KR101775070B1 - Biodegradable barrier film - Google Patents

Abstract

A biodegradable barrier film having a structure in which a first resin layer containing an aliphatic polycarbonate resin and a second resin layer comprising an aliphatic polyester resin are alternately laminated in three or more layers is biodegradable And can be used environmentally friendly for various uses such as packaging materials.

Description

Biodegradable barrier film {BIODEGRADABLE BARRIER FILM}

The present invention relates to a biodegradable barrier film which is biodegradable with good barrier properties and useful for packaging materials.

A barrier film widely used for packaging includes ethylene vinyl alcohol (EVOH) film, polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC) coating film, polyethylene (PE), and polypropylene (PP).

However, the ethylene vinyl alcohol film and the polyvinyl alcohol have a strong polar group and a strong bonding structure, which is excellent in the barrier property against gas such as oxygen, but has an OH group at the terminal group and is vulnerable to moisture. In addition, polyvinylidene chloride coating films have adequate barrier properties against oxygen and moisture, but they are classified as environmentally harmful substances and there are many restrictions on their use. In addition, although techniques for imparting barrier properties by depositing an inorganic material have been developed, cracks are generated due to a decrease in softness due to an inorganic material, which causes a drawback that the barrier property is rapidly lowered. In addition, the polyolefin-based polyethylene or polypropylene film has a non-polar group and exhibits excellent moisture barrier properties. However, since the micro-Brownian motion of molecules due to a low glass transition temperature (Tg) results in a poor gas barrier property, There is a problem that the stability is so large that decomposition can not be performed.

A biodegradable film typified by polylactic acid (PLA) is used in order to solve the problem of a barrier film which is not decomposed. However, the polylactic acid film is environmentally friendly, but is susceptible to moisture and moisture, and has a high air permeability. Therefore, when it is used for packaging, separate treatment (for example, metal deposition, laminating with other films, etc.) is required.

Therefore, an object of the present invention is to provide a biodegradable barrier film which is biodegradable while having excellent barrier properties, and which is useful for packaging materials.

In order to achieve the above object, the present invention provides a biodegradable barrier film having a structure in which a first resin layer comprising an aliphatic polycarbonate resin and a second resin layer comprising an aliphatic polyester resin are alternately laminated in three or more layers, to provide.

The biodegradable barrier film according to the present invention is characterized in that an aliphatic polycarbonate resin composed of alternating copolymerization of carbon dioxide and epoxide is alternately laminated with a polylactic acid resin and then co-extruded to obtain a film made of polylactic acid resin alone Exhibits remarkably improved barrier properties and can be used environmentally friendly for various uses such as packaging materials.

The film according to the present invention is characterized in that it is a biodegradable barrier film in which three or more layers of a first resin layer composed mainly of an aliphatic polycarbonate resin and a second resin layer composed mainly of an aliphatic polyester resin are alternately laminated do.

In the present invention, the aliphatic polycarbonate resin may be used alone or as a resin of the first resin layer by blending with a small amount of another biodegradable resin.

The aliphatic polycarbonate resin may be prepared by copolymerizing carbon dioxide with an epoxide compound selected from the group consisting of alkylene oxides, cycloalkene oxides, and mixtures thereof. As the polymerization catalyst, a zinc precursor such as diethyl zinc (U.S. Patent No. 3,585,168) or a complex compound containing an onium salt (Korean Patent No. 10-0853358) can be used.

Specific examples of the epoxide compound include ethylene oxide, propylene oxide, butene oxide, pentene oxide, hexene oxide, octene oxide, decene oxide, dodecene oxide, tetradecene oxide, hexadecene oxide, octadecene oxide, butadiene monoxide, , 2-epoxide-7-octene, cyclopentene oxide, cyclohexene oxide, cyclooctene oxide, cyclododecene oxide, 2,3-epoxide norbornene, limonene oxide and mixtures thereof.

The pressure of the carbon dioxide in the aliphatic polycarbonate resin copolymerization may be atmospheric pressure to 100 atm, preferably 5 to 30 atm. In addition, the polymerization temperature may be 20 to 120 캜, preferably 50 to 90 캜.

Examples of the method of copolymerizing the aliphatic polycarbonate resin include a batch polymerization method, a semi-batch polymerization method, and a continuous polymerization method. In the case of using the batch or semi-batch polymerization method, the reaction time may be from 1 to 24 hours, preferably from 1.5 to 4 hours, and when the continuous polymerization method is used, the average residence time of the catalyst is also from 1.5 to 4 hours .

Specific examples of the aliphatic polycarbonate resin include polyethylene carbonate, polypropylene carbonate, and mixtures thereof.

The number average molecular weight (Mn) of the aliphatic polycarbonate resin used in the present invention may be from 50,000 to 1,000,000. Here, the number average molecular weight (Mn) means the number average molecular weight measured by GPC after correcting polystyrene of a single molecular weight distribution with a standard material.

In general, aromatic polycarbonates are very dangerous from the manufacturing process because they are produced using toxic substances such as bisphenol A and phosgene, while aliphatic polycarbonates utilize carbon dioxide, which contributes to the reduction of carbon dioxide emitted to the atmosphere There are also advantages. In addition, the aromatic polycarbonate does not decompose spontaneously and emits environmentally harmful substances upon incineration, but aliphatic polycarbonate can be decomposed into carbon dioxide and water even when incinerated.

Specific examples of the biodegradable resin used for the first resin layer include aliphatic polyester resins such as polylactic acid and copolymers thereof, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid and polybutylene succinate; Cellulosic compounds; Polyhydroxy alkylate resins; Polybutylene adipate terephthalate (PBAT) resin; And mixtures thereof.

In addition, the first resin layer of the present invention may be added to the first resin layer in a range that does not impair the effects of the present invention, such as a conventional electrostatic agent, an antistatic agent, an antioxidant, a heat stabilizer, an ultraviolet screening agent, an antiblocking agent, .

In the present invention, an aliphatic polyester resin obtained by polycondensing an acid component containing an aliphatic dicarboxylic acid as a main component and a glycol component containing an alkylene glycol as a main component is used as the resin of the second resin layer. Specific examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, sebacic acid, glutaric acid, malonic acid, oxalic acid, azelaic acid, nonanedicarboxylic acid and mixtures thereof. Specific examples of the glycol component include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, propylene glycol, neopentyl glycol, Alkylene glycols such as propanediol and diethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, polyethylene glycol and mixtures thereof.

Specific examples of suitable aliphatic polyester resins include polylactic acid and its copolymers, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, polybutylene succinate, polybutylene adipate resin, and mixtures thereof. And polylactic acid resin can be preferably used.

The polylactic acid is a random copolymer of L-lactic acid and D-lactic acid, and has a weight average molecular weight of 80,000 to 500,000 g / mol in view of heat resistance and mechanical properties of the film and film processability.

The melting point of the aliphatic polyester resin used in the present invention is preferably 60 DEG C or higher, and when polylactic acid is used as the aliphatic polyester resin, it has a melting temperature of 135 DEG C to 180 DEG C in consideration of heat resistance and mechanical properties It is preferable to use polylactic acid.

In addition, the second resin layer of the present invention may be added to the second resin layer within a range that does not impair the effects of the present invention, such as an ordinary electrostatic agent, an antistatic agent, an antioxidant, a heat stabilizer, an ultraviolet screening agent, an anti- .

The biodegradable barrier film of the present invention can be produced, for example, by melt-extruding the resin of the first resin layer and the resin of the second resin layer as described above to obtain a multilayered non-stretched sheet, And then fixed. At this time, it is possible to produce an unidirectionally shrinkable film by biaxially stretching the unstretched sheet in the longitudinal and transverse directions, or uniaxially stretch only in the longitudinal or transverse direction to produce a unidirectionally shrinkable film, The stretching can be performed such that the stretching magnification is about 3 to about 25 times. Preferably, the first resin layer is divided into at least one layer, the second resin layer is divided into two or more layers, and the branched first resin layer and the second resin layer are alternately laminated. In the second and third resin layers, Let the resin layer come.

The total number of layers of the film can be adjusted in consideration of the thickness of the individual layers of the film, but preferably 3 to 220 layers.

In addition, the biodegradable barrier film of the present invention preferably has a thickness of 6 to 500 μm, and the thickness ratio (content ratio) of the first resin layer and the second resin layer is preferably 0.1 to 30: 1. When the thickness is within the above range, the film forming rate can be increased by increasing the film forming rate by improving the film forming processability.

The biodegradable barrier film of the present invention has an oxygen permeability of less than 800 cc / m ² · day · atm at 0% relative humidity and is excellent in barrier properties and has a water permeability of 400 g / m ² · day · atm or less, and has a haze of 10% or less, so that it can be applied to a packaging material requiring transparency.

Accordingly, the present invention also provides a packaging material comprising the biodegradable barrier film.

As described above, the biodegradable barrier film according to the present invention has transparency by including alternately laminated aliphatic polycarbonate first resin layer and aliphatic polyester-based second resin layer, and is excellent in barrier property, air permeability and moisture permeability Food packaging materials and the like.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are intended to illustrate the present invention, but the scope of the present invention is not limited thereto.

[ Example ]

Example  1: Biodegradability Barrier  Production of film

A polypropylene carbonate resin (Empower Co., QPAC40) obtained by alternating copolymerization of carbon dioxide and propylene oxide was used as the resin of the first resin layer. Further, a polylactic acid resin (Nature Works LLC, 4032D) having a melting temperature of 160 ° C was used as the resin of the second resin layer.

The resin of the first resin layer was dried at 40 ° C. for 3 hours to remove water and used. The resin of the second resin layer was dried at 110 ° C. for 3 hours by a hot-air drier to remove moisture, and then two extruders and two layers Using the multi-layered feed block apparatus alternately stacked, the resin of the first resin layer was melt-extruded by an extruder at a temperature of 190 DEG C and the resin of the second resin layer was melt-extruded by an extruder at a temperature of 220 DEG C.

The first resin layer is branched into 21 layers and the second resin layer is branched into 22 layers. The branched first resin layer and the second resin layer are led to a die so as to be alternately laminated, To obtain a 43-layer non-drawn laminated sheet. At this time, the extrusion amount was adjusted so that the second resin layer was positioned on the outermost layer on both sides and the content (thickness) of the first resin layer was 40 wt% (40% of the total thickness) of the total content.

The thus obtained unstretched laminated sheet was preheated at 75 DEG C and stretched 3.5 times in the machine direction, further stretched 3.8 times in the transverse direction by preheating at 80 DEG C, and then heat set at 120 DEG C to produce a 43 layer film having a total thickness of 25 mu m Respectively.

Example  2 to 5: biodegradable Barrier  Production of film

A film was prepared in the same manner as in Example 1, based on the kind of resin and process conditions as shown in Table 1 below. At this time, a polyethylene carbonate resin (Empower Co., QPAC25) was used as the PEC, and a polybutylene stearate resin (G4560, manufactured by Kagaku Kogyo Co., Ltd.) was used as the PBS.

Comparative Example  1: Biodegradability Barrier  Production of film

A single layer film having a thickness of 25 占 퐉 was prepared based on the kind of resin and the process conditions as shown in Table 1 below.

The properties of the films prepared according to Examples 1 to 5 and Comparative Example 1 were evaluated by the following methods, and the results are shown in Table 1 below.

(1) Oxygen permeability

The oxygen permeability (cc / m ² · day · atm) at 0% relative humidity was measured using an air permeability meter (OX-TRAM 2/21, MOCON, USA) according to the standard measurement method of ASTM D3985.

(2) Water vapor permeability

The sample was placed in a moisture permeability meter (PERMATRAN-W Model 3/33) and measured at 38 ° C and 100% relative humidity and expressed in terms of moisture permeability (g / m 2 · day · atm) .

(3) Hayes

The haze (%) was measured using a C-light source with a haze meter (SEP-H, Nihon Semitsu Kogaku Co., Japan).

(4) Biodegradation rate

The ratio of the biodegradation value measured by KS M3100-1 (2003) for 180 days to the reference material was calculated according to the following equation (1).

[Equation 1]

Biodegradation rate (%) = (biodegradability of sample) / (biodegradability of reference material) × 100

From the above Table 1, the biodegradable barrier films of Examples 1 to 5 according to the present invention exhibited significantly lower oxygen permeability and moisture permeability than the single-layer film of Comparative Example 1. From these results, it can be seen that the film according to the present invention has excellent barrier properties and can be used environmentally friendly for the use of packaging materials.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, It is to be understood that the invention may be practiced within the scope of the appended claims.

Claims (14)

In a biodegradable barrier film having a structure in which a first resin layer containing an aliphatic polycarbonate resin and a second resin layer comprising an aliphatic polyester resin are alternately laminated in three or more layers,
Wherein the biodegradable barrier film has a laminated structure of 43 to 145 layers,
Wherein the biodegradable barrier film has an oxygen permeability of less than 800 cc / m ² · day · atm at 0% relative humidity and a moisture permeability of less than 400 g / m ² · day · atm at 38 ° C. and 100% Biodegradable barrier film. The method according to claim 1,
Wherein the aliphatic polycarbonate resin is obtained by copolymerization of carbon dioxide with an epoxide compound selected from the group consisting of alkylene oxides, cycloalkene oxides, and mixtures thereof. 3. The method of claim 2,
Wherein the aliphatic polycarbonate resin is selected from the group consisting of polyethylene carbonate, polypropylene carbonate, and mixtures thereof. The method according to claim 1,
Wherein the aliphatic polycarbonate resin has a number average molecular weight (Mn) of 50,000 to 1,000,000 g / mol. The method according to claim 1,
Wherein the aliphatic polyester-based resin has a melting point of 60 占 폚 or higher. The method according to claim 1,
Wherein the aliphatic polyester resin is selected from the group consisting of polylactic acid and a copolymer thereof, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, polybutylene succinate, polybutylene adipate resin, and mixtures thereof Being Wherein the biodegradable barrier film is a biodegradable barrier film. delete The method according to claim 1,
Wherein the biodegradable barrier film has a second resin layer as an outermost layer on both surfaces thereof. The method according to claim 1,
Wherein the first resin layer and the second resin layer have a thickness ratio of 0.1 to 30: 1. The method according to claim 1,
Wherein the biodegradable barrier film has a thickness of 6 to 500 占 퐉. delete delete The method according to claim 1,
Wherein the biodegradable barrier film has a haze of 10% or less. A packaging material comprising the biodegradable barrier film of any one of claims 1 to 6, 8 to 10 and 13.