Gas barrier polymer resin composition and film comprising same

Abstract

The film manufactured using the polymer resin composition according to the present invention not only has biodegradability, but also has excellent oxygen and water vapor barrier properties and excellent ductility, and thus can be used as a food packaging material.

Description

[0001] Cross-references to related applications

[0002] This application is based on and claims priority to Korean Patent Application No. 10-2024-0036148, filed on March 15, 2024, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to gas barrier polymer resin compositions having excellent oxygen and water vapor barrier properties and biodegradability, and membranes comprising the compositions. Background Technology

[0004] The frequent natural disasters in recent years have highlighted the severity of environmental pollution and the resulting climate change as critical issues that must be given top priority. Reducing the use of single-use plastics is an environmental pollution mitigation activity that can be implemented in daily life, and many countries are adopting it as a policy. As part of this policy, the use of eco-friendly or biodegradable plastics is recommended, and various biodegradable plastics are being researched and developed in soil or oceans.

[0005] In the food packaging sector, where plastics dominate, the use of materials that can block gases such as oxygen and water vapor is essential to prevent spoilage during distribution and for long-term preservation. However, these gas-barrier materials are mostly based on petrochemical raw materials and, in many cases, are non-biodegradable. Therefore, research and development of food packaging materials based on biodegradable materials that can naturally degrade in soil or oceans is actively underway.

[0006] Food packaging materials need to minimize the inflow of oxygen and water vapor from the outside to prevent the food inside from oxidizing and spoiling. However, it is difficult to make the entire food packaging material biodegradable due to the use of common biodegradable materials (EVOH, MXD6, etc.) or additional metal layers (Al, alumina, etc.).

[0007] Meanwhile, polyglycolic acid (PGA), as one of the biodegradable polymer materials, has excellent oxygen and water vapor barrier properties, but it has poor ductility, making it difficult to process and use as a film or sheet for food packaging materials.

[0008] Therefore, the present invention relates to a membrane capable of blocking oxygen and water vapor, wherein polybutylene succinate (PBS) is used in conjunction with PGA, and it has been found that such a membrane can realize a biodegradable food packaging material, thus completing the present invention. Summary of the Invention

[0009] Technical issues

[0010] The present invention provides a gas barrier polymer resin composition having excellent oxygen barrier and water vapor barrier properties as well as biodegradability.

[0011] A film comprising the polymer resin composition is also provided.

[0012] Technical solution

[0013] To address the aforementioned issues, the following polymer resin composition is provided: The polymer resin composition comprises polyglycolic acid (PGA) and polybutylene succinate (PBS). The weight ratio of PGA to PBS is 40:60 to 85:15, and Based on a membrane thickness of 35 μm, the oxygen permeability of the membrane manufactured using the above-described polymer resin composition is 50 cc / m. 2 Below the heavens.

[0014] As used herein, the term "PGA" refers to a biodegradable polymer and is used to provide oxygen and water vapor barrier properties to the polymer resin compositions according to the invention. Furthermore, as used herein, the term "PBS" is used to provide ductility to the polymer resin compositions according to the invention. In other words, by using PGA and PBS in combination, the polymer resin compositions according to the invention can possess sufficient ductility as well as oxygen and water vapor barrier properties, thus making them suitable for use as food packaging materials.

[0015] Preferably, the weight-average molecular weight (Mw) of PGA is between 100,000 and 250,000. When the weight-average molecular weight of PGA is below 100,000, the low melt viscosity sometimes makes extrusion molding difficult, and the resulting molded films and other products may have poor mechanical properties. Furthermore, when the weight-average molecular weight is above 250,000, significant discoloration of PGA may occur, potentially leading to problems with the appearance of molded products such as films, and melt processing may require more energy, making efficient processing difficult. More preferably, the weight-average molecular weight (Mw) of PGA is between 100,000 and 200,000.

[0016] Furthermore, the melt index of PGA (measured according to ASTM D1238 at 230°C and a load of 2.16 kg) is 4 g / 10 min to 25 g / 10 min. Preferably, the melt index of PGA is 5 g / 10 min to 20 g / 10 min.

[0017] Preferably, the weight-average molecular weight (Mw) of PBS is between 100,000 and 250,000. When the weight-average molecular weight of PBS is below 100,000, there are concerns about poor melt strength, resulting in insufficient processing stability and insufficient miscibility with PGA. Furthermore, if the weight-average molecular weight of PBS is above 250,000, there are concerns about low flowability and reduced efficiency due to the need for more energy in processing. More preferably, the weight-average molecular weight (Mw) of PBS is between 100,000 and 200,000.

[0018] Furthermore, the melt index of PBS (measured according to ASTM D1238 at 190°C and a load of 2.16 kg) is from 1 g / 10 min to 10 g / 10 min. Preferably, the melt index of PBS is from 3 g / 10 min to 7 g / 10 min.

[0019] The weight ratio of PGA to PBS is between 40:60 and 85:15. When the weight ratio is less than 40:60, the low PGA content results in poor oxygen and water vapor barrier properties. Conversely, when the weight ratio is greater than 80:20, the low PBS content leads to poor spreadability. Preferably, the weight ratio of PGA to PBS is 45:55 or higher, 50:50 or higher, or 55:45 or higher; and 80:20 or lower, 75:20 or lower, 70:30 or lower, 65:35 or lower, or 60:40 or lower.

[0020] In addition, the polymer resin composition of the present invention contains an antioxidant in an amount of 0.01% to 3% by weight relative to the total weight of PGA and PBS, and a chain extender in an amount of 0.01% to 3% by weight relative to the total weight of PGA and PBS.

[0021] Antioxidants inhibit branching that may occur during the processing of PBS and thermal decomposition that may occur during the processing of PGA. Additionally, the addition of chain extenders to the polymer resin compositions of the present invention controls the melt index within the desired processing range.

[0022] There are no particular limitations on the antioxidants and chain extenders; materials commonly used in the art to which this invention pertains can be used. For example, Irganox 1010, available from BASF, can be mentioned as an antioxidant, and Joncryl ADR 4468, available from BASF, can be mentioned as a chain extender.

[0023] Furthermore, the melt index (measured according to ASTM D1238 at 230°C under a 2.16 kg load) of the polymer resin composition according to the invention is between 4 g / 10 min and 25 g / 10 min. If the melt index of the polymer resin composition is less than 4 g / 10 min, there is a concern that surface defects may occur during film formation or decomposition may occur during film processing. If the melt index of the polymer resin composition is greater than 25 g / 10 min, there is a concern that the melt strength may be low, thereby reducing the productivity during film production. Preferably, the melt index (measured according to ASTM D1238 at 230°C and 2.16 kg load) of the polymer resin composition according to the present invention is 5 g / 10 min or more, 6 g / 10 min or more, 7 g / 10 min or more, 8 g / 10 min or more, 9 g / 10 min or more, 10 g / 10 min or more, 11 g / 10 min or more, 12 g / 10 min or more, 13 g / 10 min or more, 14 g / 10 min or more, 14.5 g / 10 min or more, or 15.0. More than 24g / 10min; less than 23g / 10min; less than 22g / 10min; less than 21g / 10min; less than 20g / 10min; less than 19g / 10min; less than 18g / 10min; less than 17g / 10min; less than 16g / 10min; less than 15g / 10min; less than 14g / 10min; less than 13g / 10min; less than 12g / 10min; less than 11g / 10min; or less than 10g / 10min.

[0024] In addition, a film comprising the above-described polymer resin composition is provided.

[0025] The membrane of the present invention can be manufactured, for example, by extruding the polymer resin composition of the present invention described above. Preferably, the thickness of the membrane according to the present invention is from 1 μm to 1000 μm, more preferably from 10 μm to 100 μm.

[0026] The oxygen permeability of the membrane of this invention is 50 cc / m 2 • Less than 1 day. More preferably, the oxygen permeability of the membrane of the present invention is 40 cc / m. 2 · Less than 35cc / m 2 · Less than 30cc / m 2 · Less than 25cc / m 2 · Less than 20cc / m 2 · Less than 10 days, 15cc / m 2 Less than 10 days, 10cc / m 2 Less than 1 day, 5cc / m 2 · Less than 4 days, 4cc / m 2· less than 3cc / m 2 • Less than 1 day. Oxygen permeability is measured based on a film thickness of 35 μm, and the detailed method is described in the examples below.

[0027] Furthermore, the water vapor permeability of the membrane of the present invention is 50 g / m³. 2 • Less than 1 day. More preferably, the water vapor permeability of the membrane of the present invention is 40 g / m³. 2 Less than 35g / m 2 Less than 30g / m 2 Less than 25g / m 2 Less than 20 days, 20g / m 2 Less than 15g / m 2 Less than 10 days, 10g / m 2 Less than 1 day, 5g / m 2 Less than 1 day, 4g / m 2 Less than 3g / m 2 • Less than 1 day. The measurement of water vapor transmission rate is based on a film thickness of 35 μm, and the detailed method can be described in the examples below.

[0028] Furthermore, the elongation of the film of the present invention is 350% or more. If the elongation is less than 350%, there is a problem of reduced extensibility, making it difficult to use as a food packaging material. Preferably, the elongation of the film according to the present invention is 360% or more, 370% or more, 380% or more, 390% or more, 400% or more, or 405% or more, and is less than 500%, less than 490%, less than 480%, less than 470%, less than 460%, less than 450%, less than 440%, or less than 430%. The method for measuring the elongation can be as described in the embodiments below.

[0029] Furthermore, the tensile strength of the membrane of the present invention is from 45 MPa to 60 MPa. Additionally, the yield strength of the membrane of the present invention is from 30 MPa to 60 MPa. The methods for measuring the tensile strength and yield strength can be described in the examples below.

[0030] Invention Effects

[0031] The film manufactured using the polymer resin composition of the present invention is not only biodegradable, but also has excellent oxygen and water vapor barrier properties and excellent ductility, and therefore can be used as a food packaging material. Detailed Implementation

[0032] In the following embodiments, embodiments of the present invention will be described in more detail. However, the following embodiments are only for illustrating implementation of the present invention, and the content of the present invention is not limited to the following embodiments.

[0033] Examples and Comparative Examples

[0034] 1) Preparation of the composition

[0035] The materials used in the following embodiments and comparative examples are as follows.

[0036] -PGA: PJ Chem Vytal-J116 (MI=15g / 10min@230℃, 2.16 kg)

[0037] -PBS: PTT-MCC FZ91PB (MI=5g / 10min@190℃, 2.16 kg)

[0038] - Antioxidant: BASF Irganox 1010

[0039] - Chain extender: BASF Joncryl ADR 4468

[0040] The above materials were dried in a conventional oven at 80°C for 12 hours. The dried materials were weighed and mixed as described in Table 1. Subsequently, the mixtures were processed in a twin-screw extruder under the following conditions to prepare the respective compositions.

[0041] - Extruder specifications: Screw diameter - 32 pi, L / D = 40

[0042] - Processing conditions: Screw temperature = 220℃, screw speed = 200 rpm

[0043] - Flux: 20 kg / hr

[0044] Each of the above-prepared compositions was dried in a conventional oven at 80°C for 12 hours to control the water vapor content to 500 ppm or lower.

[0045] 2) Membrane manufacturing

[0046] Each of the compositions prepared above was processed in a casting machine under the following conditions. The resulting film was then manufactured to have a thickness of 35 μm.

[0047] - Extruder specifications: Screw diameter = 17.5 pi, T-die width = 120 mm

[0048] - Processing conditions: Barrel temperature = 230℃, screw speed = 50rpm, casting roll temperature = 30℃, casting roll speed = 3m / min

[0049] Table 1

[0050] Experimental Example 1

[0051] For each composition prepared above, the MI properties were measured using the following methods.

[0052] - Using a Toyoseiki melt indexer, G-02 device.

[0053] - ASTM D1238, 230°C, 2.16 kg conditions.

[0054] Experiment Example 2

[0055] The physical properties of each membrane manufactured above were determined by the following methods.

[0056] 1) Mechanical properties – tensile strength, yield strength, elongation

[0057] - Using a ZwickRoell tensile testing machine.

[0058] - The ASTM D882 standard and sample are used for measurement, and the measurement speed is 500 mm / min.

[0059] 2) Oxygen Transmission Rate (OTR)

[0060] - Using a Systech Illinois 8001 oxygen permeability analyzer.

[0061] - Use 5cm 2 A circular membrane of a certain size.

[0062] - Measurements were taken over 48 hours at a supply pressure of 1.5 bar oxygen (>99.9%), 0% relative humidity, a measurement temperature of 23°C, and 15-minute intervals.

[0063] 3) Water vapor transmission rate (WVTR)

[0064] - Using a Systech Illinois AquaSense 7101 water vapor transmission rate tester.

[0065] - Use 5cm 2 A circular membrane of a certain size.

[0066] - Measurements were taken over 48 hours at a nitrogen (carrier gas) supply pressure of 2 bar, 90% relative humidity, a measurement temperature of 23°C, and 10-minute intervals.

[0067] The measurement results are shown in Table 2 below.

[0068] Table 2

[0069] As shown in Table 2, the films of Comparative Examples 1 and 2 have poor oxygen barrier properties and are therefore unsuitable for use as food packaging materials. Furthermore, the film of Comparative Example 3 has low elongation and is therefore unsuitable for use as a food packaging material. In contrast, the films of Examples 1 to 4 of the present invention have been confirmed to have excellent oxygen and water vapor barrier properties and excellent elongation, and are therefore suitable for use as food packaging materials.

Claims

1. A polymer resin composition comprising polyglycolic acid (PGA) and polybutylene succinate (PBS), wherein a weight ratio of the PGA and PBS is 40:60 to 85:15, and The oxygen permeability of a film manufactured using the polymer resin composition is 50 cc / m 2 • Skyward.

2. The polymer resin composition according to claim 1, comprising 0.01 to 3% by weight of an antioxidant with respect to the total weight of the PGA and PBS and 0.01 to 3% by weight of a chain extender with respect to the total weight of the PGA and PBS.

3. The polymer resin composition of claim 1, wherein, a weight average molecular weight (Mw) of the PGA is 100000 to 250000.

4. The polymer resin composition of claim 1, wherein, a melt index of the PGA measured according to ASTM D1238 at 230°C under a load of 2.16 kg is 4 to 25 g / 10 min.

5. The polymer resin composition according to claim 1, wherein a weight average molecular weight (Mw) of the PBS is 100000 to 250000.

6. The polymer resin composition of claim 1, wherein, a melt index of the PBS measured according to ASTM D1238 at 190°C under a load of 2.16 kg is 1 to 10 g / 10 min.

7. The polymer resin composition of claim 1, wherein, a weight ratio of the PGA and PBS is 40:60 to 80:

20.

8. The polymer resin composition of claim 1, wherein, a melt index of the polymer resin composition measured according to ASTM D1238 at 230°C under a load of 2.16 kg is 4 to 25 g / 10 min.

9. A film comprising the polymer resin composition according to any one of claims 1 to 8.

10. The film of claim 9, wherein, a thickness of the film is 1 to 1000 μm.

11. The film of claim 9, wherein, The oxygen transmission rate of the film is 5 cc / m 2 • Skyward.

12. The film of claim 9, wherein, The water vapor transmission rate of the film is 50 g / m 2 • Skyward.

13. The film of claim 9, wherein, an elongation of the film is 350% or more.

14. The film of claim 9, wherein, an elongation of the film is 400% or more.

15. The film of claim 9, wherein, a tensile strength of the film is 45 to 60 MPa.

16. The film of claim 9, wherein, a yield strength of the film is 30 to 60 MPa.

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