BIO-POLYMER MULCH FILM AND PROCESS FOR MANUFACTURING SAME

Abstract

A process for manufacturing a bio-polymer mulch film is provided. The process comprises coating at least parts of a surface of a bio-polymer film with a functional material. The functional material may comprise a light absorber material, a light reflector material and/or a pigment.

Claims

1. A process for manufacturing a bio-polymer mulch film, comprising a step of coating at least parts of a surface of a bio-polymer film with a functional material.

2. (canceled)

3. A process according to claim 1, wherein the coating step is performed by a technique selected from the group consisting of: flexographic printing, coil printing, screen printing, rotogravure, lithography, ink-jet, roll-to-roll deposition technique, spraying technique and combinations thereof.

4. (canceled)

5. A process according to claim 1, further comprising: a pre-treatment step wherein a charge is imparted on the surface of the bio-polymer film; optionally the pre-treatment step comprises at least of corona treatment, air plasma, flame plasma and chemical plasma system; and/or a curing step; optionally, the curing step involves heat, UV light and/or an electron beam.

6. (canceled)

7. A process according to claim 1, wherein the functional material comprises a light absorber material, a light reflector material and/or a pigment; optionally the functional material comprises at least one of: nitrocellulose, polyamide, acrylic, polyurethane, rosin, titanium dioxide (TiO.sub.2), barium sulfate (BaSO.sub.4), carbon black, aluminum (Al), graphene, zein including genetically modified zein and non-genetically modified zein, magnesium carbonate (MgCO.sub.3), zinc oxide (ZnO), calcium carbonate (CaCO.sub.3), kaolin, wax, a metallic pigment including an aluminum (Al) pigment (Grandal W170), and a solvent.

8.-16. (canceled)

17. A process according to claim 1, wherein the functional material has a viscosity (Zahn Cup #2 EZ) between about 20 to 30 seconds, preferably about 23 to 28 seconds or about 25 to 30 seconds; optionally a solvent is added during the process to maintain the viscosity at a desired value.

18. A process according to claim 17, wherein the solvent comprises alcohol and/or water.

19. A process according to claim 1, wherein the coating is on the whole surface of the bio-polymer film.

20. A process according to claim 1, wherein the coating is in the form of one or more stripes on the surface of the bio-polymer film; optionally the stripes are continuous or discontinuous.

21. (canceled)

22. A process according to claim 1, wherein: the coating is of a color selected from the group consisting of: white, black, silver, blue, gray, green, yellow, orange, red and a combination thereof; optionally the color is matte (reflectance below 55%); or the coating has no color (no pigment).

23. (canceled)

24. A process according to claim 1, wherein: the bio-polymer film is of a color selected from the group consisting of: white, black, silver, blue, gray, green, brown and a combination thereof; or the bio-polymer film has its natural color.

25. (canceled)

26. A process according to claim 1, wherein: the coated side of the bio-polymer film and the coating are each of a different color; or the coated side of the bio-polymer film and the coating are of the same color; or the coated side of bio-polymer film has a color and the coating has no color (no pigment); or the bio-polymer film has no color and the coating has a color; or the bio-polymer film has no color and the coating has no color (no pigment).

27.-31. (canceled)

32. A bio-polymer mulch film comprising a layer of bio-polymer material that is at least partially coated with a layer of a functional material.

33. A bio-polymer mulch film according to claim 32, having: an average thickness that is at least about 15% less than an average thickness of an uncoated bio-polymer mulch film; and/or an average thickness that is at least about 15% less than an average thickness of a conventional mulch film; and/or an average thickness that is between about 0.3 to 3 mil.

34.-35. (canceled)

36. A method of controlling the temperature of the soil and air around a plant, comprising using a bio-polymer mulch film comprising a layer of bio-polymer material that is at least partially coated with a layer of a functional material.

37.-38. (canceled)

39. A method according to claim 36, wherein the use comprises covering the soil around the plant with the bio-polymer mulch film such that the surface of the mulch film having the coat of functional material is exposed to sunlight.

40. A composition comprising: genetically modified zein, BaSO.sub.4, Al and a solvent; optionally, the functional material comprises an Al pigment (Grandal W170); or non genetically modified zein, BaSO.sub.4, Al and a solvent; optionally, the functional material comprises an Al pigment (Grandal W170); or genetically modified zein, BaSO.sub.4, TiO.sub.2 and a solvent; or non-genetically modified zein, BaSO.sub.4, TiO.sub.2 and a solvent.

41.-47. (canceled)

48. A composition according to claim 40, wherein the solvent comprises an organic solvent including alcohol and/or water; preferably the solvent comprises a C.sub.1-C.sub.12 linear, branched, saturated or unsaturated organic solvent and/or water; more preferably the solvent comprises a C.sub.1-C.sub.12 linear, branched, saturated or unsaturated alcohol and/or water; more preferably the solvent comprises n-propanol and/or water.

49. A composition according to claim 48, wherein the solvent is selected from the group consisting of: n-propanol, n-propyl acetate, methanol, ethanol, ethyl acetate, methyl acetate, methoxy propyl acetate, 3-propoxypropan-1-ol (Propasol P), diacetone alcohol, ethoxypropanol and combinations thereof.

50.-51. (canceled)

52. A process for preparing a composition comprising zein, BaSO.sub.4, Al and a solvent, the process comprising: (a) providing a solvent comprising an organic solvent including alcohol and/or water; (b) mixing zein with a first part of the solvent of step (a) to obtain varnish zein; (c) mixing Al pellets with a second part of the solvent of step (a) to obtain a dough; (d) mixing the varnish zein obtained at step (b), BaSO.sub.4, Al, the dough obtained at step (c) and a third part of the solvent of step (a) to obtain a concentrated mixture; and (e) mixing the concentrated mixture obtained at step (d) with a fourth part of the solvent of step (a) to obtain the composition.

53. A process for preparing a composition comprising zein, BaSO.sub.4, TiO.sub.2 and a solvent, the process comprising: (a) providing a solvent comprising an organic solvent including alcohol and/or water; (b) mixing zein with a first part of the solvent of step (a) to obtain varnish zein; (c) mixing a first part of the varnish zein obtained at step (b), BaSO.sub.4 and TiO.sub.2 to obtain a concentrated mixture; and (d) mixing the mixture obtained at step (c), a second part of the varnish zein obtained at step (b) and a second part of the solvent of step (a) to obtain the composition.

54. A process according to claim 52, wherein: the solvent is obtained by gently stirring alcohol and/or water, preferably at room temperature and/or; step (b) is carried out under gentle to moderate stirring, preferably until the varnish zein is a homogenous mixture; and/or step (c) comprises (c1) soaking the Al pellets into the solvent, preferably during a period of about 30 minutes, and (c2) subjecting the mixture to a gentle stirring; preferably steps (c1) and (c2) are carried out at room temperature; and/or step (e) is carried out under gentle to moderate stirring; and/or step (e) is carried out under gentle to moderate stirring.

55.-59. (canceled)

60. A process according to claim 52, wherein: the Al pellets at step (c) comprise Grandal W170; and/or the Al at step (d) comprises finely grounded Al.

61. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In the appended drawings:

[0035] FIG. 1: Cross-section of an embodiment of the bio-polymer mulch film according to the invention.

[0036] FIG. 2: Surface of an embodiment of the bio-polymer mulch film according to the invention.

[0037] FIG. 3: Photograph of an embodiment of the bio-polymer mulch film according to the invention; the mulch film was used outdoors for 2 months.

[0038] FIG. 4: Photograph of an embodiment of the bio-polymer mulch film according to the invention; the mulch film was used outdoors for 2 months.

[0039] FIG. 5: Photograph of an embodiment of the bio-polymer mulch film according to the invention; the mulch film was used outdoors for 2 months.

[0040] FIG. 6: Tensile strengths of individual films.

[0041] FIG. 7: Ultimate elongation of individual films.

[0042] FIG. 8: Photograph of films from Example 11.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0043] Before the present invention is further described, it is to be understood that the invention is not limited to the particular embodiments described below, as variations of these embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments, and is not intended to be limiting. Instead, the scope of the present invention will be established by the appended claims.

[0044] In order to provide a clear and consistent understanding of the terms used in the present specification, a number of definitions are provided below. Moreover, unless defined otherwise, all technical and scientific terms as used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention pertains.

[0045] As used herein the term bio-polymer film refers to a film made of a polymer or resin that meets the requirements as defined by ASTM D-6400 or ISO 17088:2008 or MOD or the European norm EN-13432 or the Japanese norm GreenPla or the norm of the province of Quebec CAN/BNQ 0017-088/2010 or any norm that provides for any soil-compostability and/or biodegradability, whether such bio-polymer is produced using renewable or non-renewable sources or a combination thereof.

[0046] As used herein the term white on black bio-polymer mulch film or similar term refers to a mulch film obtained by co-extrusion.

[0047] As used herein the term black film coated with white pigment or similar term refers to a film obtained by coating a black film with a white pigment.

[0048] The use of the word a or an when used in conjunction with the term comprising in the claims and/or the specification may mean one, but it is also consistent with the meaning of one or more, at least one, and one or more than one. Similarly, the word another may mean at least a second or more.

[0049] As used in this specification and claim(s), the words comprising (and any form of comprising, such as comprise and comprises), having (and any form of having, such as have and has), including (and any form of including, such as include and includes) or containing (and any form of containing, such as contain and contains), are inclusive or open-ended and do not exclude additional, un-recited elements or process steps.

[0050] As used herein the term about is used to indicate that a value includes an inherent variation of error for the device or the method being employed to determine the value.

[0051] The inventors have discovered a process for manufacturing a bio-polymer mulch film that involves use of smaller amounts of bio-polymer material when used with a functional material. The process of the invention comprises a coating process. More specifically, the process of the invention comprises providing a coat of functional material on at least parts of a surface of a bio-polymer film.

[0052] The functional material may be a light absorber material, a light reflecting material, a pigment, or any suitable similar material, or a combination thereof. More specifically, the functional material may be selected from the group consisting of: nitrocellulose, polyamide, acrylic, titanium dioxide (TiO.sub.2), barium sulfate (BaSO.sub.4), carbon black, aluminum (Al), graphene, zein including genetically modified zein and non genetically modified zein, magnesium carbonate (MgCO.sub.3), zinc oxide (ZnO), calcium carbonate (CaCO.sub.3), kaolin, wax, a metallic pigment including an aluminum (Al) pigment (Grandal W170), a solvent and any suitable material.

[0053] The bio-polymer mulch film of the invention has an average thickness that is less than the thickness of a conventional mulch film or an uncoated bio-polymer mulch film. More specifically, the bio-polymer mulch film of the invention has an average thickness that is at least about 15% less than the thickness of an uncoated bio-polymer mulch film or a conventional mulch film with similar efficiency. In embodiments of the invention the average thickness of the bio-polymer mulch film may be between about 0.3 to 3 milli inch (0.3 to 3 mil).

[0054] The bio-polymer mulch film and the functional material are each independently of various colors. The color may be white, black, silver, blue, gray, green, brown, yellow, orange, red, or any other suitable color, or a combination thereof. The bio-polymer mulch film may also have its natural color. Also, the functional material may have its natural, unpigmented color. In embodiments of the invention, at least one of the bio-polymer mulch film and the functional material is un-colored.

[0055] Referring to the figures, FIGS. 1 and 2 illustrate embodiments of the bio-polymer mulch film 10 according to the invention. The bio-polymer mulch film 10 comprises a layer of bio-polymer (bio-polymer film) 12. A coat of functional material 14 is provided on a surface of the bio-polymer film 12. In the embodiment illustrated in FIG. 1, the coat of functional material 14 is provided on the whole surface of the bio-polymer film 12. In an embodiment of the bio-polymer mulch film 10 as illustrated for example in FIG. 2, the coat of functional material 14 is provided in the form of stripes 16. As will be understood by a skilled person, the coat of functional material 14 may be provided in any other suitable form such that only parts of the surface of the bio-polymer film 12 is covered.

[0056] The present invention is illustrated in further details by the following non-limiting examples.

Example 1Application of a Black Coating on a Bio-Polymer Film

[0057] We propose to apply a coating of carbon black or other similar light absorber, be it inorganic and organic, on the surface of the film so as to protect or block sunlight from reaching the bio-polyester film. Consequently, the bio-polyester film will be thinner, contain as much or less carbon black, depending on the overall thickness. For example, a coating weight of 1 gram of carbon black per square meter is expected to allow for a 0.5 mil film to exhibit the same or better weathering properties as the Reference Film referred to herein above in the Background section.

[0058] The coating according to the invention may be applied using a common deposition method known in the art such as flexographic printing or equivalent or similar method, including roll-to-roll deposition techniques. This may involve a solvent or no solvent, and cured with heat, UV light or using an electron beam curing system.

[0059] It is expected that the thickness of the bio-polyester film may be reduced by about 15% while exhibiting equal or superior weathering properties as the Reference film, or other uncoated bio-polyester films known in the art, regardless of their thickness. Because bio-polyester materials are expensive, the additional cost of the coating and application thereto is inferior to the cost of a thicker and highly functionalized, uncoated film.

Example 2Application of a Coating of Pigment

[0060] We propose to apply a coating of titanium dioxide or other similar white pigment, for example, magnesium carbonate, zinc oxide, calcium carbonate, kaolin, aluminum powder, either in neat form or blended, on the surface of a black film so as to protect or block the Bio-polyester film from sunlight while reducing the temperature above the soil. Consequently, the bio-polyester film will be thinner. For example, a coating weight of 3 grams of titanium dioxide per square meter is expected to allow for a 0.5 mil film to exhibit superior properties as the Reference Film 2 (referred to herein above in the Background section) after it has been exposed to 4 months of sunlight, for example, in New Jersey. This, in turn, makes it suitable for use as a mulch film for solanacees like tomatoes, bell peppers and eggplant.

[0061] The coating according to the invention may be applied using a common deposition method known in the art such as flexographic printing, or equivalent or similar method, including roll-to-roll deposition techniques. This may involve a solvent or no solvent, and cured with heat, UV or an electron beam.

[0062] An advantage of such titanium dioxide coated films is their ability to be thinner yet perform as well after outside exposure if not better than thicker white on black co-extruded films. It is expected that the improvement may be in the order of at least about 15%, meaning that a 0.5 mil white coated film with a coat weight of 1 grams per square meter will perform at least as well as a 0.7 mil white on black film.

Example 3Application of a Matte White Coating

[0063] A black film coated with a white pigment, for example titanium dioxide, with a light coating weight (for instance, 1 or even 0.5 grams per square meter) is expected to not cause for as much sun damage to the young plants as a white on black co-extruded film. This will cause for less light reflection of light and still maintain a desired lower above soil temperature.

[0064] The process of the invention may be applied to a bio-polyester film or non-compostable film.

[0065] We have observed that the stems of young pepper plants do not harden as much, when planted over white coated films, as compared to a white on black films. It is believed that plants will grow taller and will be more productive.

Example 4Application of a White Coating on a Black Film

[0066] The following example illustrates this embodiment of the invention. On May 8 at 6.45 AM, soil temperatures were collected. The ambient air temperature was 57 F and it was foggy on that morning. The temperature of the black film, the white on black film, and the black film coated with white was 61.5 F (as measured with a temperature gun). The temperature 1.5 inches below the soil was 65.5 F for the black film, 64 F for the white on black film, and 64.5 F for the white-coated film (as measured with a thermal probe).

[0067] In contrast, on June 9, at 7 PM when the ambient temperature was 80 F, the temperature 1.5 inches below the soil was 73 F for the white on black film, as compared to 75 F for the white-coated black film and 76 F for the black film. As for the actual film temperatures, the white on black film temperature was also 73 F, whereas the temperature of the white-coated black film was 78 F and the black film was 81 F.

[0068] We have observed that a low relative reflectance white-coated black film maintains a sufficiently low air temperature and does not cause the stem to harden up; see FIGS. 3-5. In addition, we have observed warmer soil temperatures. The combination of these two seems to have increased early yield for peppers.

[0069] The coating according to the invention may be applied on the whole surface of the film or in stripes, so as to further increase the soil temperature where there is no coating; see FIGS. 3-5 and maintain the appropriate air temperature around the young plant.

[0070] The invention is further illustrated by more non-limiting examples as outlined below. These examples stem from experiments conducted in the spring and summer of 2016. Several bio-polymer films were produced using the blown film process. The films were then treated by applying various printing inks using the flexographic printing process. The films so treated were exposed outdoor for several weeks. The films were then tested for ultimate tensile strength and ultimate elongation using an Instron tensile tester. In all cases, the treated films exhibited more superior weather resistance than the untreated films.

Example 5Production of Films

[0071] Six films, P1 to P6 were produced using the same blown film extrusion equipment. The process involved substantially the same recipe for each film, namely, a mixture comprising polybutylene adipate terephthalate (PBAT), polylactic acid (PLA) and limestone. The amount of carbon black pigment varied slightly for each film and was generally up to about 3%. Also, the level of ultraviolet inhibitor incorporated varied slight for each film and was generally less than about 0.0005%. Table 1 below provides the characteristics for each of the P1 to P6 films produced.

TABLE-US-00001 TABLE 1 Characteristics of the films produced Film Average identification Colour thickness Purpose P1 Black (3%) 0.55 mil Baseline (no treatment) P2 Black (3%) 0.6 mil Baseline (no treatment) P3 Clear, 0.45 mil Black treatment unpigmented P4 Black (3%) 0.55 mil White treatment P5 Black (3%) 0.55 mil White treatment P6 Black (3%) 0.55 mil Reflective treatment

Treatment of Films

[0072] Films were treated using a flexographic printing press and printing inks. The treatment comprises depositing ink on at least part of the surface of the film. In all cases, the amount of ink deposited was about 8 billion cubic microns (BCM).

Example 6Treated NP3 Film

[0073] Ink used for the NP3 film comprises nitrocellulose (2%), polyamide (53%), carbon black pigment (40%) and other suitable components including wax and additives (5%). The mixture is diluted in n-propanol (55%). The viscosity of the composition (Zahn Cup #2 EZ) is between about 20 and 24 seconds. The viscosity is kept at this level on the printing press by addition of n-propanol, as needed.

Example 7Treated BP4 and BP5 Films

[0074] Ink used for each of the BP4 and BP5 films comprises nitrocellulose (4%), polyamide (25%), wax (3%) and TiO.sub.2 (68%). The mixture is diluted in n-propanol (40%). The viscosity of the composition (Zahn Cup #2 EZ) is between about 23 and 28 seconds. The viscosity is kept at this level on the printing press by addition of n-propanol, as needed.

Example 8ATreated SP6 Film (Zein (Genetically Modified), BaSO.SUB.4.Aluminum)

[0075] Ink composition for SP6 film comprises concentrated BaSO.sub.4Al (65%) and a solvent mix (35%). The two components mixed together under gentle stirring. First, the solvent mix is prepared, by mixing together n-propanol (70%) and water (30%) at room temperature under gentle stirring. This will be used at the various steps of the process.

[0076] The concentrated BaSO.sub.4Al is obtained by mixing together zein varnish at 30%, BaSO.sub.4 (54%), Grandal W170 (Al) dough (15%) and the solvent mix (1%). The process at this step is as follows: BaSO.sub.4 is incorporated into the zein varnish and dispersed at high speed; the temperature is monitored and maintained around about 50-55 C.; the Grandal W170 (Al) dough is then added, at moderate speed until a homogenous mixture is obtained.

[0077] The Grandal W170 (Al) dough is obtained by mixing together Grandal W170 (50%) and the solvent mix (50%), according to the following process: Grandal W170 granules are soaked into the solvent mix for about 30 minutes and the mixture subjected to gentle stirring at room temperature.

[0078] The zein varnish is obtained by mixing together genetically modified zein F4000 (30%) and the solvent mix (70%) under gentle stirring until a homogenous mixture is obtained.

[0079] In this embodiment of the invention, the metallic pigment Grandal W170 is used. As will be understood by a skilled person, other suitable metallic pigments may also be used. For example other aluminum (Al) pigments may be used.

[0080] Further details on the process are provided in Table 2 below including the amounts of each component for the preparation of 100 kg of ink. The physico-chemical characteristics of the ink obtained are outlined in Table 3.

TABLE-US-00002 TABLE 2 Treatment for the SP6 film (zein (genetically modified), BaSO.sub.4-Al) 1-Solvent Mix % for 100 kg n-Propanol 70 42 Water 30 18 100 60 2-Zein varnish at 30% % for 100 kg Solvent Mix 70 16.4 Zein F4000 (genetically 30 7 modified) 100 19.5 3-Grandal W170 dough (Al) % for 100 kg Solvent Mix 50 4.85 Grandal W170 50 4.85 100 9.7 4-BaSO.sub.4-Al concentrated % for 100 kg Zein varnish 30 19.5 BaSO.sub.4 54 35.1 Grandal W170 dough 15 9.7 Solvent Mix 1 0.7 100 65 5-Ink (final) % for 100 kg BaSO.sub.4-Al concentrated 65 65 Solvent Mix 35 35 100 100

TABLE-US-00003 TABLE 3 Physico-chemical characteristics of the ink obtained Control Specifications Visco Zahn #2 EZ 25-30 (sec) Masse volumique 1.28-1.30 (g/mL) ES (%) 45.0-46.5 Reflectance 310 nm 33-37 (%)* Reflectance 380 nm 32-36 (%)* *For a full surface printing at 8 BCM-240 LPI

Example 8BTreated NP6 Film (Zein (Non Genetically Modified), BaSO.SUB.4.Aluminum)

[0081] Ink for the PS6 film may be prepared using non genetically modified zein. The ink composition comprises concentrated BaSO.sub.4Al (65%) and a solvent mix (35%). The solvent mix is obtained by mixing together n-propanol (90%) and water (10%); and the concentrated BaSO.sub.4Al is obtained by mixing together zein varnish (30%), BaSO.sub.4 (54%), Grandal W170 dough (15%) and the solvent mix (1%). The Grandal W170 dough is obtained by mixing together Grandal W170 (50%) and the solvent mix (50%); and the zein varnish is obtained by mixing together non genetically modified zein F4400 (30%) and the solvent mix (70%). The process is further outlined in Table 4 below. Details are generally as described in Example 8A above.

[0082] In this embodiment of the invention, the metallic pigment Grandal W170 is used. As will be understood by a skilled person, other suitable metallic pigments may also be used. For example other aluminum (Al) pigments may be used.

TABLE-US-00004 TABLE 4 Treatment for the SP6 film (zein (non genetically modified), BaSO.sub.4-Al) 1-Solvent Mix % n-Propanol 90 Water 10 100 2-Zein varnish at 30% % Solvent Mix 70 Zein F4400 (non genetically 30 modified) 100 3-Grandal W170 dough (Al) % Solvent Mix 50 Grandal W170 50 100 4-BaSO.sub.4-Al concentrated % Zein varnish 30 BaSO.sub.4 54 Grandal W170 dough 15 Solvent Mix 1 100 5-Ink (final) % BaSO.sub.4-Al concentrated 65 Solvent Mix 35 100

Example 8CTreated NP6 Film (Zein (Genetically Modified), BaSO.SUB.4.TiO.SUB.2.)

[0083] Alternatively, ink for PS6 may comprise concentrated BaSO.sub.4TiO.sub.2 (65%), zein varnish (20%) and a solvent mix (15%). The solvent mix is obtained by mixing together n-propanol (70%) and water (30%); zein varnish is obtained by mixing together genetically modified zein F4000 (30%); and the concentrated BaSO.sub.4TiO.sub.2 is obtained by mixing together zein varnish (40%), BaSO.sub.4 (42%), and TiO.sub.2 (18%). The process is further outlined in Table 5 below. Details are generally as described in Example 8A above.

TABLE-US-00005 TABLE 5 Treatment for the SP6 film (zein (genetically modified), BaSO.sub.4-TiO.sub.2) 1-Total Solvent % n-Propanol 70 Water 30 100 2-Zein varnish at 30% % Solvent 70 Zein F4000 (genetically 30 modified) 100 3-BaSO.sub.4-TiO.sub.2 concentrated % Zein varnish 40 BaSO.sub.4 42 TiO.sub.2 18 100 4-Ink (final) % BaSO.sub.4-TiO.sub.2 concentrated 65 Zein varnish 20 Solvent 15 100

[0084] Treatment specifications for each film used in the experiments are outlined in Table 6 below.

TABLE-US-00006 TABLE 6 Treatment specification of films Film Treated/ Ink colour and Pigment carrier identification Untreated pigment type Purpose P1 P1 (untreated) none not applicable Baseline, unweathered (n.a.) P2 P2 (untreated) none n.a. Baseline, unweathered P3 CP3 none n.a. Baseline, weathered (untreated) and compare to BP3 P3 NP3 (treated) Black, carbon Nitrocellulose and, Effect of a black black optionally coating and polyamide comparison to CP3 or acrylic P4 BP4 (treated) White, TiO.sub.2 Nitrocellulose and, Effect of a white optionally coating polyamide or acrylic P4 NP4 none n.a. Baseline, weathered (untreated) and comparison to BP4 P5 BP5 (treated) White, TiO.sub.2 Nitrocellulose and, Effect of a white optionally coating polyamide or acrylic P5 NP5 none n.a. Baseline, weathered (untreated) and comparison to BP5 P6 SP6 (treated) Silver, BaSO.sub.4-Al Zein Effect of a UV reflective powder coating

Example 9Outdoor Exposure

[0085] Films were exposed outdoors for a few weeks as outlined in Table 7 below. They were then removed and tested. The table provides the weathering data of each film. The test location and the duration of the exposure are also provided.

TABLE-US-00007 TABLE 7 Weathering specifications Total days Film of outdoor identification Test site Start date End date exposure P1 n.a. none none 0 P2 n.a. none none 0 CP3 Quebec May 18, 2016 Jun. 7, 2016 20 NP3 Quebec May 18, 2016 Jun. 7, 2016 20 BP4 Quebec May 25, 2016 Aug. 11, 2016 77 NP4 Quebec May 25, 2016 Aug. 11, 2016 77 BP5 New Jersey May 18, 2016 Aug. 17, 2016 90 NP5 New Jersey May 18, 2016 Aug. 17, 2016 90 SP6 Quebec May 25, 2016 Aug. 11, 2016 77

Example 10Tests

[0086] Films were then tested for their ultimate tensile strength and ultimate elongation strength, in the machine direction (MD), i.e., the direction in which the films are produced in extrusion, or the longitudinal direction; and in the transverse direction (TD), i.e., the direction perpendicular to which the films are produced in extrusion. This testing process is known in the art, generally referred to as ASTM D882-12 Standard Test Method for Tensile Properties of Thin Sheeting. The stretch speed used for all testing performed is 2 inches/minutes. The results obtained are outlined in Table 8 below.

TABLE-US-00008 TABLE 8 Test results for weathered and unweathered films Tensile Tensile Max Max Strength Strength Elongation Elongation Sample MD (psi) TD (psi) MD (%) TD (%) P1 4641 2950 179 526 P2 4978 4585 296 680 CP3 3454 633 99 <10 NP3 4241 1514 72 20 BP4 3182 1655 107 13 NP4 2590 1545 59 15 BP5 2235 1673 77 59 NP5 2016 1364 15 <10 SP6 3125 1455 85 14

[0087] Graphical representations of the testing results are provided in FIG. 6 (ultimate tensile strengths) and FIG. 7 (ultimate elongation strengths). As will be understood by a skilled person, tensile strength data teaches us about the amount of energy required to break the film, and ultimate elongation strength data teaches us the capacity of the film to be pulled before breaking, given a certain pull speed (2 inches/minutes).

[0088] As can be seen from the results obtained outlined in Table 8, FIG. 6 and FIG. 7, all films exhibit superior tensile strength in the longitudinal direction (MD) than in the transverse direction (TD). Further comments are provided below based on a grouping of the films in the following three groups: 1Films treated with white, TiO.sub.2; 2Films treated with carbon black; and 3Films treated with reflective BaSO.sub.4Al.

Films Treated with White, TiO.sub.2

[0089] Outdoor exposure of films has a general negative effect on the tensile strength of all films. In the MD, films NP4 and NP5, both untreated, each retained 56% and 43% of their strength, respectively as compared to the unweathered film P1. In contrast, treated films BP4 and BP5 retained 69% and 48% of their strength respectively, a gain of 23% and 12% respectively. In the TD, untreated films NP4 and NP5 retained 52% and 46% of their strength, respectively. In contrast, treated films BP4 and BP5 retained 56% and 57% of their strength, a gain of 8% and 24% respectively.

[0090] Outdoor exposure also has a general negative effect on the ultimate elongation. In the MD, films NP4 and NP5, both untreated, each retained 33% and 9% of their strength, respectively as compared to the unweathered film P1. In contrast, treated films BP4 and BP5 retained 60% and 43% of their strength respectively, a gain of 82% and 393% respectively. In the TD, untreated films NP4 and NP5 retained each about 3% of their strength. In contrast, treated films BP4 also retained 3% whereas BP5 retained 12%, about 4 times more than untreated films.

Films Treated with Carbon Black

[0091] Outdoor exposure of films has a general negative effect on the tensile strength of films. In the MD, untreated film CP3 retained 74% of its strength, whereas treated film BP3 retained 91% of its strength, a gain of 23%. In the TD, untreated film CP3 retained 21% of its strength whereas treated film NP3 retained 51% of its strength, which is more than double that of the untreated film. Regarding the ultimate elongation, in the MD, films untreated film CP3 and treated film NP3 behaved similar to one another.

Films Treated with Reflective BaSO.sub.4Aluminum

[0092] These films performed in a way similar to films treated with titanium dioxide. They retained 67% of MD strength, which is a 22% gain as compared to untreated films; 50% of TD strength (no gain) and; 47% of ultimate elongation in the MD, which is a 33% gain as compared to untreated and 3% ultimate elongation in the TD. These films were installed in the same test field as films BP4 and NP4.

[0093] Moreover, as can be seen from the results obtained and outlined above in Table 8, FIG. 6 and FIG. 7 that Coating films with titanium dioxide, carbon black and/or a mixture of barium sulfate and aluminum, whether in a nitrocellulose base, alone or combination with a polyamide or a zein base, interesting results are obtained. The ultimate tensile strength of weathered films yields gains in both the MD and TD directions. The ultimate elongation of such films yields gains for titanium dioxide and the barium sulfate and aluminum mixture in the MD direction. Generally, treated films were overall tougher than untreated films.

Example 11Experiments on Additional Films, R1 (Untreated) and R2 Film (Treated)

[0094] Two further films were produced and tested. The production method was as described above at Example 5. One film had a thickness of 0.9 mil (R1 film) and the other had a thickness of 0.7 mil including the coating (R2 film). The ink used in the coating of the R1 film is the same as describe above at Example 6 (varnish black on black). The two films were installed outdoor in Laval, Quebec on Jul. 5, 2016, and samples were collected on Aug. 29, 2016. A photograph is provided in FIG. 8. Testing was conducted in accordance with the ASTM D882-12 method referred to at Example 10 above. The results obtained show that a 25% lighter coated film resists UV deterioration better than an uncoated (heavier) film.

INDUSTRIAL APPLICABILITY

[0095] There is provided a cost-effective process for manufacturing a bio-polymer mulch film. Indeed, the process involves use of smaller amounts of bio-polymer material and functional material. The bio-polymer of the invention has an average thickness that is at least about 15% less than the thickness of an uncoated bio-polymer mulch film or a conventional mulch film with similar efficiency.

[0096] Although the present invention has been described hereinabove by way of specific embodiments thereof, it may be modified, without departing from the spirit and nature of the subject invention as defined in the appended claims.

[0097] The present description refers to a number of documents, the content of which is herein incorporated by reference in their entirety.