized coating layer provided on the third sheet, such as a coating layer comprising aluminum or an oxide thereof.

[0096] According to some embodiments, the third sheet further comprises a fourth layer comprising a mixture of PBSA and PLA. According to some such embodiments, the fourth layer comprises PBSA at a concentration of from about 50% (w / w) to about 90% (w / w) (such as about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt% or about 90 wt% PBSA) and PLA at a concentration of from about 10% (w / w) to about 50% (w / w) (such as about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt% or about 50 wt% PLA). According to some such embodiments, the fourth layer of the third sheet comprises PBSA at a concentration of about 85% (w / w) and PLA at a concentration of about 15% (w / w).

[0097] According to some embodiments, the third sheet further comprises a fourth layer comprising a mixture of PLA and PCL. According to some such embodiments, the fourth layer of the third sheet comprises PLA at a concentration of from about 50% (w / w) to about 90% (w / w) (such as about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt% or about 90 wt% PLA) and PCL at a concentration of from about 10% (w / w) to about 50% (w / w) (such as about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt% or about 50 wt% PCL). According to some such embodiments, the fourth layer of the third sheet comprises PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w).

[0098] According to a preferred embodiment, there is provided a laminated structure comprising at least 3 sheets, wherein each sheet may comprise a single layer or multiple layers.

[0099] According to some such embodiments: a) the first polymer sheet consists essentially of cellulose or is a three-layered sheet, wherein each of the three layers comprises a mixture of about 80 wt% PLA and about 20 wt% PCL; b) the second polymer sheet comprises a metallized three-layered sheet having a first layer comprising a mixture of about 85 wt% PBSA and about 15 wt% PLA, a third layer comprising a mixture of about 80 wt% PLA and about 20 wt% PCL, and a second layer comprising about 100 wt% PBAT, wherein the second layer is disposed within the first and third layers; and c) the third polymer sheet comprises one or more of the following:

[0100] - a three-layered sheet having a first layer optionally comprising a coating layer comprising aluminum or an oxide thereof and a second layer comprising a mixture of about 80 wt% PLA and about 20 wt% PCL, and a third layer comprising about 100 wt% PBSA or a mixture of about 85 wt% PBSA and about 15 wt% PLA, wherein the second layer is disposed within the first and third layers,

[0101] - a three-layered sheet having a first layer comprising a mixture of about 85 wt% PBSA and about 15 wt% PLA and optionally comprising a coating layer comprising aluminum or an oxide thereof, a second layer comprising about 100 wt% PBAT and a third layer comprising a mixture of about 80 wt% PLA and about 20 wt% PCL, wherein the second layer is disposed within the first and third layers, - a mixture of PLA and optionally aluminum or an oxide thereof,

[0102] - about 100 wt% PH A and optionally aluminum or an oxide thereof,

[0103] - a mixture of about 45 wt% PHA and about 55 wt% PLA or about 30 wt% PHA and about 70 wt% PLA,

[0104] - a mixture of about 85 wt% PBSA and about 15 wt% PLA, and

[0105] - about 80 wt% PLA and about 20 wt% PCL.

[0106] According to some embodiments, the third polymer sheet comprises three or more individual sheets, wherein at least one such sheet is an extruded layer applied during an extrusion lamination process.

[0107] According to some embodiments, the third polymer sheet comprises at least four layers wherein at least one layer is optionally provided using water-based lamination.

[0108] According to some embodiments, the laminated structure further comprises a metallized coating layer provided on the first polymer layer of the third sheet, such as a coating layer comprising aluminum or an oxide thereof.

[0109] According to some embodiments of the laminated structure as disclosed herein, the first biodegradable polymer sheet provides an outer layer, the second biodegradable polymer sheet is a core layer and the third biodegradable polymer sheet comprises a contact layer.

[0110] According to some embodiments of the laminated structure, the first sheet provides low water transmission rate (WVTR) i.e. a WVTR of less than about 2 g / sq m / day and / or a low oxygen transmission rate (OTR) i.e. an OTR of less than about 1 g / sq m / day.

[0111] According to some embodiments, the laminated structure has a total thickness in the range of from about 60 to about 120 microns, such as about 60 microns, about 65 microns, about 70 microns, about 75 microns, about 80 microns, about 85 microns, about 90 microns, about 95 microns, about 100 microns, about 105 microns, about 110 microns, about 115 microns or about 120 microns.

[0112] According to some embodiments, each of the first, second and third biodegradable sheets have the same thickness. According to some embodiments, each of the first, second and third biodegradable sheets have different thicknesses.

[0113] According to some embodiments, two of the first, second and third biodegradable sheets have the same thickness and a third sheet has a different thickness. According to some embodiments, the first biodegradable sheet is an outer layer having a thickness in the range of from about 10 to about 30 microns. According to an embodiment, the outer layer has a thickness of about 10 microns. According to an embodiment, the outer layer has a thickness of about 20 microns. According to some embodiments, each of the first and third biodegradable sheets has the same thickness. According to some such embodiments, each of the first and third sheets has a thickness in the range of from about 20 to about 25 microns and the second layer has a thickness in the range of from about 20 to about 35.

[0114] According to some embodiments, the first biodegradable sheet is an outer layer having a thickness in the range of from about 10 to about 30 microns. According to an embodiment, the outer layer has a thickness of about 10 microns. According to an embodiment, the outer layer has a thickness of about 20 microns.

[0115] According to some embodiments, the structure further comprises an extruded tie layer having thickness of about 15 microns.

[0116] According to some embodiments, the structure further comprises a water-based adhesive layer having a thickness of up to about 5 microns.

[0117] According to some embodiments, the core layer is a barrier layer, preventing migration of moisture and acid.

[0118] According to some embodiments, the laminated structures are prepared by extrusion of one or more of the layers individually to produce sheets, followed by lamination of the individual sheets. According to some such embodiments, the individual sheets are prepared by coextrusion of two of more layers.

[0119] According to some embodiments, lamination comprises adhesive lamination. According to some such embodiments, the adhesive may be selected from the group consisting of an organic solvent-based adhesive, a solvent-less adhesive and a water-based adhesive.

[0120] According to some embodiments, the adhesive is a hot melt adhesive. According to some embodiments, the hot melt adhesive is selected from the group consisting of PBAT, PHA, PLA, PBSA, a mixture of PHA with PLA, and a mixture of PBSA with PLA. According to an embodiment, the hot melt adhesive is PBAT. According to an alternative embodiment, the hot melt adhesive comprises a mixture of 45 wt% PHA with 55 wt% PLA. According to a further alternative embodiment, the hot melt adhesive comprises a mixture of 30 wt% PHA with 70 wt% PLA. According to a further alternative embodiment, the hot melt adhesive comprises a mixture of 15 wt% PLA with 85 wt% PBSA. According to some such embodiments, the adhesive is applied by extrusion, providing a tie layer.

[0121] According to some embodiments, lamination comprises heat lamination, preferably at a lamination temperature of about 120°C. According to some embodiments, the laminated structures are prepared by extrusion coating, wherein one sheet of the structure is coated directly onto at least one substrate. According to some such embodiments, the substrate may be a sheet, a film or a laminated structure.

[0122] According to an aspect of some embodiments of the present invention, there is provided a package comprising the laminated structure as disclosed herein, for storage therein of a material selected from the group consisting of a liquid, a semi-solid, a solid comprising a high content of volatile components and a solid moistened with a liquid medium.

[0123] According to some preferred embodiments, the material for storage is a wet product (i.e. having a water or oil content of at least 20 wt%). According to some embodiments, the material is a food product. According to some embodiments, the material is a toiletry product such as a wet wipe.

[0124] According to some embodiments, the package is for storage therein of a condiment (such as ketchup, mustard, vinegar, mayonnaise, a salad dressing including thousand islands dressing or vinaigrette, barbecue sauce and the like).

[0125] According to some embodiments, the package is for storage therein of a fruit product such as apple juice, apple puree, apple sauce and the like.

[0126] According to some embodiments, the package is for storage therein of a pickled vegetable product, such as olives, pickled cucumbers and the like.

[0127] According to some embodiments, the package is for storage therein of tomato puree, tomato paste and the like.

[0128] According to some embodiments, the package is for storage therein of a jam, such as a berry jam, a citrus jam and the like.

[0129] According to some embodiments, the package is for storage therein of a dairy product, such as milk, chocolate milk, sour cream, yoghurt, a dairy pudding and the like.

[0130] According to some embodiments, the package is for storage therein of a beverage such as a flavored water, a carbonated or non-carbonated soft drink and the like.

[0131] According to some embodiments, the material has a pH of less than about 8, such as about 7.5, about 7, about 6.5, about 6, about 5.5, about 5, about 4.5, about 4, about 3.5, about 3, about 2.5 or about 2.

[0132] According to some embodiments, the package is for storage therein of a fruit-derived product, such as a fruit smoothie, a fruit sauce (such as apple sauce) and the like.

[0133] According to some embodiments, the material is an oil.

[0134] Referring now to FIG. 1 , there is shown a schematic representation of a biodegradable polymer sheet 10 comprising a first biodegradable polymer layer 12, a second biodegradable polymer layer 14 and a third biodegradable polymer layer 16, wherein second layer 14 is disposed between first layer 12 and third layer 16.

[0135] FIG. 2 is a schematic representation of a laminated structure 20 comprising a first polymer sheet 22, a second polymer sheet 24 and a third polymer sheet 26, wherein second sheet 24 is disposed between first sheet 22 and third sheet 26.

[0136] FIG. 2 shows a schematic representation of a laminated structure 30, comprising a first biodegradable polymer sheet 12, a second biodegradable polymer sheet 14 and a third biodegradable polymer sheet 16, wherein second sheet 14 is positioned between first sheet 12 and third sheet 16.

[0137] EXAMPLES

[0138] In the experimental section below, all percentages are weight percentages.

[0139] Materials and Methods

[0140] All the embodiments of polymer sheets according to the teachings herein are made using commercially- available raw materials and devices, using one or more standard methods including: polymer resin drying, resin mixing, cast film extrusion, cast film co-extrusion, blown film extrusion and coextrusion and adhesive lamination.

[0141] Materials

[0142] The following polymer resins were acquired from commercial sources:

[0143] PBSA poly(butylene succinate-co-butylene adipate)

[0144] PLA poly(lactic acid)

[0145] PCL poly(caprolactone)

[0146] PBAT poly(butylene adipate terephthalate)

[0147] The resins may be used as supplied, without further drying. Optionally, before use, resins are further dried, such as by drying overnight in an air flow Shini SCD-160U-120H desiccant dryer heated to about 80 °C.

[0148] The polymer sheets according to the teachings herein include layers comprising a polymer mixture. Such layers are made by coextrusion of a polymer mixture resin.

[0149] To make the required polymer mixture resins, the appropriate amounts of the dried constituent resins were dry-blended and then introduced into the feed zone of the extruders and co-extruded as a film.

[0150] Methods

[0151] Extrusion processes Some embodiments of sheets according to the teachings herein are made by extrusion lamination and / or extrusion coating to produce the desired laminated structure.

[0152] Sheets are made using a co-extrusion line from Collin (Collin Lab and Pilot Solutions) equipped with two unwinders using standard settings, typically the mixture is feed into the extruder with the temperature zone settings 170-180-200 °C; Adaptor at 200°C; feedblock at 200 °C; Die at 200 °C. The screw speed is set to provide an extruded layer having the desired thickness in the usual way.

[0153] Cast film coextrusion of sheets

[0154] Some embodiments of sheets according to the teachings herein are made by coextrusion of two or more layers to make a desired sheet by multilayer cast film co extrusion.

[0155] Some embodiments of sheets according to the teachings herein are made by lamination of single and multilayer cast film extruded films. Films and sheets are made using a cast film coextruder Dr. Collin (Collin Lab and Pilot Solutions) using standard settings, typically the mixture is fed into the extruder with the temperature zone settings 195 °C; Adaptor at about 200°C; feedblock at about 200°C; Die at 210°C. The screw speed is set to provide an extruded layer having the desired thickness in the usual way. For multilayer films, a die having three ports, each fed by a dedicated extruder is used.

[0156] Blown film extrusion

[0157] Some embodiments of sheets according to the teachings herein are made by coextrusion of one or more layers to make a desired sheet by multilayer blown film co extrusion. These layers are extruded vertically through a circular head. Introducing air through the center of the head creates a “bubble-like” expansion and the properties and thickness of the resulting sheet may be controlled by changing the volume of air and by altering the speed at which the air is introduced.

[0158] Metallization

[0159] Metallization is performed using a physical vapor deposition process with aluminum vapor under vacuum (for standard metallization) or vacuum and oxygen (for transparent metallization) .

[0160] Coating A thin film coating of coating is optionally applied on the different sheets at a 3 g / m2concentration. In metallized films, the coating is applied on the metallized side. The film is dried overnight at ambient temperature.

[0161] Sheets

[0162] The following sheets were prepared:

[0163] Sheet A comprising three layers [

[0164] First layer: 80 wt% PLA; 20 wt% PCL

[0165] Second layer: 80 wt% PLA; 20 wt% PCL

[0166] Third layer: 80 wt% PLA; 20 wt% PCL

[0167] Sheet B comprising three layers

[0168] First layer: 80 wt% PLA; 20 wt% PCL

[0169] Second layer: 80 wt% PLA; 20 wt% PCL

[0170] Third layer: 100 wt% PBSA

[0171] Sheet C comprising three layers

[0172] First layer: 80 wt% PLA; 20 wt% PCL

[0173] Second layer: 80 wt% PLA; 20 wt% PCL

[0174] Third layer: 85 wt% PBSA: 15 wt% PLA

[0175] Sheet D comprising three layers

[0176] First layer: 85 wt% PBSA: 15 wt% PLA

[0177] Second layer: 100 wt% PBAT

[0178] Third layer: 80 wt% PLA: 20 wt% PCL

[0179] Sheet E comprising three layers

[0180] First layer: 85 wt% PBSA: 15 wt% PLA

[0181] Second layer: 100 wt% PBAT

[0182] Third layer: 80 wt% PLA: 20 wt% PCL

[0183] Sheet F comprising single layer

[0184] Cellulose

[0185] Sheet G comprising single layer

[0186] PLA

[0187] Sheet H comprising single layer

[0188] PHA

[0189] Sheet I comprising single layer

[0190] 45 wt% PHA: 55 wt% PLA Sheet J comprising single layer

[0191] 85 wt% PBSA: 15 wt% PLA

[0192] Sheet K comprising single layer

[0193] 30 wt% PHA: 70 wt% PLA

[0194] Sheet L comprising single layer

[0195] 80 wt% PLA: 20 wt% PCL

[0196] Example 1: Shrink-resistance of exemplary sheets in accordance with the principles of the present invention

[0197] Sheets A, D, E, as defined above were prepared:

[0198] The sheets were cut into 10x10 cm pieces. Samples were then placed in an oven at 80°C, for 1 minute, 3 minutes, or 5 minutes.

[0199] Shrinkage was determined by determining changes in the machine direction and of each sample after heating for the specified times.

[0200] Results:

[0201] Results are presented in Table 1 below.

[0202] Table 1

[0203] As seen above, a reduction of less than 5% was seen in each direction for each of the tested samples.

[0204] Example 2: Exemplary laminated structures a) Test structures Sheets A-L as defined above were used to prepare laminated structures #1-8, comprising at least 3 sheets in accordance with the principles of the present invention, as set out in Table 2 below. Table 2 b) Comparative structures

[0205] Laminated structures #9-11, which are outside the scope of the present invention, were prepared as set out in Table 3 below. Table 3

[0206] Example 3: Weight loss with time - sachets containing ketchup

[0207] Sachets of length 10 cm and width 10 cm were prepared from laminated structures #1-8 as defined in Table 2 above and from comparative product #9-11 as defined in Table 3, at a soldering temperature of about 120C°. Each sachet was filled with about 8-12 g of ketchup.

[0208] The initial weight of the sachet plus contents was recorded and then measured weekly using an analytic scale. The sachets were stored at a temperature of 20°C and relative humidity of about 66%, and the weight of the sachet plus contents was measured at defined intervals. Results are presented in FIG. 3 (for structures # 8 and 9); FIG. 4 (for structures #1-3); FIG. 5 (for structures #2, 4, 10 and 11); FIG. 6 (for structures #2 and 6); and FIG. 7 (for structures #2, 4 and 5); all of which show that a statistically significant decrease in weight loss of contents occurred from a sachet prepared from structures in accordance with the principles of the present invention, with respect to the tested comparative structures over a period of at least 65 days and up to about 180 days.

[0209] Example 4: Weight loss with time - sachets containing strawberry jam

[0210] Sachets were prepared from structure #2, as defined in Table 2 above, filled with strawberry jam, and weight loss determined, according to the method described in Example 3.

[0211] Results are presented in FIG. 8, showing a low weight loss of contents occurred from the sachets over a period of up to about 175 days.

[0212] Example 5: Weight loss with time - sachets containing mustard

[0213] Sachets were prepared from structure #2, as defined in Table 2 above, filled with mustard, and weight loss determined, according to the method described in Example 3.

[0214] Results are presented in FIG. 9, showing a low weight loss of contents occurred from the sachets over a period of up to about 175 days.

[0215] Example 6: Weight loss with time - sachets containing apple puree

[0216] Sachets were prepared from structure #2, as defined in Table 2 above, filled with apple puree, and weight loss determined, according to the method described in Example 3.

[0217] Results are presented in FIG. 10, showing a low weight loss of contents occurred from the sachets over a period of up to about 150 days.

[0218] Example 7: Barrier properties and corrosion with time

[0219] In order to define the barrier properties of the structures as defined in Table 3, the following test methods were used: a. Water vapor transmission rate (WVTR) was measured using the ASTM F1249 Standard Test Method for Water Vapor Transmission Rate Through Plastic Film and Sheeting Using a Modulated Infrared Sensor at 38 °C, 90%RH. b. Oxygen transmission rate (OTR) was measured using the ASTM D3985 Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using a Coulometric Sensor at 25 °C, 0%RH. In addition, corrosion, as observed by visual inspection with the naked eye, was recorded weekly for up to 6 weeks.

[0220] Results are presented in Table 4 below.

[0221] Table 4

[0222] In summary, as shown in Examples 1-5, filled sachets comprising structures in accordance with the principles of the present invention were found to exhibit low weight loss of the contents of the sachets, as well as excellent barrier properties and no corrosion for at least 6 weeks.

[0223] The invention illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise indicated.

[0224] Although the above examples have illustrated particular ways of carrying out embodiments of the invention, in practice persons skilled in the art will appreciate alternative ways of carrying out embodiments of the invention, which are not shown explicitly herein. It should be understood that the present disclosure is to be considered as an exemplification of the principles of this invention and is not intended to limit the invention to the embodiments illustrated. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, equivalents of the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

Claims

CLAIMS1. A biodegradable sheet comprising at least a first polymer layer, a second polymer layer and a third polymer layer, wherein said third polymer layer is situated between said first polymer layer and said third polymer layer, wherein each of said first layer and said third polymer layer comprises a mixture of polylactic acid (PLA) and polycaprolactone (PCL), wherein each of said first polymer layer and said third polymer layer forms from about 2.5% to about 20% of the total thickness of the sheet; and wherein said second polymer layer forms from about 60% to about 95% of the total thickness of the sheet.

2. The biodegradable sheet of claim 1, wherein said third polymer layer comprises a mixture of PLA and PCL.

3. The biodegradable sheet of claim 2, wherein each of said first polymer layer, said second polymer layer and said third polymer layer comprises PLA at a concentration of from about 50% (w / w) to about 90% (w / w) and PCL at a concentration of from about 10% (w / w) to about 50% (w / w).

4. The biodegradable sheet of claim 3, wherein each of said first polymer layer, said second polymer layer and said third polymer layer comprises PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w).

5. The biodegradable sheet of claim 1, wherein each of said first polymer layer and said second polymer layer comprise PLA at a concentration of from about 50% (w / w) to about 90% (w / w) and PCL at a concentration of from about 10% (w / w) to about 50% (w / w) and wherein said third polymer layer comprises poly(butylene succinate-co-adipate) (PBSA).

6. The biodegradable sheet of claim 5, wherein each of said first polymer layer and said second polymer layer comprise PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w).

7. The biodegradable sheet of claim 5, wherein said third polymer layer comprises 100% (w / w) PBSA.

8. The biodegradable sheet of claim 5, wherein said third polymer layer comprises a mixture of PBSA and PLA.

9. The biodegradable sheet of claim 8, wherein said third polymer layer comprises PBSA at a concentration of from about 50% (w / w) to about 90% (w / w) and PLA at a concentration of from about 10% (w / w) to about 50% (w / w).

10. The biodegradable sheet of claim 9, wherein said third polymer layer comprises PBSA at a concentration of about 85% (w / w) and PLA at a concentration of about 15% (w / w).

11. The biodegradable sheet of any one of claims 1 to 10, wherein a thickness of said first polymer layer is substantially equal to a thickness of said third polymer layer.

12. The biodegradable sheet of claim 11, wherein each of said first polymer layer and said third polymer layer forms about 20% of the total thickness of the sheet; and13. The biodegradable sheet of claim 12, wherein said sheet is biaxially oriented.

14. The biodegradable sheet of any one of claims 1 to 13, wherein a thickness of said first polymer layer is different from a thickness of said third polymer layer.

15. The biodegradable sheet of claim 14, wherein said second polymer layer forms from about 80% to about 95% of the total thickness of the sheet and wherein each of said first polymer layer and said third polymer layer together form from about 5% to about 20% of the total thickness of the sheet.

16. The biodegradable sheet of claim 14 or claim 15, wherein said sheet is produced by cast technology.

17. The biodegradable sheet of any one of claims 1 to 16, further comprising a metallized layer provided on said first polymer layer.

18. The biodegradable sheet of claim 17, wherein metallized layer comprises aluminum or an oxide thereof.

19. The biodegradable sheet according to claim 17 or claim 18, further comprising an outer coating layer on said metallized layer.

20. A laminated structure comprising as a first biodegradable sheet the biodegradable sheet of any one of claims 1 to 19, further comprising at least a second biodegradable sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PCL or a combination thereof and at least a third biodegradable sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PHA, PCL, PBAT or a combination thereof, wherein said second biodegradable sheet is located between said first biodegradable sheet and said third biodegradable sheet.

21. A laminated structure comprising a) a first biodegradable sheet comprising cellulose or a derivative thereof;b) at least a second biodegradable sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PCL or a combination thereof; and c) at least a third biodegradable sheet comprising at least one polymer selected from the group consisting of PBSA, PLA, PHA, PCL, PBAT or a combination thereof, wherein said second biodegradable sheet is located between said first biodegradable sheet and said third biodegradable sheet.

22. The laminated structure of claim 20 or claim 21, wherein said second sheet comprises at least three layers, wherein a first layer comprises a mixture of PBSA and PLA, a third layer comprises a mixture of PLA and PCL, and a second layer is located between said first layer and said third layer.

23. The laminated structure of claim 22, wherein said first layer of said second sheet comprises PBSA at a concentration of from about 50% (w / w) to about 90% (w / w) and PLA at a concentration of from about 10% (w / w) to about 50% (w / w).

24. The laminated structure of claim 23, wherein said first layer of said second sheet comprises PBSA at a concentration of about 85% (w / w) and PLA at a concentration of about 15% (w / w).

25. The laminated structure of any one of claims 20 to 24, wherein said third layer of said second sheet comprises a mixture of PLA and PCL.

26. The laminated structure of claim 25, wherein said third layer of said second sheet comprises PLA at a concentration of from about 50% (w / w) to about 90% (w / w) and PCL at a concentration of from about 10% (w / w) to about 50% (w / w).

27. The laminated structure of claim 26, wherein said third layer of said second sheet comprises PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w).

28. The laminated structure of any one of claims 20 to 27, wherein said second layer of said second sheet comprises polybutylene adipate terephthalate (PBAT).

29. The laminated structure of claim 28, wherein said second layer of said second sheet comprises 100% (w / w) PBAT.

30. The laminated structure of claim 20 or claim 21, wherein said second sheet comprises at least three layers, wherein each of a first layer and a second layer comprises a mixture of PLA and PCL, a third layer comprises PBSA, and said second layer is located between said first layer and said third layer.

31. The laminated structure of claim 30, each of said first layer and said second layer of said second sheet comprises PLA at a concentration of from about 50% (w / w) to about 90% (w / w) and PCL at a concentration of from about 10% (w / w) to about 50% (w / w).

32. The laminated structure of claim 31, wherein each of said first layer and said second layer of said second sheet comprises PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w).

33. The laminated structure of any one of claims 30 to 32, wherein said third layer of said second sheet comprises PBSA at a concentration of from about 50% (w / w) to about 90% (w / w) and PLA at a concentration of from about 10% (w / w) to about 50% (w / w).

34. The laminated structure of claim 33, wherein said third layer of said second sheet comprises about 85% (w / w) PBSA and about 15% (w / w) PLA.

35. The laminated structure of any one of claims 30 to 32, wherein said third layer of said second sheet comprises about 100% (w / w) PBSA.

36. The laminated structure of any one of claims 20 to 35, wherein said second sheet further comprises an acid scavenger and / or an acid absorber.

37. The laminated structure of claim 36, wherein said acid scavenger and / or said acid absorber is selected from the group consisting of a metal carbonate, a metal oxide, a metal salt of a carboxylic acid, chitosan, hydrotalcite and combinations thereof.

38. The laminated structure of claim 37, wherein said metal oxide is selected from the group consisting of magnesium oxide, calcium oxide, zinc oxide and combinations thereof.

39. The laminated structure of claim 37 wherein said metal salt of a carboxylic acid is selected from a calcium salt, a zinc salt, sodium stearate and combinations thereof.

40. The laminated structure of claim 37, wherein said acid absorber comprises carbon black.

41. The laminated structure of any one of claims 28 to 40, wherein said second layer of said second sheet further comprises a metallized coating layer.

42. The laminated structure of any one of claims 20 to 41, wherein said third sheet comprises at least a first polymer layer, a second polymer layer and a third polymer layer, wherein said third polymer layer is situated between said first polymer layer and said third polymer layer, wherein each of said first layer and said second polymer layer comprises a mixture of polylactic acid (PLA) and polycaprolactone (PCL), wherein each of said first polymer layer and said third polymer layer forms from about 2.5% to about 20% of the total thickness of the sheet; andwherein said second polymer layer forms from about 60% to about 95% of the total thickness of the sheet.

43. The laminated structure of claim 42, wherein each of said first polymer layer of said third sheet and said second polymer layer of said third sheet comprise PLA at a concentration of from about 50% (w / w) to about 90% (w / w) and PCL at a concentration of from about 10% (w / w) to about 50% (w / w) and wherein said third polymer layer of said third sheet comprises poly(butylene succinate-co-adipate) (PBSA).

44. The laminated structure of claim 43, wherein each of said first polymer layer of said third sheet and said second polymer layer of said third sheet comprise PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w).

45. The laminated structure of claim 43, wherein said third polymer layer of said third sheet comprises 100% (w / w) PBSA.

46. The laminated structure of claim 43, wherein said third polymer layer of said third sheet comprises a mixture of PBSA and PLA.

47. The laminated structure of claim 46, wherein said third polymer layer of said third sheet comprises PBSA at a concentration of from about 50% (w / w) to about 90% (w / w) and PLA at a concentration of from about 10% (w / w) to about 50% (w / w).

48. The laminated structure of claim 47, wherein said third polymer layer of said third sheet comprises PBSA at a concentration of about 85% (w / w) and PLA at a concentration of about 15% (w / w).

49. The laminated structure of claim 20 or 21 , wherein said third sheet comprises at least three layers, wherein a first layer comprises a mixture of PBSA and PLA, a third layer comprises a mixture of PLA and PCL, and a second layer is located between said first layer and said third layer.

50. The laminated structure of claim 49, wherein said first layer of said third sheet comprises PBSA at a concentration of from about 50% (w / w) to about 90% (w / w) and PLA at a concentration of from about 10% (w / w) to about 50% (w / w).

51. The laminated structure of claim 50, wherein said first layer of said third sheet comprises PBSA at a concentration of about 85% (w / w) and PLA at a concentration of about 15% (w / w).

52. The laminated structure of any one of claims 48 to 51, wherein said third layer of said third sheet comprises a mixture of PLA and PCL.

53. The laminated structure of claim 49, wherein said third layer of said third sheet comprises PLA at a concentration of from about 50% (w / w) to about 90% (w / w) and PCL at a concentration of from about 10% (w / w) to about 50% (w / w).

54. The laminated structure of claim 53, wherein said third layer of said third sheet comprises PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 15% (w / w).

55. The laminated structure of claim 54, wherein said second layer of said third sheet comprises 100% (w / w) PBAT.

56. The laminated structure of claim 20 or 21, wherein said third sheet comprises PLA, PHA or a combination thereof.

57. The laminated structure of claim 56, said third sheet comprising a mixture of PLA and PHA.

58. The laminated structure of claim 57, said third sheet comprising from about 30% (w / w) to about 100% (w / w) PLA.

59. The laminated structure of claim 57, said third sheet comprising PHA at a concentration of about 45 (w / w) and PLA at a concentration of about 55% (w / w).

60. The laminated structure of claim 57, said third sheet comprising PHA at a concentration of about 30 (w / w) and PLA at a concentration of about 70% (w / w).

61. The laminated structure of claim 56, said third sheet comprising about 100% (w / w) PLA.

62. The laminated structure of claim 56, said third sheet comprising about 100% (w / w) PHA.

63. The laminated structure of any one of claims 42 to 62, further comprising a metallized coating layer provided on said third sheet.

64. The laminated structure of claim 63, wherein said metallized coating layer on said third sheet comprises aluminum or an oxide thereof.

65. The laminated structure of any one of claims 20 to 64, wherein said third sheet further comprises a fourth layer comprising a mixture of PBS A and PLA.

66. The biodegradable sheet of claim 65, wherein said fourth layer of said third sheet comprises PBSA at a concentration of from about 50% (w / w) to about 90% (w / w) and PLA at a concentration of from about 10% (w / w) to about 50% (w / w).

67. The biodegradable sheet of claim 65, wherein said fourth layer of said third sheet comprises PBSA at a concentration of about 85% (w / w) and PLA at a concentration of about 15% (w / w).

68. The laminated structure of any one of claims 20 to 64, wherein said third sheet further comprises a fourth layer comprising a mixture of PLA and PCL.

69. The biodegradable sheet of claim 68, wherein said fourth layer of said third sheet comprises PLA at a concentration of from about 50% (w / w) to about 90% (w / w) and PCL at a concentration of from about 10 (w / w) to about 50% (w / w).

70. The biodegradable sheet of claim 68, wherein said fourth layer of said third sheet comprises PLA at a concentration of about 80% (w / w) and PCL at a concentration of about 20% (w / w).

71. The laminated structure of any one of claims 42 to 70, further comprising a metallized coating layer provided on said first polymer layer of said third sheet.

72. The laminated structure of claim 71, wherein said metallized coating layer comprises aluminum or an oxide thereof.

73. The laminated structure of any one of claims 20 to 72, wherein said first biodegradable polymer sheet provides an outer layer, said second biodegradable polymer sheet is a core layer and said third biodegradable polymer sheet comprises a contact layer.

74. A package comprising the laminated structure of any one of claims 20 to 73, for storage therein of a material selected from the group consisting of a liquid, a semi-solid, a solid comprising a high content of volatile components and a solid moistened with a liquid medium.

75. The package of claim 74, for storage therein of a condiment.

76. The package of claim 75, wherein said condiment is ketchup.

77. The package of claim 75, wherein said condiment is mustard.

78. The package of any one of claims 74 to 77, wherein said material has a pH of less than about 8.

79. The package of claim 74, wherein said material comprises an oil.

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