JP2016056304A - Film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film mainly composed of biodegradable resin and having excellent shape retention and degradable properties.SOLUTION: A film comprises a biodegradable resin (A). When a thickness of the film is T(μm) and a Young's modulus in a direction in which the Young's modulus becomes largest (direction a) is Ea(GPa), Ea×Tis 1,000 GPa/μmor more and 60,000 GPa/μmor less, and a weight thereof is 10 g/mor more and 50 g/mor less.SELECTED DRAWING: None

Description

  The present invention relates to a film containing a biodegradable resin, excellent in shape retention and excellent in decomposability.

  In recent years, with increasing environmental awareness, attention has been focused on soil pollution problems caused by the disposal of plastic products and global warming problems caused by increased carbon dioxide caused by incineration. As a measure against the former, various biodegradable resins, and as a measure against the latter, a resin made of biomass (plant-derived raw material) that does not give a new carbon dioxide load to the atmosphere even if it is incinerated has been extensively researched and developed. ing. For example, polylactic acid has attracted attention as a resin that satisfies both requirements and is relatively advantageous in terms of cost. However, when trying to apply polylactic acid to flexible film applications in which polyolefins such as polyethylene are used as typical materials, they lack flexibility and impact resistance, so various attempts have been made to improve these properties and put them to practical use. Has been made.

  In the field of porous films, for example, Patent Document 1 discloses a porous film obtained by stretching a sheet containing a polylactic acid resin, a thermoplastic resin other than a polylactic acid resin, and a filler. Patent Document 2 discloses a porous sheet obtained by stretching at least uniaxially a sheet containing a polylactic acid resin, a filler, and a general polyester plasticizer. Further, Patent Document 3 discloses a biodegradable porous film obtained by melting a resin composition containing an aliphatic polyester, a thermoplastic resin, a filler, and a plasticizer, forming the film or sheet, and then stretching the resin composition. It is disclosed.

WO2012 / 023465 pamphlet JP 2007-112867 A JP-A-9-291165

  In the techniques described in Patent Documents 1 to 3, a porous film satisfying a certain moisture permeability was obtained, but their performance was not sufficient. Specifically, in the invention described in Patent Document 1, as a result of inferior shape retention with respect to deformation such as pulling, wrinkles and the like are generated when processing is performed with increased tension during continuous processing at high speed for the purpose of improving productivity. When used for various purposes (especially cards, labels, adhesive tapes, medical and sanitary base materials, garbage bags, compost bags, food bags for vegetables, fruits, etc.) It was easy to deform and break. Furthermore, the techniques described in Patent Documents 2 and 3 are inferior in degradability.

  That is, until now, studies have been made on films having excellent shape retention with respect to deformation, excellent decomposability, and a high degree of biomass, but the invention of a film that achieves all of them has not yet been achieved.

  In view of the background of such conventional technology, the present invention is intended to provide a film having excellent shape retention and decomposability.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by the following, and have reached the present invention.

Aspects of the present invention are as follows.
1) contains a biodegradable resin (A),
Ea × T ³ is 1,000 GPa · μm ³ or more and 60,000 GPa · μm ³ or less, where T (μm) is the thickness of the film and Ea (GPa) is the Young's modulus in the direction with the largest Young's modulus (direction a). And
A film having a basis weight of 10 g / m ² or more and 50 g / m ² or less.

  According to the present invention, a film excellent in shape retention and decomposability is provided. In addition, when voids are formed in the present invention, particularly in a preferred embodiment in which the porosity is controlled to be 5% or more and 80% or less, it also has high moisture permeability. The film of the present invention can be preferably used for applications that mainly require shape retention and decomposability. Specifically, agricultural materials such as various labels, cards, labels, adhesive tapes and multi-films, forestry materials such as fumigation sheets, bed sheets, pillow covers, sanitary materials such as sanitary napkins and paper diapers, and for rainy weather It can be preferably used for clothing materials such as clothing and gloves, garbage bags and compost bags, food bags such as vegetables and fruits, and various packaging materials for industrial products.

The present invention is the first to succeed in solving such a problem as a result of intensive studies on a film having excellent shape retention with respect to deformation and excellent decomposability. That is, when the film of the present invention contains the biodegradable resin (A), the thickness of the film is T (μm), and the Young's modulus in the direction where the Young's modulus is the largest (direction a) is Ea (GPa), Ea × T ³ is 1,000 GPa · μm ³ or more and 60,000 GPa · μm ³ or less, and the basis weight is 10 g / m ² or more and 50 g / m ² or less.

The present inventors have found that Ea × T ³ is an important factor in the shape retention against continuous processing and pulling during use, and have found the film of the present invention excellent in shape retention.

  In addition, the decomposition of the film containing the biodegradable resin proceeds through the following steps 1) and 2). That is, in a garbage bag once collected (after use for a desired application), 1) the film collapses and the shape becomes fine. As a result, the volume can be reduced. 2) In the compost or in the soil, it is finally decomposed into water and carbon dioxide by the metabolism of microorganisms.

  In the step 2), it has been known that the factor determining the degradability is mainly due to the molecular structure of the biodegradable resin. In the film of the present invention, the basis weight of the film is important in the step 1). It was found that this was an important factor, and excellent degradability could be obtained by setting the basis weight within a specific range.

  In addition, the degradability as used in the field of this invention is mentioned later for details, but after using a film for a desired use, it decomposes | disintegrates easily, and also means that biodegradability accelerates in connection with it. As indicators of degradability, mechanical properties such as strength and elongation, and the decrease in the molecular weight of the resin constituting the film are used. Furthermore, regarding the decomposability, it is preferable that the film of the present invention undergoes shape collapse due to being exposed to weak force such as water flow.

  Hereinafter, the film of the present invention will be described.

(Biodegradable resin (A))
It is important that the film of the present invention contains a biodegradable resin (A). The biodegradable resin (A) is not particularly limited as long as it is a biodegradable resin.

  In the present invention, “having biodegradability” means that the biodegradable resin (A) in the film is JIS K6955 (2000), JIS K6951 (2000), JIS K6953-1 (2011), or JIS K6953. -2 (2010) and JIS K6955 (2006), it means that degradation of 60% or more occurs within one year.

As the biodegradable resin (A), aliphatic polyester resins, aliphatic aromatic polyester resins, polysaccharides, polyvinyl alcohol resins and the like can be used.

  Examples of the aliphatic polyester resins include polylactic acid resins (a1), polyglycolic acid resins, polyhydroxybutyrate resins, polycaprolactone resins, polybutylene succinate resins, and copolymers thereof. Can be used. These may be isomers or may be copolymerized with other components. However, the biodegradable resin (A) does not include the polymer plasticizer (B) described later.

  For example, specific examples of the polyhydroxybutyrate resin include poly (3-hydroxybutyrate), poly (3-hydroxybutyrate-3hydroxyhexanoate), poly (3-hydroxybutyrate-3hydroxy Variate) and the like. Specific examples of the polybutylene succinate resin include polybutylene succinate, poly (butylene succinate adipate), and poly (butylene succinate lactide).

  Specific examples of the aliphatic aromatic polyester-based resin include poly (ethylene succinate / terephthalate), poly (butylene succinate / terephthalate), poly (butylene adipate / terephthalate), and copolymers thereof.

  Specific examples of the polysaccharide include starch and derivatives thereof, cellulose and derivatives thereof, hemicellulose and derivatives thereof such as glucomannan, chitin / chitosan and derivatives thereof, and the like. In addition, as a resin containing starch, a biodegradable resin “Mater-bi (registered trademark)” of Novamont Co., Ltd. can be used.

  As the biodegradable resin (A), the above may be used alone or two or more of the above may be blended. Alternatively, two or more types of the above copolymers may be used.

  Among these, the biodegradable resin (A) preferably includes a polylactic acid resin (a1) from the viewpoints of biomass properties, cost, processability, and the like. Hereinafter, the polylactic acid resin (a1) will be specifically described.

  The content of the biodegradable resin (A) such as the polylactic acid resin (a1) in the film of the present invention is not particularly limited, but the polylactic acid resin (a1) or the like in 100% by mass of all the components of the film. The biodegradable resin (A) is preferably 5% by mass or more and 90% by mass or less, more preferably 10% by mass or more and 60% by mass or less, and more preferably 12% by mass or more and 30% by mass or less. Further preferred.

(Polylactic acid resin (a1))
The polylactic acid resin (a1) is a polymer mainly composed of an L-lactic acid unit and / or a D-lactic acid unit. Here, the main component means that the mass ratio of the lactic acid unit is the maximum in 100% by mass of the polymer. The mass ratio of the lactic acid unit is preferably 70% by mass or more and 100% by mass or less of the lactic acid unit in 100% by mass of the polymer.

  As the polylactic acid resin (a1), poly L-lactic acid, poly D-lactic acid and the like are preferably used. The term “poly L-lactic acid” as used in the present invention means that the content of L-lactic acid units is more than 50 mol% and not more than 100 mol% in 100 mol% of all lactic acid units in the polylactic acid polymer. On the other hand, the poly-D-lactic acid referred to in the present invention refers to those having a D-lactic acid unit content of more than 50 mol% and not more than 100 mol% in 100 mol% of all lactic acid units in the polylactic acid polymer.

  In poly L-lactic acid, the crystallinity of the resin itself varies depending on the content ratio of the D-lactic acid unit. That is, the smaller the content ratio of the D-lactic acid unit in the poly L-lactic acid or the content ratio of the L-lactic acid unit in the poly D-lactic acid, the higher the crystallinity of the poly L- or D-lactic acid. Conversely, the smaller the content ratio of the D-lactic acid unit in the poly L-lactic acid or the content ratio of the L-lactic acid unit in the poly D-lactic acid, the higher the crystallinity of the poly L- or D-lactic acid.

  The content ratio of the L-lactic acid unit in the poly L-lactic acid used in the film of the present invention or the content ratio of the D-lactic acid unit in the poly D-lactic acid used in the present invention maintains the mechanical strength of the film. From the viewpoint, it is preferably 80 mol% or more and 100 mol% or less, more preferably 85 mol% or more and 100 mol% or less, in 100 mol% of all lactic acid units.

  In the film of the present invention, the polylactic acid resin (a1) used as the biodegradable resin (A) is a mixture of a crystalline polylactic acid resin (a11) and an amorphous polylactic acid resin (a12). preferable. In that case, by containing the crystalline polylactic acid resin (a11), the shape retention, heat resistance, and blocking resistance of the film are improved. When a block copolymer plasticizer described later is used as the polymer plasticizer (B), the crystalline polylactic acid resin (a11) forms a eutectic with the polylactic acid segment of the block copolymer plasticizer. This has a great effect on bleed-out resistance. On the other hand, the inclusion of the amorphous polylactic acid resin (a12) as the polylactic acid resin (a1) is suitable for improving the moisture permeability, flexibility, and bleed-out resistance of the film. This has an effect of providing an amorphous part in which the plasticizer can be dispersed.

  The crystalline polylactic acid-based resin (a11) is a polylactic acid-based resin (a1) that is allowed to stand for 1 hour under heating at 100 ° C. and is then heated from 0 ° C. to 250 ° C. at a temperature rising rate of 20 ° C./min. When measured with a differential scanning calorimeter (DSC) up to ° C., it refers to a polylactic acid resin in which the heat of crystal melting derived from the polylactic acid component is observed. The amorphous polylactic acid resin (a12) refers to a polylactic acid resin that does not show a clear melting point when measured in the same manner.

  In the film of the present invention, when the total of the polylactic acid resin (a1) is 100% by mass (the total of the crystalline polylactic acid resin (a11) and the amorphous polylactic acid resin (a12) is 100% by mass. The mass ratio of the crystalline polylactic acid resin (a11) is preferably 5% by mass or more and 60% by mass or less, more preferably 10% by mass or more and 50% by mass or less, and more preferably 20% by mass. More preferably, it is 40 mass% or less.

  The polylactic acid resin (a1) may copolymerize other monomer units other than lactic acid. Other monomers include glycol compounds such as ethylene glycol, propylene glycol, butanediol and polyethylene glycol, dicarboxylic acids such as oxalic acid, adipic acid and terephthalic acid, hydroxycarboxylic acids such as glycolic acid and hydroxybutyric acid, caprolactone, etc. Of lactones. The copolymerization amount of the other monomer units is preferably 0 mol% or more and 30 mol% or less with respect to 100 mol% of the whole monomer units in the polymer of the polylactic acid resin (a1). More preferably, it is 10 mol% or less. In addition, it is preferable to select the component which has biodegradability among the above-mentioned monomer units according to a use.

  Moreover, about polylactic acid-type resin (a1), when a main component is poly L-lactic acid, when a main component is poly D-lactic acid, poly L-lactic acid may be mixed a little. preferable. Thereby, the heat resistance of a film improves by forming the stereocomplex crystal whose melting | fusing point is higher than the crystal | crystallization (alpha crystal) of normal polylactic acid. In addition, a main component here means the component exceeding 50 mass% when the sum total of the polylactic acid-type resin (a1) in a film is 100 mass%.

  Further, the polylactic acid resin (a1) is preferably a polylactic acid block copolymer composed of a segment composed of L-lactic acid units and a segment composed of D-lactic acid units, from the viewpoint of improving heat resistance. In this case, since the polylactic acid block copolymer forms a stereocomplex crystal in the molecule, the melting point is higher than that of a normal crystal.

  The mass average molecular weight of the polylactic acid-based resin (a1) is preferably 50,000 or more and 400,000 or less, and preferably 70,000 or more and 300,000 in order to satisfy practical mechanical properties, water resistance and decomposability. Or less, more preferably 100,000 or more and 250,000. In addition, the mass average molecular weight here refers to a molecular weight calculated by a polystyrene conversion method after measurement with a chloroform solvent by gel permeation chromatography (GPC).

(Thermoplastic resin other than polylactic acid resin (a1))
The film of the present invention can also contain a thermoplastic resin other than the polylactic acid resin (a1). Examples of thermoplastic resins other than the polylactic acid resin (a1) include polyacetal resins, polyolefin resins such as polyethylene and polypropylene, polyamide resins, acrylic resins such as poly (meth) acrylate, (polylactic acid resins Excluded) Polyester resins, polyurethane resins, polyolefin resins modified with epoxy groups or acid anhydride groups, olefin-acrylic copolymer resins, olefin-acrylic copolymers modified with epoxy groups, acid anhydride groups, etc. Polymerized resins, polyester elastomers, polyamide elastomers, polyolefin elastomers, polysaccharides, polyvinyl alcohol resins and the like can be used, and are not particularly limited. The thermoplastic resin other than the polylactic acid resin (a1) is preferably a biodegradable resin. That is, the film of the present invention preferably contains a biodegradable resin (a2) other than the polylactic acid resin (a1) as the biodegradable resin (A).

  And from the viewpoint of improving the shape-retaining property and degradability, the film of the present invention contains a biodegradable resin (a2) other than the polylactic acid-based resin (a1) as the biodegradable resin (A), and all components 100 of the film. It is preferable to contain 10 mass% or more and 80 mass% or less in the mass%. The content of the biodegradable resin (a2) in the film is more preferably 15% by mass to 50% by mass, and still more preferably 20% by mass to 45% by mass.

  Examples of the biodegradable resin (a2) include, among the biodegradable resins (A) described above, aliphatic polyester resins other than polylactic acid resins, aliphatic aromatic polyester resins, polysaccharides, and polyvinyl alcohol resins. Etc. can be used and is not particularly limited. However, the biodegradable resin (a2) does not include a polymer plasticizer (B) described later.

  Among these biodegradable resins (a2), the biodegradable resin (a2) from the viewpoint of dispersibility and processability with the polylactic acid resin (a1) when used in combination with the polylactic acid resin (a1). The polyester resin is preferable, and among them, those selected from the group consisting of aliphatic polyester resins and aliphatic aromatic polyester resins are preferable. A polybutylene succinate resin is preferably used as the aliphatic polyester resin, and poly (butylene adipate / terephthalate) is preferably used as the aliphatic aromatic polyester resin. In particular, from the viewpoint of dispersibility with the polylactic acid resin (a1), the polybutylene succinate resin is most preferable as the biodegradable resin (a2).

  In the film of the present invention, when the polylactic acid resin (a1) and the biodegradable resin (a2) other than the polylactic acid resin are used in combination, the mass ratio is (polylactic acid resin (a1) / biodegradable). Resin (a2)) = (30/70) to (95/5) is preferable, (40/60) to (80/20) is more preferable, and (20/80) to (50 / 40) is more preferable.

(Polymer plasticizer (B))
The film of the present invention preferably contains a polymer plasticizer (hereinafter referred to as polymer plasticizer (B)) from the viewpoint of imparting flexibility and improving the elongation at break. The content of the polymer plasticizer (B) in 100% by mass of the entire film is preferably 3% by mass or more and 20% by mass or less. The content of the polymeric plasticizer in the film is more preferably 5% by mass to 15% by mass. By setting the content of the polymeric plasticizer in the film to 3% by mass or more, it is possible to obtain a flexible film, and by setting the content to 20% by mass or less, good shape retention is imparted. be able to.

Specific examples of the polymer plasticizer (B) include polyester plasticizers such as polypropylene glycol sebacate, polyalkylene ether plasticizers, ether ester plasticizers, and acrylate plasticizers. Among such plasticizers, from the viewpoint of maintaining the biodegradability of the entire film, the polymer plasticizer (B) preferably has biodegradability. Furthermore, from the viewpoint of the bleed-out resistance of the plasticizer and the heat resistance and blocking resistance of the film, those which are solid at ordinary temperature (20 ° C. ± 15 ° C.), that is, those having a melting point exceeding 35 ° C. are preferred. Further, the melting point of the polymer plasticizer (B) is preferably 150 ° C. or lower in view of matching the melt processing temperature with the polylactic acid resin (a1) suitable as the biodegradable resin (A). In order to suppress bleed-out of plasticizers and improve plasticization efficiency, P.I. Small, J.M. Appl. Chem. , 3, 71 (1953), a solubility parameter that can be calculated by the method shown in (1953): SP is preferably (16-23) ^1/2 MJ / m ³ , (17-21) ^1/2 MJ / more preferably m ^3.

  From the same viewpoint, the polymer plasticizer (B) is a block copolymer having a polyether segment and a polylactic acid segment and / or a block copolymer having a polyester segment and a polylactic acid segment. Is more preferable. Hereinafter, a block copolymer having a polyether segment and a polylactic acid segment and a block copolymer having a polyester segment and a polylactic acid segment are collectively referred to as a “block copolymer plasticizer”.

  There is no particular restriction on the order of the polyether segment and / or polyester segment in the block copolymer plasticizer and the polylactic acid segment in the block copolymer, but the bleed out is more effectively suppressed. From the viewpoint, it is preferable that a polylactic acid segment is present at at least one end of the block copolymer plasticizer molecule. Furthermore, it is most preferred that the polylactic acid segments are at both ends of the block copolymer plasticizer molecule. Here, the plasticizing component in the block copolymer plasticizer is a polyether segment or a polyester segment.

  Here, the polyester segment means a segment composed of polyester other than polylactic acid, and includes polyglycolic acid, poly (3-hydroxybutyrate), poly (3-hydroxybutyrate · 3-hydroxyhexanoate), poly ( 3-hydroxybutyrate / 3-hydroxyvalerate), polycaprolactone, or polyesters composed of aliphatic diols such as ethylene glycol, propanediol and butanediol, and aliphatic dicarboxylic acids such as succinic acid, sebacic acid and adipic acid Is suitably used as the polyester segment.

  In addition, the polyether segment can impart desired flexibility with a smaller amount of addition, and contributes to improving the moisture permeability of the film because it is a hydrophilic component, so it is more preferable to have a segment made of polyalkylene ether, Specific examples of the polyether segment include polyalkylene ether segments made of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol / polypropylene glycol copolymer, and the like.

  From the viewpoints of film flexibility and bleed-out resistance, the block copolymer plasticizer preferably has a polyether segment. Among them, polyethylene glycol is preferred from the viewpoint of improvement in that moisture permeability can be further increased. Most preferably, it has a polyalkylene ether segment consisting of

  The number average molecular weight of the polyether segment or the polyester segment in one molecule of the block copolymer plasticizer is preferably 5,000 or more and 20,000 or less. By setting it as the above range, the composition constituting the film has sufficient moisture permeability and elongation at break, and when the composition containing the biodegradable resin (A) is used, the melt viscosity is at an appropriate level. And processing such as discharge and stretching during film formation can be stabilized.

  Since the mass proportion of the polylactic acid segment of the block copolymer plasticizer is 50% by mass or less in 100% by mass of the entire block copolymer plasticizer, desired flexibility can be imparted with a smaller amount of addition. Preferably, it is 5% by mass or more from the viewpoint of bleed out suppression. More preferably, in 100% by mass of the polylactic acid segment in the block copolymer plasticizer, L-lactic acid is 95% by mass to 100% by mass, or D-lactic acid is 95% by mass to 100% by mass. It is particularly preferable that bleeding out is suppressed. Further, the number average molecular weight of the polylactic acid segment in one molecule of the block copolymer plasticizer is preferably 1,200 or more and 10,000 or less. The number average molecular weight of the polylactic acid segment in one molecule of the block copolymer plasticizer is more preferably 1,500 to 6,000, and still more preferably 2,000 to 5,000. When the number average molecular weight of the polylactic acid segment of the block copolymer plasticizer is 1,200 or more, it is between the block copolymer plasticizer and the polylactic acid resin (a1) that is the biodegradable resin (A). As a result of the increased affinity, a part of the polylactic acid-based segment is incorporated into a crystal formed from the polylactic acid-based resin (a1) to form a so-called eutectic so that the block copolymer plasticizer bleeds. A great effect is exerted on the suppression of out and the blocking resistance of the film is also excellent. When the film of the present invention contains a filler (C), the film containing the block copolymer plasticizer forms a eutectic even if it is a liquid plasticizer at room temperature or a solid at room temperature. Compared with the plasticizer which does not, the eutectic formed improves the void formation efficiency by the extending | stretching mentioned later, As a result, moisture permeability can be improved.

  In 100% by mass of the block copolymer plasticizer, the mass ratio of the polylactic acid segment is 5% by mass or more and 45% by mass or less, and the mass ratio of the polyether segment or the polyester segment is 55% by mass or more and 95% by mass. The following is preferable.

  In the case where the film of the present invention includes a polymer plasticizer (B), the mass ratio of the biodegradable resin (A) and the polymer plasticizer (B) is (biodegradable resin (A) / Polymeric plasticizer (B)) = (50/50) to (95/5) is preferable, and (60/40) to (80/10) is more preferable.

(Filler (C))
The film of the present invention preferably contains a filler (C), and the content thereof is not particularly limited, but the filler (C) is contained in an amount of 1% by mass to 70% by mass in 100% by mass of all components of the film. Is preferred. The content of the filler (C) in the film is more preferably 10% by mass to 65% by mass, further preferably 20% by mass to 60% by mass, and particularly preferably 30% by mass to 55% by mass. . By setting the filler (C) to 1% by mass or more, moisture permeability can be further increased, and by setting it to 70% by mass or less, a film having good mechanical properties can be obtained.

  As the filler (C), an inorganic filler and / or an organic filler can be used. Examples of inorganic fillers include various carbonates such as calcium carbonate, various sulfates such as barium sulfate, zinc oxide, silicon oxide (silica), various oxides such as titanium oxide and alumina, and other such as aluminum hydroxide. Uses hydroxides, silicate minerals, hydroxyapatite, mica, talc, kaolin, clay, montmorillonite, various composite oxides such as zeolite, various phosphates such as calcium phosphate, various salts such as lithium chloride and lithium fluoride can do.

  Examples of organic fillers include oxalates such as calcium oxalate, terephthalates such as calcium, manganese, and magnesium, and vinyl monomers such as divinylbenzene, styrene, acrylic acid, and methacrylic acid. Fine particles, organic fine particles such as polytetrafluoroethylene, cellulosic powders such as wood powder and pulp powder, rice husks, wood chips, oats, chips such as waste paper pulverized materials, clothing pulverized materials, cotton fibers, hemp fibers Plant fibers such as bamboo fibers, animal fibers such as silk and wool, synthetic fibers such as polyester fibers, nylon fibers, and acrylic fibers can be used.

  Among these fillers (C), inorganic fillers are preferable from the viewpoints of improving the moisture permeability of the film, maintaining mechanical properties such as strength and elongation, and reducing costs. Examples of inorganic fillers include calcium carbonate and sulfuric acid. Barium, silicon oxide (silica), titanium oxide, mica, talc, kaolin, clay, montmorillonite, and zeolite are preferable, and calcium carbonate is particularly preferable.

  The average particle diameter of the filler (C) is not particularly limited, but is preferably 0.01 μm or more and 10 μm or less. More preferably, they are 0.1 micrometer or more and 8 micrometers or less, More preferably, they are 0.5 micrometer or more and 5 micrometers or less, Most preferably, they are 1 micrometer or more and 3 micrometers or less. Here, the average particle diameter is a 50% cumulative distribution average particle diameter measured by a laser diffraction scattering method. By setting the average particle size of the filler (C) to 0.01 μm or more, it becomes possible to highly fill the filler (C) in the film. As a result, the film has a potential to increase the porosity and moisture permeability. When the film becomes a high film and the average particle diameter is 10 μm or less, the stretchability of the film becomes good. As a result, the film has a high potential for increasing the porosity and moisture permeability of the film.

  The filler (C) used for the film of the present invention can be treated with a surface treatment agent as necessary. As the surface treatment agent used, phosphate ester compounds, fatty acids, resin acids, surfactants, fats and oils, waxes, carboxylic acid coupling agents, silane coupling agents, titanate coupling agents, polymer surface treatment agents Etc. are raised. Particularly, when the polylactic acid resin (a1) is used as the biodegradable resin (A) and at least one of an aliphatic polyester resin or an aliphatic aromatic polyester resin is used as the biodegradable resin (a2). From the viewpoint of improving the affinity with the biodegradable resin (A), the surface treatment agent used for treating the filler (C) is more preferably a phosphate ester compound and / or a fatty acid. By using compounds treated with these surface treatment agents as the filler (C), the affinity with the biodegradable resin (A) is improved, and the aggregation of the filler (C) is suppressed and the dispersibility is improved. There is an effect, and the filler (C) can be uniformly dispersed in the resin composition. As a result, since the voids are uniformly formed during stretching, it is possible to obtain a film excellent in moisture permeability, shrinkage resistance with time, and elongation at break.

(Organic lubricant)
The film of the present invention preferably contains 0.1% by mass or more and 5% by mass or less of an organic lubricant in 100% by mass of the entire film from the viewpoint of preventing blocking of compound pellets and film. Examples of the organic lubricant include fatty acid amides such as stearamide and ethylene bis stearamide.

(Additive)
The film of the present invention may contain additives other than those described above as long as the effects obtained by the present invention are not impaired. For example, the film of the present invention comprises an ultraviolet stabilizer, an anti-coloring agent, a matting agent, an antibacterial agent, a deodorant, a flame retardant, a weathering agent, an antistatic agent, an antioxidant, an ion exchange agent, a tackifier, An antifoaming agent, a color pigment, a dye, a crystal nucleating agent, a chain extender, a hydrolysis-resistant agent and the like can be contained.

(Thickness T, Young's modulus Ea, Ea × T ³ )
In the film of the present invention, when the film thickness is T (μm) and the Young's modulus in the direction with the largest Young's modulus (hereinafter referred to as direction a) is Ea (GPa), Ea × T ³ is 1,000 GPa · μm ^3. It is important that it is 60,000 GPa · μm ³ or less. The direction in which the Young's modulus is the largest here (direction a) is the direction in which the Young's modulus of the film is measured by changing the direction every 10 ° in the film plane and the Young's modulus is maximized. . Ea × T ³ is more preferably 2,000 GPa · μm ³ or more and 50,000 GPa · μm ³ or less, and still more preferably 4,000 GPa · μm ³ or more and 30,000 GPa · μm ³ .

When the film is continuously processed, a force is applied not only in the pulling direction but also along the roll. Further, when the film is used, it receives not only a pulling force in the surface direction of the film but also a force from various directions such as bending and twisting. The degree of deformation of the film also affects the tactile sensation when the film is touched. Here, it is known that the deformation and flexibility of the film with respect to the external force are inversely proportional to the cube of the thickness T of the film. Therefore, in the present invention, instead of the conventionally used Young's modulus, an index Ea × T ³ that takes into account the influence of thickness is used, and the value is controlled to 1,000 GPa · μm ³ or more and 60,000 GPa · μm ³ or less. It has been found that it is possible to obtain a film having both retention, flexibility and decomposability against deformation.

By setting Ea × T ³ to 1,000 GPa · μm ³ or more, it is possible to achieve excellent retention against deformation, and by setting it to 60,000 GPa · μm ³ or less, it is excellent in flexibility and decomposability. Film. It is not particularly limited to Ea × ^{T 3} as a way to 1,000GPa · μm ³ or more 60,000GPa · μm ³ or less, be a preferred content described above filler (C), the biodegradable resin ( A) In combination with the polylactic acid resin (a1) and the biodegradable resin (a2), the type and content thereof are preferably as described above, the polymer plasticizer (B) is contained, In the production method described later, the type and content are preferably described above, in the production method described later, the magnification in the stretching step is set in a preferable range, and the thickness is set in a preferable range described later. A combination of a plurality of these methods is also preferably performed.

  The film of the present invention preferably has a Young's modulus Ea in the direction a of 1 GPa or more and 3 GPa. The Young's modulus Ea in the direction a is more preferably 1.2 GPa or more and 2.5 GPa or less. When the Young's modulus Ea in the direction a is 1 GPa or more, the retention property against deformation can be further increased, and when it is 3 GPa or less, a film having excellent flexibility can be obtained. In order to set the Young's modulus Ea in the direction a to 1 GPa or more and 3 GPa, the biodegradable resin (A) contains a polylactic acid resin (a1) and a biodegradable resin (a2). In the production method to be described later, the magnification in the stretching step is set to a preferred range. That is, the porosity is set to a preferable range described later. A combination of a plurality of these methods is also preferably performed.

  In the film of the present invention, the ratio Ea / Eb is preferably 1.2 or more when the Young's modulus in the direction orthogonal to the direction a (direction b) is Eb (GPa). The ratio Ea / Eb is more preferably 1.3 or more, and still more preferably 1.4 or more. By setting the ratio Ea / Eb to be 1.2 or more, it is possible to have resistance to deformation and further excellent decomposability. The upper limit of the ratio Ea / Eb is not particularly limited, but substantially Ea / Eb is 3 or less because breakage occurs due to stretching. In order to set the ratio Ea / Eb to 1.2 or more, for example, the magnification and temperature in the stretching step are set in a preferable range, and the temperature in the heat treatment step is set in a preferable range. More preferred is a method of combining a plurality of these methods, and still more preferred is a method of combining all of these methods.

(Weight)
It is important that the film of the present invention has a basis weight of 10 g / m ² or more and 50 g / m ² or less. The basis weight is more preferably 15 g / m ² or more and 45 g / m ² or less, and further preferably 25 g / m ² or more and 40 g / m ² or less.

By setting the basis weight to 10 g / m ² or more, a film having excellent film forming stability can be obtained, and by setting the basis weight to 50 g / m ² or less, a film having excellent decomposability can be obtained. In order to make the basis weight 10 g / m ² or more and 50 g / m ² or less, for example, the filler (C) should have the above-mentioned preferable content, and the polylactic acid resin (a1) as the biodegradable resin (A) And the biodegradable resin (a2), and the types and contents thereof are preferable as described above, the polymer plasticizer (B) is included, and the types and contents thereof are preferable as described above. In the manufacturing method to be described later, the ratio in the stretching step is preferably set, and the thickness and the porosity are preferably set. More preferred is a method of combining a plurality of these methods, and still more preferred is a method of combining all of these methods.

(Porosity)
The film of the present invention preferably has a porosity of 5% or more and 80% or less. By setting the porosity to 5% or more, moisture permeability is further improved, and by setting the porosity to 80% or less, good mechanical properties of the film can be obtained. The porosity is more preferably 5% or more and 40% or less, and further preferably 5% or more and 20% or less. As a method for adjusting the porosity to 5% or more and 80% or less, for example, setting the filler (C) to the preferred content described above, and the polylactic acid resin (a1) as the biodegradable resin (A) The biodegradable resin (a2) is contained, the type and content thereof are preferably described above, and the ratio in the stretching step is preferably set in the production method described later. More preferred is a method of combining a plurality of these methods, and still more preferred is a method of combining all of these methods.

(Elongation at break)
The film of the present invention preferably has an elongation at break in the direction b of 60% or less. The elongation at break in the direction b is more preferably 50% or less, still more preferably 40% or less. When the elongation at break in the direction b is 60% or less, the decomposability is improved. The lower limit of the elongation at break in the direction b is not particularly limited, but is 1% or more from the viewpoint of maintaining the film form during handling. In order to set the elongation at break in the direction b to 60% or less, for example, the filler (C) has the above-described preferable content, and the polylactic acid resin (a1) as the biodegradable resin (A) The biodegradable resin (a2) is contained, and the type and content thereof are preferably described above. In the production method described later, the magnification in the stretching step is set to a preferable range, and the porosity is set to a preferable range. To do. More preferred is a method of combining a plurality of these methods, and still more preferred is a method of combining all of these methods.

(Breaking strength)
The film of the present invention preferably has a breaking strength in the direction b of 20 MPa or less. The breaking strength in the direction b is more preferably 15 MPa or less, still more preferably 10 MPa or less. The decomposability is further improved by setting the breaking strength in the direction b to 20 MPa or less. The lower limit of the breaking strength in the direction b is not particularly limited, but is practically 0.5 MPa or more. As a method for setting the breaking strength in the direction b to 20 MPa or less, for example, the filler (C) is set to the above-described preferable content, and the polylactic acid resin (a1) and the biodegradable resin (A) are used as the biodegradable resin (A). The decomposable resin (a2) is contained, the type and content thereof are preferably set as described above, the temperature in the heat treatment step is set in a preferable range in the production method described later, and the magnification in the stretching step is set in a preferable range. And so on. More preferred is a method of combining a plurality of these methods, and still more preferred is a method of combining all of these methods.

(Moisture permeability)
The film of the present invention preferably has a moisture permeability of 200 g / (m ² · day) or more. By setting the moisture permeability to 200 g / (m ² · day) or more, problems such as insufficient moisture permeability and condensation on the high humidity side of the film can be suppressed. The moisture permeability is more preferably 400 g / (m ² · day) or more, and further preferably 500 g / (m ² · day) or more. The upper limit of moisture permeability is not particularly limited, but is 10,000 g / (m ² · day) or less from the characteristics of the resin used and the uniaxially stretched product.

The method for setting the moisture permeability to 200 g / (m ² · day) or more is not particularly limited, but the filler (C) is preferably used as described above, and the polylactic acid resin as the biodegradable resin (A). (A1) and the biodegradable resin (a2) are contained, the type and content thereof are preferably as described above, the temperature in the heat treatment step is within a preferable range in the production method described later, and the stretching step It is mentioned to make the magnification in the preferable range. More preferred is a method of combining a plurality of these methods, and still more preferred is a method of combining all of these methods.

(Thickness)
The film of the present invention preferably has a film thickness of 5 μm or more and 50 μm or less. By setting the film thickness to 5 μm or more, the firmness of the film becomes strong and not only excellent in shape retention but also easy to handle, and roll roll shape and unwinding property are improved. By setting the film thickness to 50 μm or less, the film is excellent in flexibility and decomposability. The film thickness is more preferably 7 μm or more and 45 μm or less, and further preferably 10 μm or more and 40 μm.

(Production method)
Next, the method for producing the film of the present invention will be described in detail, but the present invention is not limited thereby.

  The polylactic acid resin (a1) which is one of the biodegradable resins (A) can be obtained, for example, by the following method. As a raw material, a lactic acid component of L-lactic acid or D-lactic acid is mainly used, and a hydroxycarboxylic acid other than the lactic acid component described above can be used in combination. Further, a cyclic ester intermediate of hydroxycarboxylic acid, for example, lactide, glycolide, etc. can be used as a raw material. Furthermore, dicarboxylic acids and glycols can also be used.

  The polylactic acid resin (a1) can be obtained by a method of directly dehydrating and condensing the raw materials or a method of ring-opening polymerization of the cyclic ester intermediate. It is also known that a high molecular weight polylactic acid-based resin can be obtained by subjecting a cyclic ester intermediate such as lactide to ring-opening polymerization using a catalyst such as tin octylate.

  Contains a composition (raw material) used to produce the film of the present invention, that is, a component such as a biodegradable resin (A), a polymer plasticizer (B), a filler (C), or an organic lubricant. In obtaining a composition, it is possible to produce a composition by uniformly mixing or dispersing a solution in which each component is dissolved in a solvent, and then removing the solvent. However, steps such as dissolution and solvent removal are unnecessary and It is preferable to employ a melt-kneading method for producing a composition by melt-kneading each component, which is a highly productive production method. There are no particular limitations on the melt-kneading method, and a commonly used known mixer such as a kneader, roll mill, Banbury mixer, single-screw or twin-screw extruder can be used. Among these, from the viewpoint of productivity, it is preferable to use a single screw or twin screw extruder.

  The temperature at the time of melt kneading is preferably in the range of 150 ° C. or higher and 240 ° C. or lower, and more preferably in the range of 180 ° C. or higher and 220 ° C. or lower in order to prevent deterioration of the biodegradable resin (A).

  In producing the film of the present invention, for example, when the composition obtained by the above-described method is once pelletized, melt-kneaded again, and extruded to form a film, the pellet is heated at 60 ° C. or higher and 100 ° C. or lower. It is preferable that the moisture content be 500 ppm (mass basis) or less, preferably 200 ppm (mass basis) or less by drying for more than an hour. Furthermore, it is preferable to reduce the amount of the lactic acid oligomer component in the composition containing the polylactic acid resin (a1) or the like by vacuum drying under a high vacuum with a degree of vacuum of 10 Torr or less.

  Although the film of this invention is not limited to this, For example, using the composition obtained by the above-mentioned method, the process of manufacturing an unstretched film, the process of extending a film in one direction (henceforth, extending | stretching) Step) and a step of heating the film (hereinafter referred to as a heat treatment step) can be obtained in this order.

  As a method for producing an unstretched film, a method such as an inflation method or a T-die casting method is preferably used.

  Regarding the stretching process, typical stretching in the length direction is roll stretching utilizing the difference in peripheral speed of the roll, and typical stretching in the width direction is gripping the width direction with a clip and stretching the clip. It is tenter stretching that runs on the rail along the pattern. In the present invention, any of the methods described above may be used for stretching the film in one direction, but from the viewpoint of productivity and simplicity of the apparatus configuration, the method is preferably roll stretching in the longitudinal direction. .

The film of the present invention is preferably stretched in only one direction (hereinafter, the stretched direction is referred to as the stretching direction, and the direction orthogonal to the stretching direction is referred to as the orthogonal direction). By stretching the film in one direction, the Young's modulus in the stretching direction can be increased (therefore, the stretching direction becomes the direction a having the largest Young's modulus), and Ea × T ³ is 1,000 GPa · μm ^3. The range can be set to 60,000 GPa · μm ³ or less, and shape retention can be imparted. Further, when the film of the present invention contains a filler (C), peeling occurs at the interface with the filler (C) during stretching, whereby the porosity is easily controlled to 5% or more and 80% or less. As a result, a film excellent in moisture permeability can be obtained. If the film is stretched in two or more directions (for example, stretched in one direction and then in the orthogonal direction), the production apparatus becomes complicated and the cost increases, and film breaks occur frequently during production. A stable film may not be collected. Furthermore, the shape retention of the obtained film may be reduced. In addition, the Young's modulus Eb in the direction b may be too high, and the above-described decomposability may be deteriorated.

  When the film of the present invention is produced by the T-die casting method, for example, the composition prepared by the method as described above is melt-extruded with an extruder, and then from a slit-shaped die having a lip interval of 0.5 mm or more and 3 mm or less. An unstretched cast film is obtained by discharging and adhering electrostatically onto a metal cooling casting drum set to a surface temperature of 0 ° C. or higher and 40 ° C. or lower.

  When the film of the present invention is produced by the inflation method, for example, the composition prepared by the above-described method is melt-extruded by an extruder, led to an annular die, and extruded from the annular die. Then, dry air is supplied from the center of the annular die to form bubbles, further air-cooled and solidified uniformly with an air ring, taken up at a predetermined speed while folded flat with a nip roll, and then both ends or one as required It is only necessary to cut the end of the wire and wind it up. If the bubble blow ratio and draw ratio are too low or too high, it is difficult to obtain a film having the desired decomposability and shape retention. It tends to be stable. The blow ratio is preferably 1.3 or more and 3.5 or less from the relationship between decomposability and film width. When the blow ratio is higher than 1.3, stable bubbles can be formed, a film can be obtained with a good width, and when it is 3.5 or less, good decomposability can be obtained. The draw ratio is preferably 15 or more and 50 or less.

When performing roll stretching in the machine direction on the unstretched film thus obtained, for example, the following method can be applied. First, the temperature is raised to a temperature at which longitudinal stretching is performed by conveying an unstretched film on a heating roll. An auxiliary heating means such as an infrared heater may be used in combination for raising the temperature. A preferable range of the stretching temperature is preferably 40 ° C. or more and 90 ° C. or less when an unstretched film is obtained by the T-die method. Moreover, when an unstretched film is obtained by the inflation method, it is preferably 50 ° C. or higher and 110 ° C. or lower. The unstretched film heated in this way is stretched in one or two or more stages in the longitudinal direction of the film using a difference in peripheral speed between heating rolls. The stretching ratio in the stretching process (the stretching ratio here means the product of the stretching ratios of each stage when stretching is performed in multiple stages) is obtained when an unstretched film is obtained by the T-die method. It is preferably 2.5 to 7 times, more preferably 4 to 6 times. The production method can be appropriately selected depending on the intended film physical properties, and when the degradation of the film is desired or when the film of the present invention contains a filler (C), a vertical gap is formed in the stretching process. T-die method may be used, also the Ea × T ³ enhanced in terms of easily enhancing the easy moisture permeability, if you want more enhanced shape retention, crystallization proceeds readily in making an unstretched film As a result, the inflation method is preferable in that a film with a higher degree of crystallinity can be obtained.

Next, the stretched film is heat-treated under tension with a fixed length in the stretching direction or while relaxing in the stretching direction. A preferable heat treatment temperature in this heat treatment step is 50 ° C. or higher and 110 ° C. or lower. In the present invention, by setting the heat treatment temperature in the range of 50 ° C. or more and 110 ° C. or less, not only imparting dimensional stability, but also controlling Ea × T ³ to the above range, the elongation at break in the direction b, Breaking strength can be made into the above-mentioned range, and decomposability can be improved more. The heat treatment time is preferably in the range of 0.2 seconds to 30 seconds, but is not particularly limited. Further, when relaxation is performed in the stretching direction after stretching, the relaxation rate is preferably 1% or more and 10% or less, and more preferably 3% or more and 5% or less.

  The film of the present invention is excellent in shape retention and decomposability. Moreover, when a space | gap is formed in the inside among this invention, it will have high moisture permeability, and it will have the especially outstanding moisture permeability especially by making a porosity into 5% or more and 80% or less. Therefore, the film of the present invention is suitable for applications requiring shape retention and decomposability, and further suitable for applications requiring moisture permeability in addition to shape retention and decomposability. Specifically, agricultural materials such as various labels, cards, labels, adhesive tapes and multi-films, forestry materials such as fumigation sheets, bed sheets, pillow covers, sanitary materials such as sanitary napkins and paper diapers, and for rainy weather It can be preferably used for clothing materials such as clothing and gloves, garbage bags and compost bags, food bags such as vegetables and fruits, and various packaging materials for industrial products.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereto.
[Measurement and evaluation method]
Measurements and evaluations shown in the examples were performed under the following conditions.

(1) Mechanical properties (Young's modulus Ea in direction a, Young's modulus Eb in direction b, breaking strength, breaking elongation)
Using TENSILON (registered trademark) UCT-100 manufactured by Orientec Co., Ltd., measurement was performed in an atmosphere at room temperature of 23 ° C. and relative humidity of 65%. Specifically, a sample was cut out into a strip shape having a length of 150 mm and a width of 10 mm, and 10 times according to the method prescribed in JIS K-7127 (1999) at an initial tensile chuck distance of 50 mm and a tensile speed of 200 mm / min. Measurements were made, and the average values were taken as Young's modulus, elongation at break, and strength at break, respectively.

  When determining the direction in which the Young's modulus is maximized, any direction is set to 0 °, and the direction is changed every 10 ° from −90 ° to 90 ° in the film plane. The direction (direction a) in which the rate becomes maximum was determined, and the Young's modulus Ea was determined. Subsequently, Young's modulus Eb, breaking elongation, and breaking strength in a direction (direction b) perpendicular to the same plane as direction a were determined.

  Further, the thickness T of the film was measured at 10 places by using a dial gauge No2110S-10 manufactured by Mitutoyo, and the thickness T was determined by the average value.

Using the obtained Young's modulus Ea value and film thickness value, Ea × T ³ was determined.

(2) Ten samples obtained by cutting the basis weight film into a size of 100 mm × 100 mm were prepared, and 10 sheets were stacked, and the weight w (g) was measured with an electronic balance. Using the obtained weight w (g), the basis weight of the film was determined by the following formula.
Weight per unit area (g / m ² ) = w × 10
The measurement was performed 5 times, and the average value was used as the basis weight of the film.

(3) Porosity (%)
The film was cut into a size of 30 mm × 40 mm and used as a sample. Using an electronic hydrometer (SD-120L manufactured by Mirage Trading Co., Ltd.), the specific gravity was measured in an atmosphere at a room temperature of 23 ° C. and a relative humidity of 65%. The measurement was performed three times, and the average value was defined as the specific gravity ρ of the film.

  Next, the measured film was hot-pressed at 240 ° C. and 5 MPa, and then rapidly cooled with water at 25 ° C. to prepare a sheet from which voids were eliminated. The specific gravity of this sheet was measured in the same manner as described above, and the average value was defined as the specific gravity (d) of the resin. From the specific gravity of the film and the specific gravity of the resin, the porosity was calculated by the following formula.

Porosity (%) = [(d−ρ) / d] × 100
(4) Moisture permeability Moisture permeability (g / (m ² · day)) was measured with a constant temperature and humidity apparatus set at 25 ° C. and 90% RH according to the method defined in JIS Z0208 (1976).

(5) For the shape-retaining film, a sample parallel to the direction a obtained in (1) is set to 150 mm in length, a direction perpendicular to the length is set to 10 mm, and a sample is cut into a strip shape. Put. Attach a weight of 200 g to one end of one side and suspend it in that state for 1 hour. Then, the sample was taken out, the dimension between marked lines was measured, and the deformation rate was calculated according to the following formula. The measurement was performed 5 times per level, and the deformation rate in the direction a was determined from the average value of the 5 measurements.
Deformation rate (%) = [{(Dimension after holding) − (Dimension before holding)} / (Dimension before holding)] × 100
The obtained deformation rate was evaluated according to the following criteria.
S: 0% or more and 1% or less.
A: Over 1% and 2% or less.
B: More than 2% and 3% or less.
C: More than 3% and 5% or less.
D: Greater than 5%.

(6) Degradability Put 800 ml of water into a 2000 ml beaker, put 4 test pieces cut into 5 cm × 5 cm, take out the film after stirring for 48 hours at 23 ° C. and 750 rpm with a magnetic stirrer, and disassemble it. The number of test pieces was observed.
Evaluation was performed according to the following criteria using the number of the test pieces.
A: 12 sheets or more.
B: 8 or more and 11 or less.
C: 5 or more and 7 or less.
D: It remains as 4 sheets and is not disassembled.

[Biodegradable resin (A) (polylactic acid resin (a1)]
(A11)
Crystalline polylactic acid resin, mass-average molecular weight = 200,000, D-form content = 1.4 mol%, melting point = 166 ° C., biodegradability = 99% (40 days, JIS K6955-2 (2010))
(A12)
Amorphous polylactic acid resin, mass average molecular weight = 200,000, D-form content = 12.0 mol%, melting point = none, biodegradability = 99% (40 days, JIS K6953-2 (2010))
In addition, said mass mean molecular weight was measured using Japan Waters Co., Ltd. product Waters2690, polystyrene as a standard, column temperature of 40 degreeC, and the chloroform solvent.

  The above melting point was determined by heating a polylactic acid resin in a hot air oven at 100 ° C. for 24 hours, using a differential scanning calorimeter RDC220 manufactured by Seiko Instruments Inc., and setting 5 mg of a sample in an aluminum tray. It was determined as the peak temperature of the crystal melting peak when the temperature was raised from 250C to 250C at a heating rate of 20C / min.

[Biodegradable resin (A) (Biodegradable resin (a2) other than polylactic acid resin (a1))]
(A2)
Polybutylene succinate resin (trade name “GSPla” (registered trademark) AZ91T, manufactured by Mitsubishi Chemical Corporation), biodegradability = 85% (40 days, JIS K6953-2 (2010))
[Polymer plasticizer (B)]
62 parts by mass of polyethylene glycol having a number average molecular weight of 8,000, 38 parts by mass of L-lactide and 0.05 parts by mass of tin octylate are mixed and polymerized in a reaction vessel equipped with a stirrer at 160 ° C. for 3 hours in a nitrogen atmosphere. As a result, a block copolymer plasticizer having polylactic acid segments having a number average molecular weight of 2,500 at both ends of polyethylene glycol having a number average molecular weight of 8,000 was obtained. Biodegradation = 80% (300 days, JIS K6953-2 (2010))
[Filler (C)]
Calcium carbonate (Ajinomoto Fine Techno Co., Ltd., trade name “Topflow H200”, average particle size: 1.7 μm, surface treatment agent: phosphate compound)
(Example 1)
As the biodegradable resin (A), a crystalline polylactic acid resin (a11) 6 mass%, an amorphous polylactic acid resin (a12) 18 mass%, and a biodegradable resin other than the polylactic acid resin (a1) ( a2) A mixture of 16% by mass, polymer plasticizer (B) 20% by mass, and filler (C) 40% by mass was supplied to a twin screw extruder with a cylinder diameter of 190 ° C. and a screw diameter of 44 mm with a vacuum vent. The composition was melt-kneaded while degassing, homogenized and then pelletized to obtain a composition.

  The dried composition pellets were supplied to a single screw extruder having a cylinder temperature of 180 ° C., and bubble-shaped at a blow ratio of 2.1 from a spiral annular die having a diameter of 250 mm, a lip clearance of 1.3 mm, and a temperature of 160 ° C. , Rolled up with a nip roll above the die, taken up while being folded, cut at both ends with an edge cutter and cut into two pieces, each wound with a winder to obtain a film with a final thickness of 100 μm It was. At this time, the draw ratio was 6. Table 1 shows the physical properties of the obtained film.

  This unstretched film is guided to a roll-type stretching machine, stretched 5 times in the length direction at a temperature of 90 ° C., once cooled on a cooling roll, and then heat-treated through a roll at a temperature of 90 ° C. to form a film having a thickness of 11 μm Got. Table 1 shows the physical properties of the obtained film. In addition, the direction a and the extending | stretching direction corresponded.

(Examples 2-5, 7, 8, 11-14, 16-18, 20, Comparative Examples 1, 3-5)
A film shown in the table was obtained in the same manner as in Example 1 except that the composition and production conditions of the film were changed as shown in Table 1. Table 1 shows the physical properties of the obtained film. In either case, the direction a and the stretching direction were the same.

(Example 6)
A pelletized composition was obtained in the same manner as in Example 1.

  The pellets of this composition were vacuum-dried at a temperature of 60 ° C. for 12 hours using a rotary drum type vacuum dryer. Pellets of this composition were supplied to a single screw extruder having a cylinder temperature of 190 ° C., extruded into a film at a T die die temperature of 190 ° C., and cast on a drum cooled to 20 ° C. to produce an unstretched film. This unstretched film is guided to a roll-type stretching machine, stretched four times in the length direction at a temperature of 70 ° C., once cooled on a cooling roll, and then heat-treated through a roll at a temperature of 70 ° C. to form a film having a thickness of 15 μm. Got. Table 1 shows the physical properties of the obtained film. In addition, the direction a and the extending | stretching direction corresponded.

(Examples 9, 10, 15, 19, 21 and Comparative Examples 2 and 6)
A film shown in the table was obtained in the same manner as in Example 6 except that the composition and production conditions of the film were changed as shown in Table 1. Table 1 shows the physical properties of the obtained film. In either case, the direction a and the stretching direction were the same.

  According to the present invention, a film excellent in shape retention and decomposability is provided. Moreover, when a space | gap is formed in the inside among this invention, it has higher moisture permeability. The film of the present invention can be preferably used for applications that mainly require shape retention and decomposability. Specifically, agricultural materials such as various labels, cards, labels, adhesive tapes and multi-films, forestry materials such as fumigation sheets, bed sheets, pillow covers, sanitary materials such as sanitary napkins and paper diapers, and for rainy weather It can be preferably used for clothing materials such as clothing and gloves, garbage bags and compost bags, food bags such as vegetables and fruits, and various packaging materials for industrial products.

Claims (8)

Containing a biodegradable resin (A),
When the thickness of the film is T (μm) and the Young's modulus in the direction where the Young's modulus is the largest (direction a) is Ea (GPa), Ea × T ³ is 1,000 GPa · μm ³ or more and 60,000 GPa · μm ³ or less. And
A film having a basis weight of 10 g / m ² or more and 50 g / m ² or less.   The film according to claim 1, wherein the ratio Ea / Eb is 1.2 or more, where Eb (GPa) is a Young's modulus in a direction (direction b) orthogonal to the direction a.   The film of Claim 1 or 2 whose Young's modulus Ea of the direction a is 1 GPa or more and 3 GPa.   The film in any one of Claims 1-4 whose porosity is 5% or more and 80% or less.   The film in any one of Claims 1-4 which contains polylactic acid-type resin (a1) as said biodegradable resin (A). Containing a biodegradable resin (a2) other than the polylactic acid resin (a1) as the biodegradable resin (A),
Furthermore, the film in any one of Claims 1-5 containing a polymeric plasticizer (B).   The polymer-based plasticizer (B) is a block copolymer having a polyether segment and a polylactic acid segment and / or a block copolymer having a polyester segment and a polylactic acid segment. The film described.   The film according to claim 6 or 7, wherein the content of the polymer plasticizer (B) is 3% by mass or more and 20% by mass or less in 100% by mass of the entire film.