JP2005111783A - Aluminized biodegradable film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable aluminized film preventing aluminum from falling off easily arfter vapor deposition, excellent in gas or steam barrier properties and particularly suitable as a packaging material. <P>SOLUTION: This aluminized biodegradable film is obtained by aluminizing at least one side of a film manufactured using a polyester resin composition composed of 97-50 pts.wt. of a polylactic acid (I) and 3-50 pts.wt. of a lactic acid type copolyester (II) constituted of a lactic acid structural unit (IIa) and a polyester structural unit (IIb) in a weight raitio (IIa)/(IIb)=10:90-90:10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a deposited film obtained by depositing a metal or metal oxide typified by aluminum on a biodegradable film made of a polyester-based resin composition. More specifically, the appearance (gloss, beauty, etc.) of the film after vapor deposition of a metal or metal oxide typified by aluminum is excellent, and the metal or metal oxide such as vapor deposited aluminum is difficult to peel off. The present invention relates to a vapor-deposited film having excellent impact properties, gas barrier properties, and water vapor barrier properties, and biodegradability.

Biodegradable films are excellent in mechanical strength and transparency, and are expected to be used in various applications. In particular, in applications for packaging films, gas barrier properties or water vapor barrier properties may be required, and in order to meet these requirements, an effective means is the deposition of a metal or metal oxide represented by aluminum on the film. It is. Therefore, the biodegradable film used for such applications is required to have good adhesion between the film after vapor deposition and the vapor-deposited material and appearance (gloss, beauty, etc.).
The “evaporation” in the present invention means, for example, that a substance such as a metal represented by aluminum or a metal oxide is evaporated in a high vacuum and deposited as a thin film on a solid surface.

  On the other hand, polyhydroxycarboxylic acids such as polylactic acid are obtained from natural raw materials such as corn, are excellent in heat resistance, melt moldability, toughness, rigidity, transparency, and biodegradability, and are therefore environmentally friendly. Although it has been attracting attention as a molding resin, particularly as a molding resin used in various applications, the industrial application is limited due to its poor impact resistance and flexibility.

Methods for improving these disadvantages include a method of blending polylactic acid and other resins, a method of copolymerizing polylactic acid and other resins, or a method of adding a plasticizer to polylactic acid, etc. Has been tried.
For example, aliphatic polyesters other than polyhydroxycarboxylic acids have flexibility, thermal stability, and relatively fast biodegradability compared to polyhydroxycarboxylic acids including polylactic acid, but they are rigid. The glass transition temperature (Tg) is usually room temperature or lower, the heat resistance temperature is low for high crystallinity, and the surface smoothness such as transparency and gloss is poor. It causes damage to the appearance afterwards.
In particular, aliphatic polyester has a problem that it tends to cause an appearance defect called “bleed out” during heat molding to various molded products. Bleed-out is a phenomenon in which low molecular weight substances in a molded product migrate to the surface of a molded product such as a film during or after heat molding, and the surface workability such as aluminum deposition is significantly reduced. Cause it.

As a method for improving the characteristics of polyhydroxycarboxylic acid such as polylactic acid, for example, there is a method of blending polylactic acid and other resins, etc., but there is a balance in mechanical properties, transparency, and surface smoothness. There is a problem that it is difficult to obtain an excellent film and the bleed-out is insufficient.
Examples of a method for copolymerizing a polyhydroxycarboxylic acid and an aliphatic polyester include a method of obtaining a copolymer by reacting a lactone with an aliphatic polyester in the presence of a ring-opening polymerization catalyst. A film obtained from this copolymer has a good balance between mechanical strength such as flexibility and impact resistance and transparency, a good surface appearance, and a good appearance after deposition of aluminum or the like. However, if the aliphatic polyester component is adjusted and more plasticizer is added to obtain desired physical properties such as impact resistance and flexibility, bleed out may occur easily. There is a problem that vapor deposition cannot be performed.

  An example of depositing aluminum on a biodegradable film is an aluminum-biodegradable plastic laminate (Patent Document 1). Among them, an aluminum-biodegradable plastic laminate in which aluminum is vapor-deposited on the surface of a biodegradable plastic film where an acid is generated upon decomposition is described. As an example of a biodegradable plastic that can be used, lactic acid is used. Examples include polylactic acid resin polymerized as a main component. However, a film produced using such a biodegradable plastic alone is excellent in flexibility, impact resistance, and appearance, but has a problem that it causes bleed out and is extremely inferior in adhesion of aluminum after vapor deposition. is there.

JP-A-8-290526

  The problem to be solved by the present invention is that aluminum or metal oxide such as aluminum after vapor deposition does not easily peel off, and has excellent gas barrier property or water vapor barrier property, and particularly excellent in biodegradability suitable for packaging materials. It is to provide a vapor deposition film.

  As a result of intensive studies to solve the above problems, the inventors of the present invention mixed polylactic acid and a lactic acid copolymer polyester composed of a lactic acid unit and a polyester unit by heat melting or solution mixing using an organic solvent. The present invention is completed by forming a thin film by vapor-depositing at least one surface of a film prepared by using a polyester resin composition obtained by dispersing and mixing by a method such as a metal such as aluminum or a metal oxide. It reached.

  That is, the present invention provides polylactic acid (I) 97 to 50 parts by weight, lactic acid structural unit (IIa) and polyester structural unit (IIb) in a weight ratio of (IIa) / (IIb) = 10: 90 to 90:10. It is characterized in that at least one surface of a film prepared by using a polyester resin composition comprising 3 to 50 parts by weight of lactic acid copolymer polyester (II) composed of An aluminum vapor deposited biodegradable film is provided.

  The present invention uses a polyester resin composition obtained by dispersing and mixing polylactic acid and a lactic acid copolymer polyester composed of a lactic acid unit and a polyester unit, such as by heat melting or solution mixing using an organic solvent. By vapor-depositing at least one surface of the film produced by aluminum with aluminum, the deposited aluminum does not easily peel off, and is excellent in gas barrier property or water vapor barrier property, particularly biodegradable aluminum vapor deposition suitable for packaging materials A film can be provided.

First, the film excellent in biodegradability which vapor-deposited aluminum of this invention is demonstrated in detail below.
The film used in the present invention is a biodegradable film produced using a polyester resin composition comprising polylactic acid (I) and lactic acid copolymer polyester (II). It is a film capable of forming a thin film by vapor-depositing at least one surface of the film with a metal such as aluminum or a metal oxide.

  The polyhydroxycarboxylic acid referred to in the present invention is composed of repeating units of aliphatic carboxylic acids having a hydroxyl group in the molecule. For example, polylactic acid, polycaprolactone, polyglycolic acid, polyhydroxybutyrate, polyhydroxybutyrate Examples thereof include valerate, polylactic acid / glycolic acid copolymer, and polyhydroxybutyrate / valerate copolymer, and a mixture thereof may be used. Of these polyhydroxycarboxylic acids, polylactic acid is particularly preferred. Moreover, when it has asymmetric carbon in a repeating unit like polylactic acid, any of L-form, D-form, the mixture of L-form and D-form (a mixing ratio is not specifically limited), and a racemate may be sufficient.

When polylactic acid (I) is used in the present invention, the composition of polylactic acid is, by weight ratio, D-lactic acid / L-lactic acid = 100/0 to 90/10, or 0/100 to 10/90. The range of D-lactic acid / L-lactic acid = 100/0 to 94/6 or the range of 0/100 to 6/94 is more preferable. In the polylactic acid, if the composition of D-lactic acid and L-lactic acid is within such a range, the melting point is high, and the heat resistance and mechanical properties are excellent.
In addition, polylactic acid obtained by using only D-lactic acid or L-lactic acid is a resin having particularly high crystallinity, has a high melting point, and tends to have excellent heat resistance and mechanical properties.
It is also possible to blend two or more types of lactic acid resins in which the mixing ratio of D-lactic acid and L-lactic acid is extremely different. For example, polylactic acid having a poly (L-lactic acid) / poly (D-lactic acid) = 70/30 to 30/70 weight ratio forms a stereocomplex, and therefore has a melting point of poly (L-lactic acid) or poly (D -Lactic acid) is significantly improved as compared with that of single substance. Particularly preferred is poly (L-lactic acid) / poly (D-lactic acid) = 50/50 weight ratio.

The polymerization method of polylactic acid (I) is not particularly limited, and 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 lactic acid-based resin having an arbitrary composition can be obtained by direct dehydration condensation polymerization in which L-lactic acid or D-lactic acid, or a mixture thereof is azeotropically dehydrated under reduced pressure in the presence of a high-boiling solvent. it can. In the ring-opening polymerization method (lactide method), a lactic acid resin can be obtained by using lactide, which is a cyclic dimer of lactic acid, using an appropriate catalyst while using a polymerization regulator or the like as necessary. .
The lactide includes L-lactide, which is a dimer of L-lactic acid, D-lactide, which is a dimer of D-lactic acid, and DL-lactide, which is a dimer of D-lactic acid and L-lactic acid. These are mixed as necessary and polymerized to obtain polylactic acid having an arbitrary composition and crystallinity.

The polylactic acid (I) used in the present invention is particularly preferably the above-mentioned homopolymer polylactic acid. For example, lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5- Copolymers with hydroxy carboxylic acids such as hydroxyvaleric acid and 6-hydroxycaproic acid, copolymers with diol / dicarboxylic acid, copolymers with polyester comprising diol / dicarboxylic acid, copolymer with polyether polyol It may be a polymer or the like. Among these, a block copolymer is preferable in order to make use of the characteristics of polylactic acid, and a copolymer with a polyester composed of diol / dicarboxylic acid is more preferable. The copolymerization ratio of these copolymers is preferably 70 parts by weight or more and more preferably 90 parts by weight or more with respect to the lactic acid component. If the copolymerization ratio of the copolymer is within this range, the heat resistance and transparency are excellent.
Other hydroxycarboxylic acids that can be copolymerized with polylactic acid (I) include, for example, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethyl. Examples thereof also include bifunctional aliphatic hydroxycarboxylic acids such as butyric acid, 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, and 2-hydroxycaproic acid, and lactones such as caprolactone, butyrolactone, and valerolactone. These may be used alone or in combination of two or more.

  Examples of the diol copolymerizable with polylactic acid (I) include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, Examples include 1,4-cyclohexanedimethanol, neopentyl glycol, and dimer diol. These may be used alone or in combination of two or more.

  Examples of the dicarboxylic acid copolymerizable with polylactic acid (I) include succinic acid, adipic acid, suberic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, terephthalic acid, and isophthalic acid. It is done. These may be used alone or in combination of two or more.

  Examples of the polyether polyol that can be copolymerized with polylactic acid (I) include polyethylene glycol, polypropylene glycol, a block copolymer of polyethylene glycol and polypropylene glycol, and polytetramethylene glycol. These may be used alone or in combination of two or more.

  For the polylactic acid (I) used in the present invention, a small amount of chain extender may be used in order to increase the molecular weight as long as the object of the present invention is not impaired. Such a chain extender is not particularly limited, and examples thereof include a diisocyanate compound, an epoxy compound, and an acid anhydride.

  The weight average molecular weight of polylactic acid (I) is preferably in the range of 50,000 to 400,000, more preferably 100,000 to 250,000. If the weight average molecular weight of the polylactic acid is within such a range, the mechanical properties, heat resistance and molding processability are excellent.

Next, in the present invention, the lactic acid copolymer polyester (II) used for the polyester resin composition together with the polylactic acid (I) will be described.
The lactic acid-based copolymer polyester (II) is a modifier that can impart impact resistance and / or flexibility by being added to polylactic acid (I), and includes lactic acid structural unit (IIa) and It is a copolyester comprising a polyester structural unit (IIb).

In the lactic acid copolymer polyester (II), the lactic acid structural unit (IIa) acts as a compatible component to improve the adhesion at the interface between the lactic acid copolymer polyester (II) and the polylactic acid (I), and peel off the interface. It effectively acts to suppress bleed out.
On the other hand, the polyester structural unit (IIb) exhibits an effect of imparting impact resistance and flexibility.

  The weight average molecular weight of the lactic acid copolymer polyester (II) is preferably in the range of 5,000 to 250,000, more preferably in the range of 20,000 to 200,000, particularly preferably 30,000 to 150,000. 000 range. If the weight average molecular weight of the lactic acid copolymer polyester is within the range, it is excellent in dispersibility in polylactic acid (I) and excellent in impact resistance and flexibility.

  The weight ratio of the lactic acid structural unit (IIa) and the polyester structural unit (IIb) constituting the lactic acid copolymer polyester (II) used in the present invention is appropriately set so that impact resistance or flexibility can be obtained depending on the application. Usually, the range of lactic acid structural unit (IIa) / polyester structural unit (IIb) = 10/90 to 90/10 is preferable, and the range of (IIa) / (IIb) = 25/75 to 70/30 is preferable. More preferably, the range of 30/70 to 60/40 is particularly preferable, and the range of 40/60 to 60/40 is most preferable. If the weight ratio of the lactic acid structural unit (IIa) and the polyester structural unit (IIb) constituting the lactic acid-based copolymerized polyester (II) is within the range, the adhesiveness at the interface with the polylactic acid (I) is excellent and bleed out. Is also suppressed, and is excellent in impact resistance and flexibility.

  The polyester resin composition used in the present invention comprises polylactic acid (I) and lactic acid copolymer polyester (II), and the amount of both used is preferably polylactic acid (I) / lactic acid copolymer polyester (II). = 97 / 3-50 / 50 weight ratio, more preferably (I) / (II) = 95 / 5-50 / 50 weight ratio. In the polyester resin composition, if the weight ratio of polylactic acid and lactic acid copolymer polyester is within the range, bleeding out is suppressed, adhesion of the deposited material is good, and impact resistance and flexibility are improved. Excellent processability, heat resistance, and transparency.

Next, the lactic acid structural unit (IIa) constituting the lactic acid-based copolymer polyester (II) is a copolymer composed of L-lactic acid, D-lactic acid, or DL-lactic acid composed of L-lactic acid and D-lactic acid. is there.
The structure of the lactic acid structural unit (IIa) is preferably D-lactic acid / L-lactic acid = 100/0 to 80/20 weight ratio or 0/100 to 20/80 weight ratio. In the range of 6-80 / 20 or 6 / 94-20 / 80, since the lactic acid structural unit (IIa) becomes amorphous, (IIa) enters the matrix of polylactic acid (I), It acts as a plasticizer for polylactic acid (I) and imparts impact resistance and flexibility more effectively. However, when heat resistance is also considered, the range of D-lactic acid / L-lactic acid = 100/0 to 90/10 weight ratio or 0/100 to 10/90 weight ratio is more preferable, and D-lactic acid / L- Lactic acid is more preferably in the range of 100/0 to 94/6 or in the range of 0/100 to 6/94 because the melting point is higher and the heat resistance, impact resistance, flexibility, and mechanical properties are excellent.

The average chain length of the lactic acid structural unit (IIa) is preferably as the chain length is longer, because the compatibility with the polylactic acid (I) tends to be improved. When the lactic acid residue excluding H and carboxyl group OH is defined as 1 unit, it is preferably in the range of 5 to 3,000 units. The lower limit of the average chain length is that the lactic acid structural unit (IIa) is polylactic acid (I ) Compatible segments, and good adhesion at the interface between the lactic acid-based copolymerized polyester (II) and polylactic acid (I) to suppress peeling at the interface and to prevent bleeding out. 10 units or more are more preferable, 50 units or more are more preferable, and 100 units or more are particularly preferable.
When the average chain length of the lactic acid structural unit (IIa) is increased, the adhesion at the interface is improved, but the molecular weight of the entire lactic acid copolymer polyester (II) is also increased, so that the viscosity is increased and polylactic acid (I) is added. Since it becomes difficult to uniformly disperse, the upper limit of the average chain length is preferably 2,000 units or less, more preferably 1,000 or less.
In order to convert the above unit into the number average molecular weight, the molecular weight of 1 unit of lactic acid residue is 72 × the number of units. For example, 10 units is 720 in number average molecular weight.

  Next, the polyester structural unit (IIb) constituting the lactic acid copolymer polyester (II) used in the present invention is a polyester block structural unit comprising a diol and a dicarboxylic acid.

  As the diol, those having 2 to 40 carbon atoms are preferable. For example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6- Hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, dimer diol, polyethylene glycol, polypropylene glycol, block copolymer of polyethylene glycol and polypropylene glycol, polytetramethylene glycol, etc. And at least one of these diols can be used.

  The dicarboxylic acid is preferably one having 2 to 42 carbon atoms, such as succinic acid, adipic acid, suberic acid, sebacic acid, azelaic acid, decanedioic acid, dodecanedioic acid, dimer acid, terephthalic acid and isophthalic acid. An acid etc. are mentioned, At least 1 type or more in these dicarboxylic acids can be used. Among these dicarboxylic acids, aliphatic dicarboxylic acids are more preferable when considering biodegradability.

  In addition to these, in order to branch the polyester or increase the molecular weight, a small amount of trihydric or higher polyhydric alcohol or carboxylic acid such as glycerin, pentaerythritol, trimellitic acid or the like may be used in a range that does not impair the purpose of the present invention. It doesn't matter.

  In addition, the average chain length of the polyester structural unit (IIb) is preferably as long as the polyester block structural unit is long in order to impart impact resistance and flexibility. The range of 5,000 to 250,000 is preferable, the range of 10,000 to 200,000 is more preferable, the range of 10,000 to 100,000 is particularly preferable, and the range of 20,000 to 100,000 is the most preferable. Therefore, the weight average molecular weight of the polyester used as the polyester structural unit (IIb) used when producing the lactic acid copolymer polyester (II) is preferably in the same range as described above.

Next, the manufacturing method of polyester used as polyester structural unit (IIb) is demonstrated below.
The method for producing the polyester to be the polyester structural unit (IIb) is, for example, preparing raw material diol and dicarboxylic acid in a ratio of diol / dicarboxylic acid = 1/1 to 1.5 / 1 molar ratio, and in a nitrogen atmosphere. The water is distilled off with stirring while gradually raising the temperature from 130 to 220 ° C. at a rate of 5 to 20 ° C./hour. After the reaction for 4 to 12 hours, an excess of glycol is distilled off while gradually increasing the degree of vacuum by adding a transesterification catalyst and an antioxidant, and finally 200 to 250 ° C. while reducing the pressure to 0.5 kPa or less. And react for 4 to 12 hours to obtain a highly viscous polyester.

  Examples of the catalyst used in the transesterification reaction include metal catalysts such as titanium, tin, zinc, and zirconium. Examples of these metal catalysts include titanium tetrapropoxide, titanium tetrabutoxide, titanium bisacetylacetonate, aluminum acetylacetonate, zirconium tetrachloride, zirconium tetrachloride 2THF complex, hafnium tetrachloride, hafnium tetrachloride 2THF complex, and the like. .

Further, it is desirable to remove these catalysts after completion of the reaction or to deactivate them with a catalyst deactivator.
In the present invention, the catalyst deactivator used for inactivating the catalyst is preferably a chelating agent and / or an acidic phosphate ester.
Examples of the chelating agent include, but are not limited to, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, succinic acid, phosphoric acid, pyrophosphoric acid, alizarin, acetylacetone, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, catechol, 4- t-butylcatechol, L (+)-tartaric acid, DL-tartaric acid, glycine, chromotropic acid, benzoylacetone, citric acid, gallic acid, dimercaptopropanol, triethanolamine, cyclohexanediaminetetraacetic acid, ditoluoyltartaric acid, dibenzoyltartaric acid, etc. Is mentioned. These may be used alone or in combination of two or more.

In addition, the acidic phosphate esters form a complex with the metal ion of the catalyst contained in the hydroxycarboxylic acid polyester, lose the catalytic activity, and exhibit the effect of inhibiting the cleavage of the polymer chain.
Examples of the acidic phosphoric acid esters include conventionally known acidic phosphoric acid esters, phosphonic acid esters, alkylphosphonic acid, and the like, as mentioned in US Pat. No. 5,686,540, and the like. Acidic phosphate esters have excellent workability due to their relatively good solubility in organic solvents, excellent reactivity with lactic acid-based polyesters, and excellent deactivation of polymerization catalysts.

  In the present invention, the polyester obtained by the above production method can be further reacted with an acid anhydride such as pyromellitic anhydride or an isocyanate such as hexamethylene diisocyanate to increase the molecular weight.

Next, conditions for expressing the modification effect of the lactic acid-based copolymer polyester (II) will be described below.
When the conditions for developing the effect of imparting impact resistance are considered from the diol and dicarboxylic acid of the polyester structural unit (IIb), a diol or dimer in which 50 parts by weight or more of the diol has a side chain such as propylene glycol. A diol is preferable because the impact resistance is improved, preferably 70 parts by weight or more, and more preferably 90 parts by weight or more. Alternatively, when 10 parts by weight or more of the diol is a polyether polyol such as polyethylene glycol, the impact resistance is good, preferably 30 parts by weight or more, and more preferably 50 parts by weight or more.

  As the dicarboxylic acid, 50 parts by weight or more of the dicarboxylic acid component is preferably a dicarboxylic acid having 8 or more carbon atoms (sebacic acid) excluding carbon of the dimer acid or carboxylic acid group, more preferably 70 parts by weight or more, 90 parts by weight or more is more preferable.

Considering the conditions for the lactic acid-based copolymerized polyester (II) to exert the modification effect that imparts flexibility, considering the diol and dicarboxylic acid components, the impact resistance mentioned above is given for the diol component conditions. It is preferable that it is the same as the thing quoted in order to express the effect to do.
As the dicarboxylic acid, a dicarboxylic acid having less than 8 carbon atoms, excluding the carbon of the carboxylic acid group, preferably having 4 or less carbon atoms, preferably 50 parts by weight or more of the dicarboxylic acid component, 70 parts by weight or more. Is more preferable, and 90 parts by weight or more is still more preferable.

When the conditions for the lactic acid-based copolymerized polyester (II) to exhibit the effect of maintaining the transparency of the polyester-based resin composition are considered from diol and dicarboxylic acid, the diol component has the same conditions as impact resistance. It is preferable.
The dicarboxylic acid is a dicarboxylic acid having 8 or less carbon atoms, preferably 4 or less, excluding carbon of the carboxylic acid group, preferably 50 parts by weight or more, more preferably 70 parts by weight or more of the dicarboxylic acid. 90 parts by weight or more is more preferable.

  When the conditions for the lactic acid-based copolymerized polyester (II) to exhibit a modification effect imparting impact resistance are considered from the polyester unit (IIb), the number of carbons in the main chain of the diol and dicarboxylic acid (ester group) The total of (excluding carbon) is preferably 10 or more. On the other hand, when flexibility is imparted, the total number of carbon atoms in the main chain of diol and dicarboxylic acid (excluding the carbon of the ester group) is preferably less than 10. In order to maintain transparency, the total number of carbon atoms (excluding the ester group carbon) of the diol and dicarboxylic acid main chain is preferably 11 or less.

In addition, the conditions for the lactic acid copolymer polyester (II) to maintain the impact resistance, flexibility, and transparency, and to exhibit the modification effect that imparts the vapor deposition property of aluminum are the conditions for the polyester structural unit (IIb) σ. Considering from the viewpoint of / ρ value, it is as follows.
First, σ / ρ value is explained. Hoy's formula (D.R.Paul, Seamall Newman, “Polymer blend”, Volume 1, Academic Press, p. 46-47 (1978) (English title; DRPAUL and SEYMOUR NEWMAN, POLYMER BLENDS, vol 1, ACADEMIC PRESS, p.46-47 (1978))). The calculation formula is a value obtained by calculating the substituent constant obtained by Hui as a numerical value per repeating unit of the polymer and dividing this by the molecular weight per repeating unit. That is, σ / ρ = ΣFi / M (where Fi is a substituent constant, and M is a molar molecular weight per repeating unit). Table 1 shows examples of substituent constants.

As an example, a specific calculation method for an aliphatic polyester obtained by polycondensation of ethylene glycol and succinic acid will be described. The aliphatic polyester can be calculated as follows. That is,
Since it has a repeating unit represented by — (CH ₂ —CH ₂ —COO—CH ₂ —CH ₂ —COO) —, it has four substituents — (CH ₂ ) — and two substituents —COO. Therefore, ΣFi = (131.5 × 4 + 326.58 × 2) = 1179.16.
On the other hand, since the molar molecular weight (M) per repeating unit is 144.13, a value of σ / ρ = 1179.16 / 144.13 = 8.2 is obtained. Some examples are shown in the right column of Table 1.

In Table 1, each abbreviation means the following.
EG: Ethylene glycol SuA: Succinic acid DA: Dimer acid PLA: Polylactic acid

  From Table 1, a polymer having a σ / ρ value that approximates the matrix polymer polylactic acid (I) is highly compatible with the polylactic acid (I), that is, has a strong effect of imparting flexibility or transparency. When the σ / ρ value is greatly different, the compatibility is lowered, so that the dispersed phase of the lactic acid-based copolymer polyester (II) in the polylactic acid (I) matrix becomes large, and the tendency to improve the impact resistance becomes strong. .

  In the present invention, the specific value of σ / ρ value of the polyester structural unit (IIb) is in the range of 7.80 or more and less than 9.20, and when it is less than 8.54, flexibility or transparency is maintained. The effect of imparting is preferably increased, more preferably 8.40 or less, and still more preferably 8.37 or less. On the contrary, when it is 8.54 or more, the effect of imparting impact resistance becomes strong, preferably 8.58 or more, more preferably 8.70 or more.

  Furthermore, when producing a film suitable for vapor deposition, the σ / ρ value of the polyester unit (IIb) is preferably 7.80 or more and less than 8.35 from the viewpoint of suppressing bleeding out and imparting flexibility.

In addition, the conditions for the lactic acid-based copolymer polyester (II) to exert a modification effect imparting maintenance of impact resistance, flexibility, and transparency are the melting point (Tm) of the polyester unit (IIb) or glass transition. Considering the temperature (Tg), it is preferable that Tm is 120 ° C. or lower or Tg is 20 ° C. or lower.
In particular, the lower Tg is, the lower the impact resistance or flexibility is expressed at a lower temperature, so 0 ° C or lower is preferable, -20 ° C or lower is more preferable, -30 ° C or lower is particularly preferable, and -40 ° C or lower is most preferable. There is no particular lower limit for Tg, but -70 ° C is considered the limit when considering the current polyester.
Considering the effect of imparting flexibility and maintaining transparency, the melting point (Tm) is desirably low or non-existent (amorphous polyester). When present, it is preferably 100 ° C. or lower, more preferably 80 ° C. or lower. If the temperature is 60 ° C. or lower, the polyester is liquid at room temperature, and the polyester structural unit (IIb) is easy to move and easily exhibits flexibility and contributes to maintaining transparency. Particularly preferred is −20 ° C. or lower.
Furthermore, when the Tm is 120 ° C. or lower or the Tg is 20 ° C. or lower, the crystallization temperature (Tc) of the polylactic acid composition is lower than the Tc of the polylactic acid (I) which is a homopolymer. The crystallization temperature can be kept low. In addition, the crystallization speed can be increased. That is, the lactic acid copolymer polyester (II) has a function of promoting crystallization of polylactic acid (I).

In addition, the conditions for the lactic acid-based copolymer polyester (II) to exhibit a modification effect that imparts impact resistance, flexibility, and transparency maintenance are the same as those of polylactic acid (I) and lactic acid-based copolymer polyester (II). Considering from the morphology, the lactic acid copolymer polyester (II) becomes a dispersed phase with respect to the matrix of polylactic acid (I). If the average particle size of this dispersed phase is small, it is excellent in flexibility and transparency maintenance. Excellent impact resistance.
The average particle size of the dispersed phase is preferably in the range of 0.20 to 2 μm, more preferably in the range of 0.2 to 1 μm, still more preferably in the range of 0.3 to 1 μm, most preferably. It is in the range of 0.5-1 μm. If the average particle size of the dispersed phase is within this range, the interfacial adhesion between the polylactic acid (I) and the lactic acid copolymer polyester (II) is good, the impact resistance is excellent, and the flexibility and transparency are also excellent. .
In the present invention, the “average particle diameter” refers to an average value of the lengths of the major axis and minor axis of the dispersed phase.

  As described above, the lactic acid-based copolymer polyester (II) used in the present invention has a number of conditions for exhibiting a modification effect that imparts impact resistance, flexibility, and transparency maintenance. It is preferable to design so as to meet any one of the above conditions, and it is more preferable to satisfy many conditions.

Next, a method for producing the lactic acid copolymer polyester (II) will be described below.
There is no particular limitation as long as it is a production method for obtaining a block copolymer comprising lactic acid structural unit (IIa) (that is, lactic acid segment) and polyester structural unit (IIb) (that is, polyester segment).
(Method 1) A method of reacting lactide and polyester in the presence of a polymerization catalyst,
(Method 2) Polylactic acid obtained by direct polycondensation of lactic acid or ring-opening polymerization of lactide and polyester are melt-mixed and then dehydrated and polycondensed in the presence of an esterification or transesterification catalyst under reduced pressure conditions. , A method for obtaining a polylactic acid-polyester block copolymer,
(Method 3) In the presence of polylactic acid obtained by direct polycondensation of lactic acid or ring-opening polymerization of lactide, polyester and a high-boiling solvent, a transesterification catalyst is added, and azeotropic dehydration polycondensation, that is, direct polycondensation under reduced pressure Although the method of obtaining a polylactic acid-polyester block copolymer by carrying out condensation reaction is mentioned, In this invention, it does not specifically limit to these methods.

First, (Method 1) As a method of reacting lactide and polyester in the presence of a polymerization catalyst, for example, the reaction temperature is preferably 220 ° C. or less, more preferably 200 ° C. in terms of preventing the coloring and decomposition of lactide. Hereinafter, the reaction is particularly preferably performed at 190 ° C. or lower, and the reaction is preferably performed in an atmosphere of an inert gas such as nitrogen or argon. In addition, since the presence of moisture in the reaction system causes decomposition, it is not preferable. Therefore, it is necessary to use an aliphatic polyester that has been sufficiently dried before the reaction. Under such conditions, polyester and lactide are mixed and dissolved at 100 to 220 ° C. At this time, if necessary, preferably 1 to 30 parts by weight, more preferably 5 to 30 parts by weight, particularly preferably 15 to 30 parts by weight of a non-reactive solvent such as toluene based on the total weight of these. It may be used. Further, a polymerization catalyst (for example, tin octoate) is preferably added in a range of 50 to 5000 ppm with respect to the total amount of lactide and polyester at 140 to 220 ° C. in an inert gas atmosphere such as nitrogen or argon.
As the lactide used in the above reaction, L-lactide, D-lactide, or meso-lactide may be used alone or in combination.
As the polymerization catalyst used in the above reaction, any of catalysts generally known as esterification catalysts, transesterification catalysts, and ring-opening polymerization catalysts can be used. For example, Sn, Ti, Zr, Zn, Ge, Co, Fe, Examples thereof include alkoxides such as Al, Mn and Hf, acetates, oxides and chlorides. Among these, tin powder, tin 2-ethylhexylate, dibutyltin dilaurate, tetraisopropyl titanate, tetrabutoxy titanium, titanium oxyacetylacetonate, iron (III) acetylacetonate, iron (III) ethoxide, aluminum isopropoxide, aluminum Acetylacetonate is preferred because of its high activity effect on the reaction.

Next, (Method 2) as a copolymerization method of polylactic acid and polyester, for example, polylactic acid obtained by direct dehydration polycondensation of lactic acid or ring-opening polymerization of lactide and polyester are melt-mixed and then reduced in the presence of a catalyst. A lactic acid copolymer polyester (II) can be obtained by performing a polycondensation reaction under the conditions. The higher the polylactic acid (I), the more preferable the copolymerization reaction after the addition of the polyester in a short time because the high molecular weight lactic acid-based copolymerized polyester (II) can be obtained. The weight average molecular weight of the polylactic acid (I) to be used is preferably 50,000 or more, more preferably 100,000 or more, and particularly preferably 150,000 or more.
Further, before the polyester is melt mixed with the polylactic acid (I), it is preferable to remove the catalyst used in the synthesis of the polyester or to deactivate the catalyst with a catalyst deactivator. The reason for this is that the active catalyst remaining in the polyester acts as a transesterification catalyst for polylactic acid (I), thereby excessively cleaving the molecular chain of polylactic acid and significantly reducing the molecular weight of polylactic acid at the start of polymerization. This is because the molecular weight of the lactic acid copolymer polyester (II) obtained after completion of the polycondensation reaction is unnecessarily lowered.
When the polymerization temperature is too high, polylactic acid is decomposed into lactide by thermal decomposition, and therefore the range of 170 to 220 ° C is preferable, and the range of 180 to 210 ° C is more preferable.
The higher the degree of vacuum, the faster the polymerization reaction proceeds, preferably 2 kPa or less, more preferably 1 kPa or less, and particularly preferably 0.5 kPa or less.
As the polymerization catalyst to be used, any catalyst generally known as an esterification catalyst or a transesterification catalyst can be used. For example, Sn, Ti, Zr, Zn, Ge, Ni, Co, Fe, Al, Mn, Hf, etc. Alkoxides, acetates, oxides, chlorides, and the like. Among these, tin 2-ethylhexylate, dibutyltin dilaurate, tetraisopropyl titanate, tetrabutoxy titanium, titanium oxyacetylacetonate, iron (III) acetylacetonate, aluminum acetylacetonate, zirconium tetrachloride, zirconium tetrachloride, 2THF complex Hafnium chloride, 4 hafnium chloride / 2THF complex is preferable because the reaction is accelerated, and aluminum acetylacetonate, 4 zirconium chloride, 4 zirconium chloride-2THF complex, hafnium chloride, 4 hafnium chloride-2THF complex are colored polymers. Less is more preferable.
The amount of the catalyst used is preferably in the range of 50 to 500 ppm, more preferably in the range of 50 to 300 ppm, particularly preferably in the range of 50 to 200 ppm with respect to the total amount of polylactic acid and polyester. In Method 2, if the amount of the catalyst used is within this range, excessive polylactic acid molecular chain cleavage during the reaction is suppressed, the decrease in the molecular weight of the lactic acid copolymer polyester (II) is suppressed, and the reaction time is also long. The polymer is shortened and a good color is obtained.

  Next, (Method 3) A method in which a transesterification catalyst is added in the coexistence of polylactic acid, polyester, and a high-boiling solvent, and azeotropic dehydration polycondensation, that is, direct polycondensation reaction is performed under reduced pressure conditions includes xylene, anisole, diphenyl ether The above-mentioned (Method 2) is performed under the same conditions except that a high boiling point solvent is used. However, as compared with (Method 2), (Method 3) needs to finally remove the solvent. Therefore, the production method is (Method 1) or (Method 2) rather than (Method 3). Is preferred.

  Furthermore, the lactic acid-based copolymer polyester (II) further improves the storage stability by extracting the polymerization catalyst with a solvent after the polymerization is completed, or by deactivating the polymerization catalyst with the catalyst deactivator described above. be able to.

The lactic acid copolymer polyester (II) obtained by the above production method can be used as a modifier of polylactic acid (I).
The lactic acid copolymer polyester (II) as a modifier for polylactic acid preferably has a weight average molecular weight of 10,000 or more, more preferably in the range of 15,000 to 300,000, particularly preferably 20 The range is from 50,000 to 250,000, and most preferably from 25,000 to 200,000. If the weight average molecular weight of the lactic acid-based copolymer polyester is within such a range, transparency can be maintained, bleeding out can be suppressed, and excellent impact resistance and flexibility can be imparted.

  The glass transition temperature (Tg) of the lactic acid copolymer polyester (II) is preferably 60 ° C. or less, more preferably −70 to 60 ° C., and particularly preferably −65 to 60 ° C. Addition of lactic acid-based copolyester (II) (ie, polylactic acid modifier) to polylactic acid (I) improves the impact resistance and flexibility of polylactic acid, and improves heat resistance and transparency. And the occurrence of bleed-out can be suppressed, and stable deposition of a metal or metal oxide typified by aluminum can be performed.

In the present invention, a film used for depositing a metal or metal oxide typified by aluminum will be described below.
Normally, when handling packaging materials, sheets and films are conventionally used according to their thickness, but in order to avoid confusion, they are collectively referred to as “films”.
Moreover, there is no restriction | limiting in particular in the thickness of the film used by this invention, The thickness generally used means the thing of the range of 5 micrometers-2 mm.

Next, the polyester resin composition comprising lactic acid copolymer polyester (II) and polylactic acid (I) used in the present invention will be described below.
The polyester resin composition used in the present invention contains polylactic acid (I) and lactic acid copolymer polyester (II).
The polylactic acid (I) used in the polyester resin composition preferably has a weight average molecular weight of 10,000 or more, more preferably 50,000 or more, and particularly preferably 100,000 or more. If the weight average molecular weight of the polylactic acid used for the polyester composition of the present invention is within such a range, it has excellent mechanical strength.

In the polyester resin composition used in the present invention, the polylactic acid (I) and the lactic acid copolymer polyester (II) must be microscopically dispersed and mixed, but for efficient mixing, a single screw extruder or It is preferable to use a processing apparatus such as a twin screw extruder.
Further, if the dispersion mixing is good, for example, solution mixing or melt mixing may be performed in a solvent using an organic solvent.

Next, film formation of the above-described polyester resin composition by an extrusion method will be described below.
When using an extruder having functions of melt kneading and resin transfer, water management is particularly important because lactic acid polymers are usually hygroscopic and easily hydrolyzed. When extrusion is performed using a general uniaxial extruder, the polymer is preferably dehumidified and dried by a suitable drying facility such as a vacuum dryer or a dehumidifying dryer using a dew point before film formation.
Further, the film formation by the vent type twin-screw extruder has a high dehydration effect, and the normal drying process can be omitted, so that an efficient film formation is possible. In this case, however, a drying step may be performed as necessary.

Although the melt extrusion temperature at the time of film-forming the polyester-type resin composition used by this invention is not restrict | limited, Usually, the range of 150 to 250 degreeC is preferable.
In general, a film melt-extruded through a die such as a T-die is cast to have a predetermined thickness, and is cooled as necessary. At that time, when the thickness is thick, a touch roll, an air knife or the like is used, and when the thickness is thin, electrostatic pinning or the like is used properly to obtain a film having a uniform thickness.
The distance between die lips such as a T-die for performing melt extrusion is usually in the range of 0.2 to 3.0 mm, but this distance may be adjusted depending on the film forming condition, and is not particularly limited to this range. For example, when the resin pressure in a die such as a T-die is relatively high, widening the lip interval may improve the appearance of the molded product. It may be preferable to improve the thickness distribution.

The polyester-based resin composition used in the present invention can be formed into a film even by heat-melting and pressing methods such as hot press molding and injection molding. The heating and melting temperature at this time is not particularly limited, but is usually in the range of 150 to 270 ° C., and the pressure in the pressure molding is in the range of 0.1 to 100 MPa.
In addition, it is preferable to appropriately dry the polyester resin composition before molding.
A film using the polyester resin composition produced by these methods has a good film surface suitable for vapor deposition of aluminum or the like without any bleed material (that is, bleed out) that particularly harms the film surface.

  The polyester-based resin composition used in the present invention can be stretched into a stretched film by an existing method, and the stretched film can satisfactorily deposit a metal typified by aluminum or a metal oxide. .

The conditions for the stretching treatment are not particularly limited. For example, rolling, longitudinal uniaxial stretching, lateral uniaxial stretching, simultaneous biaxial stretching, and sequential biaxial stretching can be applied to a sheet immediately after melt extrusion of the polyester resin composition or after storage. It can be performed by any preferred method such as axial stretching.
The heating temperature condition in this case is preferably less than the melting point (Tm) from the glass transition temperature (Tg) of the polyester resin composition, and a temperature range from the glass transition temperature (Tg) to 50 ° C. higher than the glass transition temperature (Tg). Further preferred. Among these, a temperature range 10 to 40 ° C. higher than the glass transition temperature (Tg) is particularly preferable because a film having a good surface state can be obtained.

  A film produced using the polyester resin composition can be stretched in at least one direction. As the magnification, the surface magnification is preferably in the range of 1.2 to 16 times, more preferably in the range of 2 to 16 times, whereby an excellent surface state and good transparency can be obtained.

  The stretching method performed in the present invention is not particularly limited. For example, the method is a method of heating for a certain period of time by radiant heat such as forced convection air or an infrared heater, or heating by contacting a hot plate, mold, or roll for a certain period of time. Methods and the like. In particular, a method using a device called a tenter is capable of forcibly convection of heated air and continuously performing heat setting, which will be described later, on a sheet or film, and is excellent in productivity. Since this apparatus is an apparatus intended for stretching treatment, stretching and heat setting can be performed in a short time, and the productivity is excellent.

Next, the heat setting process will be described below.
The film produced using the polyester resin composition used in the present invention can be subjected to crystallization treatment by heat setting.
The temperature conditions and treatment time in the crystallization treatment by heat setting of the film are not particularly limited and can be set as appropriate.
In order to obtain an appropriate crystallization rate, it is preferable that the heating temperature is in the range of 40 ° C. lower than the crystallization temperature (Tc) of the polyester resin composition to less than the melting point (Tm). Among these, in order to obtain a good surface state and good heat resistance, it is particularly preferable that the heat setting is in the range of 40 ° C. higher than the crystallization temperature (Tc).

  Furthermore, if the stretching treatment is performed before heat setting or simultaneously with heat setting, the crystallization speed can be increased, for example, heat resistance can be improved in a short heat treatment time of about 5 to 30 seconds, and this is accompanied by crystallization due to orientation. It is also a method that can improve heat resistance while maintaining good transparency of the lactic acid-based polymer.

  In the present invention, a film obtained from a polyester resin composition comprising polylactic acid (I) and lactic acid copolymer polyester (II) is stretched in at least one direction and subjected to crystallization treatment by heat setting. However, there is no generation of a bleed material (bleed out) that harms the film surface, and a stretched film having a good surface state suitable for vapor deposition of metals such as aluminum or metal oxides can be obtained.

  In addition, the stretched film subjected to the crystallization treatment has an advantage that it has better heat resistance than an untreated film, and is less likely to be deformed by heat during vacuum deposition performed by heating, melting, and evaporating aluminum.

The glass transition temperature (Tg), crystallization temperature (Tc), and melting point (Tm) referred to in the present invention are T _ig , T _pc , and T _pm as defined in JIS K 7121, and the rate of temperature increase is 10 ° C./min. Measured with

  The mixing ratio of the polylactic acid (I) and the lactic acid copolymer polyester (II) in the polyester resin composition used in the present invention is such that the polylactic acid (I) is 97 to 50 parts by weight with respect to the polylactic acid modifier. It is preferable to mix the lactic acid-based copolymer polyester (II) in the range of 3 to 50 parts by weight, more preferably (I) / (II) = 95 to 55/5 to 45 parts by weight, (I ) / (II) = 95-60 / 5 to 40 parts by weight is particularly preferable. In the polyester resin composition, if the mixing ratio of polylactic acid (I) and lactic acid copolymer polyester (II) is within such a range, the impact resistance and flexibility are improved and the bleed is maintained while maintaining the heat resistance. Generation | occurrence | production of out can be suppressed and vapor deposition of the metal represented by aluminum, or a metal oxide can be performed favorably.

  The polyester resin composition used in the present invention is prepared by adjusting the addition amount of the lactic acid copolymer polyester (II), for example, an unstretched film having a thickness of 200 μm and a DuPont impact value of 0.20 to 5.0 J. The film impact value is in the range of 1 to 10 J with a stretched film having a thickness of 50 μm.

  Furthermore, using the polyester resin composition of the present invention, a film having a thickness of 200 μm was prepared, and measured with RSAII manufactured by Rheometrics Co., Ltd. at a measurement temperature of 20 ° C. and a measurement frequency of 6.28 (rad / s). When compared with the storage elastic modulus (E ′), the storage elastic modulus of the polylactic acid (I) is 3.0 to 3.5 GPa, whereas the storage elastic modulus of the polyester resin composition of the present invention is 1. It is 0-3.0 GPa, and shows 0.6-2.4 GPa depending on the addition amount and kind of lactic acid system copolyester (II).

  The lactic acid copolymer polyester (II), which is a polylactic acid modifier used in the present invention, can impart impact resistance while maintaining the heat resistance of the polylactic acid (I). For example, in the present invention, a polyester resin composition containing lactic acid copolymer polyester (II) and polylactic acid (I) suppresses a significant decrease in Tg (55 to 62 ° C.) of polylactic acid (I). When 30 parts of lactic acid copolymer polyester (II) is added to 100 parts of polylactic acid (I), it has a Tg of 50 ° C. or higher.

Furthermore, the lactic acid copolymer polyester (II), which is a modifier for polylactic acid used in the present invention, has a characteristic that the transparency of the polylactic acid (I) is not impaired. For example, in the polyester resin composition, when the addition amount of the lactic acid copolymer polyester (II) is 13 parts by weight or less, a transparent film having a haze value of 20% or less can be obtained with a press film having a thickness of 100 μm. it can.
Moreover, when there is little addition amount of lactic acid type copolyester (II) used by this invention, it is further excellent in transparency and a film with a haze value of 10% or less can be obtained.

Next, vapor deposition using aluminum will be described below.
A processing method generally called aluminum vapor deposition (or aluminum vapor deposition) is originally called aluminum vacuum vapor deposition, in which aluminum is heated and evaporated in a high vacuum apparatus to form a thin metal aluminum film on the surface of the adherend. It is.
The film made of the polyester resin composition used in the present invention is excellent as an adherend, and allows good aluminum deposition.
Films subjected to aluminum deposition are newly added with excellent functions such as metallic luster, gas barrier properties, and water vapor barrier properties inherent to aluminum.

However, the film to be adhered is required to have adhesion with aluminum.
Also, if the metallic luster of aluminum is to be reproduced on a film, the film needs to be smooth.
The film produced from the polyester resin composition used in the present invention has good aluminum adhesion because there is no bleed out, and the polylactic acid (I) and the lactic acid copolymer polyester (II) contain the lactic acid structural unit (IIa). As a result, the compatibility is good and the film has good smoothness.

  The purity of aluminum used for vacuum deposition on the biodegradable film used in the present invention is preferably 99% or more, more preferably 99.5% or more, in order to exhibit excellent performance. .9% or more is particularly preferable.

  In addition, the shape of the raw material such as aluminum used for vapor deposition is not particularly limited and may be any shape, for example, foil shape, rod shape, granular shape, powder shape, pellet, and the like. If it is suitable for the shape of a heating body such as a heating filament, there is no particular limitation.

  The distance between the heating body and the film produced from the polyester-based resin composition as the adherend is not particularly limited as long as it is appropriately set. However, in consideration of the deformation of the film due to heat and the deposition state of aluminum or the like, it is usually preferably 10. The distance is ˜60 cm, more preferably 20 to 50 cm, and particularly preferably 30 to 50 cm. If the distance between the heating body and the film made from the polyester-based resin composition that is the adherend is within such a distance, the film will not be deformed by the heat of the heating body, and an evaporated film such as aluminum can be efficiently formed. Can be formed.

The degree of vacuum in the vapor deposition furnace for depositing aluminum is preferably smaller than 10 ⁻³ Torr, more preferably 10 ⁻⁴ Torr or less, and particularly preferably 10 ⁻⁵ Torr or less.

  The film produced from the polyester-based resin composition used in the present invention is subjected to chemical etching treatment such as corona discharge treatment, flame plasma treatment, and chromic acid treatment, if necessary, in order to make vapor deposition of aluminum or the like stronger. Adhesion may be improved by surface treatment such as ozone / ultraviolet treatment or surface unevenness treatment such as sandblasting.

  The aluminum vapor deposition biodegradable film of the present invention includes known and commonly used organic fillers, inorganic fillers, antioxidants, ultraviolet absorbers, stabilizers, lubricants, antiblocking agents, surfactants, colorants, foaming agents, plasticizers, and the like. These additives may be used as necessary. The addition amount of these additives is not particularly limited as long as the effect of the present invention is not impaired, but is usually in the range of 0.01 to 30% in terms of mass with respect to the polyester resin composition. In the range of 0.01 to 20%, more preferably in the range of 0.01 to 10%.

The aluminum-deposited biodegradable film of the present invention is a bleed material of 200 cm or more from the surface of these molded products when the 10 cm × 10 cm square and 250 μm thick film is left in a constant temperature and humidity chamber at 35 ° C. and 80% humidity. Does not occur, and the aluminum deposition property is also good.
Furthermore, it has good degradability and is subject to degradation by hydrolysis, biodegradation, etc. even when it is dumped in the sea. If compost is used, it will be biodegraded in a short period of time until it remains in its original form, and even if incinerated, no toxic gases or substances will be emitted.

  The aluminum vapor deposition biodegradable film of the present invention is useful as various molded products, packaging materials, medical materials, and agricultural materials that require gas barrier properties, water vapor barrier properties, or decoration. For example, various molded products As trays, cups, dishes, blisters, blow-molded products, injection-molded products bonded with vapor-deposited films, packaging materials include sheet materials, film materials, more specifically food packaging, other general packaging, Examples of agricultural materials such as garbage bags, plastic bags, general standard bags, heavy bags, and the like include agricultural multi-films and curing films.

EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example and a comparative example, this invention is not limited to these Examples. In the examples, “parts” or “%” are based on mass unless otherwise specified.
Various characteristics were measured by the methods described below.

[Method of measuring number average molecular weight (Mn) and weight average molecular weight (Mw)]
Using a gel permeation chromatography measuring apparatus (hereinafter abbreviated as GPC) “HLC-8020” manufactured by Tosoh Corporation, tetrahydrofuran was used as a developing solvent, and the measurement was performed in comparison with standard polystyrene.

[Measurement method of thermal properties]
The glass transition temperature (Tg) and the melting point (Tm) were measured according to JIS K 7121 using a differential scanning calorimeter “DSC 220C” (hereinafter abbreviated as DSC) manufactured by Seiko Denshi Kogyo Co., Ltd.

[Measurement method of proton nuclear magnetic resonance (hereinafter abbreviated as ¹ H-NMR)]
^In order to determine the weight ratio of polylactic acid (I) and lactic acid copolymer polyester (II) in the molding resin using a ¹ H-NMR apparatus (JNM-LA300, manufactured by JEOL Ltd.), chloroform- Measured as a solution of d (CDCl ₃ ).

[Measurement Method of Storage Elastic Modulus (E ′)]
A test piece of lactic acid copolymer polyester and polyester resin composition having a frequency of 6.28 rad / s, a thickness of 200 μm, a width of 5 mm, and a length of 35 mm was measured with a FILM TEXTURE geometry using RSAII manufactured by Rheometrics. The value at was defined as the storage elastic modulus (E ′).

[Glossiness measurement method]
The film produced using the polyester resin composition was subjected to gloss measurement with a gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd.).

[Method for measuring film thickness]
The thickness of the film produced using the polyester resin composition was measured with a micrometer.

[Method for producing aluminum vapor deposition film and method for evaluating vapor deposition strength]
Using a 650S type semi-automatic vacuum vapor deposition apparatus (manufactured by Shinko Seiki Co., Ltd.), aluminum vapor deposition was performed on the film produced using the polyester resin composition. The vapor deposition strength was evaluated as “◯” when the aluminum was not peeled off by rubbing with a finger, and “×” was evaluated when it was easily peeled off.

[Evaluation of gas barrier properties]
Of a film produced using a polyester resin composition for carbon dioxide (CO ₂ ), oxygen (O ₂ ), and nitrogen (N ₂ ) using a mixed gas permeability measurement device (GPM-250 manufactured by GL Sciences Inc.) Gas permeability was measured.

[Biodegradability evaluation]
5 kg of raw garbage was put in an outdoor compost (capacity 100 liters), and a 10 cm square test piece cut out from the obtained film was placed thereon. Furthermore, the state of the test piece one month later was visually evaluated by placing garbage with a thickness of about 5 cm. This test was conducted in the summer. The evaluation criteria are as follows.
○ indicates that the physical properties are significantly deteriorated and it is difficult to maintain the shape. △ indicates that there is deformation or whitening. However, if the shape is maintained, × indicates that there is no whitening or deformation, and the state before the start of the test is maintained. What

[Production Example 1]
Production of Aliphatic Polyester (B-1) to be a Polyester Structural Unit A reactor is charged with 1 molar equivalent of sebacic acid (hereinafter abbreviated as SeA) and 1.4 molar equivalent of propylene glycol (hereinafter abbreviated as PG). Then, the temperature was raised from 150 ° C. to 10 ° C. per hour under a nitrogen stream, and the esterification reaction was carried out by heating and stirring to 230 ° C. while distilling off the generated water. Two hours later, titanium tetraisopropoxide was added as a polymerization catalyst at a rate of 100 ppm with respect to the amount of the raw material, and the reaction was continued for 8 hours under reduced pressure to 200 Pa. After completion of the reaction, 2-ethylhexanoic acid phosphate was charged as a polymerization catalyst deactivator, 110 ppm was added to the amount of the raw material, the pressure was reduced to 333 Pa, and the mixture was stirred at 220 ° C. for 1 hour. As a result, an aliphatic polyester (B-1) having a number average molecular weight (Mn) of 35,000 and an important average molecular weight (Mw) of 63,000 was obtained.

[Production Example 2]
Production of Aliphatic Polyester (B-2) to be a Polyester Structural Unit A reactor is charged with 1 molar equivalent of SuA and 1.4 molar equivalent of PG, and the temperature is increased from 150 ° C. to 10 ° C. per hour under a nitrogen stream. While distilling off the water produced, the mixture was heated to 220 ° C. and stirred for esterification. After 2 hours, titanium tetraisopropoxide was added as a polymerization catalyst at a ratio of 150 ppm with respect to the amount of raw material, and the pressure was reduced to 133 Pa and the reaction was continued for 7 hours. After completion of the reaction, 2-ethylhexanoic acid phosphate was charged as a polymerization catalyst deactivator, 150 ppm was added to the amount of raw material, and the pressure was reduced to 133 Pa, followed by stirring at 220 ° C. for 1 hour. As a result, an aliphatic polyester (B-2) having an Mn of 18,000 and an Mw of 27,000 was obtained.

[Production Example 3]
Production of Lactic Acid Copolyester (C-1) Aliphatic polyester (B-1) obtained in Production Example 1 in a reactor was charged with 50 parts of polylactic acid to be added later, under a nitrogen atmosphere, Heated at a jacket temperature of 200 ° C. Thereafter, 50 parts of polylactic acid (Mn 92,000, Mw 170,000, L / D = 98.5 / 1.5 (molar ratio); hereinafter abbreviated as PLA1) was added. Melt mixed. When the molecular weight was measured after visually confirming that (B-1) and PLA1 were uniformly melt-mixed, Mn was 51,000 and Mw was 105,000. Further, the mixture was melt mixed for 2 hours and the molecular weight was measured. As a result, a melt mixture having Mn of 51,000 and Mw of 104,000 was obtained. Thereafter, 200 ppm of titanium tetrabutoxide was added to the molten mixture and reacted at a reduced pressure of 80 Pa for 4 hours. After completion of the reaction, 500 ppm of 2-ethylhexanoic acid phosphate was added to the reaction product to obtain a lactic acid copolymer polyester (C-1) having an Mn of 58,000 and an Mw of 125,000. The obtained (C-1) had a remarkably high molecular weight as compared with the molecular weight after melting, and was solid. Further, GPC measurement showed a unimodal single peak.

[Production Example 4]
Production of Lactic Acid Copolyester (C-2) 50 parts of the aliphatic polyester (B-2) obtained in Production Example 2 was charged into a reactor and heated at a jacket temperature of 190 ° C. in a nitrogen atmosphere. Thereafter, 50 parts of polylactic acid (Mn of 150,000, Mw of 250,000, L-form / D-form = 100/0 (molar ratio); hereinafter abbreviated as PLA2) was added and melt mixed. . When the molecular weight was measured after visually confirming that (B-2) and PLA2 were uniformly melt-mixed, Mn was 56,000 and Mw was 136,000. The mixture was further melt-mixed for 1 hour, and the molecular weight of the obtained melt mixture was measured. As a result, Mn was 51,000 and Mw was 134,000. Then, 100 ppm of titanium tetrabutoxide was added to the molten mixture and reacted at a reduced pressure of 200 Pa for 3 hours. After completion of the reaction, 500 ppm of 2-ethylhexanoic acid phosphate was added to the reaction product to obtain a lactic acid copolymer polyester (C-2) having an Mn of 72,000 and an Mw of 155,000. The obtained (C-2) was remarkably higher than the molecular weight after melting, and the property was solid. Further, GPC measurement showed a unimodal single peak.

[Production Example 5]
Production of Lactic Acid Copolyester (C-3) Aliphatic polyester (B-1) obtained in Production Example 1 in a reactor was charged with 25 parts of polylactic acid to be added later, under a nitrogen atmosphere, Heated at a jacket temperature of 200 ° C. Thereafter, 70 parts of polylactic acid (PLA1) was added and melt mixed. When the molecular weight was measured after visually confirming that (B-1) and PLA1 were uniformly melted and mixed, Mn was 52,000 and Mw was 106,000. Further, the mixture was melt-mixed for 2 hours and the molecular weight was measured. As a result, a melt mixture having Mn of 52,000 and Mw of 105,000 was obtained. Thereafter, 200 ppm of titanium tetrabutoxide was added to the molten mixture and reacted at a reduced pressure of 80 Pa for 4 hours. After completion of the reaction, 500 ppm of 2-ethylhexanoic acid phosphate was added to the reaction product to obtain a lactic acid copolymer polyester (C-3) having Mn of 59,000 and Mw of 126,000. The obtained (C-3) had a remarkably high molecular weight as compared with the molecular weight after melting, and was solid. Further, GPC measurement showed a unimodal single peak.

[Production Example 6]
Production of Lactic Acid Copolyester (C-4) 50 parts of the aliphatic polyester (B-2) obtained in Production Example 2 and 50 parts of L-lactide were added to the reactor, and the jacket temperature was 170 ° C. in a nitrogen atmosphere. And heated for 1 hour. Thereafter, 0.02 part by weight of tin octoate was added as an esterification catalyst and reacted for 8 hours. Thereafter, 0.04 part of 2-ethylhexanoic acid phosphate was added and kneaded. Furthermore, the volatile matter generated from the resin was removed under heating and reduced pressure by a twin screw extruder. This removal process of volatile matter is referred to as “devolatilization” in the present invention. The devolatilization conditions are a devolatilization time of 120 seconds, a temperature of 200 ° C., and a reduced pressure of 5 Torr. The obtained lactic acid copolymer polyester (C-4) had Mn of 50,400 and Mw of 110,000.

[Examples 1 to 3]
25 parts of each of lactic acid-based copolymer polyesters (C-1), (C-2), and (C-4), which are modifiers obtained in Production Example 3, Production Example 4, and Production Example 6, After mixing with 75 parts of PLA (polylactic acid) and vacuum drying at 80 ° C. for 2 hours, a stretching sheet having a thickness of 225 μm was formed by extrusion using a single screw extruder (manufactured by Tanabe Plastics).
Next, with a single biaxial stretching machine (manufactured by Iwamoto Seisakusho Co., Ltd.), the stretching temperature is 65 ° C., the preheating time is 5 minutes, the stretching speed is 100% / minute, the stretching ratio is 3 × 3 (length × width): A stretched film of 25 μm was produced. The film was sandwiched and fixed between 30 cm square frames, and heat-set in an air oven at 120 ° C. for 50 seconds. Furthermore, aluminum vapor deposition was performed to the film produced using the obtained polyester-type resin composition.
Regarding the aluminum vapor-deposited film prepared in (C-1), Example 1, the aluminum vapor-deposited film produced from (C-2) as Example 2, and the aluminum vapor-deposited film produced from (C-4) as Example 3. . The aluminum adhesion strength, gas barrier property, and gloss of each aluminum deposited film were evaluated. Table 2 shows the results of comparative evaluation with a film not subjected to the aluminum vapor deposition treatment. The adhesion strength of aluminum of the film subjected to the vapor deposition treatment is good, and the gas barrier property and gloss are improved as compared with those not subjected to the vapor deposition treatment. All of the samples had a good biodegradability “◯”.

[Comparative Example 1] and [Comparative Example 2]
On the one hand, the polyester resin composition comprising 25 parts of aliphatic polyester (B-1) obtained in Production Example 1 and 75 parts of PLA (polylactic acid), and on the other hand, the lactic acid copolymer obtained in Production Example 5. The polymerized polyester (C-3) was vacuum-dried at 80 ° C. for 2 hours, and then a stretching sheet having a thickness of 225 μm was formed by extrusion using a single screw extruder (manufactured by Tanabe Plastics).
Next, with a single biaxial stretching machine (Iwamoto Seisakusho Co., Ltd.), a stretching temperature of 65 ° C., a preheating time of 1 minute, a stretching speed of 100% / minute, a stretching ratio of 3 × 3 (length × width): 25 μm under a surface magnification of 9 A stretched film was prepared. The film was sandwiched and fixed between 30 cm square frames, and heat-set in an air oven at 120 ° C. for 50 seconds.
Furthermore, aluminum vapor deposition was performed to the film produced using the obtained polyester-type resin composition. The film produced from (B-1) is referred to as Comparative Example 1, and the film produced from (C-3) is referred to as Comparative Example 2. In both (B-1) and (C-3), bleed out occurred from the beginning of film formation.
Moreover, although aluminum vapor deposition was tried to each film of the comparative example 1 and the comparative example 2, the vapor deposition state of aluminum was missing so that it could understand visually, and aluminum of the vapor deposition part fell off easily. Moreover, all the samples had good biodegradability. These evaluation results are summarized in Table 3.

[Comparative Example 3]
Using a single screw extruder (manufactured by Tanabe Plastics), a 25 μm film was prepared from HOPP (Sumitomo Nobrene FS7011) resin. The film forming conditions are such that the tip temperature of the extruder is 240 ° C. and the temperature of the cooling roll is 70 ° C. The biodegradability of the film was evaluated, but no degradability was found (×).

According to the present invention, a polyester resin composition obtained by dispersing and mixing polylactic acid and a lactic acid copolymer polyester composed of a lactic acid unit and a polyester unit by heat melting or solution mixing using an organic solvent. By vapor-depositing at least one surface of a film produced using aluminum with aluminum, the vapor-deposited aluminum does not easily peel off, and is excellent in gas barrier properties or water vapor barrier properties, particularly biodegradable suitable for packaging materials. An aluminum vapor deposition film can be provided. Therefore, the present invention is extremely useful industrially.

Claims (3)

97 to 50 parts by weight of polylactic acid (I) and lactic acid structural unit (IIa) and polyester structural unit (IIb) are used in a weight ratio of (IIa) / (IIb) = 10: 90 to 90:10. An aluminum-deposited biodegradable film characterized in that at least one surface of a film prepared by using a polyester-based resin composition comprising 3 to 50 parts by weight of lactic acid-based copolymerized polyester (II) is vapor-deposited with aluminum. . The aluminum vapor deposition biodegradable film according to claim 1, wherein the film produced using the polyester resin composition is a film stretched in a range of 1.2 to 16 times in at least one direction. The aluminum vapor deposition biodegradable film according to claim 1, wherein the film produced using the polyester-based resin composition is a film obtained by stretching in a range of 1.2 to 16 times in at least one direction and then crystallizing the film. .