KR20220002558A - biodegradable sheet - Google Patents

Abstract

The present invention relates to a biodegradable sheet, particularly a first outer polymer layer and a second outer polymer layer comprising PBS or PBSA, and about 70% (w/w) to about 80% (w/w) PLA and about 20% ( w/w) to about 30% (w/w) PCL.

Description

biodegradable sheet

The present invention relates to a biodegradable sheet, particularly a first outer polymer layer and a second outer polymer layer comprising PBS or PBSA, and about 70% (w/w) to about 80% (w/w) PLA and about 20% ( w/w) to about 30% (w/w) PCL.

The use of biodegradable materials has increased over the past few years due to the environmentally beneficial properties of these materials. These materials are now commonly used in the manufacture of a wide range of products, including various types of plastic bags and other types of packaging. In response to the need for more environmentally friendly packaging materials, many new biopolymers have been developed that have been shown to be biodegradable when disposed of in the environment.

Examples of such polymers are polyhydroxyalkano including polylactic acid (PLA), polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and polyhydroxybutyrate-hydroxyvalerate copolymer (PHBV). ate (PHA), and biopolymers based on poly (epsilon-caprolactone) (PCL).

Each of these 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 these biopolymers a poor candidate when a flexible sheet is desired, such as for use in making wraps, bags and other packaging materials requiring good bend and folding capabilities. makes

On the other hand, biopolymers such as polybutylene adipate terphthalate (PBAT) are many times more flexible than the biopolymers discussed above and have a relatively low melting point, which means that they self-adhesive when freshly processed and/or exposed to heat. Tendency to become sexual and unstable.

Furthermore, due to the limited number of biodegradable polymers, it is often difficult or even impossible to identify homopolymers or copolymers that meet all or even most of the desired performance criteria for a given application. For these and other reasons, biodegradable polymers are not widely used in the field of food packaging materials, especially in the field of liquid containers, if desired for ecological reasons.

In addition, biodegradable sheets known today are generally opaque and have low light transmission and high haze. Further, the known biodegradable sheet does not contain a barrier layer, or it generally contains a barrier layer of an amount and type that results in a sheet highly permeable to gases, both of which have both high oxygen permeability and high water vapor permeability, and thus They cannot serve as food or beverage containers for long periods of time. In addition, the physical strength of the known biodegradable sheet, measured by parameters such as stress at maximum load, strain at break, and Young's Modulus, is lacking, and thus the packaging It is insufficient when used as a liquid, especially when it is desirable to package liquids.

Background art includes Applicants' PCT publications WO 2011/158240, WO 2013/088443, WO 2013/186778, WO 2015/059709, WO 2016/067285, WO 2016/174665 and WO 2016/207888.

A need exists for a biodegradable sheet for packaging that is free of at least some of the shortcomings of the prior art.

The present invention provides, in at least some embodiments, a first outer polymer layer and a second outer polymer layer comprising PBS or PBSA, and from about 70% (w/w) to about 80% (w/w) PLA and about 20% and an inner polymeric layer comprising (w/w) to about 30% (w/w) PCL.

The biodegradable sheets disclosed herein, in at least some embodiments thereof, have high physical strength and temperature resistance, and thus can withstand coating processes including metallization. The sheet further has high light transmittance and good barrier properties.

Moreover, the sheet of the present invention is sealable without the need for an additional sealing layer which would require additional processing steps in the manufacture of packaging from such sheets, thus increasing the efficiency of the manufacturing process and reducing costs.

The physical properties of the biodegradable sheets disclosed herein are similar to polypropylene (PP), with the added advantage of being compostable as opposed to PP.

According to an aspect of some embodiments of the present invention, there is provided a biodegradable sheet, wherein the biodegradable sheet comprises a first outer polymer layer, a second outer polymer layer and between the first outer polymer layer and the second outer polymer layer. at least a first inner polymer layer, wherein the first outer polymer layer and the second outer polymer layer each comprise PBS or PBSA; The first inner polymeric layer comprises from about 70% (w/w) to about 80% (w/w) PLA and from about 20% (w/w) to about 30% (w/w) PCL.

In some embodiments, the first outer polymer layer and the second outer polymer layer each consist essentially of 100% (w/w) PBS or PBSA.

In some embodiments, the first outer polymer layer and the second outer polymer layer each consist essentially of 100% (w/w) PBS.

In some embodiments, the first outer polymer layer and the second outer polymer layer each consist essentially of 100% (w/w) PBSA.

In some embodiments, the first inner polymer layer comprises about 70% (w/w) PLA and about 30% (w/w) PCL.

In some embodiments, the first inner polymer layer comprises about 80% (w/w) PLA and about 20% (w/w) PCL.

According to an aspect of some embodiments of the present invention, there is provided a biodegradable sheet, wherein the biodegradable sheet consists essentially of a first inner polymer layer and a second inner polymer layer each consisting of about 100% PBS, and about 70% and a first inner polymer layer consisting of (w/w) PLA and about 30% (w/w) PCL.

According to one aspect of some embodiments of the present invention, there is provided a biodegradable sheet, wherein the biodegradable sheet consists essentially of a first inner polymer layer and a second inner polymer layer each consisting of about 100% PBS, and about 80% and a first inner polymer layer consisting of (w/w) PLA and about 20% (w/w) PCL.

According to one aspect of some embodiments of the present invention, a biodegradable sheet is provided, wherein the biodegradable sheet consists essentially of a first inner polymer layer and a second inner polymer layer each consisting of about 100% PBSA, and about 70% and a first inner polymer layer consisting of (w/w) PLA and about 30% (w/w) PCL.

In some embodiments of any of the biodegradable sheets disclosed herein, the first outer polymer layer, the second outer polymer layer, and the first inner polymer layer are each prepared by cast sheet extrusion.

In some embodiments of any of the biodegradable sheets disclosed herein, the first outer polymer layer, the second outer polymer layer, and the first inner polymer layer are prepared by blown sheet extrusion.

In some embodiments of any of the biodegradable sheets disclosed herein, the first outer polymer layer, the second outer polymer layer, and the first inner polymer layer are coextruded.

Some embodiments of the invention are described herein with reference to the accompanying drawings. The detailed description in conjunction with the drawings enables those skilled in the art to understand how embodiments of the present invention may be practiced. The drawings are for illustrative discussion and are not intended to represent structural details of implementations in more detail than are necessary for a fundamental understanding of the invention. For clarity, some objects shown in the figures are not to scale.
From the drawing:
1 is a schematic diagram of the structure of a three-layer sheet according to the principles of the present invention;
2 shows comparative WVTR properties of a sheet according to the principles of the present invention having an inner layer comprising a PLA:PCL ratio of 80:20 compared to a reference sheet having an inner layer comprising a PLA:PCL ratio of 95:5; is a bar graph showing ;
3 shows comparative WVTR properties of a sheet according to the principles of the present invention having an inner layer comprising a PLA:PCL ratio of 70:30 compared to a reference sheet having an inner layer comprising a PLA:PCL ratio of 55:45; is a bar graph showing ;
4 shows comparative Young's modulus and yield stress ( a bar graph showing stress at yield;
5 is a sheet according to the principles of the present invention having an inner layer comprising a PLA:PCL ratio of 80:20, compared to a reference sheet having an inner layer comprising PLA and PBAT at a PLA:PBAT ratio of 80:20; is a bar graph depicting the comparative WVTR characteristics of ;
6 is a sheet according to the principles of the present invention having an inner layer comprising a PLA:PCL ratio of 80:20, compared to a reference sheet having an inner layer comprising PLA and PBAT at a PLA:PBAT ratio of 80:20; is a bar graph showing the comparative haze values of ;
7 shows a sheet according to the principles of the present invention having an inner layer comprising a PLA:PCL ratio of 70:30, compared to a reference sheet having an inner layer comprising PLA and PBAT at a PLA:PBAT ratio of 70:30; is a bar graph depicting the comparative WVTR characteristics of ;
8 is a sheet according to the principles of the present invention having an inner layer comprising a PLA:PCL ratio of 70:30 as compared to a reference sheet having an inner layer comprising PLA and PBAT at a PLA:PBAT ratio of 70:30; is a bar graph showing the comparative haze values of

Justice

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the specification, including definitions, will control.

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be understood by one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and ingredients have not been described in detail in order to not make the present invention difficult.

Note that, as used herein, the singular forms "a", "an" and "the" include the plural unless the context clearly dictates otherwise. Where aspects or embodiments are described in terms of Markush groups or other alternative groupings, those skilled in the art will recognize that the invention is also described in terms of individual elements or subgroups of elements of the group. .

As used herein, when the term “about” precedes a numerical value, the term “about” is intended to indicate +/-10%.

As used herein, the terms “comprising,” “including,” “having,” and grammatical variations thereof, are deemed to specify the stated feature, integer, step or ingredient. However, it does not exclude 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”.

Biodegradable compositions according to the present invention can be used to prepare a wide variety of articles of manufacture, including articles useful for packaging solid, semi-solid or liquid ingredients, including ingestible ingredients such as food ingredients, beverages, and pharmaceuticals.

The term “biodegradable” as used herein refers to a polymer that degrades through the action of living organisms, air, water, or any combination thereof within 180 days in a controlled-condition industrial fertilizer plant with high ventilation and controlled humidity. , polymer mixtures, or polymer-containing sheets. Biodegradable polyester degradation occurs initially by hydrolysis, eventually cleaving the polymer into short oligomers, followed by microbial degradation or microbial digestion.

As used herein, the term “sheet” should be understood to have its ordinary meaning as used in the fields of thermoplastics and packaging, and includes the term “film”. In general, “film” refers to a sheet having a thickness of about 250 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, or 70 μm or less. Such sheets may have any suitable thickness and may be a single polymer layer or may be multiple polymer layers having from 2 to 10 layers. Such sheets may be made using any suitable method, including blown film extrusion and cast film extrusion.

Referring now to FIG. 1 , a first outer layer 12 , a second outer layer 14 and a first inner layer 16 positioned between the first outer layer 12 and the second outer layer 14 . A three-layer sheet 10 comprising

In some embodiments, the total thickness of the sheet is less than about 40 μm, and in some embodiments less than about 35 μm, less than about 30 μm, less than about 25 μm, less than about 20 μm, less than about 15 μm, or even about 10 μm. is less than

In some embodiments, the thickness ratio of the first outer polymer layer: the first inner polymer layer: the second outer polymer layer is from about 1:2:1 to about 1:5:1, such as about 1:2:1 , about 1:3:1, about 1:4:1 or about 1:5:1.

The sheet according to the invention may further comprise one or more additional inner and/or outer layers. Biodegradable compositions according to the present invention can be used to prepare a wide variety of articles of manufacture, including articles useful for packaging solid and liquid ingredients, including food ingredients. Therefore, the sheet according to the invention includes a sheet having a wide variety of thicknesses (both measured and calculated) and layers, for example 3, 4, 5 or more layers. Sheets may be produced by methods known in the art, for example, cast film extrusion, blown film extrusion, coextrusion.

As is known in the art, multilayer sheets are produced by coextrusion, lamination, or combinations thereof. In lamination, at least two previously-made sheets are adhered to each other, for example by heat, pressure and/or adhesive.

As is known to those skilled in the art, some of the polymers discussed herein have one or more names or spellings thereof. For example, poly(epsilon-caprolactone), poly(caprolactone), and polycaprolactone are synonymous and these terms are used interchangeably. Similarly, polylactic acid and poly(lactic acid) are synonymous.

The present invention provides, in at least some embodiments, a first outer polymer layer and a second outer polymer layer comprising (in some embodiments consisting of) PBS or PBSA, and from about 70 to about 80% (w/w) PLA and A biodegradable sheet comprising (in some embodiments consisting of) an inner polymeric layer comprising (consisting of) from about 20 to about 30% (w/w) PCL.

In some embodiments, the first outer polymeric layer comprises PBSA. In some embodiments, the second outer polymeric layer comprises PBSA. In some embodiments, both the first outer polymer layer and the second outer polymer layer each comprise PBSA.

In some embodiments, the first outer polymeric layer is comprised of PBSA. In some embodiments, the second outer polymer layer is comprised of PBSA. In some embodiments, the first outer polymer layer and the second outer polymer layer are each comprised of PBSA.

In some embodiments, the first outer polymeric layer comprises PBS. In some embodiments, the second outer polymeric layer comprises PBS. In some embodiments, the first outer polymer layer and the second outer polymer layer each comprise PBS.

In some embodiments, the first outer polymer layer is comprised of PBS. In some embodiments, the second outer polymer layer is comprised of PBS. In some embodiments, the first outer polymer layer and the second outer polymer layer are each comprised of PBS.

In some embodiments, the first outer polymeric layer comprises or consists of PBS and the second outer polymeric layer comprises or consists of PBSA.

In some embodiments, at least one of the first inner polymer layer, the first outer polymer layer, and the second outer polymer layer is prepared by cast film extrusion.

In some embodiments, at least one of the first inner polymer layer, the first outer polymer layer, and the second outer polymer layer is prepared by blown film extrusion.

In some embodiments, at least two of the first inner polymer layer, the first outer polymer layer, and the second outer polymer layer are coextruded. In some embodiments, the first outer polymer layer and the first inner polymer layer are coextruded. In some embodiments, the second outer layer and the first inner polymer layer are coextruded. In some embodiments, the first inner polymer layer, the first outer polymer layer, and the second outer polymer layer are coextruded.

In some embodiments, the biodegradable sheets disclosed herein comprise a laminated structure, i.e., the sheet is made by producing at least two layers by extrusion, followed by laminating the layers; form a sheet

In some embodiments, the biodegradable sheet further comprises one or more additional polymeric layers.

In some embodiments, either the first outer polymer layer or the second outer polymer layer is metallized.

In some embodiments, at least one of the first inner polymer layer, the first outer polymer layer, and the second outer polymer layer comprises a coating on one or both sides. In some embodiments, at least the first inner polymeric layer comprises a coating on one side. In some embodiments, at least the first inner polymeric layer comprises a coating on both sides. In some embodiments, at least the first outer polymeric layer comprises a coating on one side. In some embodiments, at least the first outer polymeric layer comprises a coating on both sides. In some embodiments, at least the second outer polymeric layer comprises a coating on one side. In some embodiments, at least the second outer polymeric layer comprises a coating on both sides. In some embodiments, the coating is a shellac-based coating, a cellulose-based coating (such as a nitrocellulose coating), polyvinylidene chloride (PVdC), plasma-deposited alumina and/or siloxane-based coating, an acrylic coating, or a mixture thereof.

In some embodiments, either the first outer polymer layer or the second outer polymer layer is coated and also metallized. In some such embodiments, either the first outer polymer layer or the second outer polymer layer is first coated and then metallized. In some alternative embodiments, either the first outer polymer layer or the second outer polymer layer is first metallized and then coated.

In some embodiments, a biodegradable sheet as disclosed herein is a biodegradable package, such as a bag or pouch, containing therein an ingestible ingredient, such as a food, beverage or medicament, which may be, for example, a solid, semi-solid or liquid ingredient. used to manufacture For example, in some embodiments, the biodegradable package is made by heat sealing two or more parts of the same sheet or two or more sheets. In some such embodiments, the layer referred to herein as the first outer layer serves as a contact layer having direct contact with the contents of the biodegradable package.

In some embodiments, the biodegradable sheet according to the present invention has a decomposition time in the range of 4 months to 24 months. In some embodiments, the biodegradable sheet according to the present invention has a shelf life of 12 months or less or 18 months or less.

Many modifications and variations are possible in light of the above teachings. Accordingly, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise unless specifically described.

The specific embodiments listed below illustrate aspects of the teachings herein and are not to be considered limiting.

Throughout this application, various publications, including US patents, are referenced by author and year and number of patents. The disclosures of these publications and patents and patent applications are incorporated herein by reference in their entirety to more fully describe the art to which this invention pertains.

Citation of any document herein is not an admission that such document is prior art to which it relates, or is not construed as a material for the patentability of any claims of this disclosure. Any reference to the content or date of any document is based on the information available to the applicant at the filing date and is not an admission as a correction of such reference.

Example

In the experimental sections below, all percentages are percentages by weight.

Materials and Methods

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

material

The following polymeric resin rials are obtained from commercial sources:

PCL Poly(epsilon-caprolactone)

PLA poly(lactic acid)

PBS poly(butylene succinate)

PBSA Poly(butylene succinate adipate)

The resin is used as supplied without further drying. Optionally, prior to use, the resin is further dried, for example, by drying overnight in an air flow Shini SCD-160U-120H desiccant dryer heated to about 80°C.

resin mixture

A polymer sheet according to the teachings herein includes a layer comprising a polymer mixture. This layer is prepared by coextrusion of a polymer mixture resin.

To prepare the required polymer mixture resin, an appropriate amount of dried constituent resin is dry-blended, introduced into the feed of a twin screw compounder, and then melt extruded to form the polymer mixture resin. During melt extrusion in the compounder, the temperature zoning is from 190°C to 170-175-180-185-190°C die. Alternatively, the required polymer blend resin may be blow extruded using a temperature zoning of the die from about 150° C. to about 120-125-130-135-140° C.

The compounded polymer resin is pelletized into 1-5 mm diameter pellets using a strand pelletizer.

Cast film coextrusion of sheet

Some embodiments of sheets according to the teachings herein are made by coextrusion of three layers, so that the desired sheet is made by coextrusion of a multilayer cast film.

Some embodiments of sheets according to the teachings herein are made by lamination of single-layer and multi-layer cast film extruded films. Film and sheet, cast film coextruder using standard settings Dr. Prepared using Collin (Collin Lab and Pilot Solutions), typically mixing the mixture with temperature zoning 170-180-200°C; adapter at 200°C; feedblock at 200°C; Feed into an extruder with a die at 200°C. The screw speed is set in a conventional manner to provide an extruded layer having the desired thickness. For multilayer films, a die with three ports is used, each port fed by a dedicated extruder.

Example 1: Specific embodiment of a sheet according to the teachings disclosed herein

Exemplary sheets 1-8, representing specific embodiments according to the teachings disclosed herein, were prepared according to Table 1, where T refers to the layer thickness, in micrometers (μm).

A sheet is prepared as follows:

Sheet #1 prepared by co-extrusion of a cast film of the following components

5 μm PBS (Extruder I),

15 μm 70% PLA: 30% PCL (Extruder II),

5 μm PBS (Extruder III)

Sheet #2 prepared by co-extrusion of a cast film of the following components

5 μm PBS (Extruder I),

15 μm 70% PLA: 30% PCL (Extruder II),

5 μm PBSA (Extruder III),

Sheet #3 prepared by co-extrusion of a cast film of the following components

5 μm PBSA (Extruder I),

15 μm 70% PLA: 30% PCL (Extruder II),

5 μm PBSA (Extruder III),

Sheet #4 prepared by co-extrusion of a cast film of the following components

5 μm PBSA (Extruder I),

15 μm 70% PLA: 30% PCL (Extruder II),

5 μm PBS (Extruder III)

Sheet #5 prepared by co-extrusion of a cast film of the following components

5 μm PBS (Extruder I),

15 μm 80% PLA: 20% PCL (Extruder II),

5 μm PBS (Extruder III),

Sheet #6 prepared by co-extrusion of a cast film of the following components

5 μm PBS (Extruder I),

15 μm 80% PLA: 20% PCL (Extruder II),

5 μm PBSA (Extruder III)

Sheet #7 prepared by co-extrusion of a cast film of the following components

5 μm PBSA (Extruder I),

15 μm 80% PLA: 20% PCL (Extruder II),

5 μm PBSA (Extruder III),

Sheet #8 prepared by co-extrusion of a cast film of the following components

5 μm PBSA (Extruder I),

15 μm 70% PLA: 30% PCL (Extruder II),

5 μm PBS (Extruder III)

Example 2: Physical Properties of Sheets of the Invention

To define the physical properties of the biodegradable sheets disclosed herein, the following test methods were used:

a. ASTM D882-10 Standard Test Method for Tensile Properties of Thin It was measured using plastic sheeting).

b. Heat seal was measured using ASTM F2029/F88 Standard Test Method for Seal Strength of Flexible Barrier Materials in the machine direction.

c. Light transmittance and haze were measured using ASTM D1003 - 07e1 Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics.

d. The water vapor transmission rate of the biodegradable sheet of the present invention was evaluated using a controlled infrared sensor, ASTM F1249 Standard Test Method for Water Vapor Transmission Rate (WVTR) through plastic film and sheeting (WVTR) Through Plastic Film and Sheeting Using a Modulated Infrared Sensor).

The test methods are summarized in Table 2 below.

The following reference sheets were prepared for comparative purposes.

i. Advantages of Specific PLA:PCL Ratios of the Invention

WVTR at 38° C., 90%RH was determined for sheet 7 as defined in Table 1 and for Reference Sheet 9 as defined in Table 3. The results are presented in FIG. 2 .

WVTR at 38°C, 90%RH was determined for sheet 3 as defined in Table 1 and for reference sheet 10 as defined in Table 3. The results are presented in FIG. 3 .

2 and 3 , a three-layer sheet having an inner layer comprising PLA:PCL at a ratio according to the principles of the present invention has an inner layer comprising PLA:PCL at a ratio outside this range. It had significantly lower WVTR values than the reference sheet. Specifically, in FIG. 2 , the WVTR of sheet 7 was 74 g/m ^{2 /day compared to 210 g/m 2} /day for reference sheet 9, ie, a 65% decrease; The WVTR of sheet 3 was 27 g/m ^{2 /day compared to 142 g/m 2} /day for reference sheet 10, ie, a decrease of 81%.

A sheet with a lower WVTR is particularly advantageous for the manufacture of packaging of food items, where less water enters the package and thus maintains the freshness of the items packaged therein.

ii. Advantages of 3-Layer Sheets of the Invention Over Single Layers

Young's modulus in machine direction (MD) and yield stress in MD and transverse directions (TD); and sealing temperatures were determined for sheet 7 as defined in Table 1 and for single layer reference sheet 11 as defined in Table 3 having the same composition as the inner layer of sheet 7. The results are presented in Figure 4 and Table 4.

As shown in FIG. 4 , the inclusion of the first outer layer and the second outer layer comprising 100 wt % PBSA or PBS, compared to a single layer comprising the same composition as the inner layers of sheets 5 and 7, It has an effect:

One. The modulus in the machine direction MD is lowered by 15%-30%. As a result, brittleness is reduced.

2. The yield stress point in the machine direction MD is increased by 40% from 15 N/mm to about 25 N/mm. These improvements are important for subsequent processes.

3. The yield stress point in the TD direction increases by 87% from 4 N/mm to about 30 N/mm. These improvements are important for subsequent processes.

As shown in Table 4, the inclusion of a first outer layer and a second outer layer comprising 100 wt % PBSA or PBS increases the sealing temperature range compared to a single layer. When the first outer layer and the second outer layer comprise 100 wt % PBSA, the lower threshold of sealing range is lower (80 °C instead of 110 °C) compared to the monolayer. When the first outer layer and the second outer layer comprise 100 wt % PBS, the upper threshold of sealing range is higher (150° C. instead of 140° C.) compared to the monolayer.

iii. Advantages of Specific Polymers of the Sheets of the Invention

WVTR and haze values at 38° C., 90% RH were determined for Sheet 5 as defined in Table 1 and for Reference Sheet 12 as defined in Table 3. Results for WVTR are presented in FIG. 5 . The results for haze are presented in FIG. 6 .

WVTR and haze values at 38°C, 90%RH were determined for Sheet 3 as defined in Table 1 and for Reference Sheet 13 as defined in Table 3. The results for WVTR are presented in FIG. 7 . The results for haze are presented in FIG. 8 .

As shown in Figures 5 and 7, a three-layer sheet having an inner layer comprising PLA:PCL at a ratio according to the principles of the present invention is significantly higher than a reference sheet having an inner layer in which PCL is replaced by PBAT. significantly lower WVTR values. Specifically, the WVTR of sheet 5 was 74 g/m ^{2 /day, compared to 190 g/m 2} /day for reference sheet 12, ie, a decrease of 61%; The WVTR of sheet 3 was 25 g/m ^{2 /day compared to 255 g/m 2} /day for reference sheet 13, ie, a 90% decrease.

As shown in Figures 6 and 8, a three-layer sheet with an inner layer comprising PLA:PCL at a ratio according to the principles of the present invention was significantly higher than a reference sheet with an inner layer in which PCL was replaced by PBAT. It has significantly improved clarity. Specifically, the clarity of sheet 5 was increased by 115% compared to the reference sheet 12, and the haze value of sheet 5 was 17.5% compared to 38% for sheet 12. Similarly, the clarity of sheet 3 was increased by 130% compared to sheet 13, and the haze value of sheet 3 was 9% compared to 21% for sheet 13.

conclusion

As shown above and in the accompanying drawings, a three-layer sheet having an inner layer comprising a specific polymer and an outer layer comprising PBS and/or PBSA at specific ratios is a polymer in which at least one of the polymers of the inner layer is different. It has been found to be surprisingly advantageous compared to sheets replaced by or in which the polymer in the inner layer is present in different ratios or in which the outer layer is absent.

Benefits include lowered WVTR, reduced Young's modulus, improved yield stress point, wider seal temperature range, increased clarity and lowered haze.

Moreover, compared to an outer layer comprising a polymer other than PBS and/or PBSA, specific advantages of PBS and/or PBSA as an outer layer include convenience for subsequent processing such as printing, metallization and coating; easy control of the coefficient of friction; good sealing properties; and good processability. Moreover, PBS and PBSA are fertilizable, while PBSA is even fertilizable at home.

The invention illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Reference to a range of values herein is only intended to serve as a shorthand method of individually referring to each separate value falling within that range, unless otherwise indicated herein, and each separate value indicates that it is individually recited herein. incorporated into the specification as such. 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 (eg, "such as") provided herein, is merely intended to better exemplify the invention and does not pose a limitation on the scope of the invention unless otherwise indicated. does not

Although the above examples have illustrated specific ways for carrying out embodiments of the present invention, in fact, those skilled in the art will understand alternative ways for carrying out embodiments of the present invention, which alternative modes are not explicitly shown herein. .

It is to be understood that the present disclosure is to be regarded as illustrative of the principles of the invention and is not intended to limit the invention to the illustrated embodiments.

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

Claims (13)

A biodegradable sheet comprising:
wherein the biodegradable sheet comprises a first outer polymer layer, a second outer polymer layer, and at least a first inner polymer layer between the first outer polymer layer and the second outer polymer layer;
the first outer polymer layer and the second outer polymer layer each comprise PBS or PBSA;
wherein the first inner polymer layer comprises from about 70% (w/w) to about 80% (w/w) PLA and from about 20% (w/w) to about 30% (w/w) PCL. Sheet. According to claim 1,
wherein said first outer polymer layer and said second outer polymer layer each consist essentially of 100% (w/w) PBS or PBSA. 3. The method of claim 1 or 2,
wherein said first outer polymer layer and said second outer polymer layer each consist essentially of 100% (w/w) PBS. 3. The method of claim 1 or 2,
wherein said first outer polymer layer and said second outer polymer layer each consist essentially of 100% (w/w) PBSA. 5. The method according to any one of claims 1 to 4,
wherein the first inner polymer layer comprises about 70% (w/w) PLA and about 30% (w/w) PCL. 5. The method according to any one of claims 1 to 4,
wherein the first inner polymeric layer comprises about 80% (w/w) PLA and about 20% (w/w) PCL. A biodegradable sheet comprising:
The biodegradable sheet consists essentially of a first outer polymer layer and a second outer polymer layer each consisting of about 100% PBS, and about 70% (w/w) PLA and about 30% (w/w) PCL A biodegradable sheet consisting of a first inner polymer layer. A biodegradable sheet comprising:
The biodegradable sheet comprises a first outer polymer layer and a second outer polymer layer each comprised of about 100% PBS, and a first inner layer comprised of about 80% (w/w) PLA and about 20% (w/w) PCL, respectively. A biodegradable sheet consisting essentially of a polymer layer. A biodegradable sheet comprising:
The biodegradable sheet comprises a first outer polymer layer and a second outer polymer layer each consisting of about 100% PBSA, and a first outer polymer layer consisting of about 70% (w/w) PLA and about 30% (w/w) PCL A biodegradable sheet consisting essentially of an inner polymeric layer. A biodegradable sheet comprising:
The biodegradable sheet comprises a first outer polymer layer and a second outer polymer layer each consisting of about 100% PBSA, and a first outer polymer layer consisting of about 80% (w/w) PLA and about 20% (w/w) PCL A biodegradable sheet consisting essentially of an inner polymeric layer. 9. The method according to any one of claims 1 to 8,
wherein the first inner polymer layer, the first outer polymer layer and the second outer polymer layer are produced by cast sheet extrusion. 9. The method according to any one of claims 1 to 8,
wherein the first inner polymer layer, the first outer polymer layer and the second outer polymer layer are produced by blown sheet extrusion. 9. The method according to any one of claims 1 to 8,
wherein at least two of the first inner polymer layer, the first outer polymer layer and the second outer polymer layer are coextruded.

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