JP2009292158A - Aliphatic polyester-based film and moistureproof aliphatic polyester-based film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aliphatic polyester-based film keeping moistureproofness even if forming a vapor deposited film, and a moistureproof aliphatic polyester-based film formed with the vapor deposited film thereon. <P>SOLUTION: The aliphatic polyester-based film includes at least three layers, at least one layer out of two outermost layers is an inorganic particle-containing layer. Assuming the thickness of the inorganic particle-containing layer as a μm, the maximum particle size of the inorganic particle size as b μm, and an average particle size of the inorganic particles as c μm, all of following expressions 1-4 are satisfied simultaneously, and a static friction coefficient is set to 0.8 or less: (1) 1≤a≤15; (2) 0.5≤b≤2.5a; (3) 0.1≤c≤5; and (4) c≤a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a biaxially oriented aliphatic polyester film and an aliphatic polyester film imparted with moisture resistance to the film.

  Many of the conventional plastic products, especially plastic packaging materials, are often discarded immediately after use, and problems with their processing have been pointed out. Typical examples of general packaging plastics include polyethylene, polypropylene, and PET. However, these materials generate a large amount of heat during combustion, and may damage the combustion furnace during the combustion process. Furthermore, even today, polyvinyl chloride, which is used in large quantities, cannot be burned due to self-extinguishing properties. In addition, plastic products, including materials that cannot be incinerated, are often landfilled. However, due to their chemical and biological stability, they remain almost undecomposed and shorten the life of landfills. I am waking up. On the other hand, a low heat of combustion, decomposition in the soil, and safety are desired, and many studies have been conducted.

  One example is polylactic acid. Polylactic acid has a heat of combustion less than half that of polyethylene, and naturally undergoes hydrolysis in soil and water, and then becomes a harmless decomposition product by microorganisms. Currently, studies are being made to obtain molded articles, specifically containers such as films, sheets and bottles, using polylactic acid.

By the way, when producing a film made of polylactic acid, if the film slips poorly, during film production or in secondary processing such as printing or laminating, when winding continuously with a winder or the like, , Causing wrinkles.
On the other hand, a film having improved surface slipperiness by incorporating inorganic particles or the like in the film has been studied.

  However, when forming a vapor-deposited film on the above-described improved slippery film to impart moisture resistance, pinholes are generated due to falling off or movement of the inorganic particles in rewinding the moisture-proof film. , Dampproofness may be reduced.

  Accordingly, an object of the present invention is to provide an aliphatic polyester film that retains moisture resistance even when a deposited film is formed, and a moisture-proof aliphatic polyester film that has a deposited film formed thereon.

This invention relates to a coextruded biaxially oriented aliphatic polyester film comprising at least three layers, wherein at least one of the two outermost layers is an inorganic particle-containing layer, and the thickness of the inorganic particle-containing layer is defined as a (Μm), where the maximum particle size of inorganic particles is b (μm) and the average particle size of inorganic particles is c (μm), all of the following formulas (1) to (4) are satisfied simultaneously. By solving this problem, the above-mentioned problems have been solved.
1 ≦ a ≦ 15 (1)
0.5 ≦ b ≦ 2.5a (2)
0.1 ≦ c ≦ 5 (3)
c ≦ a (4)

  In addition, at least one side of the inorganic particle-containing layer constituting the aliphatic polyester film is selected from the group consisting of magnesium, silicon, tantalum, titanium, boron, calcium, barium, carbon, and manganese with aluminum as a main component. Furthermore, a moisture-proof aliphatic polyester film can be obtained by forming a thin film layer of an alloy containing at least one element.

  Since the thickness of the inorganic particle-containing layer, the maximum particle diameter and the average particle diameter of the inorganic particles are set in a predetermined relationship, even if a vapor deposition film is formed, the generation of pinholes is suppressed and moisture resistance is maintained. .

  According to the present invention, since the thickness of the inorganic particle-containing layer, the maximum particle diameter and the average particle diameter of the inorganic particles are set in a predetermined relationship, the generation of pinholes is suppressed even when the vapor deposition film is formed, and the moisture proof Sex is preserved.

  In addition, the slipperiness, transparency and heat resistance of the film are improved.

Embodiments of the present invention will be described below.
The aliphatic polyester film according to the present invention is a coextruded biaxially oriented aliphatic polyester film comprising at least three layers, and at least one of the two outermost layers on the front and back surfaces is an inorganic particle-containing layer.

  The said aliphatic polyester is resin which has a polylactic acid-type polymer as a main component. The polylactic acid-based polymer refers to a polymer mainly composed of L-, D-, or DL-lactic acid units, and is a polymer containing only polylactic acid, or L-, D-, or DL-lactic acid. Examples thereof include copolymers with hydroxycarboxylic acid, aliphatic dicarboxylic acid (including alicyclics, the same shall apply hereinafter) and / or aliphatic diols and containing 50% or more of a polylactic acid component.

  As a polymerization method for the polylactic acid polymer, known methods such as a condensation polymerization method and a ring-opening polymerization method can be employed. For example, in the condensation polymerization method, a polylactic acid polymer having an arbitrary composition can be obtained by direct dehydration condensation polymerization of L-lactic acid, D-lactic acid, or a mixture of these and other monomers. .

  Further, in the ring-opening polymerization method (lactide method), lactide, which is a cyclic dimer of lactic acid, is used with a selected catalyst while using a polymerization regulator as necessary. A polylactic acid polymer can be obtained by mixing and polymerizing these monomers.

  The preferred range of the weight average molecular weight of the polylactic acid polymer used in the present invention is 60,000 to 700,000, more preferably 60,000 to 400,000, and particularly preferably 60,000 to 300,000. When the molecular weight is less than 60,000, practical properties such as mechanical properties and heat resistance are hardly exhibited, and when it is more than 700,000, the melt viscosity is too high and the molding processability may be inferior.

  The weight average molecular weight of the polylactic acid polymer constituting the inorganic particle-containing layer is not less than the weight average molecular weight of the polylactic acid polymer constituting at least one intermediate layer sandwiched between the two outermost layers. It is preferable that the inorganic particles contained in the surface layer are partly buried on the intermediate layer side and are difficult to fall off.

That is, when the weight average molecular weight of the polylactic acid constituting the inorganic particle-containing layer is X and the weight average molecular weight of the polylactic acid constituting at least one of the intermediate layers is Y, the following formula is preferably satisfied. .
60,000 ≦ Y ≦ X

  The ratio of L-lactic acid and D-lactic acid in the polylactic acid-based polymer in the aliphatic polyester constituting at least one of the inorganic particle-containing layer and the intermediate layer is 100: 0-94: 6 or 6: 94-0: 100 is preferable. If it is smaller than 94: 6 or larger than 6:94, it cannot be sufficiently crystallized in the heat treatment after stretching, and the thermal shrinkage rate of the film may not be suppressed. In addition, orientation may be relaxed after stretching, and physical properties may not be improved due to the orientation effect. Furthermore, as will be described later, the inorganic particles blended at the time of stretching protrude to roughen the surface and improve the slipperiness of the film. However, in the polylactic acid polymer having low crystallinity or not crystallizing, In some cases, the inorganic particles protruding along with the relaxation of the orientation are buried again inside the film, and a film with good sliding cannot be obtained. In this invention, it is very important to use the polylactic acid polymer in the above-mentioned range having high crystallinity together with the blending of the inorganic particles in the production of the oriented film through the heat treatment step.

  Further, the content of the polylactic acid polymer in the aliphatic polyester constituting at least one of the inorganic particle-containing layer and the intermediate layer is preferably 70% by weight or more, and more preferably 80% by weight or more. If it is less than 70% by weight, the heat resistance may be inferior.

  Other monomers such as hydroxycarboxylic acid, aliphatic dicarboxylic acid, or aliphatic diol copolymerized with the polylactic acid include the following. That is, when lactic acid has lactic acid having a predetermined optical isomer, lactic acid having other optical isomers (for example, D-lactic acid for L-lactic acid and L-lactic acid for D-lactic acid) is listed. It is done. Examples of the hydroxycarboxylic acid include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2 -Bifunctional aliphatic hydroxycarboxylic acids such as methyl lactic acid and 2-hydroxycaproic acid and lactones such as caprolactone, butyrolactone and valerolactone.

  Examples of the aliphatic dicarboxylic acid include aliphatic dicarboxylic acids such as succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanedioic acid, and anhydrides and derivatives thereof. Examples of the aliphatic diol include aliphatic diols such as ethylene glycol, butanediol, hexanediol, octanediol, cyclopentanediol, cyclohexanediol, and cyclohexanedimethanol, or derivatives thereof. In any case, the main component is a bifunctional compound having an alkylene group or cycloalkylene group having 2 to 10 carbon atoms. Of course, two or more of these carboxylic acid components or alcohol components may be used.

In addition, the aliphatic polyester as a small amount copolymerization,
(A) a carboxylic acid, alcohol or hydroxycarboxylic acid unit having three or more functional groups,
(B) a non-aliphatic dicarboxylic acid unit and / or a non-aliphatic diol unit,
And may contain small amounts of chain extender residues.

  The unit (a) is used for the purpose of providing a branch in the polymer for improving the melt viscosity. Specifically, malic acid, tartaric acid, citric acid, trimellitic acid, pyromellitic acid, pentaerythritol, A multifunctional component such as trimethylolpropane is exemplified. If these components are used in a large amount, the resulting polymer will have a crosslinked structure and will not be thermoplastic, or even if it is thermoplastic, a microgel having a highly crosslinked structure will be formed, and when it is made into a film, There is a risk of becoming. Therefore, the proportion of these polyfunctional components contained in the polymer is very small and is limited to such an extent that the chemical properties and physical properties of the polymer are not greatly affected.

  In the above (b), specific examples of the non-aliphatic dicarboxylic acid include terephthalic acid, and the non-aliphatic diol includes an ethylene oxide adduct of bisphenol A.

The aliphatic polyester contains a polylactic acid-based polymer as a main component, but may contain other resin components (hereinafter referred to as “other resin components”). From the viewpoint of transparency, it is preferably 30% by weight or less, and more preferably 20% by weight or less. Examples of other resin components include aliphatic polyesters other than polylactic acid polymers. Aliphatic polyesters other than polylactic acid-based polymers include polymers of hydroxycarboxylic acids other than lactic acid, polyesters composed of aliphatic dicarboxylic acids and / or aliphatic diols, and the like. The hydroxycarboxylic acid, aliphatic dicarboxylic acid and aliphatic diol used here are the same as described above.
Further, the aliphatic polyester may contain the same small amount of copolymerized units as described above, or may contain a small amount of chain extender residue.

  In order to adjust the polyester comprising the aliphatic carboxylic acid and the aliphatic diol, a known method such as a direct method or an indirect method can be employed. For example, the direct method is a method in which an aliphatic carboxylic acid and an aliphatic diol are directly polymerized while removing water contained in these components or generated during polymerization to obtain a high molecular weight product. The indirect method is an indirect production method in which the polymer is polymerized to the level of an oligomer and then increased in molecular weight using a small amount of chain extender, as in the case of the polylactic acid polymer.

The weight average molecular weight of the other resin component is preferably 50,000 to 250,000. When the weight average molecular weight is less than 50,000, the properties as a polymer are inferior, and in particular, not only does not lead to improvement in heat sealability, but also causes problems such as bleeding on the film surface over time. On the other hand, if it is larger than 250,000, the melt viscosity becomes too high, resulting in a decrease in miscibility with polylactic acid and a decrease in extrusion moldability when forming a film in the same manner as polylactic acid.
In addition, it is preferable that the glass transition point (Tg) of other resin components is 0 degreeC or less from the point of the impact-resistant improvement effect and cold resistance.

  Particularly preferred other resin components include, for example, polyethylene suberate, polyethylene sebacate, polyethylene decanedicarboxylate, polybutylene succinate, polybutylene adipate, polybutylene sebacate, polybutylene succinate adipate and copolymers thereof. can give.

  In this invention, together with the other resin component or in place of the other resin component, a block copolymer of the polylactic acid polymer and the other resin component (partially transesterified product, small amount of chain extender residue) Can also be used). This block copolymer can be prepared by any method. For example, either a polylactic acid polymer or another resin component is separately prepared as a polymer, and the other constituent monomer is polymerized in the presence of this polymer. Usually, a block copolymer of polylactic acid and another resin component is obtained by polymerizing lactide in the presence of another resin component prepared in advance. Basically, the polymerization can be carried out in the same manner as in the case of preparing a polylactic acid polymer by the lactide method, except that the other resin component is allowed to coexist. At this time, lactide polymerization proceeds, and at the same time, an appropriate transesterification reaction occurs between the polylactic acid and the other resin components, and a copolymer having relatively high randomness is obtained. When an aliphatic polyester urethane having a urethane bond is used as a starting material, ester-amide exchange is also generated.

  The inorganic particles contained in the inorganic particle-containing layer are inorganic substance particles. Examples of the inorganic substance constituting the inorganic particles include silicon dioxide such as silica, calcium carbonate, magnesium carbonate, talc, titanium dioxide, kaolin, and alumina. Preferably, silicon dioxide such as silica, calcium carbonate, carbonate Examples thereof include magnesium, talc, titanium dioxide, and kaolin, and silicon dioxide such as silica is particularly preferable. Furthermore, it is preferable to use the chain-like silicon dioxide particles because there is little dropout of the particles during film production, anchor coating, and thin film formation process. The inorganic particles may be used alone or in combination of two or more.

  The blending amount of the inorganic particles is preferably 0.01 to 6 parts by weight, more preferably 0.01 to 5 parts by weight, and more preferably 0.01 to 100 parts by weight of the aliphatic polyester in the inorganic particle-containing layer. 1 part by weight is more preferred. If the amount is less than 0.01 part by weight, the effect of imparting lubricity may not be obtained. On the other hand, when the amount is more than 6 parts by weight, dropout of particles or deterioration of transparency may occur.

  Further, in a film that requires transparency, it is desirable to reduce the blending amount of the inorganic particles as much as possible. Moreover, even if the blending amount is reduced, it is difficult to obtain a transparent film if the particle size is large. Haze can be used as the definition of transparency. This can be measured by JISK 7105. The haze is preferably 10% or less. If the haze exceeds 10%, sufficient transparency may not be obtained.

  Furthermore, when it is desired to obtain transparency, although it depends on the kind and particle size of the inorganic particles to be blended and the thickness of the film, it is preferably about 0.5 parts at most. If it is added more, the haze of the film exceeds 10% and the clearness is lacking.

Further, as will be described later, in order to impart moisture resistance, it is necessary to prevent the occurrence of pinholes when forming a thin film layer. Therefore, when the thickness of the inorganic particle-containing layer is a (μm), the maximum particle size of the inorganic particles is b (μm), and the average particle size of the inorganic particles is c (μm), the following formula ( It is necessary to satisfy all of 1) to (4) at the same time.
1 ≦ a ≦ 15 (1)
0.5 ≦ b ≦ 2.5a (2)
0.1 ≦ c ≦ 5 (3)
c ≦ a (4)

  When the thickness of the inorganic particle-containing layer is thinner than 1 μm, it becomes difficult to substantially support the contained particles, and the particles easily fall off. On the other hand, when it is thicker than 15 μm, it is difficult to impart surface properties necessary for imparting slipperiness. A more preferable thickness is 1.5 to 10 μm.

  On the other hand, if the maximum particle size of the inorganic particles is smaller than 0.5 μm, the slipperiness suitable for the running property of the film cannot be imparted. On the other hand, if it is larger than 2.5 times the thickness of the inorganic particle-containing layer, sufficient moisture resistance cannot be imparted. A more preferable maximum particle size is 2.0 to 15 μm and at the same time satisfies the above formula (2).

Furthermore, as the average particle size of the inorganic particles is larger, the surface of the film is roughened, the slipperiness is improved, and the friction coefficient is reduced. However, if the average particle size of the inorganic particles is smaller than 0.1 μm, the effect of imparting lubricity is too low. On the other hand, if it is larger than 5 μm, the surface smoothness is lowered, the particles are likely to fall off, and when a thin film for imparting a moisture-proofing effect to the film is formed, a thin film is lost and a pinhole is generated. In the case of inorganic particles having high hardness, scratches or the like occur in the thin film when they are rubbed between the film surfaces. A more preferable average particle diameter is 0.4 to 4.5 μm. Further, when an inorganic thin film is provided for the purpose of imparting moisture resistance, it is possible to impart good moisture resistance (10 g / m ² · 24 hr or less) by further selecting the particle size within the scope of the present invention. it can. The average particle size of the inorganic particles can be measured using a sedimentation balance type measurement method, a Coulter counter measurement method, a light scattering method, or the like.

  Further, the average particle size of the inorganic particles is not more than the thickness of the inorganic particle-containing layer. If the average particle size of the inorganic particles is larger than the thickness of the inorganic particle-containing layer, the particles are likely to fall off.

A coextrusion method is employed as a method for producing the multilayer biaxially oriented polylactic acid film according to the present invention. Hereinafter, an example of lamination by this coextrusion method will be described.
First, an aliphatic polyester mainly composed of a polylactic acid-based polymer that forms each layer, inorganic particles, and the like are supplied to an extrusion apparatus for coextrusion lamination.
These may be preliminarily extruded into a strand shape by another extruder to produce pellets.
In any case, a decrease in molecular weight due to decomposition must be taken into consideration, but the latter is better selected for uniform mixing.

  The aliphatic polyester is sufficiently dried to remove moisture, and then melted with an extruder. The melting point of the polylactic acid polymer is appropriately selected in consideration of the melting point changing depending on the composition ratio of the L-lactic acid structure and the D-lactic acid structure, and the melting point of the aliphatic polyester and the mixing ratio. In practice, a temperature range of 100 to 250 ° C. is usually selected.

  Laminate using 2 or 3 or more multi-manifolds or feed blocks and extrude as a molten sheet of 3 or more layers from a slit-shaped die. At that time, the thickness of each layer is a quantitative feeder such as a gear pump installed in the melt line Can be set by adjusting the flow rate of the polymer. Further, the inorganic particles are supplied into the molten resin in the multi-manifold or the feed block for constituting the outer layer.

Next, the molten sheet extruded from the die is rapidly cooled and solidified on the rotating cooling drum below the glass transition temperature to obtain a substantially amorphous unoriented sheet. At this time, it is preferable to improve the adhesion between the sheet and the rotating cooling drum for the purpose of improving the smoothness and thickness of the sheet. In this invention, the electrostatic application adhesion method and / or the liquid application adhesion method are used. Preferably it is used.
In order to adjust various physical properties, a heat stabilizer, a light stabilizer, a light absorber, a plasticizer, an inorganic filler, a colorant, a pigment, and the like can be added to these mixtures.

In the film thus obtained, when the draw ratio is low, the particles do not protrude on the film surface. For this reason, in order to make the particles protrude and improve the surface roughness of the film, it is necessary to sufficiently orient the film. Specifically, an oriented film (hereinafter referred to as “biaxially oriented aliphatic polyester film”) is preferably obtained by biaxial stretching. The orientation index at this time is preferably 3.0 × 10 ⁻³ or more in terms of the plane orientation ΔP. In order to achieve this, it is necessary to stretch at least 1.5 times in one axial direction.

  This biaxially oriented aliphatic polyester film is stretched in the biaxial direction and then heat-treated while being fixed. As a result, a heat-fixed biaxially oriented aliphatic polyester film is obtained. It is preferable that the shrinkage rate at 80 ° C. in at least one of the longitudinal direction and the transverse direction of the film is 10% or less. If the shrinkage rate exceeds 10%, heat shrinkage tends to occur, which is not preferable.

  The resulting multilayer biaxially oriented aliphatic polyester film preferably has a surface roughness Ra (centerline average roughness) of 0.01 <Ra ≦ 0.08, and in this range, Rz (ten points). The average roughness is more preferably 2.0 or less. The larger the Ra, the rougher the surface of the film and the higher the slipperiness. However, if Ra is too large, the smoothness of the film will be inferior. Rz can be used as an index of smoothness. The larger this value compared to Ra, the more uneven the film (roughness), and there is no uniformity. The closer the Ra value, the more uniform the unevenness. Ra and Rz can be measured according to JIS B 0601.

  The friction coefficient of the multilayer biaxially oriented aliphatic polyester film is preferably 0.8 or less, preferably 0.5 or less, and more preferably 0.3 or less in terms of static friction coefficient. The friction coefficient includes a static friction coefficient and a dynamic friction coefficient. Generally, when the static friction coefficient is small, the dynamic friction is also small. Further, the static friction coefficient is larger than the dynamic friction coefficient. The film is produced continuously and is usually rolled. At this time, since the films are in contact with each other, if the coefficient of friction of the film is large, the films do not slip and cannot be wound uniformly and cleanly. In addition, the subsequent vapor deposition process and film processing, for example, printing, laminating, and bag making are also problematic, and in some cases, static electricity is generated, and productivity may be significantly reduced. For this reason, when it evaluates by a static friction coefficient, it is good to satisfy said requirements.

  As an application of the obtained biaxially oriented aliphatic polyester film, an adhesive may be applied on the film surface and bonded to paper, metal thin film, other plastic films, etc. The film is shrunk due to the warm heat, and problems such as deterioration of the appearance such as wrinkles and curling of the laminate easily occur. For this reason, in order to give moisture resistance to the obtained biaxially oriented aliphatic polyester film, the thin film layer is preferably formed by a vapor deposition method. By depositing this thin film layer on the aliphatic polyester, a moisture-proof aliphatic polyester film can be obtained.

  Examples of the vapor deposition method include known methods such as EB vapor deposition, induction heating vapor deposition, magnetron sputtering, and CVD. If necessary, ion bombardment may be performed by introducing a little air or oxygen for the purpose of improving adhesion. The minimum with which sufficient moisture resistance of the thickness of an inorganic thin film can be provided is 20 nm, and the upper limit of economical thickness is 100 nm. A more preferable range is 30 to 70 nm.

  The thin film layer is preferably an inorganic thin film, and pure aluminum (99.9 at% or more) can be used as this material. In addition to this, aluminum as a main component is made 90.0 to 99.8 at%. , Magnesium, silicon, tantalum, titanium, boron, calcium, barium, carbon, manganese containing at least one additive element selected from the group of 0.2 to 10.0 at% is preferable, and aluminum is 92 to A material containing 99.5 at% and containing an additive element of 0.5 to 8 at% is preferable. Compared to pure aluminum, the crystal of the thin film layer is made finer, so that the path of the permeate gas becomes longer, the strength of the thin film is improved, and the additive particles forming irregularities on the surface fall off. This is thought to be difficult. In order to improve the glossiness of the film, the upper limit of the additive amount of the additive element is preferably 10 at% or less, more preferably 8 at% or less.

  In applications where transparency is particularly necessary, a thin film made of the above-mentioned material that has been oxidized or nitrided may be used. In the vapor deposition method, an oxide or nitride having a low reaction order is irradiated and heated in advance in a high vacuum container with an electron beam or the like. At this time, the reaction order is controlled by appropriately introducing some oxygen and nitrogen. In the sputtering method, the target film can be manufactured by using an alloy target and forming a film while mixing and reacting an appropriate amount of nitrogen and / or oxygen with argon gas.

  For the purpose of improving the adhesion between the thin film layer and the aliphatic polyester film serving as the substrate, anchor coating may be performed before forming the thin film layer. The thickness of this anchor coat is preferably 0.01 to 5 μm, more preferably 0.1 to 2 μm. The anchor coat layer is not particularly limited as long as it is a resin that is conventionally used as an undercoat layer when vapor deposition is performed on a film, but in consideration of environmental problems after biodegradation of the base material, a polyester resin or a polyurethane resin It is preferable that it is 1 or more types selected from polyacrylic resin, polyvinyl alcohol resin, and polyolefin resin.

  As the solvent for the coating resin, alcohol solvents such as methyl alcohol, ethyl alcohol, isopropanol, cyclohexane, dimethylformamide, ethyl acetate, benzene, acetone, tetrahydrofuran, dioxane, chloroform can be used. From the viewpoint of adhesion to the polymer, it is preferable to use one or two or more mixed solvents selected from the group consisting of alcohol solvents such as methyl alcohol, ethyl alcohol and isopropanol, cyclohexane, dimethylformamide, ethyl acetate and benzene.

  By applying the anchor coat, the adhesion of the inorganic thin film can be enhanced. The method for forming the undercoat layer is not particularly limited, and a method used for coating a resin liquid such as gravure coating or reverse coating may be appropriately selected from the properties of the resin liquid.

  The glossiness measured from the thin film layer side of the obtained moisture-proof aliphatic polyester film is preferably 400% or more, and more preferably 500% or more. If it is lower than 400%, it lacks a sense of quality.

Further, the moisture permeability of the resulting moisture aliphatic polyester ^{film, 10g / m 2 · 24hr ·} atm or less ^well, or less preferably 7g / m 2 · 24hr · atm . When it is larger than 10 g / m ² · 24 hr · atm, the moisture-proof function is not sufficient. For example, use as a packaging material becomes unsuitable.

  Hereinafter, although this invention is demonstrated in detail using an Example, this invention does not receive a restriction | limiting at all by these. In addition, the physical-property value in an Example and a comparative example was measured and evaluated by the following method, and the used polylactic acid-type polymer was manufactured by the following method.

[Weight average molecular weight]
Using a Tosoh HLC-8120GPC gel permeation chromatograph apparatus, a calibration curve was prepared with standard polystyrene under the following measurement conditions, and the weight average molecular weight was determined.
-Column used: Shimadzu Shim-Pack series GPC-801C
GPC-804C
GPC-806C
GPC-8025C
GPC-800CP
Solvent: Chloroform Sample solution concentration: O.I. 2wt / vol%
Sample solution injection volume: 200 μl
・ Solvent flow rate: 1.0 ml / min ・ Pump, column, detector temperature: 40 ° C.

[Glossiness measurement method]
It measured according to JISK7105. The measurement angle was 60 °.
[Measurement method of film haze]
It measured according to JISK7105.
[Moisture permeability]
It measured according to JISK7129B method.
[Peel strength]
After adhering 25 microns of PET to the vapor-deposited surface with a urethane-based adhesive, it was cut to a width of 15 mm, and the strength of the T-type peel test was measured. The peeling speed was 200 mm / min.

[Running damage]
A film roll is attached to a roll-to-roll type vacuum deposition apparatus, the pressure is reduced to a vacuum of 10 ⁻⁴ TORR, aluminum is deposited and wound at a speed of 100 m / min, and then rewound at normal pressure. Scratchability was determined on the basis of criteria.
◎: Particularly good ○: Good △: Slightly good and usable as a product ×: Cannot be used as a product

[Average particle size]
The particle size distribution was measured and calculated by a Coulter counter measurement method (Coulter Counter II, manufactured by Coulter).
[Maximum particle size]
The maximum particle size was measured through a sieve.
[Film thickness]
Ten points were measured with a dial gauge SM-1201 manufactured by Teclock Co., Ltd., and the average value was used as the thickness. The unit is μm.

[Comprehensive evaluation]
Considering all of the measured values of moisture permeability, total thickness, peel strength, haze, and evaluation of running scratch resistance, the following criteria were used for evaluation.
◎: Particularly excellent ○: Excellent △: Practical range ×: Unusable

[Production 1 of polylactic acid polymer]
15 ppm of tin octylate was added to 100 kg of L-lactide (trade name: PURASORB L) manufactured by Pulac Japan, and the mixture was placed in a 500 L batch polymerization tank equipped with a stirrer and a heating device. Nitrogen substitution was performed, and polymerization was performed at 185 ° C. and a stirring speed of 100 rpm for 60 minutes. The obtained melt was subjected to a 40 mmφ co-directional twin-screw extruder manufactured by Mitsubishi Heavy Industries equipped with three stages of vacuum vents, extruded at 200 ° C. into a strand shape while being devolatilized at a vent pressure of 4 torr, and pelletized. The resulting polylactic acid polymer (hereinafter abbreviated as “PLA1”) had a weight average molecular weight of 250,000 and an L-form content of 99.5%.

[Production of polylactic acid polymer 2, 3]
The PLA 1 was sufficiently absorbed at room temperature, then subjected to a 40 mmφ co-directional twin screw extruder, extruded in a strand at 220 ° C. while being devolatilized at a vent pressure of 4 torr, and pelletized. The resulting polylactic acid polymer (hereinafter abbreviated as “PLA2”) had a weight average molecular weight of 200,000 and an L-form content of 99.5%.
Further, the same steps were repeated to obtain pellets of a polylactic acid polymer (hereinafter abbreviated as “PLA3”) having a weight average molecular weight of 180,000 and an L-form content of 99.5%.

(Examples 1-8, Comparative Examples 1-4)
As inorganic particles, 1 part by weight of granular silicon dioxide (silica) having an average particle size shown in Table 1 (manufactured by Fuji Silysia Chemical Co., Ltd., trade name: Silo Hovic) was dried to remove water sufficiently. Thereafter, it was put into a twin screw extruder of Φ40 mm in the same direction, melted and mixed at about 200 ° C., extruded as a strand, and cut into a pellet while cooling. This pellet was used as a master batch, dried again, and the same amount of the polylactic acid-based polymer shown in Table 1 was mixed with the amount shown in Table 1 to form a surface layer. The surface layer and the intermediate layer shown in Table 1 were fed into the outermost layer Φ40 mm co-directional twin-screw extruder of the two-layer / three-layer coextrusion laminating apparatus at the thickness ratio shown in Table 1, and the set temperature was 210 ° C. The sheet was coextruded into a sheet and rapidly cooled and solidified with a rotating cooling drum to obtain a substantially amorphous sheet.

  Using the film tenter manufactured by Mitsubishi Heavy Industries, Ltd., the obtained sheet was heated to 75 ° C. in combination with an infrared heater while being in contact with a hot water circulating roll, and stretched 3.0 times in the longitudinal direction between the peripheral speed difference rolls. Next, this longitudinally stretched sheet is guided to a tenter while being held with a clip, stretched 3.0 times at 75 ° C. in the vertical direction of the sheet flow, and then heat-treated at 140 ° C. for about 15 seconds to produce a film having a thickness of 25 μm. did. The film was subjected to corona treatment immediately before being wound up by a winder.

Next, for the purpose of improving the adhesion, 0.2 μm of a polyester resin as an anchor coating agent was applied to the corona-treated side as an anchor coating agent before vapor deposition and dried at 100 ° C. There was no occurrence of wrinkles in the resulting aliphatic polyester film. Then, one surface layer is continuously vapor-deposited in an atmosphere having a degree of vacuum of 1 × 10 ⁻⁴ hPa using an electron beam heating type vacuum vapor deposition machine (manufactured by Leoholt) to form a 60 nm aluminum vapor deposition film thickness. did.
The film obtained was measured and evaluated for moisture permeability, peel strength, haze and running scratch resistance by the above methods. The results are shown in Table 1.

Example 9
Aluminum or an aluminum-silica-manganese alloy was formed on the aliphatic polyester film produced in Example 1 by electron beam evaporation. The average grain size of the deposited film (film thickness: 60 nm) at a vacuum degree of 1 × 10 ⁻⁴ hPa of pure aluminum (99.9 at%) was 100 nm. The grain size of the AlSiMn alloy (98.1 at% / 1.1 at% / 0.8 at%) film under the same conditions was 30 nm. The moisture permeability of the former was 6 g / m ² · 24 hr · atm, and the latter was as good as 3 g / m ² · 24 hr · atm. The former glossiness was 766%, indicating a very good metallic luster. Further, the glossiness of the latter was 722%, indicating a good metallic luster. In addition, the glossiness of the surface before vapor deposition of the aliphatic polyester film manufactured in Example 1 was 120%.

(Comparative Example 5)
An aluminum alloy having an aluminum content of 89 at%, magnesium 4.5 at%, and tantalum 6.5 at% was formed on the aliphatic polyester film manufactured in Example 1 by DC magnetron sputtering. Argon gas was introduced into the apparatus at 100 SCCM, the degree of vacuum was maintained at 1 mTorr, and DC power of 10 W / cm ² per target area was applied. The film thickness was 60 nm. Although the moisture permeability of the obtained film was 8 g / m ² · 24 hr · atm, the glossiness was 380%, it was dull in white, and was a level that could not be used as a packaging product.

(Example 10)
A vapor deposition film was formed in the same manner as in Example 7 except that the aliphatic polyester film manufactured in Example 1 was made of an aluminum alloy having an aluminum content of 91 at%, magnesium 4.5 at%, and tantalum 3.5 at%. The film obtained had a moisture permeability of 6 g / m ² · 24 hr · atm and a gloss level of 550%, which was a level usable as a packaging product.

Example 11
A film test piece obtained by cutting the film having a thickness of 40 μm obtained in Example 3 into a size of 100 mm in the longitudinal direction and 15 mm in the width direction was sandwiched between 20-mesh SUS net holders, and 20 kg of fully matured humus soil, Along with 10kg dog food (Nippon Pet Food Co., Ltd. Vitawan), put it in a household conposter (Shizuoka Seiki Co., Ltd. Ecolonpo EC-25D). The recovery rate (the rate remaining in the holder) was measured. The recovery was clearly 30% or less, and the decomposition was clearly progressing, indicating good biodegradability.

Claims (1)

At least one side of the inorganic particle-containing layer constituting the following coextruded biaxially oriented aliphatic polyester film, 90.0 to 99.8 at% aluminum, magnesium, silicon, tantalum, titanium, boron, calcium, barium A moisture-proof aliphatic polyester film characterized by forming a thin film layer of an alloy containing 0.2 to 10.0 at% of at least one element selected from the group consisting of carbon, manganese.
-A film using a resin mainly composed of a polylactic acid polymer as an aliphatic polyester,
Consisting of at least three layers,
At least one of the two outermost layers is an inorganic particle-containing layer,
When the thickness of the inorganic particle-containing layer is a (μm), the maximum particle size of the inorganic particles is b (μm), and the average particle size of the inorganic particles is c (μm), the following formula (1) to Satisfy all of Equation (4) simultaneously,
Static friction coefficient Ri der 0.8,
The center line average roughness Ra is larger than 0.01 and not larger than 0.08.
Coextruded biaxially oriented aliphatic polyester off Irumu the ten-point average roughness Rz is at 2.0 or less.
1 ≦ a ≦ 15 (1)
0.5 ≦ b ≦ 2.5a (2)
0.1 ≦ c ≦ 5 (3)
c ≦ a (4)