JP2002273845A - Biodegradable laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable laminated film having decomposition properties under the natural environment and excellent in heat sealability and impact resistance. SOLUTION: The biodegradable laminated film includes a base material layer and a heat-sealing layer, and the heat-sealing layer is at least one outermost layer. The base material layer is a biaxially stretched film comprising a polylactic acid type polymer and the heat-sealing layer is a film containing aliphatic-aromatic copolymerized polyester.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable laminated film which has decomposability in a natural environment, and has excellent heat sealability and impact resistance.

[0002]

2. Description of the Related Art Conventionally, paper and plastic films have been used in a wide range of applications, such as packaging materials for liquids, powders and granules, and solids for various foods, beverages, medicines, miscellaneous goods, agricultural materials, and building materials. , Aluminum foil and the like are used. In particular,
Plastic films have excellent properties such as strength, water resistance, moldability, transparency, and cost performance, and are used in many applications as bags and thermoformed containers. Properties required for these uses include heat sealing properties, impact resistance, heat resistance, and the like.

At present, plastics used for these applications include polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate and the like. However, films made of the above-mentioned plastics do not biodegrade or hydrolyze in a natural environment, or have a very low decomposition rate.
When buried, it may remain in the soil. If it is dumped, it may damage the landscape or destroy the living environment of living things. In addition, even when incinerated, there is a problem that harmful gas is generated or the incinerator is deteriorated.

[0004] In order to solve these problems, Japanese Patent Laid-Open No.
JP-323946 discloses a multilayer biodegradable plastic film comprising a polylactic acid-based polymer and a biodegradable plastic having a melting point of at least 10 ° C. lower than the melting point of the polylactic acid-based polymer. It is described as having a sealing property. However, the heat sealability of the film at low temperature was not satisfactory. JP-A-10-100353 discloses a biodegradable laminated film comprising a stretched film of a polylactic acid-based polymer and an unstretched film containing a polylactic acid-based polymer and another biodegradable aliphatic polyester. It is disclosed and described as having excellent transparency and heat sealing properties. However, even with this film, the heat sealability at a low temperature was not a satisfactory performance. Also, since polylactic acid has a hard and brittle property, even when an aliphatic polyester different from the polylactic acid-based polymer is mixed within a certain range, the impact resistance cannot be sufficiently satisfied, and further improvement is required. Was required. JP-A-10-15
No. 1715 discloses a lactic acid-based polymer laminate having a base layer made of a crystallized lactic acid-based polymer and a seal layer made of an amorphous lactic acid-based polymer having a softening point lower than the melting point of the lactic acid-based polymer. It is described as having heat resistance of 60 ° C. or more and excellent sealing strength. However, the amorphous polymer has a problem that the operability is reduced because the crystallinity is low and blocking is likely to occur.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a biodegradable laminated film which has decomposability in a natural environment and is excellent in heat sealability and impact resistance at low temperatures. It is.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that at least one outermost layer of a film made of a polylactic acid-based polymer or a composition containing this as a main component,
The present inventors have found that a biodegradable laminated film provided with a film containing an aliphatic-aromatic copolymerized polyester can solve the above-described problems, and have reached the present invention. That is, the gist of the present invention is as follows. (1) A laminated film comprising a base layer and a heat seal layer, wherein the heat seal layer is at least one outermost layer, wherein the base layer is a biaxially stretched film made of a polylactic acid-based polymer, A biodegradable laminated film, wherein the seal layer is a film containing an aliphatic-aromatic copolymerized polyester. (2) The heat-sealing layer is composed of a polylactic acid-based polymer and an aliphatic-
When the mass ratio of the aromatic copolymerized polyester is 90/10 to 0 /
100. The biodegradable laminated film according to (1), wherein the film is 100. (3) The biodegradable laminated film according to (1) or (2), wherein the aliphatic-aromatic copolymerized polyester is crystalline. (4) The aliphatic-aromatic copolymerized polyester has a heat of crystal fusion of 40 J / g or less.
The biodegradable laminated film according to any one of (3).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the laminated film of the present invention, the polylactic acid-based polymer used in the base layer and the heat seal layer may be any one having polylactic acid or a lactic acid component as a main component, and may be polylactic acid, lactic acid, or lactide. And a blend with hydroxycarboxylic acid, dicarboxylic acid, diol, and cyclic lactone. These include
Urethane bonds, amide bonds, ether bonds, and the like can be introduced within a range that does not affect biodegradability.

In the laminated film of the present invention, the aliphatic-aromatic copolymer polyester used in the heat seal layer may be any polyester having an aliphatic component and an aromatic component. Examples thereof include lactic acid and glycolic acid. , Hydroxybutyric acid, hydroxycarboxylic acids such as hydroxycaproic acid, caprolactone, butyrolactone, lactide,
Cyclic lactones such as glycolide, ethylene glycol,
Butanediol, cyclohexanedimethanol, bis-
Hydroxymethylbenzene, diols such as toluenediol, succinic acid, adipic acid, suberic acid, sebacic acid, terephthalic acid, isophthalic acid, dicarboxylic acids such as naphthalenedicarboxylic acid, cyclic acid anhydrides, oxiranes, fats Copolymers having a group component and an aromatic component are exemplified. Copolymerized polyesters having succinic acid, adipic acid, ethylene glycol or 1,4-butanediol as the aliphatic component and terephthalic acid or isophthalic acid as the aromatic component are preferred. In addition, urethane bonds, as long as they do not affect biodegradability,
An amide bond, an ether bond or the like can be introduced.

In the present invention, the aliphatic-aromatic copolymer polyester preferably has crystallinity. Having crystalline means that the aliphatic-aromatic copolymer polyester has a melting point and a crystal melting peak, and that the aliphatic-aromatic copolymer polyester has crystallinity,
It is preferable from the viewpoint of operability since the heat seal layer does not cause blocking or the like.

The heat of crystal fusion of the aliphatic-aromatic copolymerized polyester is preferably 40 J / g or less. When an aliphatic-aromatic copolyester having a heat of crystal fusion of 40 J / g or less is used, a film obtained therefrom has excellent heat sealing properties, particularly, low-temperature heat sealing properties, and is thus preferable.

In the laminated film of the present invention, the heat-sealing layer needs to contain an aliphatic-aromatic copolymerized polyester. Generally, when other components are copolymerized with the polyester, the crystallinity is reduced, so that the flexibility is increased, which is suitable for improving the flexibility of the film.
Blocking is likely to occur and the operability is reduced, and the melting point and the glass transition point are also lowered, so that a problem that the heat resistance is inferior may occur. Aliphatic-aromatic copolymerized polyester obtained by copolymerizing an aliphatic component and an aromatic component used in the present invention has an aromatic portion, and generally has a higher melting point than an aliphatic polyester, Even if the melting point of the aliphatic-aromatic copolymerized polyester is lowered by the copolymerization, the aliphatic-aromatic copolymerized polyester can have higher heat resistance than the aliphatic copolymerized polyester. Accordingly, the aliphatic-aromatic copolymerized polyester can have a higher copolymerization ratio than the aliphatic copolymerized polyester, has heat resistance and excellent flexibility,
Since it has a low heat of crystal fusion, it has excellent heat sealing properties at low temperatures.

The aliphatic-aromatic copolymer polyester of the heat seal layer is preferably mixed with a polylactic acid-based polymer, and the mixing ratio is not particularly limited.
The mixing ratio of the aromatic copolymerized polyester is preferably 10% by mass or more, more preferably 20% by mass or more. Aliphatic
When the mixing ratio of the aromatic copolymerized polyester is 10% by mass or more, impact resistance is remarkably exhibited, which is preferable.

The method for polymerizing the polylactic acid-based polymer and the aliphatic-aromatic copolymerized polyester is not particularly limited, and examples thereof include a condensation polymerization method and a ring-opening polymerization method. It is also possible to add one or more additional components such as another polymer, monomer, or oligomer component during or immediately after the polymerization, and further proceed with the polymerization.

The polylactic acid-based polymer and the aliphatic-aromatic copolymer polyester used in the present invention may be used at any stage of polymerization, but a small amount of a chain extender such as a diisocyanate compound may be used for the purpose of increasing the molecular weight. , An epoxy compound, an acid anhydride and the like can be added. The polylactic acid-based polymer and the aliphatic-aromatic copolymer polyester used in the present invention include a plasticizer, a lubricant, and an inorganic filler for the purpose of adjusting the physical properties and processability of the film within a range that does not impair the effects of the present invention. , Additives such as ultraviolet absorbers, modifiers,
It is also possible to add a crosslinking agent or another polymer material.

The plasticizer is not particularly limited, but preferably has excellent compatibility with the polymer used in the present invention. Specifically, aliphatic polycarboxylic acid ester derivatives, aliphatic polyhydric alcohols Single or plural mixtures selected from ester derivatives, aliphatic oxyacid ester derivatives, aliphatic polyether derivatives, aliphatic polyether polycarboxylic acid ester derivatives, and the like.

Examples of the aliphatic polycarboxylic acid ester derivatives include dimethyl adipate, dibutyl adipate and diisobutyl adipate, and examples of the aliphatic polyhydric alcohol ester derivatives include triethylene glycol diacetate and polypropylene glycol dibutyrate. As ester derivatives, methyl acetyl ricinoleate, acetyl tributyl citric acid, etc., and as aliphatic polyether derivatives, polyethylene glycol, polypropylene glycol, copolymerized polyalkylene glycols such as ethylene glycol and butylene glycol, aliphatic polyether polyvalent carboxylic acids, etc. Acid ester derivatives include bismethyldiethylene glycol succinate, bismethyldiethylene glycol adipate, bisbutyldiethylene glycol Adipate, and the like.

The lubricant is not particularly limited, but is preferably an aliphatic carboxylic acid amide. Examples of such an aliphatic carboxylic acid amide include stearic acid amide, oleic acid amide, erucic acid amide, and behenic acid amide.

The inorganic filler is not particularly limited, but is preferably a natural or synthetic silicate compound, titanium oxide, barium sulfate, calcium phosphate, calcium carbonate, sodium phosphate and the like. Examples of the silicate compound include layered silicates such as kaolinite, halloysite, talc, smectite, vermiculite, and mica. These layered silicates may be swellable or non-swellable, and may be surface-treated.

The method of mixing the polylactic acid-based polymer and the aliphatic-aromatic copolymerized polyester is not particularly limited, but a method in which the blended raw material chips are melt-mixed in the same extruder, and a method in which the blended chips are melted in separate extruders. And then mixing. In the case of mixing for a long time at a high melting temperature or under a high shear as a melt mixing condition, a transesterification reaction or a decomposition reaction may proceed, and the characteristics of the mixture may be changed.

In the laminated film of the present invention, the film containing the aliphatic-aromatic copolymer polyester forming the heat seal layer is preferably an unstretched film in order to obtain particularly excellent heat sealability. .

The laminated film of the present invention comprises a biaxially stretched film made of a polylactic acid-based polymer as a base layer, and at least one of the outermost layers contains an aliphatic-aromatic copolymerized polyester. The heat seal layer is not particularly limited, and may have a multilayer structure of three or more layers in order to provide other functions such as gas barrier properties. For example, as a method of imparting gas barrier properties, a method of laminating a PVA layer and a metal or metal oxide vapor deposited layer can be mentioned.

The method of laminating the base layer film and the heat seal layer film is not particularly limited. However, after being melted and kneaded by a plurality of extruders, they are laminated in a die or a previous feed block and co-extruded. , A method of coating on an unwound film, a method of thermocompression bonding a plurality of films with a roll or a press, or a method of bonding with an adhesive.

In the method of manufacturing a laminated film using an adhesive, a vinyl-based, acrylic-based,
Polyamides, polyesters, rubbers, urethanes and the like are generally used, but from the viewpoint of biodegradability, starch, amylose, polysaccharides such as amylopectin, and proteins such as glue, gelatin, casein, zein and collagen. And polypeptides, natural materials such as unvulcanized natural rubber, aliphatic polyesters, aliphatic-aromatic copolymerized polyesters, aliphatic polyester urethanes, aliphatic polyester modified polyvinyl alcohol vinyl acetate copolymers and the like are preferable. .

The method for producing a film in the laminated film, the base material layer and the heat seal layer of the present invention is not particularly limited. For example, after thoroughly drying the raw materials and removing moisture, at a melting temperature suitable for the composition. , A T-die, an I-die, a round die, or the like, is extruded to a predetermined thickness and cooled or solidified by a cooling roll, water, compressed air, or the like. In addition, as the resin composition of the raw material, a melt-kneaded material may be used in advance for sufficient mixing. Thereafter, uniaxial or biaxial stretching may be performed by a roll method, a tenter method, a tubular method, or the like. In the case of stretching, the stretching is performed at a stretching temperature of 50 ° C to 110 ° C and a stretching ratio of 1.5 to 10 times in the longitudinal and transverse directions, respectively. After the stretching, a heat treatment such as a method of blowing hot air, a method of irradiating infrared rays, a method of irradiating microwaves, or a method of contacting a heat roll may be performed. A method of blowing hot air is preferable because heating can be performed uniformly and accurately.
Heat treatment is performed at 0 ° C. for 3 seconds or more.

[0025]

Next, the present invention will be described in detail with reference to Examples, but it should not be construed that the invention is limited thereto. The evaluation method in the present invention is as follows.

(1) Heat Sealability The film is cut into a strip having a length of 15 mm × 100 mm in the MD direction, and two of the strip samples are overlapped with each other to be orthogonal to a heat sealer having a heat seal bar having a width of 20 mm. After being set as described above, it was heated from one side at a predetermined temperature, and heat-sealed at a pressure of 0.2 MPa for 2 seconds. At this time, when a laminated film was used, it was set so that the heat seal layers were inside. The above sample was manufactured by Shimadzu Corporation:
According to SK-6854, a T-type peeling test was performed until peeling was performed at a peeling rate of 300 mm / min or until the bonded portion became 1 mm. The peak value is defined as the heat sealing strength.
の も の, less than 7 N / cm, 10 N / c
m and ○ were 10 N / cm or more.

(2) Impact resistance: Toyo Seiki Seisakusho Co., Ltd .: Using a film impact tester, a pendulum capacity of 30 kg in an atmosphere at a measurement temperature of 23 ° C. and 50% RH.
The measurement was performed using an impact head of cm and 12.7 mmφ.

(3) Biodegradability A sample having a width of 250 mm and a length of 500 mm was used.
The composting treatment was performed at 5% at a temperature of 80 ° C. The state of the film after 5 days was visually observed. A sample that had disappeared 50% or more was rated as △, a sample that had disappeared 80% or more was rated as ○, and a sample that had completely disappeared was rated ◎.

(4) Heat of Crystal Melting A sample was dried using a DSC manufactured by Perkin Elmer, weighed 7 mg, melted at 200 ° C. for 3 minutes, and rapidly cooled to −40 ° C. at a cooling rate of 300 ° C./min. And 2
The sample was heated at a heating rate of 0 ° C./min, and the heat of crystal fusion was measured.

The method of preparing the base layer film and the heat seal layer film is as follows.

Film A Polylactic acid (Cargill Dow Polymer Co., Ltd .: D-form = 1)
%) And extruded from a T-die to obtain an unstretched film having a thickness of 180 μm. This unstretched film is tripled in the machine direction at 70 ° C., and then three times in the transverse direction at 80 ° C.
The film is stretched at a draw ratio of 20 times and heat-treated at 130 ° C.
A μm biaxially stretched film A was obtained.

Film B Polylactic acid (Cargill Dow Polymer Co., Ltd .: D-form = 3.
7%) and melted at 210 ° C. and extruded from a T-die to obtain an unstretched film having a thickness of 180 μm. This unstretched film was simultaneously biaxially stretched at 105 ° C. with a stretching ratio of 3 times the length × 3 times the width, and a biaxially stretched film B of 20 μm was obtained.
I got

Film C: polylactic acid (Cargill Dow Polymer: D-form = 3.
7%) 70% by mass and an aliphatic-aromatic copolymerized polyester (Eastman Chemical Company: EASTER BIO GP Co
polyester, heat of crystal fusion 18.5 J / g) 30% by mass
Was melted at 210 ° C. and extruded from a T-die to obtain an unstretched film C having a thickness of 30 μm.

Film D Polylactic acid (Cargill Dow Polymer: D-form = 1)
%) 30% by mass, aliphatic-aromatic copolymerized polyester (manufactured by BASF: Ecoflex F, heat of crystal fusion =
Film D was obtained in the same manner as film C using a composition consisting of 60 mass% of 21.5 J / g) and 10 mass% of acetyltributyl citric acid (ATBC, manufactured by Taoka Chemical Co., Ltd.).

Film E Polylactic acid (Cargill Dow Polymer Co., Ltd .: D-form = 1)
%): 70% by mass of a composition composed of an aliphatic-aromatic copolymerized polyester (Ecoflex F, manufactured by BASF) = 1: 1 (mass ratio), 15% by mass of bisdimethyldiethylene glycol adipate (MXA, manufactured by Daihachi Chemical Co., Ltd.) %, Talc 15% by mass, melted at 180 ° C., extruded from an inflation film-forming machine having a die diameter of 100 mm, and formed a film E having a fold diameter of 350 mm and a thickness of 30 μm under a condition of a take-up speed of 20 m / min. Obtained.

Film F Aliphatic-aromatic copolymerized polyester (manufactured by BASF: E
Using Coflex F), the mixture was melted at 180 ° C. to obtain a film F in the same manner as the film E.

Film G Polylactic acid (Cargill Dow Polymer Co., Ltd .: D-form = 1)
%) To obtain a film G in the same manner as the film C.

Film H Polylactic acid (Cargill Dow Polymer Co., Ltd .: D-form = 3.
7%) 70% by mass and aliphatic polyester (manufactured by Showa Polymer Co., Ltd .: Vionore # 3001, heat of crystal fusion: 45.6 J)
/ G) Using a composition consisting of 30% by mass, a film H was obtained in the same manner as the film C.

Film I Aliphatic polyester (manufactured by Showa Polymer Co., Ltd .: Bionole # 1)
010, heat of crystal fusion of 52.6 J / g),
C., and extruded from a T-die to obtain an unstretched film I having a thickness of 30 μm.

Example 1 Polylactic acid (manufactured by Cargill Dow Polymer: D-form = 1%) as the base material layer, and polylactic acid (D-form = 3.7% manufactured by Cargill-Dow Polymer) as the heat seal layer Using 80% by mass and 20% by mass of an aliphatic-aromatic copolymerized polyester (manufactured by BASF: Ecoflex F) at 210 ° C.
And co-extruded with a thickness of 360 μm (base layer: 180 μm).
m, heat seal layer: 180 μm). The unstretched film is heated at 70 ° C. in the longitudinal direction by 2.4.
Then, the film was stretched in the transverse direction at 80 ° C. at a stretch ratio of 3 times, and heat-treated at 130 ° C. to obtain a 50 μm biaxially stretched laminated film.

Examples 2 to 5 and Comparative Examples 1 to 3 Films A and B were used as base layers, and an adhesive made of an aliphatic polyester-added polyvinyl alcohol / vinyl acetate copolymer was applied to a thickness of 1 μm. After drying at ℃
Films C to I were pressure-bonded with a heating roll at 90 ° C. as a heat seal layer, and further aged at 40 ° C. for 3 days to obtain a laminated film.

Comparative Example 4 Polylactic acid (D-form = 1%, manufactured by Cargill Dow Polymer) as a base material layer, and amorphous polylactic acid (D-form = 20, manufactured by Cargill Dow Polymer) as a heat seal layer %) To obtain a biaxially stretched laminated film in the same manner as in Example 1.

[0043]

[Table 1]

In Examples 1 to 5, a laminated film having excellent heat sealability, impact resistance, and biodegradability was obtained. In Comparative Example 1, heat resistance and impact resistance were poor.
In Comparative Examples 2 to 4, only those having poor heat sealability and impact resistance at low temperatures were obtained.

[0045]

According to the present invention, it is possible to provide a biodegradable laminated film having decomposability in a natural environment, and having excellent heat sealability and impact resistance.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA43 AA43X AA45X AA89 AF59 AH04 AH05 BB06 BB08 BC01 BC05 4F100 AK41A AK41B AL01B AL05B AR00B AT00A BA02 BA07 EH20 EJ38 JA11B JC00 JL12B

Claims (4)

[Claims] 1. A laminated film comprising a base layer and a heat seal layer, wherein the heat seal layer is at least one outermost layer, wherein the base layer is a biaxially stretched film made of a polylactic acid-based polymer. A biodegradable laminated film, wherein the heat seal layer is a film containing an aliphatic-aromatic copolymerized polyester. 2. The heat seal layer according to claim 1, wherein the mass ratio of the polylactic acid-based polymer to the aliphatic-aromatic copolymerized polyester is 90/1.
The biodegradable laminated film according to claim 1, wherein the film is 0 to 0/100. 3. The biodegradable laminated film according to claim 1, wherein the aliphatic-aromatic copolymerized polyester is crystalline. 4. The biodegradable laminated film according to claim 1, wherein the aliphatic-aromatic copolymerized polyester has a heat of crystal fusion of 40 J / g or less.