JP4836194B2 - Transparent biodegradable resin stretched film and resin product with improved gas barrier properties - Google Patents

Description

  The present invention is a stretched transparent biodegradable resin film that is easy to melt knead and co-extrusion with a heat-sealable biodegradable resin and has improved gas barrier properties, and a packaging film or bag using the same. The present invention relates to a resin product such as a laminate material and an ostomy bag, and more particularly to a highly transparent airbag cushioning material having biodegradability and having excellent compression creep resistance and pressure strength.

  Synthetic polymer compounds have been widely used as plastics due to their excellent properties, but the amount of waste has increased with the increase in the amount of use, and how to treat this waste plastic is a big society. It is a problem. There is a problem that the incinerator tends to damage the incinerator because it generates a large amount of heat when it is incinerated, and there is a risk that harmful substances may be generated. . Furthermore, considering the cost of separation, collection, and regeneration, it is difficult to completely solve the problem only by recycling.

  As interest in such environmental issues increases, biodegradable plastics that decompose in the natural environment after disposal are being demanded in order to reduce the burden on the environment and protect the natural environment. .

  Biodegradable plastics known so far include starch polymers, aliphatic polyester resins produced by microorganisms, aliphatic polyester resins by chemical synthesis, and types of chemical structures that have been partially modified. Resins, biodegradable aliphatic aromatic polyester resins and the like are known. Among them, examples of materials having good gas barrier properties and transparency include polyvinyl alcohol (PVOH) -based resins and polyglycolic acid (PGA) -based resins. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-203036) discloses heat. A laminate with a thermoplastic biodegradable resin having good sealing properties is disclosed. Polyvinyl alcohol-based resins, polyglycolic acid-based resins, etc. all have a melting point Tm of 200 ° C. or higher and a processing temperature of about 230. Since it is about ˜260 ° C., an aliphatic polyester-based resin (for example, polybutylene succinate-based resin or the like) or an aliphatic aromatic polyester-based resin (for example, a thermoplastic biodegradable resin having a good heat sealability) Poly (butylene terephthalate / adipate) resin, etc.), etc.), which is higher than the processing temperature (about 160 to 200 ° C.). When co-extrusion or melt-kneading, etc., there are problems such as thermal deterioration and flow spots of heat-sealable biodegradable resin, and biodegradation of transparent packaging films and bags that have both gas barrier properties and heat-sealability It was difficult to manufacture a functional resin product.

A biodegradable resin composition that has a processing temperature of about 160 to 200 ° C. and can be melt-kneaded with an aliphatic polyester resin or an aliphatic aromatic polyester resin that is a thermoplastic biodegradable resin with good heat sealability. For example, in Patent Document 2 (Japanese Patent Laid-Open No. 9-111107) and Patent Document 3 (Japanese Patent Publication No. 2004-506792), a polylactic acid (PLA) polymer and a glass transition point Tg are 0 ° C. or lower. A polymer blend and a film comprising a biodegradable aliphatic polyester are disclosed, and a comparative example of Patent Document 4 (Japanese Patent Laid-Open No. 2001-114997) and Patent Document 5 (US Pat. No. 5,883,199) include A polymer blend and a film comprising a lactic acid resin and a polyethylene succinate resin are disclosed. Nothing is disclosed that the gas barrier property is greatly improved by stretching the draw ratio (area ratio) from the outlet to a specific range compared to the resin alone before mixing, and there is a problem that the transparency is poor. .
In particular, Patent Document 6 (Japanese Patent Application Laid-Open No. 2000-204142) discloses a molded body containing a polyethylene succinate resin having a gas barrier property of less than 4000 (cc × μm) / (m ² · day · atm). However, there is no disclosure regarding mixing with a polylactic acid resin, and there is a problem of poor transparency.

  In general, resin films made of transparent films that have both gas barrier properties and heat sealing properties include packaging films and bags, and laminate materials that control gas permeation. For example, ostomy (colostomy) is used as a medical material. And / or bags or pouches used for urostomy (artificial cystoplasty) are widely used. Conventionally, these film materials generally have a vinylidene chloride-based resin layer exhibiting extremely excellent barrier properties in a multilayer structure, and contain environmental problems due to containing chlorine. No.-211075) discloses a biodegradable coextruded laminated film of a polyvinyl alcohol (PVOH) resin and a biodegradable ester-amide copolymer having a melting point Tm of 125 ° C., but the molding temperature of the polyvinyl alcohol resin is disclosed. In some cases, the biodegradable ester-amide copolymer is difficult to produce due to thermal degradation, flow spots, and the like.

  Furthermore, as a resin product consisting of a transparent film that has both gas barrier properties and heat sealing properties, it can be stored without using space before use, and can be easily expanded using a gas such as air when necessary to exhibit buffering performance. In addition, the contents can be confirmed during use, and the volume can be reduced by removing the air after use. The bag-like sealed rose-shaped air bag cushioning material and the continuous sealed type with multiple air bags connected. In recent years, an airbag-type cushioning material made of a film using a rebound resilience at the time of compression of an enclosed gas, such as an airbag cushioning material and an airbag cushioning material with a self-sealing check valve, has attracted attention.

  Patent Document 8 (Japanese Utility Model Publication No. 57-104753) discloses a plastic packaging cushion, but the units work together as a result of connecting and forming hollow units, and with less raw materials. Although it aims at making it the cheap buffer material obtained, it does not describe the compression creep resistance and pressure strength as a buffer material, and nothing is disclosed about a raw material or a biodegradable polymer. Patent Document 9 (Japanese Patent Laid-Open No. 4-154570) discloses an airbag cushioning material sheet that is inflatable and includes a self-sealing valve. Nylon and polyethylene laminate film has been disclosed as a material that has heat sealability, non-breathability, flexibility, and some mechanical strength, but it is practical for films made of biodegradable polymers An air bag cushioning material having sufficient compression creep resistance and pressure strength is not disclosed. Further, Patent Document 10 (Japanese Patent No. 2670210) discloses an airbag cushioning material that can be inflated into an annular polygonal shape. Patent Document 11 (Japanese Patent No. 3149130) discloses a large number of continuous airbags in the connecting direction. Although an air cushioning material having an open band attached along is disclosed, an airbag cushioning material using a biodegradable polymer is not disclosed.

That is, a stretchable biodegradable resin film that is melt-kneaded and co-extruded with an aliphatic polyester resin having a melting point Tm of 200 ° C. or less, which is a material with good heat sealability, and has improved gas barrier properties and transparency, In addition, resin products such as packaging films, bags and ostomy bags using the same, and compression creep resistance that maintains the buffering performance by retaining the gas even when held under load for a long time In addition, a transparent biodegradable airbag cushioning material that is excellent in pressure resistance and excellent in pressure resistance, can sustain practically sufficient buffer performance for a long period of time, and can confirm the contents during use has not been found yet.
JP 2004-203036 A JP-A-9-111107 Japanese translation of PCT publication No. 2004-506792 JP 2001-114997 A US Pat. No. 5,883,199 JP 2000-204142 A JP 2000-211075 A Japanese Utility Model Publication No. 57-104753 JP-A-4-154570 Japanese Patent No. 2670210 Japanese Patent No. 3149130

  The present invention relates to a stretched transparent biodegradable resin film having improved gas barrier properties that can be easily melt kneaded and coextruded with a heat-sealable biodegradable resin, and a packaging film, bag, and gas permeable film using the same. An object of the present invention is to provide an air bag cushioning material having good transparency, having a laminate material to be adjusted, a resin product such as an ostomy bag, in particular, biodegradable, excellent compression creep resistance and pressure strength.

  There is no transparent biodegradable resin that is easy to melt-knead and co-extrusion with heat-sealable biodegradable resin and has excellent gas barrier properties. In order to obtain a resin product (for example, an airbag cushioning material) that can be used, a transparent film having a high tensile strength and a high sealing strength is required. is necessary.

  As a result of intensive studies to solve the above problems, the present inventors have been able to melt and knead with a low-melting-point thermoplastic biodegradable resin having good sealing strength, and have a processing temperature of less than 230 ° C. With a specific resin combination and a specific range of draw ratios from the die lip outlet, the gas barrier property is highly improved compared to the resin alone before kneading, and a highly biodegradable resin stretch I found a film. Furthermore, as one of the resin products made of the stretched film, it has a specific oxygen permeability, and even if it is held for a long time under a load, it retains the gas therein and maintains the buffer performance. A biodegradable airbag cushioning material using a stretched biodegradable resin stretched film that has excellent compression creep resistance and compressive strength and can sustain practically sufficient buffer performance for a long period of time was found, and the present invention was completed. .

That is, the present invention is as follows.
1) Polylactic acid resin (A) having 50% by weight or more of lactic acid units, and polyethylene succinate having a melting point Tm (based on JIS-K7121) having 50% by weight or more of succinic acid units and ethylene glycol units of 200 ° C. or less. When the film comprising the composition (C) with the resin (B) satisfies the following formulas (1), (2) and (5) , and the composition (C) is melt extruded to form a film: It was obtained by stretching at least uniaxially so that the final film thickness would be in the range of 1/200 times to 1/40 times the distance between the die lips. A featured biodegradable resin stretched film.
(1) O _H = [(100 × O _A × O _B ) / (O _A × X _B + O _B × X _A )]
(2) O _C <O _H
(5) Haze ≦ 40
However, when the total weight of the polylactic acid resin (A) and the aliphatic polyester (B) is 100, the weight ratio (unit%) is X _A and X _B , respectively. Further, the unit of% Haze (cloudiness) (according to ASTM-D1003-95), _{O A} is oxygen transmission rate of the polylactic acid based resin (A), _{O B} is aliphatic polyester (B), _{O C} the composition things oxygen permeability (C) (measured value), _{O H} is the harmonic mean of _{O a} and OB (calculated) (units ^{(cc × μm) / (m} 2 · day · atm), conforming to ASTM D3985, 23 Measured in an atmosphere at 65 ° C. and a relative humidity of 65%.
2) Polylactic acid resin (A) having 50% by weight or more of lactic acid units, and polyethylene succinate having a melting point Tm (based on JIS-K7121) having 50% by weight or more of succinic acid units and ethylene glycol units of 200 ° C. or less. A biodegradable resin stretched film characterized by satisfying all of the following formulas (3) to (5) in a film comprising a composition (C) with a resin based resin (B).
(3) 90> X _A > 25 and 10 <X _B <75
(4) O _C <5000
(5) Haze ≦ 40
However, the weight ratio (unit%) when the total weight of the polylactic acid-based resin (A) and the polyethylene succinate-based resin (B) is 100 was defined as X _A and X _B , respectively. Further, the unit of% Haze (cloudiness) (according to ASTM-D1003-95), _{O C} compositions oxygen permeability (C) (measured value), (unit ^{(cc × μm) / (m} 2 · day · atm), measured in an atmosphere of 23 ° C. and 65% relative humidity in accordance with ASTM D3985).
3) The biodegradable resin stretched film according to 1) or 2), which satisfies all of the following formulas (6) and (7):
(6) 10000 ≦ O _A ≦ 25000
(7) 100 ≦ O _B ≦ 5000
However, _{O A} polylactic acid resin (A), _{O B} is the oxygen transmission rate of the aliphatic polyester (B) (units ^{(cc × μm) / (m} 2 · day · atm), conforming to ASTM D3985, 23 ° C. Measured in an atmosphere with a relative humidity of 65%.
4 ) A biodegradable resin product comprising a film containing at least one layer of the stretchable biodegradable resin film according to 1) or 2).
5 ) The biodegradable resin according to 4 ), comprising a film containing at least one layer having an aliphatic polyester resin having a melting point Tm (conforming to JIS-K7121) of not more than 200 ° C. of 50% by weight or more. Product.
6 ) Seal strength measured in accordance with JIS Z1707 with an oxygen transmission rate of 250 cc / (m ² · day · atm) or less in an atmosphere of 23 ° C. and 65% relative humidity in accordance with ASTM D3985. 4 ) The biodegradable resin product according to 4 ), comprising a film having a length direction (MD direction) and a width direction (TD direction) of 15 N / 15 mm or more.
7 ) In accordance with ASTM D3985, the oxygen permeability measured in an atmosphere of 23 ° C. and a relative humidity of 65% is 200 cc / (m ² · day · atm) or less, and the film thickness is within the range of 10 to 200 μm. 4. The biodegradable resin product according to 4 ), comprising a certain film.
8 ) The biodegradable resin product according to 4 ), comprising a film having a tensile strength measured in accordance with ASTM D882 of 25 MPa or more in both the MD direction and the TD direction of the film.
9 ) The biodegradable resin product according to 4 ), comprising a film having a Haze measured by a turbidimeter (ASTM-D1OO3-95) of 40% or less.
10 ) The biodegradable resin product according to 4 ), which is a multilayer film, wherein a sealing layer made of a thermoplastic biodegradable resin forms at least one surface of the multilayer film.
11 ) The biodegradable resin product according to 4 ), comprising a film formed by an inflation method.
12 ) The biodegradable resin product according to any one of 4) to 11), which is a packaging film.
13 ) The biodegradable resin product according to any one of 4 ) to 11 ), which is a bag
14 ) The biodegradable resin product according to any one of 4 ) to 11 ), which is a laminate material.
15 ) The biodegradable resin product according to any one of 4 ) to 11 ), which is an ostomy bag.
16 ) The biodegradable resin product according to any one of 4 ) to 11 ), which is an airbag cushioning material.

  According to the present invention, a highly transparent biodegradable resin stretched film having easy gas coextruding and melt kneading with a biodegradable resin having heat sealability and having excellent gas barrier properties can be obtained. Using the stretched film, a biodegradable resin product such as a packaging film, a bag, a laminate material for adjusting gas permeation, and an ostomy bag can be obtained. One of the biodegradable airbag cushioning materials is reduced after use. In addition, it is effective from the viewpoint of protecting the natural environment because it biodegrades when discarded, and excellent compression-resistant creep that maintains the buffering performance by holding gas for a long time under a load. Air bag cushioning material with improved transparency that can sustain practically sufficient cushioning performance for a long period of time, so that the contents can be confirmed and relatively heavy There is an effect that stable buffer performance can be exhibited both in storage and in long-term storage.

The present invention will be specifically described below.
The polylactic acid resin (A) having 50% by weight or more of lactic acid units used in the present invention is a polylactic acid homopolymer and a copolymer containing 50% by weight or more of lactic acid units, and is a polylactic acid homopolymer. And a copolymer of lactic acid and a compound selected from the group consisting of other hydroxycarboxylic acids and lactones, and the processing temperature is preferably less than 230 ° C. from the viewpoint of thermal deterioration of the ester bond by lactic acid. . From the viewpoint of heat resistance and transparency of the film, the content of the polylactic acid homopolymer and the lactic acid unit is 50% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more. Or a mixture of these copolymers.

  L-lactic acid and L-lactic acid are present as optical isomers in lactic acid, and polylactic acid obtained by polymerizing them contains about 10% by weight or less of D-lactic acid unit and about 90% by weight of L-lactic acid unit. Or a polylactic acid having an L-lactic acid unit of about 10% by weight or less and a D-lactic acid unit of about 90% by weight or more, an optical purity of about 80% by weight or more, and a D-lactic acid unit It is known that there is an amorphous polylactic acid having an optical purity of about 80% by weight or less, which is a polylactic acid having 10% to 90% by weight and L-lactic acid units of 90% to 10% by weight. Preferred is crystalline polylactic acid having an optical purity of 85% by weight or more, or a mixture of crystalline polylactic acid having an optical purity of 85% by weight or more and amorphous polylactic acid having an optical purity of 80% by weight or less.

  As a monomer used as a copolymerization component with lactic acid, for example, the following can be used. Examples of the hydroxycarboxylic acid include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid and the like. Examples of the aliphatic cyclic ester include glycolide, lactide, β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, and lactones substituted with various groups such as a methyl group. . Examples of the dicarboxylic acid include succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, terephthalic acid, and isophthalic acid. Examples of the polyhydric alcohol include aromatic polyhydric alcohols such as bisphenol / ethylene oxide addition reaction products, Aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, glycerin, sorbitan, trimethylolpropane, neopentyl glycol, ether glycols such as diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, etc. Is mentioned.

As a polymerization method of the polylactic acid resin (A), known methods such as a condensation polymerization method and a ring-opening polymerization method can be employed. Moreover, the method of increasing molecular weight using binders, such as a polyisocyanate, a polyepoxy compound, an acid anhydride, and polyfunctional acid chloride, can also be used.
The weight average molecular weight of the polylactic acid resin (A) is preferably in the range of 10,000 to 1,000,000. When the molecular weight is 10,000 or more, a film having excellent mechanical properties can be obtained. When the molecular weight is 1,000,000 or less, a melt viscosity is low, and a film having stable physical properties can be obtained with a normal processing machine. Compared with other biodegradable resins, the polylactic acid-based resin (A) has a haze of less than about 4% (based on ASTM-D1003-95) and a gloss level (based on ASTM-D2457-70: 45 degrees). ) Is 130% or more, and the tensile modulus (according to ASTM-D882-95a) is about 3 to 5 GPa, which is excellent in transparency, gloss and rigidity. The strength (according to ASTM-D882-95a) is about 70 to 300 MPa and the mechanical strength is strong. For example, in the case of a film / sheet-like product, it is excellent in mechanical suitability and transparency such as continuous cutting of a wound film. On the other hand, since the higher in glass transition temperature Tg of about 60 ° C. In other biodegradable resins, a brittle at room temperature (23 ° C.), inflexible and flexible, oxygen permeability O _A 10000 ≦ O _A ≦ 25000 and inferior in gas barrier properties.

  The aliphatic polyester (B) used in the present invention conforms to at least one of JIS-K6950 (2000), JIS-K6951 (2000), JIS-K6953 (2000), OECD-301C or ISO-17556. The degree of biodegradation measured in this manner is preferably 60% (theoretical value) or more within each test method description period, and the aliphatic dicarboxylic acid having 2 to 6 carbon atoms selected from oxalic acid, succinic acid, adipic acid and the like The melting point Tm (having 50% by weight or more, preferably 80% by weight or more, of the unit and the sum of the aliphatic glycol units having 2 to 3 carbon atoms selected from ethylene glycol, propylene glycol, 1,3-propanediol, etc. (Based on JIS-K7121) is a crystalline biodegradable polymer of 200 ° C. or lower. The aliphatic dicarboxylic acid unit and the aliphatic glycol unit in the aliphatic polyester (B) are preferably 1: 1 by weight.

The melting point Tm (based on JIS-K7121) of the aliphatic polyester (B) is easy to be melt-kneaded or co-extruded with a biodegradable resin having good heat sealability, and related to thermal deterioration, flow spots, etc. Therefore, the temperature is 200 ° C. or lower. Further, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, hydroxycarboxylic acid such as 6-hydroxycaproic acid, glycolide, lactide, β-propiolactone, γ- Aliphatic cyclic ester monomers such as butyrolactone, δ-valerolactone, ε-caprolactone and lactones substituted with various groups such as a methyl group may be further used as a copolymerization component.
The preferred aliphatic polyester (B) is a polyethylene succinate resin obtained with succinic acid units and ethylene glycol units as the main components (total 80% by weight or more). Particularly preferred examples include polyethylene succinate, poly (ethylene succinate / adipate) obtained by copolymerizing polyethylene succinate with less than 5% by weight of adipic acid as the third component, and the like.

The stretched biodegradable resin film comprising the composition (C) with the polylactic acid resin (A) and the aliphatic polyester (B) of the present invention is the oxygen permeability of the composition (C) as shown in the following formula. O _C is less than the harmonic mean value O _H oxygen permeability of the polylactic acid based resin before mixing (a) and aliphatic polyester (B), and the gas barrier property is improved.
O _H = [(100 × O _A × O _B ) / (O _A × X _B + O _B × X _A )]> O _C
However, when the total weight of the polylactic acid resin (A) and the aliphatic polyester (B) is 100, the weight ratio (unit%) is X _A and X _B , respectively. Also, _{O A} polylactic acid resin (A), _{O B} is the oxygen transmission rate of the aliphatic polyester (B), _{O C} composition (C) (measured value), _{O H} is the harmonic mean of the oxygen transmission rate ( (Calculated value) (unit (cc × μm) / (m ² · day · atm), based on ASTM D3985, measured in an atmosphere of 23 ° C. and 65% relative humidity).
In general, the average value is an arithmetic average obtained by adding all n data and dividing by n (arithmetic mean), a geometric mean obtained by multiplying all n data by the 1 / n power root (geometric mean), and an inverse number There is a harmonic mean that is the reciprocal of the arithmetic mean (arithmetic mean) of, and the relation of “arithmetic mean ≧ geometric mean ≧≧ harmonic mean” is established.

The present inventors have surprisingly found that the oxygen permeability O _C biodegradable resin stretched film comprising a composition of the present invention (C) is a polylactic acid based resin (A) and aliphatic polyester (B) be smaller than the lowest harmonic mean value is a small average value of values O _H calculated from the oxygen transmission rate, in other words, a specific combination of biodegradable resins, the stretch ratio from the die lip outlet (area ratio) By making it into a specific range, the present inventors have found a stretched biodegradable resin film that exhibits gas barrier properties improved more than expected, has good transparency, and has a processing temperature of less than 230 ° C., leading to the present invention.

Preferred mixing composition ratio _X A: _{X B} is 90: 10 to 10: 90, more preferably 90: 10 to 25: is in the 75 range of oxygen permeability _{O C} and transparency within this range (Haze) is Improved and shows good gas barrier properties.
Specifically, the oxygen permeability of the polylactic acid resin (A) is 10,000 (cc × μm) / (m ² · day · atm) to 25000 (cc × μm) / (m ² · day · atm), The aliphatic polyester (B) preferably has a range of 100 (cc × μm) / (m ² · day · atm) to 5000 (cc × μm) / (m ² · day · atm), and is polylactic acid-based The oxygen permeability of (C), which is a composition of the resin (A) and the aliphatic polyester (B), is 5000 (cc × μm) / (which is a gas barrier property better than that of (A) or (B) alone. m ² · day · atm), and further, Haze is 40% or less, and the transparency is also superior to (B).

  The composition (C) used in the present invention is pre-weighed, in which the polylactic acid resin (A) and the aliphatic polyester (B) are metered into the same extruder, put into a hopper and directly mixed to form. It can be obtained by a method such as putting the raw material dry-blended into a hopper and molding, or melt-kneading the metered raw material using a twin-screw extruder, extruding it into a strand shape and molding it into a pellet . Regardless of which method is used to obtain the composition (C), it is necessary to consider a decrease in molecular weight due to the decomposition of (C), but the latter is more preferable for uniform mixing.

  The biodegradable resin product using the stretched biodegradable resin film comprising the composition (C) of the present invention is a simple product obtained by hot melt molding such as coextrusion molding including at least one layer comprising the stretched film. It is preferably made of a layer or a multilayer film, more preferably a film containing at least one layer having an aliphatic polyester resin having a melting point Tm (based on JIS-K7121) of 200 ° C. or less of 50% by weight or more. Specifically, packaging films and bags for packaging, transporting and storing various products such as food and non-food, laminate materials with gas permeation control function, ostomy (colostomy) and / or urostomy ( It is used as a gas barrier material such as a medical material such as an ostomy bag used for artificial cystoplasty), and an air bag cushioning material having a shape such as a back valve that can inject additional gas many times. is there.

The film used for the biodegradable resin product of the present invention has an oxygen permeability of 250 cc / (m ² · day · atm) or less measured in an atmosphere of 23 ° C. and 65% relative humidity in accordance with ASTM D3985. Preferably there is. More preferably, the film is 200 cc / (m ² · day · atm) or less, more preferably 150 cc / (m ² · day · atm) or less, and most preferably 120 cc / (m ² · day · atm). ) The following film. For example, an airbag cushioning material made of a film having an oxygen permeability measured under an atmosphere of 23 ° C. and a relative humidity of 65% of 250 cc / (m ² · day · atm) or less is excellent in compression creep resistance and under load Even if the air bag is held for a long time, the internal gas does not escape and shows high buffering performance.

In order to obtain a resin product such as an air bag cushioning material with a film having an oxygen permeability of 250 cc / (m ² · day · atm) or less measured in an atmosphere of 23 ° C. and 65% relative humidity, the melting point is 200 ° C. or less. It is preferable to use the above-described biodegradable resin composition with improved gas barrier properties, which is easy to co-extrusion and melt-kneading with a biodegradable resin having a heat sealability, unless it is contrary to the object of the present invention. A polymer in which layered silicates such as mica and montmorillonite are nano-dispersed, and a mixture of these polymers can be used. By calculating and using the film thickness according to the gas barrier properties of the polymer, A film having the desired oxygen permeability can be obtained.

  The film used for the biodegradable resin product of the present invention preferably has a seal strength measured in accordance with JIS Z1707 of 15 N / 15 mm or more in both the MD direction and the TD direction of the film. More preferably, the film has a seal strength of 20 N / 15 mm or more in both the MD direction and the TD direction, and more preferably a film having a seal strength of 25 N / 15 mm or more in both the MD direction and the TD direction. For example, an air bag cushioning material made of a film having a seal strength of 15 N / 15 mm or more in both the MD direction and the TD direction tends to increase the pressure resistance, and the possibility of the air bag bursting when a large load is applied is low. Become.

  To obtain a film with high sealing strength, 1) increase the tensile strength of the film. 2) A multilayer film having a seal layer is formed. 3) A combination of resins having high delamination strength between the seal layer and the layer in contact with the seal layer is selected. 4) The thickness of the seal layer is preferably 4 μm or more, more preferably 5 μm or more, and even more preferably 6 μm or more. 5) In the case of a single layer film, there is a method of making a polymer blend preferably containing 15% by weight or more of a polymer having a melting point of 140 ° C. or lower. The seal strength was measured by heat sealing in accordance with JIS Z1707 under the conditions of a seal pressure of 0.5 MPa and a seal time of 0.2 seconds.

  The thermoplastic biodegradable resin with good heat sealability used for the sealing layer of the film used in the biodegradable resin product of the present invention includes thermoplastic starch polymers, aliphatic polyester resins produced by microorganisms. , Aliphatic polyester resins by chemical synthesis, and resins whose types are partially modified, biodegradable aliphatic aromatic polyester resins, and resins obtained by adding a plasticizer to these resins, Examples thereof include a resin mixture obtained by blending resins. Preferably, it is an amorphous polylactic acid resin and a biodegradable polyester other than the polylactic acid resin (A) having a glass transition temperature Tg of 10 ° C. or lower, more preferably a glass transition temperature Tg of 10 ° C. or lower. And a crystalline polymer or an amorphous polymer having a melting point of 140 ° C. or lower, more preferably a crystalline polymer or an amorphous polymer having a glass transition temperature Tg of 10 ° C. or lower and a melting point of 120 ° C. or lower. It is. Particularly preferred examples include polybutylene succinate, poly (butylene succinate / adipate), polyethylene succinate, poly (ethylene succinate / adipate), poly (butylene terephthalate / adipate) and the like.

  The film used for the biodegradable resin product of the present invention preferably has a tensile strength measured according to ASTD D882 of 25 MPa or more in both the MD direction and the TD direction of the film. A film of 30 MPa or more is more preferable, and a film of 35 MPa or more is more preferable. For example, an air bag cushioning material made of a film of 25 MPa or more in both the MD direction and the TD direction tends to have a high pressure resistance without the film breaking before the seal portion in a direction where the tensile strength is weak. In order to increase the tensile strength of the film, it is necessary to select a polymer having a high tensile strength, and to perform stretching orientation at a larger magnification at the time of film formation if the same polymer is used.

The film used for the biodegradable resin product of the present invention preferably has a haze of 40% or less as measured in accordance with ASTM D1003. More preferred is a film having a Haze of 30% or less, and further preferred is a film having a Haze of 20% or less. If the haze is 40% or less, the transparency of the film is high. For example, even when the article protected by the airbag cushioning material is a small article, the contents can be confirmed, and the problem of forgetting to take the article is less likely to occur.
In order to obtain a film having a haze of 40% or less, 1) a method of rapidly cooling the film at the time of film formation, a method of minimizing spherulites formed in the film by a method such as adding a nucleating agent, and 2) a polymer blend When forming a micro phase separation state of sea islands in the layer, a twin screw extruder with good kneadability is used to make the size of the island domain smaller than 300 to 350 nm which is not more than the wavelength of visible light. A method of kneading, selecting by controlling the viscosity of the polymer to be blended, or using a compatibilizer may be used in combination.

  In addition to the above resins, the film used in the biodegradable resin product of the present invention includes a plasticizer, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antifogging agent, an antistatic agent, an antirust agent, etc. It is possible to mix | blend this well-known additive in the range which does not impair the requirements and characteristics of this invention. In particular, in the case of applications where flexibility is required for the film, it is preferable to add flexibility to the film by adding a plasticizer or the like as necessary. The plasticizer can be selected from those generally used in the industry, and preferably does not bleed out even when added to the resin composition by about 10% by weight. For example, aliphatic polycarboxylic acid ester, fatty acid polyhydric alcohol ester, oxy acid ester, epoxy plasticizer and the like are included. Specific examples include triacetin (TA), tributyrin (TB), butylphthalyl butyl glycolate (BPBG), tributyl acetylcitrate (ATBC), dioctyl sebacate (DBS), triethylene glycol diacetate, glycerin esters, Examples include butyl oleate (BO), adipic acid ether ester, epoxidized soybean oil (ESO), and the like.

The film used for the biodegradable resin product of the present invention is a single layer or a multilayer film. In particular, when improving only the surface properties of the film while maintaining the physical properties of the film body, the intermediate layer maintains the film physical properties by adding an additive that expresses the function only to the surface layer controlled to the minimum necessary thickness. A multilayer film having a composition is preferable because the desired surface characteristics can be imparted while minimizing changes in physical properties of the film body. Particularly preferred is a multilayer film having a surface layer containing an organic and / or inorganic slip agent, antistatic agent, antifogging agent, and the like on the surface layer. Moreover, it is preferable to use a layer structure having a layer containing an anti-blocking agent on the surface layer because blocking and wrinkling of the resin before stretching and the film after stretching can be prevented and processability is improved.
In addition, as raw material resin used for the film used for the biodegradable resin product of the present invention, in addition to the above-described virgin raw material, trim waste generated during film formation of the resin is processed again to be pelletized or pulverized. Recycled raw materials can be used alone or mixed with the virgin raw material.

Next, the manufacturing method of the biodegradable resin stretched film of this invention is described.
As a film forming method of the biodegradable resin stretched film of the present invention, a method of casting from a T die to a cooling roll, a conventionally known film forming method such as an inflation method or a tenter method, uniaxial stretching, or simultaneously or There are methods such as sequential biaxial stretching. Specifically, (1) a method in which an extruded tube-like or sheet-like resin is melt-stretched from a molten state by an inflation method or a cast method, and (2) an extruded tube-like or sheet-like resin is melted. After rapidly cooling from the state and solidifying in a state close to an amorphous state, the tube-shaped or sheet-shaped resin is subsequently reheated to a temperature not lower than the glass transition temperature and not higher than the melting point, and then stretched by an inflation method or a roll tenter method. It can be obtained by a method of forming a film by an intermediate stretching method, or a method of obtaining a film by performing a heat treatment while holding the film after melt stretching or cold stretching in order to suppress heat shrinkage of the film.

The stretching ratio of the film is melt-stretched in at least one axial direction so that the final film thickness is in the range of 1/200 to 1/40 with respect to the extrusion die (die lip) interval, regardless of the stretching method. Or it is preferable to carry out cold drawing.
In particular, in the cold drawing method, in the case where a material that has been rapidly cooled from a melted state and solidified in a state close to an amorphous state (referred to as a parison in the present invention) is cold-drawn after reheating, the polylactic acid resin is melted. Extruded in a state, so that the parison thickness is in the range of 1/2 to 1/20 times the die (die lip) interval, and at least in one axial direction so that the area magnification is 2 to 20 times After melt stretching, the film is cold-stretched 1.5 to 6 times in the MD direction (film longitudinal direction) and TD direction (film width direction) with respect to the parison, and finally the stretched film of the stretched film with respect to the die lip interval. It is preferable that the film is stretched in at least one axial direction so that the area magnification from the die outlet is in the range of 40 to 200 times so that the thickness is in the range of 1/200 to 1/40. (Hereinafter, the ratio of the area of the film or sheet immediately after the exit of the extrusion die (die lip) / the area of the final stretched film or sheet is referred to as “area magnification from the die exit”) 40 times or more in terms of the area magnification from the die exit Then, the dispersion state of the polylactic acid resin (A) and the aliphatic polyester (B) is improved, and the gas barrier property and transparency are improved. On the other hand, if the area magnification from the die exit is 200 times or less, the stretching stability is maintained and stable film formation can be performed.

  A preferred production method is the inflation method. The advantage of this inflation method is that the equipment cost is relatively low and easy to operate, the range of applicable resins is wide, it is not suitable for mass production, but it is suitable for medium-scale production and multi-product production, molding By controlling the conditions, it is possible to obtain a balanced film in the longitudinal direction (MD direction) and lateral direction (TD direction) of the film, less ear loss compared to the T-die method, A seamless bag can be obtained as a packaging bag, it is convenient only with a bottom seal, it can be cut wide at one end, and it can be cut into two films at both ends. For example, the film width can be changed over a wide range by adjusting the blowing amount.

  In addition, the film formation technology by the tenter method has less film thickness unevenness than the inflation method, can increase the production per unit time, and if the film is thick, the film cannot be formed by the tenter method. Although it is advantageous in comparison with the inflation method, the construction cost is several times higher than that of the inflation method, and it is suitable for mass production of small varieties, but the film market is relatively small, Inflation methods become economically advantageous when small volume production is required and when the thickness is reduced and the inflation method can be applied.

  In order to obtain the film used for the biodegradable resin product of the present invention by the inflation method, the raw biodegradable polymer is set to a predetermined resin composition, resin temperature, resin extrusion amount, the amount of air to be injected, the die A film having a desired thickness is obtained by controlling the film cooling speed at the outlet and the speed at which the resulting film is taken up by the rotational speed of the pinch roll. In order to obtain a multi-layer film, a multi-layer die is used to control the resin composition of each layer and the extrusion speed of the extruder to obtain a multi-layer film having a desired thickness, composition and layer structure in the same manner as described above.

  The final thickness of the film used for the biodegradable resin product of the present invention after film formation is preferably 10 to 200 μm, more preferably 15 to 150 μm, and particularly preferably 20 to 130 μm. When the film thickness is 10 μm or more, gas retention, sealing strength, compression creep resistance and pressure resistance are high. Further, when the film thickness is 200 μm or less, it is economically advantageous in terms of material cost. Further, in the case of an air bag cushioning material, flexibility tends to be improved and handling becomes easier.

  When the film used for the biodegradable resin product of the present invention is heat-sealed to form a bag-like material such as an air bag, it is preferable to perform a heat treatment after film formation so as not to cause thermal shrinkage. . As the method, if it is a film formed by an inflation method, a method of heating and heat-treating with hot air or the like from the outside while keeping the pressure sealed in the gas after film formation and keeping the film in a tension state, Or the method of passing through a heat treatment zone in the state which held both ends with the clip once cut out to a flat film, or the method of heat-processing by making it contact with a heat roll, etc. are mentioned. In the case of the T die casting method, there are a method of passing through a heat treatment zone while holding both ends with a clip, or a method of heat treatment by contacting with a hot roll. Preferable heat treatment conditions are a method of heat treatment for 1 second or more in a temperature range of a glass transition temperature Tg or more and a melting point Tm or less of the film, particularly preferably a method of heat treatment for 2 seconds or more in a temperature range of Tg + 5 ° C. or more and a melting point or less. It is. In order to reduce the heat shrinkage rate, it is also effective to reduce the heat shrinkage rate by heat treatment by relaxing the tension in the TD direction and / or the MD direction.

  For example, when the film used in the biodegradable resin product of the present invention is used as a cushioning material, it may be used after being coated with an antistatic agent, a slip agent, an antiblocking agent, etc. preferable. In this case, in order to uniformly apply an antistatic agent, a slipping agent, an antiblocking agent and the like to the surface of the film, it is preferable to hydrophilize the film surface serving as an application surface by corona treatment. By this hydrophilic treatment, the uniformity of the coating film is improved, and antistatic properties and slipperiness are efficiently exhibited. The surface tension at that time is preferably in the range of 400 μN / cm to 600 μN / cm.

The present invention will be described based on examples.
The evaluation methods used in the examples and comparative examples are described below.
(1) D, L lactic acid composition and optical purity of polylactic acid polymer The optical purity of the polylactic acid polymer is the composition of L-lactic acid and / or D-lactic acid monomer units constituting the polylactic acid polymer as described above. It is calculated from the ratio by the following formula.
Optical purity (%) = | [L] − [D] |, where [L] + [D] = 100
(| [L]-[D] | represents the absolute value of [L]-[D].)
The composition ratio of L-lactic acid and / or D-lactic acid monomer units constituting the polylactic acid polymer is determined by hydrolysis of the sample with 1N-NaOH, neutralized with 1N-HCl, and then adjusted with distilled water. Detection of L-lactic acid and D-lactic acid at UV UV of 254 nm on a sample (liquid) by high performance liquid chromatography (trade name, HPLC: LC-10A-VP) manufactured by Shimadzu Corporation equipped with an optical isomer separation column From the peak area ratio (area measurement by perpendicular method), the weight ratio [L] (unit%) of L-lactic acid constituting the polylactic acid polymer, the weight ratio [D] of D-lactic acid constituting the polylactic acid polymer (D) ( (Unit%) was obtained, and the arithmetic value (rounded off) of 3 points per polymer was taken as the measured value.

(2) Weight average molecular weight Mw of polylactic acid polymer
Using a gel permeation chromatography device (GPC: data processing unit, trade name GPC-8020, detector, trade name RI-8020) manufactured by Tosoh, polystyrene conversion was performed using standard polystyrene under the following measurement conditions. Thus, the weight average molecular weight Mw was determined, and an arithmetic average (rounded off) of 3 points per polymer was taken as a measured value.
Column: Showa Denko, trade name Shodex K-805 and K-801
[7.8mm diameter 60cm length]
Eluent: Chloroform Sample solution concentration: 0.2 wt / vol%
Sample solution injection volume: 200 μl
Solvent flow rate: 1 ml / min Column / detector temperature: 40 ° C
(3) Glass transition point (Tg), melting point (Tm)
Based on JIS-K-7121 and JIS-K-7122, it heated up from -100 degreeC to 200 degreeC with the differential scanning calorimeter (DSC), and measured Tg and Tm. That is, after cutting out about 10 mg from a sample that was conditioned at 23 ° C. and 65% RH (left at 23 ° C. for 1 week), a differential scanning calorimeter (thermal flow rate DSC manufactured by Perkin-Elmer) was used. ), Using a product name DSC-7 model, raise the temperature from −100 ° C. to 200 ° C. at a nitrogen gas flow rate of 25 ml / min, 10 ° C./min, and the melting (endothermic) peak apex of the drawn DSC curve To the melting point Tm (° C), and the intersection (midpoint glass transition temperature) of the step-like change partial curve at the time of temperature rise and the straight line equidistant from the baseline extension in the vertical axis direction is measured as Tg (unit ° C). The measured value was the arithmetic average (rounded off) of 4 points per product.

(4) Total film thickness, each layer thickness (μm)
The total thickness of the film was measured according to JIS-K-7130 using a micrometer, and the thickness of each layer was measured by observing the cross section of the multilayer film with a microscope.
(5) Oxygen permeability (cc / (m ² · day · atm))
The oxygen permeability of the film was measured in accordance with ASTM D3985 under an atmosphere of 23 ° C. and a relative humidity of 65%, and a composition (C) of polylactic acid resin (A) and aliphatic polyester (B) as follows: average of the measured values O _C of oxygen permeability conditioner was evaluated in three stages from the relationship of (calculated) O _H.
○: O _C <(O _A and O _B ) <O _H
Δ: (O _A or O _B ) <O _C <O _H
×: _{O H} <O _C
(6) Seal strength (N / 15mm)
The seal strength of the film is measured according to JIS Z1707, the seal pressure is 0.5 MPa, the seal time is 0.2 seconds, and the seal strength is measured every 10 ° C. in the temperature range from 80 ° C. until the film melts. Was the sealing strength of the film. A seal bar having a width of 1/2 inch (about 12.7 mm) was used. Further, the seal strength was measured in both the MD direction (film longitudinal direction) and the TD direction (film width direction).

(7) Tensile strength (MPa)
The tensile strength of the film was measured according to ASTM-D882. The tensile breaking strength and the tensile yield strength were measured, and the larger one was taken as the tensile strength.
(8) Haze (Haze,%)
Nihon Denshoku Industries Co., Ltd. was cut out from a film sample that had been conditioned at 23 ° C. and 65% RH (left at 23 ° C. for 1 week) as a 50 mm square film as a test piece, and in accordance with ASTM D1003-95. The haze (Haze: unit%) was measured under standard conditions using a turbidity meter (haze meter) manufactured by NDH-1001DP, and an arithmetic average value of 6 points per kind of film (significant number 2) (Digit) was taken as the measured value. Evaluation was made according to the following criteria.
○: Haze ≦ 40%, which is a practical level where the presence or absence of an object can be confirmed through watermarking.
×: 40% <Haze, and it is a problematic level because the presence or absence of an object is difficult to see through.

(9) Compression-resistant creep resistance test of airbag cushioning material A film cut out to a width of 200 mm is heat-sealed in the vertical direction (MD direction), and the length is 130 mm while putting air into the resulting tube. The top and bottom were heat-sealed to become a pillow-type air bag. The heat seal conditions were the temperature at which the highest seal strength was recorded in (6), the seal pressure was 0.5 MPa, and the seal time was 0.2 seconds. The air bag made in this way is sandwiched between rectangular pressure plates with a length of 120 mm and a width of 50 mm (area 60 cm ² ), and a weight is placed so that the weight of the upper pressure plate is 6 kg. The specimen was held for 200 days in an atmosphere with a humidity of 65%, and the compression creep (%) was determined from the lowering degree of the pressure plate placed on the top using the following formula.
Compression creep (%) = ((interval between upper and lower pressure plates immediately after the start of the test) − (interval between upper and lower pressure plates after 200 days from the start of the test)) ÷ (interval between the upper and lower pressure plates immediately after the start of the test) × 100
From the measurement result of compression creep (%), the compression creep resistance of the used film was evaluated according to the following criteria.
A: A level at which the compression creep is 25% or less, the compression creep resistance is most excellent, and it functions sufficiently as a cushioning material used for a long time and / or under a high load.
B: A level at which compression creep is 26 to 35%, compression resistance is excellent, and functions as a cushioning material used for a long period of time and / or under a high load.
C: Compression creep is 36 to 50%, compression creep resistance is slightly inferior, and functions as a cushioning material used for a long time and / or under a high load, but slightly inferior.
X: A level where the compression creep exceeds 50%, the compression creep resistance is poor, and the function may be problematic as a cushioning material used for a long time and / or under a high load.

(10) Rupture resistance test of air bag cushioning material A film cut out to a width of 150 mm is heat-sealed in the vertical direction (MD direction), and the length is 130 mm while putting air into the tube. The top and bottom were also heat-sealed to form a pillow-type air bag. The heat seal conditions were the temperature at which the highest seal strength was recorded in (6), the seal pressure was 0.5 MPa, and the seal time was 0.2 seconds. The air bag thus formed was sandwiched between rectangular pressure plates having a length of 120 mm and a width of 50 mm (area 60 cm ² ). The load was applied by pressing the pressure plate at a speed of 10 mm / min from the top, and the load at the time of rupture was measured. . The results were evaluated according to the following criteria.
A: Film ruptured at a load of 330 kg or more (breaking pressure 55 N / cm ² or more) B: Film ruptured at a load of 270 kg or more (breaking pressure 44 N / cm ² or more) C: Load 200 kg or more (breaking pressure 33 N) / cm ² or higher) breakage films × in: about less than load 200 Kg (breakage pressure breakage films 33N / in cm less than ²⁾ (11) the biodegradable resin stretched film of comprehensive judgment present invention (monolayer films) The evaluation was made in three stages of ◯, Δ, and × according to the following criteria based on the oxygen permeability and haze. Moreover, the evaluation regarding the biodegradable resin product of the present invention was evaluated based on the following criteria based on the four criteria A to X based on the evaluation results of the compression creep resistance test and the burst resistance test.
Evaluation on biodegradable stretched resin film (single layer film) ○: All are ○ and excellent in gas barrier property and transparency, and the problem is achieved at a high level.
Δ: No x and Δ, the problem has been achieved and is at a practical level.
×: When there is ×, the problem has not been achieved.
Evaluation of biodegradable resin products (multilayer film products) A: Air bag to be used under long-term use and / or high load, with either one of the compression creep resistance test or the burst resistance test being A and the remainder being A or more Excellent as a buffer material film.
B: Either one of the compression creep resistance test and the burst resistance test is B, and the remainder is B or more, which is moderately excellent as a film for an air bag cushioning material used for a long period of time and / or under a high load.
C: Either one of the compression creep resistance test and the burst resistance test is C, and the remainder is C or more, which is the minimum level that can be practically used as a film for an air bag cushioning material used for a long period of time and / or under a high load.
×: Either one or both of the compression creep resistance test and the burst resistance test is ×, and there may be a problem when used as a film for an air bag cushioning material used for a long time and / or under a high load. level.

  The biodegradable polymers used in the following Examples and Comparative Examples are the polymers shown in Table 1, and are Lacty 5000 (trade name), Lacty 9030 (trade name), and Lacty 9800 (polylactic acid manufactured by Shimadzu Corporation). (Trade name), Bionore # 3001 (trade name) which is poly (butylene succinate / adipate) manufactured by Showa Polymer Co., Ltd., Lunare SE-P5000 (trade name) which is poly (ethylene succinate / adipate) manufactured by Nippon Shokubai Co., Ltd. Lunare SE-P3000D (trade name), which is a polyethylene succinate manufactured by Nippon Shokubai Co., Ltd., and Ecoflex (trade name), which is an aliphatic aromatic copolyester manufactured by BASF Corporation, were used. All of these polymers have already been confirmed to be biodegradable. However, the composition of the resin in the present invention is not limited to this.

[Reference Examples 1 to 3, Examples 1 to 3 and Comparative Example 1]
Reference Examples 1 to 3 are physical property results when the polylactic acid resin (A) and the aliphatic polyester (B) used in the present invention shown in Table 1 are each formed into a single film. In Examples 1 to 3 and Comparative Example 1, Lacty 5000 (trade name), Lacty 9030 (trade name), Lacty 9800 (trade name) which are polylactic acids shown in Table 1, and Bionore which is polybutylene succinate adipate. Using # 3001 (trade name), lunale SE-P5000 (trade name) and lunale SE-P3000D (trade name), which are polyethylene succinate resins, are dry blended to the compositions in Table 2 and from a single screw extruder. Extruded from a single-layer cylindrical die with an outer die lip diameter of 110 mm, an inner die lip diameter of 105 mm, and a lip clearance of 2.5 mm. Inside the tube, air is blown from the cooling ring onto the molten resin extruded in a tube shape. Air is injected to form bubbles, and the resulting film is guided to a pinch roll and tube The film was wound up at a take-up roll as a flat-shaped two films. Next, after the bubbles were stabilized, the resin extrusion speed, the amount of air injected into the bubbles, and the film winding speed in the pinch roll were finely adjusted to obtain a single-layer film having the final thickness shown in Table 2 (die (The area magnification from the exit is about 83 times). The evaluation results of oxygen permeability (gas barrier property) and haze (transparency) of the film are shown in the same table. It turns out that the biodegradable resin stretched film of this invention which is an Example can make favorable gas barrier property and transparency compatible.

[Comparative Example 2]
In Comparative Example 2, Reference Examples 1 to 3, Examples 1 to 3 and Comparative Example 1 were changed to a single-layer cylindrical die having an outer die lip diameter of 110 mm, an inner die lip diameter of 105 mm, and a lip clearance of 0.8 mm. In the same manner, a single-layer film having the final thickness shown in Table 2 was obtained (the area magnification from the die exit was about 27 times). The evaluation results of oxygen permeability (gas barrier property) and haze (transparency) of the film are shown in the same table. In Comparative Example 2, which is a region of the prior art (Patent Document 4, Patent Document 5, etc.) having no or low stretch ratio (area ratio from the die exit) such as press molding or injection molding, the gas barrier property and transparency are It turns out that it has not improved.

[Example 4 and Comparative Example 3]
In Example 4 and Comparative Example 3, in the same manner as in Reference Examples 1 to 3, Examples 1 to 3 and Comparative Example 1, using the raw material polymers shown in Table 1, the compositions shown in Tables 3 to 5 were dried. Blending was performed, and the extruder of each layer was controlled by a single screw extruder so as to have the composition shown in Tables 3 to 5, and the molten resin was extruded using a three-layer die. At the time of extrusion, the film was extruded from a three-layered cylindrical die having an outer die lip diameter of 110 mm, an inner die lip diameter of 105 mm, and a lip clearance of 2.5 mm to obtain a film having the final thickness shown in Tables 3 to 5 (area from the die outlet) The magnification is about 42 to 100 times), and the physical property evaluation results of the airbag cushioning material are shown in the same table. It can be seen that the biodegradable resin product of the present invention as an example satisfies all of good gas barrier properties, strength (compression resistance and burst resistance) and transparency.

Transparent biodegradable resin stretched film with improved gas barrier properties of the present invention, and packaging films, bags, laminate materials, resin products such as ostomy bags, etc. Since it is not only reduced in volume when it is disposed of as a cushioning material, but also biodegraded, it is advantageous from the viewpoint of protecting the natural environment, and retains the gas even if it is held for a long time under a load. Excellent compression creep resistance that lasts buffer performance and excellent pressure resistance that can withstand large loads, and air with excellent transparency that can sustain practically sufficient buffer performance for a long period of time It can be suitably used in the field of bag cushioning materials.

Claims (16)

Polylactic acid resin (A) having 50% by weight or more of lactic acid units, and polyethylene succinate resin having a melting point Tm (based on JIS-K7121) having 50% by weight or more of succinic acid units and ethylene glycol units of 200 ° C. or less In the film comprising the composition (C) with (B), the following formulas (1), (2) and (5) are all satisfied , and the composition (C) is melt-extruded to form a film. The film is obtained by stretching in at least one axial direction so that a typical film thickness is in a range of 1/200 times or more and 1/40 times or less with respect to an interval between die dies (die lips). A biodegradable resin stretched film.
(1) O _H = [(100 × O _A × O _B ) / (O _A × X _B + O _B × X _A )]
(2) O _C <O _H
(5) Haze ≦ 40
However, the weight ratio (unit%) when the total weight of the polylactic acid-based resin (A) and the polyethylene succinate-based resin (B) is 100 was defined as X _A and X _B , respectively. Further, the unit of% Haze (cloudiness) (according to ASTM-D1003-95), _{O A} is oxygen transmission rate of the polylactic acid based resin (A), _{O B} is aliphatic polyester (B), _{O C} the composition things oxygen permeability (C) (measured value), _{O H} is the harmonic mean of _{O a} and OB (calculated) (units ^{(cc × μm) / (m} 2 · day · atm), conforming to ASTM D3985, 23 Measured in an atmosphere at 65 ° C. and a relative humidity of 65%. Polylactic acid resin (A) having 50% by weight or more of lactic acid units, and polyethylene succinate resin having a melting point Tm (based on JIS-K7121) having 50% by weight or more of succinic acid units and ethylene glycol units of 200 ° C. or less A stretchable biodegradable resin film characterized by satisfying all of the following formulas (3) to (5) in the film comprising the composition (C) with (B).
(3) 90> X _A > 25 and 10 <X _B <75
(4) O _C <5000
(5) Haze ≦ 40
However, the weight ratio (unit%) when the total weight of the polylactic acid-based resin (A) and the polyethylene succinate-based resin (B) is 100 was defined as X _A and X _B , respectively. Further, the unit of% Haze (cloudiness) (according to ASTM-D1003-95), _{O C} compositions oxygen permeability (C) (measured value), (unit ^{(cc × μm) / (m} 2 · day · atm), measured in an atmosphere of 23 ° C. and 65% relative humidity in accordance with ASTM D3985). The biodegradable resin stretched film according to claim 1 or 2, wherein the following formulas (6) and (7) are all satisfied.
(6) 10000 ≦ O _A ≦ 25000
(7) 100 ≦ O _B ≦ 5000
However, _{O A} polylactic acid resin (A), _{O B} represents oxygen permeability of polyethylene succinate-based resin (B) (units ^{(cc × μm) / (m} 2 · day · atm), conforming to ASTM D3985, Measured in an atmosphere of 23 ° C. and 65% relative humidity).   A biodegradable resin product comprising a film containing at least one layer of the biodegradable resin stretched film according to claim 1. The biodegradable resin product according to claim 4 , comprising a film containing at least one layer having an aliphatic polyester resin having a melting point Tm (conforming to JIS-K7121) of not more than 200 ° C of 50% by weight or more. . According to ASTM D3985, the oxygen permeability measured under an atmosphere of 23 ° C. and 65% relative humidity is 250 cc / (m ² · day · atm) or less, and the seal strength measured according to JIS Z1707 is film. The biodegradable resin product according to claim 4 , comprising a film having a length direction (MD direction) and a width direction (TD direction) of 15 N / 15 mm or more. Film having an oxygen permeability of 200 cc / (m ² · day · atm) or less and a film thickness in the range of 10 to 200 μm measured in an atmosphere of 23 ° C. and 65% relative humidity in accordance with ASTM D3985 The biodegradable resin product according to claim 4 , comprising: The biodegradable resin product according to claim 4 , comprising a film having a tensile strength measured in accordance with ASTM D882 of 25 MPa or more in both the MD direction and the TD direction of the film. The biodegradable resin product according to claim 4 , comprising a film having a haze measured by a turbidimeter (ASTM-D1OO3-95) of 40% or less. The biodegradable resin product according to claim 4 , wherein the multi-layer film has a sealing layer made of a thermoplastic biodegradable resin and forms at least one surface of the multi-layer film. The biodegradable resin product according to claim 4 , comprising a film formed by an inflation method. It is a film for packaging, The biodegradable resin product in any one of Claims 4-11 characterized by the above-mentioned. It is a bag, The biodegradable resin product in any one of Claims 4-11 characterized by the above-mentioned. The biodegradable resin product according to any one of claims 4 to 11 , which is a laminate material. It is an ostomy bag, The biodegradable resin product in any one of Claims 4-11 characterized by the above-mentioned. It is an airbag cushioning material, The biodegradable resin product in any one of Claims 4-11 characterized by the above-mentioned.