WO2023163327A1 - Multilayer barrier film and packaging material comprising same - Google Patents

Abstract

A multilayer barrier film according to one embodiment of the present specification comprises: a base layer including an aliphatic polyester resin; and a barrier layer including an ethylene-vinyl alcohol resin. The base layer and the barrier layer are alternately layered. The multilayer barrier film has a biodegradability of 90% or higher and a water permeability of 30 cc/(m²*atm*day) or lower. The multilayer barrier film can exhibit excellent biodegradability, oxygen barrier property and the like while the peeling resistance thereof is effectively improved.

Description

Multi-layer barrier film and packaging material including the same

[Cross Reference of Related Applications]

This application claims priority to Korean Patent Application No. 10-2022-0025067 filed on February 25, 2022, and the contents of the above patent document are all included in the present invention for reference.

Embodiments relate to a multilayer barrier film and a packaging material including the same.

Synthetic resins applied to packaging films include polyvinyl chloride, polyester, polyethylene terephthalate, and polyethylene. However, these synthetic resins do not decompose for a long time when landfilled, generate harmful gases when incinerated, and have a significantly lower recycling rate than other materials such as metal or glass. Due to this, these synthetic resins may cause serious environmental pollution problems in the disposal process.

As environmental problems caused by existing synthetic resins become more serious, biodegradable resins are attracting more attention. Biodegradable resins are naturally decomposed into carbon dioxide and water by microorganisms in the soil in a relatively short time.

The biodegradable resin may be an aliphatic polyester resin. Examples of the aliphatic polyester resin include polylactic acid, polycaprolactone, and polyglycolic acid.

On the other hand, the barrier film is applied to the packaging of foods, medicines, electronic materials, etc. that are easily deteriorated by oxygen in the air. The barrier film may be required to have transparency and durability, as well as oxygen barrier properties for suppressing oxidation of products. In the case of a film using only a biodegradable resin, a problem may occur when applied as a barrier film having relatively high oxygen permeability and low mechanical strength.

(Prior art literature)

Japanese Laid-open Patent No. 2008-155433

Korean Registered Patent No. 10-1937867

Domestic Patent Publication No. 10-2012-0045148

An object of embodiments is to provide a multilayer barrier film, etc., in which exfoliation is effectively inhibited, and biodegradability and oxygen barrier properties are excellent.

A multilayer barrier film according to an embodiment includes a base layer containing an aliphatic polyester resin and a barrier layer containing an ethylene-vinyl alcohol resin.

The base layer and the barrier layer are alternately laminated.

The biodegradability of the multilayer barrier film is 90% or more.

The oxygen permeability of the multilayer barrier film is 30 cc/(m ² *atm*day) or less.

The resin included in the barrier layer may include a repeating unit having a hydroxyl group.

The ethylene-vinyl alcohol resin may include an ethylene-based repeating unit and a vinyl alcohol-based repeating unit.

An Adf value [unitless] according to Equation 1 below of the multilayer barrier film may be 30 to 500.

[Equation 1]

In Equation 1, n is the total number of layers of the multilayer barrier film.

t is the thickness [unit: μm] of the multilayer barrier film.

The C _OH is the content of the repeating unit having a hydroxyl group of the resin included in the barrier layer [unit: mol%].

The total number of layers of the multilayer barrier film may be 5 to 225 layers.

The multilayer barrier film may have a thickness of 5 μm to 100 μm.

The multilayer barrier film may include two or more layers of the base layer.

One surface of at least one of the base layers may be disposed in contact with the barrier layer.

The multilayer barrier film may include one side and the other side.

The base layer may be disposed as an outermost layer on the one surface side and the other surface side.

The sum of the thicknesses of the outermost layers of the one surface side and the other surface side may be 5% or more and 50% or less of the total thickness of the multilayer barrier film.

The aliphatic polyester resin may include at least one of polylactic acid, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, polybutylene succinate, polybutylene adipate, and copolymers thereof. .

The multilayer barrier film may include 75% by weight or more of the aliphatic polyester resin.

The ethylene-vinyl alcohol resin may include an ethylene-based repeating unit and a vinyl alcohol-based repeating unit.

The ethylene-vinyl alcohol resin may include 70 mol% or less of the ethylene-based repeating unit.

A haze of the multilayer barrier film may be 10% or less.

A packaging material according to another embodiment includes a multilayer barrier film.

The multilayer barrier film includes a base layer including an aliphatic polyester resin; and a barrier layer comprising ethylene-vinyl alcohol resin.

The base layer and the barrier layer are alternately laminated.

The biodegradability of the multilayer barrier film is 90% or more.

The oxygen permeability of the multilayer barrier film is 30 cc/(m ² *atm*day) or less.

The multilayer barrier film according to the embodiment may have excellent biodegradability and oxygen barrier properties while effectively suppressing exfoliation.

Hereinafter, embodiments will be described in detail so that those skilled in the art can easily implement them. However, implementations may be implemented in many different forms and are not limited to the embodiments described herein.

As used herein, the terms "about," "substantially," and the like are used in a sense at or approximating that number when manufacturing and material tolerances inherent in the stated meaning are given, and are intended to assist in the understanding of embodiments. Accurate or absolute figures are used to prevent undue exploitation by unscrupulous infringers of the stated disclosure.

Throughout this specification, the term "combination of these" included in the expression of the Markush form means a mixture or combination of one or more selected from the group consisting of the components described in the expression of the Markush form, and the components It means including one or more selected from the group consisting of.

Throughout this specification, reference to "A and/or B" means "A, B, or A and B".

Throughout this specification, terms such as “first” and “second” or “A” and “B” are used to distinguish the same terms from each other unless otherwise specified.

In this specification, the meaning that B is located on A means that B is located on A or that B is located on A while another layer is located therebetween, and B is located so as to come into contact with the surface of A It is not construed as being limited to

In this specification, a singular expression is interpreted as a meaning including a singular number or a plurality interpreted in context unless otherwise specified.

The resin described herein is meant to include the resin itself and compounds derived from the resin. Illustratively, the aliphatic polyester resins described herein refer to aliphatic polyester resins and derivatives of aliphatic polyester resins.

In the present specification, the ethylene-based repeating unit means a repeating unit derived from ethylene.

In the present specification, the vinyl alcohol-based repeating unit means a repeating unit derived from vinyl alcohol.

In order to further increase the oxygen barrier properties of the film containing the aliphatic polyester resin, a multilayer film may be formed by laminating a layer containing a resin having oxygen barrier properties on a layer containing the aliphatic polyester resin. However, in this case, a peeling phenomenon may occur because sufficient adhesive strength is not formed between the layer containing the aliphatic polyester resin and the layer having oxygen barrier properties. In addition, since the biodegradability of the laminated film is lowered, an environmental pollution problem may occur due to the disposal of the multilayer film.

The inventors of the embodiment applied a film in which a layer containing an aliphatic polyester resin and a layer containing an ethylene-vinyl alcohol resin were alternately laminated, and the biodegradability and oxygen permeability of the film were controlled within a range preset in the embodiment, It was experimentally confirmed that a film having excellent biodegradability and oxygen barrier properties while effectively suppressing exfoliation could be provided, and the embodiment was completed.

Hereinafter, an embodiment will be described in detail.

Layer structure and physical properties of multilayer barrier film

A multilayer barrier film according to an embodiment includes a base layer containing an aliphatic polyester resin and a barrier layer containing an ethylene-vinyl alcohol resin.

The base layer and the barrier layer are alternately laminated. A multilayer barrier film having an alternating base layer/barrier layer structure may have relatively high biodegradability, transparency, oxygen barrier properties, etc. compared to a single layer film formed by blending a biodegradable resin and a resin having oxygen barrier properties. .

The multilayer barrier film may include two or more basic layers. In the multilayer barrier film, at least one of the base layers may be disposed in contact with the barrier layer on one surface. The base layer may be disposed on one surface or in contact with the barrier layer on one surface and the other surface. That is, the adhesive layer may be disposed only between some base layers and the barrier layer, or the adhesive layer may not be applied between the base layer and the barrier layer. In this case, the biodegradability of the multilayer barrier film can be further increased.

The resin included in the barrier layer includes a repeating unit having a hydroxyl group.

The barrier layer contains ethylene vinyl alcohol resin.

The ethylene-vinyl alcohol resin may include an ethylene-based repeating unit and a vinyl alcohol-based repeating unit.

The multilayer barrier film may have an Adf value of 30 to 500 according to Equation 1 below.

[Equation 1]

In Equation 1, n is the total number of layers included in the multilayer barrier film.

t is the thickness [unit: μm] of the barrier film.

The C _OH is the content of the repeating unit having a hydroxyl group of the resin included in the barrier layer [unit: mol%]. When the resin of the barrier layer is made of the ethylene-vinyl alcohol resin, the C _OH is substantially the content of vinyl alcohol-based repeating units included in the ethylene-vinyl alcohol resin [unit: mol%].

The Adf value is a unitless parameter.

When the number of barrier layers included in the multilayer barrier film is two or more, and the content of vinyl alcohol-based repeating units in the ethylene-vinyl alcohol resin is different for each barrier layer, the average value of the vinyl alcohol-based repeating unit content of each barrier layer is _COH value do.

When the compatibility between the base layer and the barrier layer is relatively low, sufficient bonding strength may not be formed at the interface formed between the base layer and the barrier layer, and peeling between the layers may easily occur.

Embodiments may improve peel resistance of the film by controlling the Adf value of the multilayer barrier film. Specifically, by controlling the Adf value of the multilayer barrier film, it is possible to control the number of interlayer interfaces per unit thickness of the film and simultaneously control the surface energy of the barrier layer. Through this, when shear stress is applied to the multilayer barrier film, it is possible to suppress excessive stress from being concentrated on the interlayer interface, and to improve bonding strength due to intermolecular interactions formed between the base layer and the barrier layer. In addition, the thickness of each layer included in the multilayer barrier film becomes relatively thin, and interfacial tension acts between different thin-thickness layers, and the force is accumulated, thereby forming between adjacent layers Intermolecular forces of attraction can be very strong.

The total thickness of the multilayer barrier film, the thickness of each layer included in the multilayer barrier film, and the total number of layers of the multilayer barrier film can be measured through scanning electron microscopy (SEM).

The C _OH value of the multilayer barrier film can be measured by H-NMR (H-Nuclear Magnetic Resonance).

The Adf value of the multilayer barrier film may be 30 to 500. The Adf value may be 50 or more. The Adf value may be 70 or more. The Adf value may be 100 or more. The Adf value may be 400 or less. The Adf value may be 300 or less. The Adf value of the multilayer barrier film may be 250 or less. The Adf value of the multilayer barrier film may be 230 or less. The Adf value of the multilayer barrier film may be 210 or less. In this case, it is possible to effectively suppress the occurrence of peeling between layers in the multilayer barrier film.

The total number of layers of the multilayer barrier film may be 5 to 225 layers. The total number of layers may be 10 or more. The total number of layers may be 20 or more. The total number of layers may be 30 or more. The total number of layers may be 40 or more. The total number of layers may be 50 or more. The total number of layers may be 180 or less. The total number of layers may be 150 or less. The total number of layers may be 120 or less. The total number of layers may be 100 or less. The total number of layers may be 80 or less. The total number of floors may be 65 or less. In this case, it can help improve the durability of the multilayer barrier film.

The thickness of the multilayer barrier film may be 5 μm to 100 μm. The thickness may be 10 μm or more. The thickness may be 12 μm or more. The thickness may be 15 μm or more. The thickness may be 80 μm or less. The thickness may be 50 μm or less. The thickness may be 40 μm or less. The thickness may be 30 μm or less. In this case, it can help to improve the peeling resistance of the multilayer barrier film, and can stably protect the product to be packaged.

In the multilayer barrier film, the average thickness of each base layer except for the outermost layer may be 10 nm or more. The average thickness may be 50 nm or more. The average thickness may be 100 nm or more. The average thickness may be 150 nm or more. The average thickness may be 200 nm or more. The average thickness may be 1000 nm or less. The average thickness may be 800 nm or less. The average thickness may be 700 nm or less. The average thickness may be 500 nm or less. In this case, when an external force is applied to the multilayer barrier film, it is possible to suppress a phenomenon in which stress of excessive intensity is concentrated at the interface within the film.

In the multilayer barrier film, the sum of thicknesses of each base layer excluding the outermost layer may be 1 μm or more. The sum of the thicknesses may be greater than or equal to 3 μm. The sum of the thicknesses may be 5 μm or more. The sum of the thicknesses may be greater than or equal to 7 μm. The sum of the thicknesses may be 50 μm or less. The sum of the thicknesses may be 30 μm or less. The sum of the thicknesses may be 20 μm or less. The sum of the thicknesses may be 10 μm or less. In this case, the base layer can stably support and protect the barrier layer.

In the multilayer barrier film, the average thickness of each barrier layer may be 10 nm or more. The average thickness may be 50 nm or more. The average thickness may be 100 nm or more. The average thickness may be 150 nm or more. The average thickness may be 200 nm or more. The average thickness may be 1000 nm or less. The average thickness may be 800 nm or less. The average thickness may be 700 nm or less. The average thickness may be 500 nm or less. In this case, peeling resistance of the multilayer barrier film can be effectively improved.

In the multilayer barrier film, the sum of the thicknesses of each barrier layer may be 1 μm or more. The sum of the thicknesses may be greater than or equal to 3 μm. The sum of the thicknesses may be 5 μm or more. The sum of the thicknesses may be greater than or equal to 7 μm. The sum of the thicknesses may be 50 μm or less. The sum of the thicknesses may be 30 μm or less. The sum of the thicknesses may be 20 μm or less. The sum of the thicknesses may be 10 μm or less. In this case, the oxygen barrier property of the multilayer barrier film can be further improved.

The multilayer barrier film may include one side and the other side. A base layer may be disposed as an outermost layer on one side and the other side of the multilayer barrier film. The sum of the thicknesses of the outermost layers on one side and the other side may be 5% or more and 50% or less of the total thickness of the multilayer barrier film.

In an embodiment, the base layer is disposed as the outermost layer of the multilayer barrier film, and the thickness of the outermost layer is controlled within a preset range to improve the fairness of the multilayer barrier film. Specifically, by disposing the base layer, which is superior in processability to the barrier layer, as the outermost layer, it can serve to support and fix the laminated structure inside the film during manufacturing processes such as extrusion and stretching. Through this, it is possible to suppress the generation of wave patterns in the manufactured film, and it is possible to improve the thickness uniformity of the film in the in-plane direction.

The sum of the thicknesses of the outermost layers on one side and the other side of the multilayer barrier film may be 5% or more of the total thickness of the multilayer barrier film. The sum of the thicknesses of the outermost layers may be 10% or more of the total thickness of the multilayer barrier film. The sum of the thicknesses of the outermost layers may be 20% or more of the total thickness of the multilayer barrier film. The sum of the thicknesses of the outermost layers may be 30% or more of the total thickness of the multilayer barrier film. The sum of the thicknesses of the outermost layers may be 50% or less of the total thickness of the multilayer barrier film. The sum of the thicknesses of the outermost layers may be 45% or less of the total thickness of the multilayer barrier film. The sum of the thicknesses of the outermost layers may be 40% or less of the total thickness of the multilayer barrier film. In this case, the formation of defects such as wrinkles in the multilayer barrier film can be substantially suppressed.

The biodegradability of the multilayer barrier film is more than 90%.

Embodiments may reduce the amount of plastic residues generated in the disposal process of the multilayer barrier film by controlling the biodegradability of the multilayer barrier film.

The biodegradability of multilayer barrier films is measured according to ISO_14855. Specifically, an inoculum container containing compost prepared in a compost factory is prepared. Carbon dioxide generated from the inoculum container is collected, and the amount of carbon dioxide generated is measured by titrating the collected carbon dioxide with an aqueous solution of phenolphthalein.

Thereafter, a test container is prepared in which the multilayer barrier film is put into the compost in the inoculum container. The amount of the multi-layer barrier film added to the compost is 5% by weight of the dry weight of the compost. Thereafter, the microorganisms in the compost of the test container are cultured for 180 days under conditions of 58 ± 2 ° C, moisture content of 50%, and oxygen concentration of 6% or more, while capturing carbon dioxide generated in the test container. The captured carbon dioxide is titrated with an aqueous solution of phenolphthalein to measure the amount of carbon dioxide generated. Calculate the degree of biodegradation according to Equation 2 below from the measured amount of carbon dioxide.

[Equation 2]

The biodegradability of the multilayer barrier film may be 90% or more. The biodegradability may be 100% or less. The biodegradability may be 99% or less. In this case, contamination caused by discarding the multilayer barrier film can be reduced.

The oxygen permeability of the multilayer barrier film is 30 cc/(m ² *atm*day) or less.

In the embodiment, it is possible to effectively suppress damage due to oxidation of a product to be packaged by controlling the oxygen permeability of the multilayer barrier film.

Oxygen permeability is measured based on ASTM D3895. Specifically, it is measured at room temperature using an oxygen permeability measuring device under the condition of a permeable area of 50 cm ² . Illustratively, the oxygen permeability of the multilayer barrier film can be measured using MOCON's OX-TRAN 2/21 MD.

The oxygen permeability of the multilayer barrier film may be 30 cc/(m ² *atm*day) or less. The oxygen permeability may be 25 cc/(m ² *atm*day) or less. The oxygen permeability may be 20 cc/(m ² *atm*day) or less. The oxygen permeability may be 15 cc/(m ² *atm*day) or less. The oxygen permeability may be greater than or equal to 1 cc/(m ² *atm*day). The oxygen permeability may be 5cc/(m ² *atm*day) or more. In this case, it is possible to effectively suppress contact between oxygen and a product packaged with the multilayer barrier film.

Embodiments can simultaneously control the biodegradability and oxygen permeability of the multilayer barrier film. When the thickness of the barrier layer in the multilayer barrier film is increased in consideration of only the aspect of improving the oxygen permeability, the biodegradability of the entire multilayer barrier film may be lowered due to the low biodegradability of the resin included in the barrier layer. In addition, when the thickness of the barrier layer in the multilayer barrier film is reduced in consideration of only the aspect of improving biodegradability, oxygen permeation may not be stably prevented. In an embodiment, by simultaneously adjusting the biodegradability and oxygen permeability of the multilayer barrier film, the multilayer barrier film can have oxygen barrier properties suitable for application as a barrier film, and at the same time, environmental pollution caused by film disposal can be reduced.

The haze value of the multilayer barrier film may be 10% or less.

Embodiments may improve the transparency of the film by controlling the haze value of the multilayer barrier film.

The haze value of the multilayer barrier film is measured with a haze meter. Illustratively, the haze value may be measured using the Nihon Semitsu Kogaku SEP-H model.

The haze value of the multilayer barrier film may be 10% or less. The haze value may be 7% or less. The haze value may be 5% or less. The haze value may be 3% or less. The haze value may be greater than or equal to 0.1%.

Light transmittance of the multilayer barrier film measured with light having a wavelength of 550 nm may be 85% or more. The light transmittance may be 90% or more. The light transmittance may be 95% or less. The light transmittance may be 99% or less.

In this case, the multilayer barrier film can have excellent transparency.

Tensile strength of the multilayer barrier film may be 5 kg/mm ² or more. The tensile strength may be 10 kg/mm ² or more. The tensile strength may be 30 kg/mm ² or less. The tensile strength may be 25 kg/mm ² or less.

The elongation of the multilayer barrier film may be 30% or more. The elongation may be 50% or more. The elongation may be 300% or less. The elongation may be 250% or less. The elongation may be 200% or less.

The multilayer barrier film may have a Young's modulus of 100 kg/mm ² or greater. The Young's modulus of the multilayer barrier film may be 200 kg/mm ² or more. The multilayer barrier film may have a Young's modulus of 500 kg/mm ² or less. The Young's modulus of the multilayer barrier film may be 400 kg/mm ² or less.

In this case, the multilayer barrier film can stably control mechanical properties and have high formability and processability.

Tensile strength, elongation and Young's modulus of the multilayer barrier film are measured based on ASTM D882.

Layer-by-layer composition and physical properties of multilayer barrier film

1. Base layer

The base layer contains an aliphatic polyester resin. Aliphatic polyester resins include polylactic acid, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, polybutylene succinate, polybutylene It may include at least one of len adipate (Polybutylene Adipate) and their respective copolymers. Specifically, the aliphatic polyester resin may include polylactic acid. The aliphatic polyester resin may be a polylactic acid resin.

These aliphatic polyester resins can be manufactured based on biomass, and are environmentally friendly due to their high degree of biodegradation by microorganisms when landfilled.

The base layer may include 50% by weight or more of the aliphatic polyester resin. The base layer may include 70% by weight or more of the aliphatic polyester resin. The base layer may include 80% by weight or more of the aliphatic polyester resin. The base layer may include 90% by weight or more of the aliphatic polyester resin. The base layer may include 99% by weight or more of the aliphatic polyester resin. The base layer may include 100% by weight or less of the aliphatic polyester resin. In this case, the biodegradation characteristics of the multilayer barrier film can be further improved.

The polylactic acid resin may have a weight average molecular weight of 100,000 g/mol or more. The weight average molecular weight may be 1,000,000 g/mol or less. The weight average molecular weight may be 800,000 g/mol or less. The weight average molecular weight may be 500,000 g/mol or less. The weight average molecular weight may be 300,000 g/mol or less. In this case, mechanical properties and optical properties of the multilayer barrier film may be further improved.

The weight average molecular weight is determined by gel permeation chromatography, GPC) can be measured.

The polylactic acid resin may include L-lactic acid-based repeating units. The polylactic acid resin may include a D-lactic acid-based repeating unit. The polylactic acid resin may include an L-lactic acid-based repeating unit and a D-lactic acid-based repeating unit.

The polylactic acid resin may include 1% by weight or more of the D-lactic acid-based repeating unit. The polylactic acid resin may include 2% by weight or more of the D-lactic acid-based repeating unit. The polylactic acid resin may include 5% by weight or less of the D-lactic acid-based repeating unit. The polylactic acid resin may include 4% by weight or less of the D-lactic acid-based repeating unit. The polylactic acid resin may include 3% by weight or less of the D-lactic acid-based repeating unit.

The polylactic acid resin may include 80% by weight or more of L-lactic acid-based repeating units. The polylactic acid resin may include 83% by weight or more of L-lactic acid-based repeating units. The polylactic acid resin may include 85% by weight or more of L-lactic acid-based repeating units. The polylactic acid resin may include 90% by weight or more of L-lactic acid-based repeating units. The polylactic acid resin may include 99% by weight or less of L-lactic acid-based repeating units.

In this case, fairness may be improved in the process of stretching the multilayer barrier film.

The melting temperature of the polylactic acid resin may be 50°C or higher. The melting temperature may be 100 °C or higher. The melting temperature may be 110 °C or higher. The melting temperature may be 120 °C or higher. The melting temperature may be 300 °C or less. The melting temperature may be 250 °C or less. The melting temperature may be less than or equal to 220°C. The melting temperature may be 200 °C or less.

The glass transition temperature of the polylactic acid resin may be 30 °C or higher. The glass transition temperature may be 40 °C or higher. The glass transition temperature may be 45 ℃ or more. The glass transition temperature may be 100 °C or less. The glass transition temperature may be 80 °C or less. The glass transition temperature may be 70 °C or less. The glass transition temperature may be 65 °C or less.

In this case, the heat resistance of the base layer can be stably controlled.

The polylactic acid resin may have a melt viscosity of 5,000 poise or more at 210°C. The melt viscosity may be 7,000 poise or more. The melt viscosity may be 7,500 poise or more. The melt viscosity may be 8,000 poise or more. The melt viscosity may be 15,000 poise or less. The melt viscosity may be 12,000 poise or less. The melt viscosity may be 11,000 poise or less. The melt viscosity may be 10,000 poise or less.

The base layer may have a melt viscosity of 5,000 poise or more at 210°C. The base layer may have a melt viscosity of 7,000 poise or more at 210°C. The base layer may have a melt viscosity of 8,000 poise or more at 210°C. The base layer may have a melt viscosity of 15,000 poise or less at 210°C. The base layer may have a melt viscosity of 12,000 poise or less at 210°C. The base layer may have a melt viscosity of 11,000 poise or less at 210°C. The base layer may have a melt viscosity of 10,000 poise or less at 210°C.

In this case, formability and processability of the base layer can be improved.

Melt viscosity is measured using a rheometer at 210°C and a shear rate of 100 s ^-1 .

The base layer may further include additives. Additives may include electrostatic agents, antistatic agents, antioxidants, heat stabilizers, sunscreens, antiblocking agents, and other inorganic lubricants commonly applicable in the film field.

2. Barrier layer

The barrier layer may include ethylene vinyl alcohol (Ethylene Vinyl Alcohol) resin. The ethylene-vinyl alcohol resin may include an ethylene-based repeating unit and a vinyl alcohol-based repeating unit.

Embodiments can control the content of each monomer of the ethylene vinyl alcohol resin. Through this, it is possible to impart excellent oxygen barrier properties to the multilayer barrier film. In addition, since the difference in surface energy between the barrier layer and the base layer is controlled, adhesion between the barrier layer and the base layer may be improved.

The content of each monomer of the ethylene vinyl alcohol resin can be measured by H-NMR (H-Nuclear Magnetic Resonance).

The ethylene-vinyl alcohol resin may include 70 mol% or less of the ethylene-based repeating unit. The ethylene-vinyl alcohol resin may include 60 mol% or less of the ethylene-based repeating unit. The ethylene-vinyl alcohol resin may include 50 mol% or less of the ethylene-based repeating unit. The ethylene-vinyl alcohol resin may contain 10 mol% or more of ethylene-based repeating units. The ethylene-vinyl alcohol resin may include 20 mol% or more of ethylene-based repeating units. The ethylene-vinyl alcohol resin may include 35 mol% or more of the ethylene-based repeating unit.

The ethylene-vinyl alcohol resin may include 30 mol% or more of the vinyl alcohol-based repeating unit. The ethylene-vinyl alcohol resin may include 40 mol% or more of the vinyl alcohol-based repeating unit. The ethylene-vinyl alcohol resin may include 50 mol% or more of vinyl alcohol-based repeating units. The ethylene-vinyl alcohol resin may include 55 mol% or more of the vinyl alcohol-based repeating unit. The ethylene-vinyl alcohol resin may include 60 mol% or more of vinyl alcohol-based repeating units. The ethylene-vinyl alcohol resin may include 90 mol% or less of vinyl alcohol-based repeating units. The ethylene-vinyl alcohol resin may include 80 mol% or less of vinyl alcohol-based repeating units. The ethylene-vinyl alcohol resin may include 75 mol% or less of the vinyl alcohol-based repeating unit.

In this case, the oxygen permeability of the multilayer barrier film can be effectively lowered, and peeling resistance of the multilayer barrier film can be improved.

The barrier layer may include 80% by weight or more of ethylene vinyl alcohol resin. The barrier layer may include 90% by weight or more of ethylene vinyl alcohol resin. The barrier layer may include 95% by weight or more of ethylene vinyl alcohol resin. The barrier layer may include 100% by weight or less of ethylene vinyl alcohol resin. In this case, damage due to oxidation of the product to be packaged can be suppressed.

The polymerization degree of the ethylene vinyl alcohol resin may be 1,000 or more. The polymerization degree may be 1,300 or more. The polymerization degree may be 6,000 or less. The degree of polymerization may be 5,000 or less.

The weight average molecular weight of the ethylene vinyl alcohol resin may be 50,000 or more. The weight average molecular weight may be 100,000 or more. The weight average molecular weight may be 600,000 or less. The weight average molecular weight may be 500,000 or less. The weight average molecular weight may be 400,000 or less.

In this case, the barrier layer may exhibit excellent oxygen barrier properties while having stable mechanical properties.

The polymerization degree and weight average molecular weight of ethylene vinyl alcohol resin were determined by gel permeation chromatography, GPC) can be measured.

The melting temperature of the ethylene vinyl alcohol resin may be 130° C. or higher. The melting temperature may be 150 °C or higher. The melting temperature may be 210 °C or less. The melting temperature may be 200 °C or less. The melting temperature may be 190 °C or less.

The glass transition temperature of the ethylene vinyl alcohol resin may be 40 °C or higher. The glass transition temperature may be 50 °C or higher. The glass transition temperature may be 90 °C or less. The glass transition temperature may be 80 °C or less. The glass transition temperature may be 70 °C or less.

In this case, the heat resistance of the barrier layer can be stably controlled.

Ethylene vinyl alcohol resin may have a melt viscosity of 3,000 poise or more at 210°C. The melt viscosity may be 4,000 poise or more. The melt viscosity may be 15,000 poise or less. The melt viscosity may be 12,000 poise or less. The melt viscosity may be 10,000 poise or less. The melt viscosity may be 9,000 poise or less.

The barrier layer may have a melt viscosity of 3,000 poise or more at 210°C. The melt viscosity may be 4,000 poise or more. The melt viscosity may be 15,000 poise or less. The melt viscosity may be 12,000 poise or less. The melt viscosity may be 10,000 poise or less. The melt viscosity may be 9,000 poise or less.

Melt viscosity is measured at 210°C and a shear rate of 100 s ^-1 using a rheometer.

Ethylene vinyl alcohol may have a melt index of 1 g/10 min or more when measured at 210° C. and 2.16 kg. The melt index may be 2 g/10 min or more. The melt index may be 2.5 g/10 min or more. The melt index may be 20 g/10 min or less. The melt index may be 18 g/10 min or less. The melt index may be 16 g/10 min or less. The melt index may be 14 g/10 min or less.

In this case, the processability of the barrier layer can be improved in the extrusion process.

The barrier layer may further include additives. Additives may include electrostatic agents, antistatic agents, antioxidants, heat stabilizers, sunscreens, antiblocking agents, and other inorganic lubricants commonly applicable in the film field.

Manufacturing method of multilayer barrier film

A method for manufacturing a multilayer barrier film according to another embodiment includes a preparation step of preparing a resin composition for preparing a base layer and a resin composition for preparing a barrier layer; An extrusion step of obtaining a multilayer barrier sheet in which a base layer and a barrier layer are alternately laminated by melt-extruding a resin composition for preparing a base layer and a resin composition for preparing a barrier layer, respectively; and a stretching step of biaxially stretching and heat-setting the multilayer barrier sheet to obtain a multilayer barrier film.

The multilayer barrier film includes a base layer containing an aliphatic polyester resin and a barrier layer containing an ethylene-vinyl alcohol resin. In the multilayer barrier film, the base layer and the barrier layer are alternately laminated. The biodegradability of the multilayer barrier film is more than 90%. The oxygen permeability of the multilayer barrier film is 30 cc/(m ² *atm*day) or less.

In the preparation step, the resin composition for preparing the base layer may include an aliphatic polyester resin. The resin composition for preparing the barrier layer may include an ethylene-vinyl alcohol resin. Descriptions of the aliphatic polyester resin and the ethylene-vinyl alcohol resin are omitted because they overlap with the foregoing.

The resin composition for preparing the base layer may further include additives commonly applied in the film field. The resin composition for preparing the barrier layer may further include additives commonly applied in the film field.

In the preparation step, the processability of the resin composition may be improved by removing moisture contained in the resin composition. The resin composition for preparing the base layer may be dehumidified and dried for 2 to 10 hours at a temperature of 50° C. to 120° C. through a dehumidifying dryer. The resin composition for preparing the barrier layer may be dehumidified and dried for 30 minutes to 5 hours at a temperature of 50° C. to 120° C. through a dehumidifying dryer.

In the extrusion step, the resin composition for preparing the base layer and the resin composition for preparing the barrier layer may be put into different extruders and extruded. The extruder may be a single screw extruder or a twin screw extruder.

The melt extrusion temperature of the resin composition for preparing the base layer may be 160° C. or higher. The melt extrusion temperature of the resin composition for preparing the base layer may be 180° C. or higher. The melt extrusion temperature of the resin composition for preparing the base layer may be 190° C. or higher. The melt extrusion temperature of the resin composition for preparing the base layer may be 230° C. or less. The melt extrusion temperature of the resin composition for preparing the base layer may be 220° C. or less. The melt extrusion temperature of the resin composition for preparing the base layer may be 210° C. or less.

The melt extrusion temperature of the resin composition for preparing the barrier layer may be 160° C. or higher. The melt extrusion temperature of the resin composition for preparing the barrier layer may be 180° C. or higher. The melt extrusion temperature of the resin composition for preparing the barrier layer may be 190° C. or higher. The melt extrusion temperature of the resin composition for preparing the barrier layer may be 230° C. or less. The melt extrusion temperature of the resin composition for preparing the barrier layer may be 220° C. or less. The melt extrusion temperature of the resin composition for preparing the barrier layer may be 210° C. or less.

In this case, while improving the processability of the resin composition for preparing the base layer and the barrier layer, it is possible to suppress thermal damage to the resin composition.

In the extrusion step, a multilayer barrier sheet may be formed by extruding and then stacking the base layer and the barrier layer, respectively, and a multilayer barrier sheet in which the base layer and the barrier layer are alternately laminated may be formed by applying a multilayer feed block. Specifically, after branching the base layer and the barrier layer in the multilayer feed block, the base layer and the barrier layer may be alternately stacked. In this case, the base layer may be stacked so as to be disposed on the outermost side, and the thickness of the base layer located on the outermost side of both sides may be adjusted to be different from the thickness of the base layer not located on the outermost side. After the extrudate in which the base layer and the barrier layer are alternately laminated is passed through a die, a multilayer barrier sheet may be obtained by adhering to a cooling roll.

The temperature of the cooling roll may be 10° C. or higher. The temperature of the cooling roll may be 15° C. or higher. The temperature of the cooling roll may be 40°C or less. The temperature of the cooling roll may be 25° C. or lower.

The total number of layers of the multilayer barrier sheet may be 5 to 225 layers. The total number of layers may be 10 or more. The total number of layers may be 20 or more. The total number of layers may be 30 or more. The total number of layers may be 40 or more. The total number of layers may be 50 or more. The total number of layers may be 180 or less. The total number of layers may be 150 or less. The total number of layers may be 120 or less. The total number of layers may be 100 or less. The total number of layers may be 80 or less. The total number of floors may be 65 or less.

The stretching step is a process of preheating at 50 ° C to 80 ° C, a process of longitudinally stretching the multilayer barrier sheet 2 to 4 times in the longitudinal direction at 40 ° C to 100 ° C, and a multilayer barrier sheet at 50 ° C to 150 ° C in the transverse direction It may include a process of transverse stretching 3 to 6 times and a heat setting process. In this case, the manufactured multilayer barrier film may have stable mechanical properties and formability may be further improved.

The heat setting process may be carried out at a temperature of 50° C. or higher. The heat setting process may be carried out at a temperature of 70° C. or higher. The heat setting process may be carried out at a temperature of 100° C. or higher. The heat setting process may be carried out at a temperature of 110° C. or higher. Heat setting process may be carried out at a temperature of 150 ℃ or less. The heat setting process may be carried out at a temperature of 140° C. or higher.

Description of the multilayer barrier film manufactured through the stretching step is omitted because it overlaps with the previous content.

packaging material

A packaging material according to another embodiment includes a multilayer barrier film. The multilayer barrier film includes a base layer containing an aliphatic polyester resin and a barrier layer containing an ethylene-vinyl alcohol resin. The base layer and the barrier layer are alternately laminated. The biodegradability of the multilayer barrier film is more than 90%. The oxygen permeability of the multilayer barrier film is 30 cc/m ² *atm*day or less.

The packaging material may be in the form of a film or in the form of a container.

A packaging material including a multi-layered barrier film may be environmentally friendly due to its high biodegradability while having excellent durability and oxygen barrier properties.

Description of the multi-layer barrier film included in the packaging material is omitted because it overlaps with the previous content.

Hereinafter, specific embodiments will be described in more detail.

Preparation Example: Preparation of multilayer barrier film

Example 1: Polylactic acid resin 4032D model from Nature Works LLC, which has a D-lactic acid content of 1.4% by weight and a melt viscosity of about 8,770 poise at 210 ° C, was prepared as a resin for preparing a base layer, and a resin for preparing a barrier layer at 210 ° C An ethylene-vinyl alcohol resin having a melt viscosity of about 4,800 poise, an ethylene-based repeating unit content of 44 mol%, and a vinyl alcohol-based repeating unit content of 56 mol% was prepared.

The base layer preparation resin was dried at about 80° C. for 6 hours using a dehumidifying dryer, and the barrier layer preparation resin was dried at about 80° C. for 2 hours using a dehumidifying dryer.

The resin for preparing the base layer and the resin for preparing the barrier layer were put into different extruders, and the base layer was branched into 15 layers and the barrier layer was branched into 14 layers using a multi-layer feed block to obtain an alternately laminated extrudate. The extrusion temperature of the resin for preparing the base layer and the resin for preparing the barrier layer was applied at 210°C. The alternately laminated extrudates were passed through a die and adhered to a cooling roll cooled to 21° C. to obtain a 29-layer unstretched multilayer barrier sheet. At this time, a base layer was disposed on both outermost layers of the multilayer barrier sheet, and the sum of the thicknesses of the outermost layers was 30% of the total thickness. The ethylene vinyl alcohol resin content in the multilayer barrier sheet was applied at 10% by weight.

The multilayer barrier sheet was stretched 3.0 times in the machine direction at 65 ° C and 3.9 times in the transverse direction at about 120 ° C, heat-set at 120 ° C, and a relaxation rate of 1% was applied to prepare a multilayer barrier film with a thickness of 20 μm and 29 layers. did

Example 2: The base layer is laminated with 22 layers and the barrier layer is laminated with 21 layers, the thickness is applied at 25 μm, the ethylene vinyl alcohol resin content in the multilayer barrier sheet is applied at 5% by weight, and the thickness of both outermost layers is A multilayer barrier film was prepared in the same manner as in Example 1, except that the sum was 32% of the total film thickness.

Example 3: 29 base layers and 28 barrier layers are laminated, the ethylene vinyl alcohol resin content in the multilayer barrier sheet is applied at 8% by weight, and the sum of the thicknesses of both outermost layers is 40% of the total film thickness A multilayer barrier film was prepared in the same manner as in Example 1 except that

Example 4: An ethylene-vinyl alcohol resin in which the base layer is 29 layers and the barrier layer is 28 layers, and the ethylene-based repeating unit content is 38 mol% and the vinyl alcohol-based repeating unit content is 62 mol% as a resin for preparing the barrier layer Multi-layer barrier in the same manner as in Example 1, except that the content of ethylene vinyl alcohol resin in the multi-layer barrier sheet was applied at 7% by weight, and the sum of the thicknesses of both outermost layers was 40% of the total film thickness. A film was made.

Example 5: An ethylene-vinyl alcohol resin having a base layer of 29 layers and a barrier layer of 28 layers and having an ethylene-based repeating unit content of 29 mol% and a vinyl alcohol-based repeating unit content of 71 mol% as a resin for preparing the barrier layer was prepared. Multi-layer barrier in the same manner as in Example 1, except that the content of ethylene vinyl alcohol resin in the multi-layer barrier sheet was applied at 8% by weight, and the sum of the thicknesses of both outermost layers was 40% of the total film thickness. A film was made.

Comparative Example 1: except that the base layer is laminated with two layers and the barrier layer is one layer, the thickness ratio of the base layer:barrier layer:base layer is applied as 1:1:1, and stretching is performed 3.8 times in the transverse direction. Then, a multilayer barrier film was prepared in the same manner as in Example 1.

Comparative Example 2: A multilayer barrier film was prepared in the same manner as in Example 1, except that 30% by weight of the ethylene vinyl alcohol resin in the entire multilayer barrier sheet was applied.

Comparative Example 3: The resin for preparing the base layer applied in Example 1 was dried in a dehumidifying dryer at 60° C. for 8 hours, and then melt-extruded at 210° C. to prepare a single-layer barrier sheet. The single-layer barrier sheet was stretched 3.0 times in the machine direction at 65°C and 3.9 times in the transverse direction at about 120°C, heat-set at 120°C, and a relaxation rate of 1% was applied to prepare a multilayer barrier film having a thickness of 20 μm.

Comparative Example 4: 70% by weight of the resin for preparing the base layer and 30% by weight of the resin for preparing the barrier layer applied in Example 1 were hand-mixed and then blended at 200° C. with a 45 pie twin screw extruder. After drying the blended resin at 60 ° C. for 8 hours in a dehumidifying dryer, melt extrusion at 210 ° C. to prepare a multilayer barrier sheet. The multilayer barrier sheet was stretched 3.0 times in the longitudinal direction at 65 ° C and 3.9 times in the transverse direction at about 120 ° C, heat-set at 120 ° C, and a relaxation rate of 1% was applied to prepare a multilayer barrier film having a thickness of 20 μm.

Comparative Example 5: Polybutylene adipate terephthalate having a melt viscosity of 6,300 poise at 210° C. and containing 50 mol% of aliphatic dicarboxylic acid-based repeating units among all dicarboxylic acid-based repeating units as a resin for preparing a barrier layer (Polubutylene Adipate terephthalate) resin was applied, the polybutylene adipate terephthalate resin content in the multilayer barrier sheet was applied at 30% by weight, and the multilayer barrier film was prepared in the same manner as in Example 1 except that the thickness was applied at 25 μm. manufactured.

The composition and layer structure of the multilayer barrier film according to Examples and Comparative Examples are shown in Table 1 below.

Evaluation Example: Peeling Resistance Evaluation

After crumpling the multilayer barrier film according to Examples and Comparative Examples by applying force for a certain period of time by hand, it was visually checked and evaluated as O if peeling between the base layer and the barrier layer did not occur and X if peeling occurred.

Evaluation results for each Example and Comparative Example are listed in Table 1 below.

Evaluation Example: Oxygen Permeability Measurement

Oxygen permeability of the multilayer barrier film according to Examples and Comparative Examples was measured using an oxygen permeability measuring device of MOCON's OX-TRAN 2/21 MD. Oxygen permeability was measured based on ASTM D3895, and measured at room temperature (Room temperature, 23±2° C.) by setting the permeation area to 50 cm ² .

Evaluation results for each Example and Comparative Example are listed in Table 1 below.

Evaluation Example: Haze Evaluation

The haze of the multilayer barrier film according to Examples and Comparative Examples was measured using a haze meter SEP-H model manufactured by Nihon Semitsu Kogaku. Haze was measured based on ASTM D1003.

Evaluation results for each Example and Comparative Example are listed in Table 1 below.

Evaluation Example: Evaluation of biodegradability

The biodegradability of the multilayer barrier films according to Examples and Comparative Examples was measured according to ISO_14855. Specifically, an inoculum container containing compost prepared in a compost factory was prepared. Carbon dioxide generated from the inoculum container was collected, and the amount of carbon dioxide generated was measured by titrating the collected carbon dioxide with an aqueous solution of phenolphthalein.

Thereafter, a test container was prepared in which the multilayer barrier film was put into the compost in the inoculum container. The amount of the multilayer barrier film added to the compost was 5% by weight of the dry weight of the compost. Thereafter, the microorganisms in the compost of the test vessel were cultured for 180 days under conditions of 58±2° C., moisture content of 50%, and oxygen concentration of 6% or more, while carbon dioxide generated in the test vessel was collected. The captured carbon dioxide was titrated with an aqueous solution of phenolphthalein to measure the amount of carbon dioxide generated. The biodegradability was calculated according to Equation 2 below with the measured amount of carbon dioxide.

[Equation 2]

If the biodegradability calculated for each specimen was 90% or more, it was evaluated as O, and if the biodegradability was less than 90%, it was evaluated as X.

Evaluation results for each Example and Comparative Example are listed in Table 1 below.

		Example 1	Example 2	Example 3	Example 4	Example 5	Comparative Example 1	Comparative Example 2	Comparative Example 3	Comparative Example 4	Comparative Example 5
base layer for manufacturing profit	resin type	PLA	PLA	PLA	PLA	PLA	PLA	PLA	PLA	PLA	PLA
	Number of floors (floors)	15	22	29	29	29	2	15	-	-	15
	Total film thickness contrast amount thickness of the outermost layer Total percentage (%)	30	32	40	40	40	66.7	30	-	-	30
	Extrusion temperature (℃)	210	210	210	210	210	210	210	210	210	210
barrier layer resin for manufacturing	resin type	EVOH	EVOH	EVOH	EVOH	EVOH	EVOH	EVOH	-	EVOH*	PBAT
	Ethylene-based repeating unit content (mol%)	44	44	44	38	29	44	44	-	44	-
	Vinyl alcohol-based repeating unit content (mol%)	56	56	56	62	71	56	56	-	56	-
	Number of floors (floors)	14	21	28	28	28	One	14	-	-	14
	Extrusion temperature (℃)	210	210	210	210	210	210	210	-	210	210
The weight of the second resin compared to the total film weight (% by weight)		10	5	8	7	8	10	30	-	30	-
Adf		78.4	117.6	156.8	173.6	198.8	5.6	78.4	0	0	0
Total number of floors (floors)		29	43	57	57	57	3	29	One	One	29
Film thickness (μm)		20	25	20	20	20	20	20	20	20	25
Phil name water castle	Haze (%)	2.6	2.4	2.9	2.9	2.9	3.1	2.6	1.5	15	3.5
	oxygen permeability (cc/(m 2 *atm*day))	10	20	13	13	13	11	7	755	250	1130
	Peeling resistance evaluation	O	O	O	O	O	X	O	-	-	O
	Biodegradability evaluation	O	O	O	O	O	O	X	O	X	O

In Table 1, PLA means polylactic acid resin, EVOH means ethylene vinyl alcohol resin, and PBAT means polybutylene adipate terephthalate resin. , applied to blend resin preparation.

In Table 1, Examples 1 to 5 were evaluated as O in the evaluation of biodegradability and peeling resistance, and showed relatively low values in the evaluation of oxygen permeability and haze.

In the case of Comparative Example 1, which is a polylactic acid/ethylene vinyl alcohol three-layer film, it was evaluated as X in peeling resistance evaluation.

In the case of Comparative Example 2 in which 30% by weight of the resin for preparing the barrier layer was applied, it was evaluated as X in the biodegradability evaluation.

In the case of Comparative Example 3, which is a polylactic acid single layer film, the oxygen permeability was greater than 700 cc/(m ² *atm*day).

In the case of Comparative Example 4, which is a single-layer film made of a polylactic acid/ethylene vinyl alcohol blend resin, the oxygen permeability was greater than 200 cc/(m ² *atm*day) and the haze was greater than 10%. , was evaluated as X in the biodegradability evaluation.

In the case of Comparative Example 5, which is a polylactic acid/polybutylene adipate terephthalate laminated film, the oxygen permeability was greater than 1100 cc/(m ² *atm*day).

Although the preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the embodiments defined in the following claims are also within the scope of the present invention. it belongs

Claims (11)

1. A base layer containing an aliphatic polyester resin; And a barrier layer comprising an ethylene-vinyl alcohol resin;

   The base layer and the barrier layer are alternately laminated,

   biodegradability is more than 90%,

   A multilayer barrier film having an oxygen permeability of 30 cc/(m ² *atm*day) or less.
2. According to claim 1,

   The resin included in the barrier layer includes a repeating unit having a hydroxyl group,

   A multilayer barrier film having an Adf value of 30 to 500 according to Equation 1 below;

   [Equation 1]

   

   In Equation 1 above,

   Wherein n is the total number of layers of the multilayer barrier film,

   Wherein t is the thickness [unit: μm] of the multilayer barrier film,

   The C _OH is the content of the repeating unit having a hydroxyl group of the resin included in the barrier layer [unit: mol%].
3. According to claim 1,

   The total number of layers of the multilayer barrier film is 5 to 225 layers, the multilayer barrier film.
4. According to claim 1,

   A multilayer barrier film having a thickness of 5 μm to 100 μm.
5. According to claim 1,

   Including two or more layers of the base layer,

   At least one of the base layers is disposed on one surface in contact with the barrier layer, a multilayer barrier film.
6. According to claim 1,

   The multilayer barrier film includes one side and the other side,

   The base layer is disposed as the outermost layer on the one side and the other side,

   The sum of the thicknesses of the outermost layers of the one surface side and the other surface side is 5% or more and 50% or less of the total thickness of the multilayer barrier film.
7. According to claim 1,

   The aliphatic polyester resin includes at least one of polylactic acid, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, polybutylene succinate, polybutylene adipate, and copolymers thereof, multilayer barrier film.
8. According to claim 1,

   A multilayer barrier film comprising 75% by weight or more of the aliphatic polyester resin.
9. According to claim 1,

   The ethylene-vinyl alcohol resin includes an ethylene-based repeating unit and a vinyl alcohol-based repeating unit,

   The ethylene-vinyl alcohol resin comprises 70 mol% or less of the ethylene-based repeating unit, a multilayer barrier film.
10. According to claim 1,

    A multilayer barrier film having a haze of 10% or less.
11. Including a multi-layer barrier film,

    The multilayer barrier film includes a base layer including an aliphatic polyester resin; And a barrier layer comprising an ethylene vinyl alcohol resin;

    The base layer and the barrier layer are alternately laminated,

    The biodegradability of the multilayer barrier film is 90% or more,

    Packaging material wherein the multilayer barrier film has an oxygen permeability of 30 cc/(m ² *atm*day) or less.