Biodegradable items

Abstract

The present invention provides a biodegradable article comprising a cellulosic film coated on one side with a natural wax composition and laminated on an opposite side to a support layer comprising a paper-based substrate.

Description

[Technical field]

[0001] The present invention relates to a biodegradable article comprising a wax-coated cellulose film and preferably also a paper-based substrate. [Background technology]

[0002] Paper-based substrates are defined as materials produced by mechanically or chemically treating cellulose fibers, and therefore include materials such as paper, card and cardboard. Paper-based substrates are commonly used in disposable products such as paper plates. These products are usually coated with plastics and / or synthetic resins to provide the necessary moisture resistance and food contact properties. However, these chemically modified or synthetic coating materials, even if biodegradable, are problematic in terms of sustainability and environmental impact, as outlined in EU Directive No. 2019 / 904 (Single-Use Plastics Directive). Therefore, there is a societal drive towards reducing the use of these chemically modified or synthetic coating materials.

[0003] It is known to use cellulose films in biodegradable laminate structures. For example, EP 3266608 discloses a two-layer structure in which a cellulose film is laminated onto a modified starch layer, and a three-layer structure in which a cellulose film is laminated between a paper layer and a modified starch layer. However, the starch layer used is chemically modified, and the coating on the cellulose film contains a chemically synthesized resin.

[0004] EP 2829396 relates to a container for storing food, formed from a laminate comprising a first carrier layer made from cardboard, at least one second barrier layer made from a food-compatible oil or fat, a water- and heat-resistant material on the side facing the food to be stored, and an adhesive connecting the first carrier layer and the second barrier layer. The first carrier layer, the adhesive and the second barrier layer are food-safe, and the barrier layer comprises a hydrated cellulose film provided with a first vapour barrier coating at least on the side facing or opposite the food to be stored. The vapour barrier coating is preferably a biopolymer coating comprising a polyvinylidene chloride component that is not biodegradable.

[0005] WO2012 / 081041 relates to a paper substrate in which at least one regenerated cellulose layer is bonded by means of a water-based adhesive to at least one layer of a material having a barrier function against the penetration of water, the barrier being preferably a paraffin mixture in the form of a wax.

[0006] No. 4,543,282 relates to a food casing comprising cellulose and having a coating on its interior surface, the coating comprising a homogenous mixture comprising a first component selected from water-soluble cellulose ethers, starch ethers or combinations thereof, and a second component comprising a wax.

[0007] US Patent No. 6,558,719 relates to a cellulose-based food crust having an outer surface with a water vapor impermeable layer and an inner surface with a coating consisting of at least two components, the coating including a crosslinked polyaminoamide / epichlorohydrin resin and a wax.

[0008] US Patent No. 1,983,875 relates to a laminate material comprising at least one ply or stack of a moisture barrier sheet or film of regenerated cellulose.

[0009] Therefore, there remains a need in the art for fully biodegradable articles that are preferably substantially or completely free of chemically modified or synthetic ingredients that have the necessary moisture resistance and food contact properties. Summary of the Invention [Problem to be solved by the invention]

[0010] According to a first aspect of the present invention, there is provided a biodegradable article comprising a cellulose film coated on one side with a natural wax composition and laminated on an opposite side to a support layer comprising a paper-based substrate.

[0011] The inventors of the present invention have identified a construction in which the layers of the article (i.e., the substrate, the cellulose film, and the wax composition) are biodegradable and compostable, as well as free of chemically modified or synthetic ingredients, and also possess the necessary moisture resistance, heat resistance, and food contact properties. This is accomplished by using a natural wax composition that is suitable for food contact and increases the hydrophobicity of the cellulose film.

[0012] Waxes are known in the art for use as coating materials, with paraffin wax being the most commonly used. However, paraffin wax is not biodegradable. Therefore, the present invention instead utilizes natural wax compositions, i.e., compositions containing natural waxes derived from plants or animals. These waxes are biodegradable, compostable, and provide the necessary food contact and moisture resistance properties.

[0013] Furthermore, the inventors have surprisingly found that the biodegradable articles of the present invention have moisture resistance, heat resistance and food contact properties at least equivalent to articles coated with chemically modified or synthetic coating materials, but without the associated issues of sustainability and environmental impact.

[0014] The term "biodegradable" herein refers to a material that is capable of being physically and biologically broken down and ultimately decomposed into carbon dioxide (CO2), biomass and water, which can be recovered by composting and anaerobic digestion. A material may be defined as "biodegradable" if it undergoes at least 90% biodegradation in less than six months (Laboratory Test Method EN14855).

[0015] The cellulose film may be laminated to the support layer using any suitable technique. The cellulose film may be laminated to one side of the support layer, or may be laminated to two or more, or all, sides of the support layer.

[0016] There may be an adhesive layer between the cellulose film and the support layer. In other words, the cellulose film may be attached to the support layer using an adhesive. Preferably, the adhesive is a compostable adhesive. The adhesive may be solvent-based, water-based or solvent-free.

[0017] Alternatively, the cellulose film may be thermally laminated to the backing layer without the use of an adhesive.

[0018] A portion of the cellulose film may not be laminated to the support layer and may form a window in the article. The window may be at least partially surrounded by the portion of the cellulose film that is laminated to the support layer. The window may contain only the wax-coated cellulose film and may be transparent or partially transparent. Thus, the cellulose film can create a window in the article while providing the necessary water vapor barrier properties.

[0019] The wax composition is preferably on the surface of the article intended to contact food, thereby providing the necessary heat and moisture resistance, so the wax composition may be present on the outermost surface of the article, or, if the film forms a package, the wax composition may be on the inside of the package.

[0020] The wax composition may comprise a single wax or a blend of two or more waxes. The use of a blend of waxes has been found to provide improved heat and humidity resistance.

[0021] In embodiments where the wax composition comprises a blend of two waxes, the weight ratio of the two waxes is from about 10:1 to about 1:10, or from about 5:1 to about 1:5, or from about 3:1 to about 1:3, or from about 2:1 to about 1:2, or about 1:1.

[0022] All of the waxes in the wax composition may be natural waxes, i.e. waxes of vegetable or animal origin. The wax composition may include beeswax. The wax composition may include or consist of one or more vegetable waxes.

[0023] The wax composition may comprise one or more of candelilla wax, carnauba wax, soy wax, hemp wax, jojoba wax, ouricury wax and rice bran wax. Preferably, the wax composition comprises one or more of candelilla wax and carnauba wax.

[0024] One or more, or all, of the waxes in the wax composition may have a melting point of at least 60° C., or at least 65° C., or at least 70° C., or at least 75° C., thereby providing the necessary heat resistance for the coating. One or more waxes may have a relatively high melting point, for example, 75° C. or higher, or 80° C. or higher, thereby providing increased heat resistance so that the article can be used in combination with heated food products.

[0025] In some embodiments, the wax composition is free of petroleum-based waxes, in other words, the wax composition may be free of petroleum-based waxes, such as paraffin wax.

[0026] In addition to the one or more waxes, the wax composition may include one or more additives. The wax composition may include at least 50% by weight of wax, preferably at least 60% by weight of wax.

[0027] The inventors have found that the amount and type of natural wax present in the wax composition can be advantageously altered to adjust the properties and performance of the resulting film.For example, the amount and type of natural wax present by weight can be adjusted to adjust the gloss of the film, the optical properties of the film, the barrier properties of the film and / or the heat resistance of the film.Furthermore, a blend of waxes can be used to fine-tune the moisture barrier and heat resistance of the article, depending on the barrier properties and melting temperatures of the waxes included.

[0028] The additives may include one or more of: antiblock; viscosity modifier; natural resins other than wax; inorganic fillers; thickeners; and polysaccharide additives.

[0029] Preferably, none of the additives are chemically modified or synthetic polymers, and thus the article is preferably devoid of chemically modified or synthetic polymers.

[0030] The antiblock may be selected from any suitable material, but is preferably selected from one or more of amorphous silica and clay.

[0031] The viscosity modifier may be selected from any suitable material. The inventors of the present invention have found that the use of a viscosity modifier to increase the viscosity of the wax composition allows for the use of conventional coating techniques for cellulose films.

[0032] The non-wax natural resin can be selected from any suitable material, but is preferably rosin, more preferably rosin. The inventors of the present invention have surprisingly found that the use of non-wax natural resin in the wax composition provides improved coating laydown and surface appearance with a high gloss finish, which is particularly preferred for paper plate applications. The term "natural resin" refers to any resin derived from a plant or animal source without significant chemical modification.

[0033] In some embodiments, the natural resin other than wax may be one or more of dammar, respin, and shellac.

[0034] The weight ratio of wax to natural resin (other than wax) may be from about 1:1 to about 4:1, preferably from about 1:1 to about 3:1.

[0035] The inorganic filler may be selected from any suitable material, including, for example, one or more of quartz, carbon nanotubes, graphene, and clay. The inorganic filler may advantageously help to prevent water absorption into the cellulose film.

[0036] The polysaccharide additive may be selected from one or more of xanthan gum, alginic acid, sodium alginate, guar gum, and starch. The polysaccharide additive may act as a viscosity modifier.

[0037] The cellulose film may comprise cellulose. The cellulose film may comprise regenerated cellulose. The cellulose film may comprise a derivative of cellulose, such as hydroxypropyl cellulose or carboxymethyl cellulose. The cellulosic material in the cellulose film may come from any material containing cellulose, including agricultural waste or wood pulp. The agricultural waste may be selected from oat husks, tomato leaves, rice husks, jute, straw, wheat, miscanthus, hemp, grass, flax, or food crop waste. Other suitable agricultural waste sources may include palm fiber, tea waste, rice husk fiber, dates, stalks, or ginger.

[0038] The cellulose film may have a thickness of 10 to 100 microns, preferably 15 to 80 microns, more preferably 20 to 30 microns. The cellulose film is preferably transparent.

[0039] The wax composition may be coated onto the cellulose film at a coating weight of from about 0.1 gsm to about 6 gsm, preferably from about 0.3 gsm to about 5 gsm.

[0040] The natural wax composition may be in the form of a wax film on the surface of the cellulose film. By the term "wax film" it should be understood that the wax composition is in the form of a continuous, uniform film.

[0041] This may be accomplished by curing the wax composition after it has been coated onto the cellulose film. Curing of the composition may be accomplished by heat. The curing temperature may be above the melting temperature of the wax composition. The temperature may be about 50-120°C, or about 60-100°C, or about 70-90°C. If a blend of waxes is used, the temperature may be above the melting point of one or both of the waxes. Without being bound by theory, this may allow the deposited wax droplets to melt on the cellulose film surface, and then upon cooling, create a continuous wax film. In the form of a wax film, natural waxes may provide water vapor barrier properties comparable to paraffin wax.

[0042] The article may include a print. In some embodiments, the cellulose film is printed on the side opposite the wax composition. Additionally or alternatively, the support layer is printed. This advantageously means that the article is protected by the coated cellulose film, but can have a pattern visible through it.

[0043] The paper-based substrate may be selected from any suitable material including, for example, paper, cardboard, or card. The paper-based substrate may be opaque.

[0044] The support layer may be a flexible sheet. The flexible sheet may be formed into a bag. The bag may include a window formed from a wax-coated cellulose film.

[0045] Alternatively, the support layer may be molded. By "molded" we mean that the support layer independently maintains a three-dimensional shape (such as the shape of a paper plate) without the application of an external force, as compared to being a flexible layer that does not have a defined three-dimensional shape (such as a film) or a structure that has only a two-dimensional shape (such as a sheet of card). Thus, articles may also be molded.

[0046] The three-dimensional shape may be formed using any conventional technique, such as casting.

[0047] The support layer may have a substantially flat shape. By "substantially flat" it is meant that the majority of the support layer may be a continuous flat surface. Preferably, not all of the support layer is a continuous flat surface. Thus, preferably, the part of the support layer adjacent to the flat surface does not extend in the same plane as the flat surface. The inventors have found that having a substantially flat shape advantageously prevents the cellulose film from peeling off the support layer.

[0048] Any portion of the support layer adjacent to the flat surface may be at an angle of 90° or more, preferably 120° or more, and most preferably 140° or more, relative to the flat surface. The portion adjacent to the flat surface may be a border that extends around the periphery of the article. The article may have a depth that is substantially smaller than its width. In other words, the article may have a shallow shape (as opposed to a deep shape). This may also help prevent the cellulose film from peeling away from the support layer.

[0049] The support layer may have a thickness of 100 to 800 microns, preferably 200 to 700 microns. The support layer may have a weight of 50 to 500 gsm, preferably 100 to 400 gsm. This ensures that the article has sufficient structural integrity to hold items such as food.

[0050] The article may be a plate, tray, or bowl. The article may be a paper plate, paper tray, or paper bowl. Plates and bowls may be generally circular or oval in appearance. Trays may be generally square, rectangular, circular, or oval in appearance.

[0051] The article may be a straw, such as a paper straw, or a cup, such as a paper cup. The article may be any article mentioned in EU Directive No. 2019 / 904.

[0052] The article is preferably suitable for food contact. Thus, the article may comply with EU Regulation No. 1935 / 2004 of 27 October 2004 on materials and articles intended to come into contact with food. In particular, the article may comply with Article 3 of said EU Regulation No. 1935 / 2004. The article may also comply with the "specific measures for groups of materials and articles" provided in Article 5 of said EU Regulation No. 1935 / 2004 and / or the "national specific measures" provided in Article 6.

[0053] The coated cellulose film may comply with EU Directive No. 2007 / 42 of 29 June 2007 on materials and articles made of regenerated cellulose film intended to come into contact with food.

[0054] The wax and any additives present may only contain ingredients mentioned in EU Regulation No. 10 / 2011 of 14 January 2011 on plastic materials and articles intended to come into contact with food. Of course, the wax and any additives present are biodegradable.

[0055] Preferably, the biodegradable article is compostable. In other words, the biodegradable article may be a compostable article. The compostable article may comply with EN13432. For the avoidance of doubt, it should be understood that "compostable" is a stricter requirement than "biodegradable" since it also requires other requirements including "biodegradable" and decomposition and low levels of heavy metals.

[0056] The articles may comply with EU Directive No. 2019 / 904 of 5 June 2019 on the reduction of the environmental impact of certain plastic products.

[0057] Coated cellulose film is 50g / 24h / m 2 Less than 40g / 24hrs / m 2 Less than 30g / 24hr / m 2 Less than 20g / 24hr / m 2 Less than 15g / 24hr / m 2 Less than 10g / 24hr / m 2 It may have a water vapor transmission rate (measured at 25° C. / 75% RH) of less than

[0058] Coated cellulose film has a strength of 200 g / 24 h / m 2 Less than or equal to 190g / 24hrs / m 2 Less than or equal to 180g / 24hrs / m 2 It may have a water vapor transmission rate (measured at 38° C. / 90% RH) of less than

[0059] The article may be substantially or completely free of plastics, particularly fossil fuel plastics. Fossil fuel plastics are plastics derived from petroleum or natural gas. Fossil fuel plastics may also be referred to as "non-natural plastics." The article may be free of polyethylene and / or polypropylene. The article may be free of polyvinylidene chloride or polyvinylidene dichloride (PVDC).

[0060] The article may be substantially or completely free of chemically modified or synthetic polymers, where the term "free" refers to being present in an amount of less than 1% by weight, or less than 0.1% by weight, or 0% by weight.

[0061] According to a second aspect, there is provided a cellulose film coated with a wax composition comprising a natural wax. The wax composition may further comprise a natural resin other than wax.

[0062] The cellulose film and wax composition may have any of the characteristics discussed above in relation to the first aspect of the invention.

[0063] The coated cellulose film according to the second aspect has various uses. The coated cellulose film may be laminated to a substrate and, if necessary, glued. The substrate may be a paper-based substrate or a non-paper-based substrate. The substrate may be flexible or molded. This lamination to the substrate may thus produce an article according to the first aspect of the present invention.

[0064] The substrate may be opaque and the cellulose film may be transparent. The substrate may not cover the entire cellulose film. Thus, the areas of the cellulose film that are not adhered to the substrate may form a transparent or at least partially transparent window in the resulting article. The window may be formed only from the coated cellulose film.

[0065] The coated cellulose film may be used as a packaging material by itself without being attached to any supporting layer or substrate.As a non-limiting example, the coated cellulose film may be used as a packaging material for fruits and vegetables.Surprisingly, it has been found that the wax-coated cellulose film of the present invention has good water vapor barrier and optical properties, even though it does not contain any chemically synthesized or modified polymer.The coated cellulose film may be sealed to itself or to another film to make packaging material.

[0066] The coated cellulose film may be used for at least a portion of a packaging article. The coated cellulose film may be used in combination with other conventional packaging materials, such as trays or boxes.

[0067] According to a third aspect, there is provided a method of producing a biodegradable article, the method comprising laminating a cellulose film to a support layer comprising a paper-based substrate, and further coating the cellulose film on an opposite side of the film adjacent to the support layer with a natural wax composition.

[0068] In some embodiments, the cellulose film is coated with the natural wax composition prior to lamination to the support layer. In some embodiments, the cellulose film is coated with the natural wax composition after lamination to the support layer.

[0069] The natural wax composition may be coated onto the cellulose film using any suitable technique, hi some embodiments, the natural wax composition is spray coated onto the cellulose film.

[0070] The method may further include a step of curing the natural wax composition to produce a wax film on the surface of the cellulose film. This may involve heating the composition to a temperature higher than that of the wax composition after applying the composition to the surface of the cellulose film. The temperature may be about 50-120°C, or about 60-100°C, or about 70-90°C. If a blend of waxes is used, the temperature may be above the melting point of one or both of the waxes.

[0071] The third aspect of the invention may have any of the features discussed above in relation to the first aspect of the invention.

[0072] The invention will now be described in more detail with reference to the following examples and figures. [Brief description of the drawings]

[0073] [Figure 1] FIG. 1 illustrates a cross-sectional surface of an article according to an embodiment of the present invention. [Diagram 2] FIG. 2 illustrates a cross-sectional surface of a printed article according to an embodiment of the present invention. [Diagram 3] FIG. 3 illustrates a cross section of a paper plate according to an embodiment of the present invention. [Figure 4] FIG. 4 illustrates a top view photograph of a cellulose film according to an embodiment of the invention having a wax film on its surface (left), and the same cellulose film where the wax is not in the form of a film (right). [Diagram 5] FIG. 5 illustrates a top view photograph of a cellulose film according to an embodiment of the invention having a wax film on its surface (right), and the same cellulose film where the wax is not in the form of a film (left). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0074] Figure 1 shows an article according to an embodiment of the invention. The article comprises a cellulose film 1 that is coated on one side with a wax composition 2. On the opposite side, the cellulose film 1 is laminated to a paper substrate 3 using an adhesive layer 4.

[0075] Figure 2 shows a printed article according to an embodiment of the invention. The article has a cellulose film 1 that is coated on one side with a wax composition 2. On the opposite side, the cellulose film 1 is laminated to a paper substrate 3 using an adhesive layer 4. Between the cellulose film 1 and the paper substrate 3 is a printing layer 5. The printing layer 5 is applied to the cellulose film 1 (the side opposite the wax composition 2) before the cellulose film 1 is laminated to the paper substrate 3 using the adhesive layer 4.

[0076] In an alternative embodiment, the printing layer 5 may be applied to the paper substrate 3 before the cellulose film 1 is laminated to the paper substrate 3 using the adhesive layer 4. In this arrangement, the order of the adhesive layer 4 and the printing layer 5 of Figure 2 is reversed.

[0077] 3 illustrates a paper plate 6 according to an embodiment of the present invention. The paper plate 6 is formed from a molded paper base substrate to which is laminated a cellulose film (not shown) coated with a wax composition. The paper plate 6 has a width w that is substantially greater than its depth d. The angle a between the flat surface of the plate and the edge adjacent to the flat surface of the plate is greater than 90°. As such, the paper plate 6 can be described as a "shallow" plate, as opposed to a "deep" plate.

[0078] Figures 4 and 5 show embodiments of cellulose films coated with a wax composition comprising natural wax according to the present invention. Two of the films, 40, 50, have been heated so that the wax composition forms a wax film on the surface of the cellulose film. The other two films, 41, 51, have not been so treated.

[0079] As can be clearly seen in these photographs, the cured wax film has a higher gloss and lower haze than the uncured wax composition.

[0080] Measurement method Water Vapor Transmission Rate (WVP) WVP is defined as the weight of water vapor in grams that passes through one square meter of film during a 24 hour period. To measure WVP, a sufficient amount of silica gel was placed in a cup so that the bottom was covered to a depth of about 0.8 cm. A circular film sample was then cut, approximately 10 cm in diameter. A thin layer of paraffin wax was wiped off the surface of the cup. The circular sample was placed so that its edge was touching the surface and pressed down to avoid wrinkles. The coated side of the film was placed towards the outside of the cup. The cup was then placed in an oven at the desired temperature and relative humidity (RH). After 24 hours, the cup was removed and immediately weighed. The cup was placed back in the oven and weighed every 24 hours until a constant increase was obtained (usually after 72 hours).

[0081] 45° gloss Gloss was measured at 45° according to ASTM D2457.

[0082] Wide angle haze (%) Wide angle haze was measured at 2.5° according to ASTM D1003.

[0083] Block Test (g) After coating, eight strips of film were cut (6 in. x 2 in.), with the longest length in the machine direction. The film strips were separated into pairs and strips of paper (2 in. x 2 in.) were placed between adjacent pairs to form a stack of film pairs, each separated by paper.

[0084] The samples were then placed in a square on 2" x 2" glass plates and a glass plate was placed on top of each sample. The samples were placed in a thermostatically controlled oven and a 1.25 kg weight was placed on top of each glass plate. The samples were left at 38°C for 1 hour. After 1 hour, the samples were removed from the oven and allowed to cool for at least 15 minutes before further measurements.

[0085] After cooling, one end of the film of the film pair is bonded to the top plate using double-sided tape, and the other end of the film pair is bonded to the bottom plate using double-sided tape along the first edge of each film pair. The same is done along the second edge of the film pair where the second edge is opposite the first edge. The plates are then pulled apart in a direction perpendicular to the plane of the films, and the weight (in grams) required to separate the two films from each other is measured. The average of the four measured samples is taken.

[0086] Examples of coated cellulose films Several coated cellulose films were made, with each coating containing a different wax composition as outlined in Table 1. In each example, the film was a regenerated cellulose film.

[0087] Table 1 [Table 1]

[0088] For each film, the temperate and tropical water vapor transmission rates were measured according to the methods described above. The temperate water vapor transmission rate was measured at 25±0.5°C and 75±2% RH, and the tropical water vapor transmission rate was measured at 38±0.5°C and 90±2% RH. In addition, the hydrophobic surface properties were visually observed, and the 45° gloss and wide angle haze were measured. The results can be found in Table 2.

[0089] Table 2 [Table 2]

[0090] As can be seen, all of the films provide a surface that easily repels water, indicating good moisture resistance.

[0091] The highest water vapor transmission rates were observed in examples containing blends of waxes, ie, those containing both candelilla and carnauba waxes at coating weights above 1 gsm.

[0092] A comparable commercially available film is NatureFlex™ 22 DNE, which is also coated on only one side. It has a viscosity of 25 g / m2 at 25° C. and 75% RH. 2 1 / 24 hour water vapor transmission rate. Thus, the coatings listed above and especially those containing blends of waxes exhibit water vapor barrier properties comparable to, but not improved upon, conventional chemically modified or synthetic coatings.

[0093] Moreover, Example 4 in particular exhibited very good surface appearance, and Example 7 exhibited improved surface appearance compared to Example 3. This improved surface appearance is exemplified by the lower wide angle haze, which can be attributed to the presence of rosin in the coating.

[0094] The highest water vapor transmission rates were also observed for examples with coating weights greater than 1 gsm. For example, Example 7 exhibited improved water vapor transmission rates compared to Example 9, and Example 4 exhibited improved water vapor transmission rates compared to Example 10.

[0095] Additionally, the lower coating weight examples exhibited improved surface appearance compared to the higher coating weight examples, e.g., Example 10 exhibits improved surface appearance compared to Example 4, and Example 8 exhibits improved surface appearance compared to Example 5, as exemplified by lower wide angle haze.

[0096] Additionally, it is found that the amount of wax present in the wax composition affects the properties of the resulting film.

[0097] For example, the examples with increased wax percentages provided improved barrier properties. Both Examples 8 and 12, which have a wax:resin ratio of 2:1, exhibited improved barrier properties compared to Example 10, which has a wax:resin ratio of 1:1. This is a result of the waxes, particularly candelilla wax, having superior water vapor barrier properties.

[0098] The optical properties of the wax can also affect the properties of the film. For example, carnauba wax does not have as good optical and barrier properties as candelilla wax. This can be seen by comparing Examples 8 and 9, both of which have a 2:1 wax:rosin ratio. Example 9 has a much better water vapor transmission rate than Example 8 due to the presence of carnauba wax.

[0099] Thus, the amount and type of wax present can be adjusted to balance the moisture barrier and heat barrier properties of the article.

[0100] Commercially available Natureflex™ films have a wide angle haze of 5-6, so the coatings of the present invention have optical properties comparable to films made using chemically modified or synthesized polymers.

[0101] The melting point of the wax is also important, since carnauba wax is not as hydrophobic as candelilla wax and does not produce the same level of moisture barrier, but it has a higher melting point (81°C vs. 71°C for candelilla). Therefore, this wax can improve the heat resistance of the coating. Additionally, dammar resin has a melting point above 100°C. Thus, a blend of waxes can balance the moisture barrier and heat barrier properties of the article.

[0102] Block tests were performed in Examples 8-15 and measured according to the methods described above. The results can be found in Table 3.

[0103] Table 3 [Table 3]

[0104] As can be seen, none of the films of Examples 8-15 exhibit any blocking, demonstrating that the films do not adhere well to each other.

[0105] The results summarized in Tables 1-3 were measured on cellulose films that were coated with the wax composition and heat cured to form a wax film on the surface. Tables 5 and 6 compare the properties of the heat cured films to films in which the wax composition had not been heat treated. The films were measured according to the methods described above.

[0106] The final coating weights for Examples 8-15 are outlined in Table 1.

[0107] Table 4 [Table 4]

[0108] Table 5 [Table 5]

[0109] The highest water vapor transmission rate was found for the heat-cured films, as there was a significant increase in water vapor transmission rate for non-heat-cured films in both temperate and tropical conditions.

[0110] Table 6 [Table 6]

[0111] As can be seen, the heat cured films provide improved surface appearance as exemplified by lower wide angle haze and increased 45° gloss compared to the non-heat cured films.

[0112] Without being bound by theory, it is believed that when a cellulose film is coated with a natural wax composition, the droplets of the wax composition do not provide a uniform coating on the surface of the film, and as a result, these droplets create a fuzzy appearance as a result of light diffraction and / or refraction, and also act to increase the water vapor transmission rate through the entire film.

[0113] In contrast, when the film is heat-set, the individual wax droplets on the cellulose film melt and create a continuous wax film that is understood to be relatively uniform and transparent, thus significantly reducing the wide-angle haze and water vapor transmission rate.

Claims

1. A biodegradable article comprising a cellulose film coated on one side with a natural wax composition and laminated on an opposite side to a support layer comprising a paper-based substrate.

2. The article of claim 1 , comprising an adhesive between the cellulose film and a support layer.

3. The article of claim 2 , wherein the adhesive is a compostable adhesive.

4. The article of claim 1 , wherein there is a portion of the cellulose film that is not laminated to the support layer, creating a transparent window.

5. The article of claim 1 , wherein the natural wax composition comprises a vegetable wax.

6. 10. The article of claim 1, wherein the natural wax composition comprises a blend of two or more waxes and / or the natural wax composition coating is in the form of a wax film on the surface of a cellulose film.

7. 7. The article of claim 5 or claim 6, wherein the natural wax composition comprises one or more of candelilla wax and carnauba wax.

8. 10. The article of claim 1, wherein the wax composition further comprises one or more additives, optionally one or more of antiblock; viscosity modifier; natural resin other than wax; inorganic filler; thickener; and polysaccharide additive, and optionally the wax composition comprises at least 50% by weight, preferably 60% by weight, of natural wax.

9. The article of claim 1 , which does not include chemically modified or synthetic polymers.

10. The article of claim 1 , wherein the cellulose film is printed on the side opposite the natural wax composition.

11. The article of claim 1 , wherein the support layer is printed.

12. The article of claim 1 , wherein the support layer is molded.

13. The article of claim 12 , wherein the support layer has a substantially flat shape.

14. The article of claim 1 which is a plate, tray, or bowl.

15. The article of claim 1 having a depth that is substantially less than its width.

16. 10. The article of claim 1, which is intended for food contact.

17. 10. The article of claim 1, which undergoes at least 90% biodegradation in less than six months (Laboratory Test Method EN 14855).

18. The coated cellulose film has a coating density of 50 g / 24 h / m ２ Less than 40 g / 24 hours / m ２ Less than 30 g / 24 hours / m ２ Less than or equal to 20 g / 24 hours / m ２ Less than or equal to 15 g / 24 hours / m ２ Less than or equal to 10 g / 24 hours / m ２ 10. The article of claim 1, having a water vapor transmission rate (measured at 25±0.5° C. / 75±2% RH) of less than

19. The coated cellulose film has a coating density of 200 g / 24 h / m ２ Less than or equal to 190 g / 24 hrs / m ２ Less than or equal to 180 g / 24 hours / m ２ 10. The article of claim 1, having a water vapor transmission rate (measured at 38±0.5° C. / 90±2% RH) of less than

20. A cellulose film coated with a wax composition comprising a natural wax.

21. A method for producing a biodegradable article, the method further comprising laminating a cellulose film to a support layer comprising a paper-based substrate, and coating the cellulose film with a natural wax composition on an opposite side of the film adjacent to the support layer.

22. 22. The method of claim 21, wherein the cellulose film is coated with a wax composition before laminating it to the support layer.

23. 22. The method of claim 21, wherein the cellulose film is coated with a wax composition after being laminated to the support layer.

24. 22. The method of claim 21, wherein the natural wax composition is spray coated onto the cellulose film.

25. 22. The method of claim 21, further comprising curing the natural wax composition to create a wax film on the surface of the cellulose film.

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