JP4817947B2 - Biodegradable multilayer film - Google Patents

Description

The present invention relates to a multilayer film comprising an aliphatic polyester and polylactic acid. More specifically, the present invention relates to a multilayer film suitable for use as a sealant film by laminating with a polylactic acid stretched film.

In order to facilitate the disposal of plastic films, biodegradable films have attracted attention and various films have been developed. The biodegradable film is subject to hydrolysis and biodegradation in soil and water, gradually breaking down and decomposing the film, and finally changing to a harmless degradation product by the action of microorganisms. As such a film, a film formed from an aromatic polyester resin, an aliphatic polyester resin such as polylactic acid or polybutylene succinate, polyvinyl alcohol, cellulose acetate, starch or the like is known. A biaxially stretched film made of polylactic acid, which is one of such biodegradable resins, has begun to be used as a packaging film because of its excellent transparency, but as it is, there is no heat-fusibility (heat-sealability). As a method for imparting heat-fusibility to a polylactic acid biaxially stretched film, a polylactic acid-based laminated biaxial structure in which a polylactic acid-based polymer having a high content of D-lactic acid is laminated on one side of a biaxially stretched film made of polylactic acid Stretched film (Patent Document 1), Multi-layer biodegradable plastic film in which a low melting point aliphatic polyester such as succinic acid and 1,4-butanediol is laminated on one side of a biaxially stretched film made of polylactic acid (Patent Document 2, 3) Although it has been proposed, heat sealability is imparted, but the heat seal strength is insufficient or the film is inferior in optical properties. It is.

JP 2001-219522 A (Claim 1) Japanese Patent Publication No. 3236842 (Claim 1) Japanese Patent Publication No. 3084239 (Claim 1)

An object of the present invention is to provide a biodegradable sealant film suitable for imparting heat seal strength by laminating to a biaxially stretched polylactic acid film, paper, aluminum foil, or other plastic film.

The present invention does not impair the excellent transparency, surface gloss and biodegradability of the biaxially stretched polylactic acid film, paper, aluminum foil, and other plastic films, especially the polylactic acid biaxially stretched film. The purpose is to improve the suitability of automatic filling machines such as packaging.

That is, the present invention relates to an aliphatic polyester copolymer comprising an aliphatic or alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional aliphatic hydroxycarboxylic acid component (a3). The first layer (I) of the composition (D1) comprising (A) 80 to 99% by weight, polylactic acid (B) 20 to 1% by weight (the total of (A) and (B) is 100% by weight) ), An aliphatic polyester copolymer (A) comprising an aliphatic or alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional aliphatic hydroxycarboxylic acid component (a3) A second layer (II) of the composition (D2) comprising 1 to 20% by weight, polylactic acid (B) 99 to 80% by weight, (the total of (A) and (B) is 100% by weight), Stacked, first The thickness of each layer of (I) and the second layer (II) is 20% or more of the total thickness (the total thickness of the first layer (I) and the second layer (II) is 100%). The present invention relates to a multilayer film having a first layer (I) / second layer (II) structure.

The present invention also relates to an aliphatic polyester copolymer comprising an aliphatic or alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional aliphatic hydroxycarboxylic acid component (a3). The first layer (I) of the composition (D1) comprising (A) 80 to 99% by weight, polylactic acid (B) 20 to 1% by weight (the total of (A) and (B) is 100% by weight) ), An aliphatic polyester copolymer (A) comprising an aliphatic or alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional aliphatic hydroxycarboxylic acid component (a3) 2nd layer (II) of composition (D2) comprising 1 to 20% by weight, polylactic acid (B) 99 to 80% by weight, (total of (A) and (B) is 100% by weight), fat Aromatic or cycloaliphatic dicarbo 80 to 99% by weight of an aliphatic polyester copolymer (A) comprising an acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2) and a bifunctional aliphatic hydroxycarboxylic acid component (a3), polylactic acid ( B) The third layer (III) of the composition (D3) consisting of 20 to 1% by weight (the total of (A) and (B) is 100% by weight) is laminated in this order, The thickness of each of the layer (I), the second layer (II), and the third layer (III) is the total thickness (the thickness of the first layer (I), the second layer (II), and the third layer (III). It is related with the multilayer film of the structure of 1st layer (I) / 2nd layer (II) / 3rd layer (III) characterized by being 20% or more of the total of 100%.

Furthermore, the present invention provides the multilayer film as described above, wherein the second layer (II) comprises an aliphatic or alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional fat. An aliphatic polyester copolymer (A) composed of an aliphatic hydroxycarboxylic acid component (a3) 1 to 20% by weight, a polylactic acid (B) 94 to 65% by weight, and a polylactic acid block (e1) 25 to 98% by weight; Polyester block (e2) composed of a chain hydrocarbon and / or an alicyclic hydrocarbon containing a —COO— group 75 to 2% by weight (total of (e1) and (e2) is 100% by weight. And a linear lactic acid copolymer polyester (E) having a weight average molecular weight of 15,000 to 100,000 (E) in a total of 5 to 15 wt% ((A), (B) and (E) 100 weight A multilayer film characterized by comprising a make).

The multilayer film of the present invention can improve the biaxially stretched polylactic acid film, paper, aluminum foil, and other plastic films, in particular, the heat seal strength of the polylactic acid biaxially stretched film, suitability for automatic filling machines by pillow packaging, and the like.

The present invention is a multilayer film composed of a first layer (I) / second layer (II) and a multilayer film composed of a first layer (I) / second layer (II) / third layer (III). A polylactic acid biaxially stretched laminate film obtained by laminating with each of these layers, a multilayer film, and a polylactic acid biaxially stretched film will be described below.

First layer (I) The first layer (I) comprises an aliphatic or alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional aliphatic hydroxycarboxylic acid component (a3). ) Of an aliphatic polyester copolymer (A) 80 to 99% by weight and polylactic acid (B) 20 to 1% by weight (the total of (A) and (B) is 100% by weight) (D1 ). Second layer (II) The second layer (II) comprises an aliphatic or alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional aliphatic hydroxycarboxylic acid component (a3). 1) to 20% by weight of an aliphatic polyester copolymer (A) and 99 to 80% by weight of polylactic acid (B) (the total of (A) and (B) is 100% by weight) (D2) ). Third layer (III) The third layer (III) comprises an aliphatic or alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional aliphatic hydroxycarboxylic acid component (a3). ) Aliphatic polyester copolymer (A) 80 to 99% by weight and polylactic acid (B) 20 to 1% by weight (the total of (A) and (B) is 100% by weight) (D3) ).

The laminated film used in the present invention is a laminated film composed of the first layer (I) / second layer (II) and the first layer (I) / second layer (II) / third layer (III). A polylactic acid biaxially stretched laminated film of the present invention can be obtained by laminating it with a polylactic acid biaxially stretched film so that it has the first layer (I) as a sealant layer on the outer surface. Each of these layers, laminated film, and polylactic acid biaxially stretched laminated film will be described below. In addition, as long as each is in the range prescribed | regulated, the kind of polymer used for each layer, a composition, etc. may each be the same, and may be different. Therefore, even if each layer has the same definition, each layer can have a different type and composition within the specified range. In addition, in consideration of the efficiency at the time of molding, the same type and composition can be used in the case of the same rule. The polymer used for each layer will be described below.

Aliphatic polyester copolymer (A) The aliphatic polyester copolymer (A) according to the present invention comprises an aliphatic or alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2) and It is the aliphatic polyester copolymer (A) which consists of a bifunctional aliphatic hydroxycarboxylic acid component (a3). The aliphatic polyester copolymer (A) is an aliphatic polyester copolymer constituting one layer (I), second layer (II), and third layer (III), and its melting point (Tm) is 80 to It is preferable to set it as the range of 120 degreeC. The aliphatic polyester copolymer (A) having a melting point (Tm) of less than 80 ° C. has a melting point that is too low, and when used as a packaging film, for example, when fusing and sealing, the sealing portion is slow to solidify, so that There is a possibility that the film is fused to the blade, and there is a possibility that the packaging suitability is inferior. On the other hand, the aliphatic polyester copolymer (A) having a melting point (Tm) exceeding 120 ° C. has a small melting point difference from the polylactic acid biaxially stretched film to be laminated, and is used as a laminate with the polylactic acid biaxially stretched film. There is a possibility that the speed during automatic packaging is reduced. The crystallization temperature (Tc) of the aliphatic polyester copolymer (A) is preferably 35 to 75 ° C, more preferably 37 to 73 ° C. Further, (Tm)-(Tc) of the aliphatic polyester copolymer (A) is preferably 30 to 55 ° C, more preferably 35 to 50 ° C. Aliphatic polyester copolymers having a crystallization temperature (Tc) of less than 35 ° C. are too low in crystallization temperature, and even if an attempt is made to obtain a film from such a copolymer, the normal cooling temperature (5 to 30 ° C.) is not sufficient. The film is not solidified, and imprints such as nip rolls are transferred to the obtained film or are not easily peeled off from the cooling roll, resulting in a film with poor appearance. When the aliphatic polyester copolymer (A) having (Tm)-(Tc) of less than 30 ° C. is used as a laminate with a polylactic acid biaxially stretched film, the transparency and heat of the obtained polylactic acid biaxially stretched laminate film There is a possibility that sealability (particularly heat seal strength) is inferior.

In the aliphatic polyester copolymer (A) used in the present invention, the content of the bifunctional aliphatic hydroxycarboxylic acid component (a3) is preferably 0.1 to 25 mol%, more preferably 1 to 10 mol% [ An aliphatic or alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional aliphatic hydroxycarboxylic acid component (a3), an aliphatic or alicyclic dicarboxylic acid component (a1) ) And the aliphatic or alicyclic dihydroxy compound component (a2) are substantially equal in amount, the aliphatic or alicyclic dicarboxylic acid component (a1), the aliphatic or alicyclic dihydroxy compound component (a2) and the bifunctional fat The total amount of the group hydroxycarboxylic acid component (a3) is 100 mol%. ] In the range. The melt flow rate (MFR: ASTM D-1238, 190 ° C., load 2160 g) of the aliphatic polyester copolymer (A) according to the present invention is not particularly limited as long as it has a film-forming ability. It is in the range of 100 g / 10 min, preferably 0.2-50 g / 10 min, more preferably 0.5-20 g / 10 min.

Aliphatic or alicyclic dicarboxylic acid component (a1) The aliphatic or alicyclic dicarboxylic acid component (a1) which is a component constituting the aliphatic polyester copolymer (A) according to the present invention is not particularly limited. In general, the aliphatic dicarboxylic acid component is a compound having 2 to 10 carbon atoms (including carbon of the carboxyl group), preferably 4 to 6 carbon atoms, and is branched even if linear. You may do it. The alicyclic dicarboxylic acid component is usually preferably one having 7 to 10 carbon atoms, particularly 8 carbon atoms. Further, the aliphatic or alicyclic dicarboxylic acid component (a) has a larger number of carbon atoms, for example, up to 30 carbon atoms, as long as the main component is an aliphatic dicarboxylic acid having 2 to 10 carbon atoms. The dicarboxylic acid component can be included.

Specific examples of the aliphatic or alicyclic dicarboxylic acid component (a) include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, fumaric acid, 2, 2-dimethylglutaric acid, suberic acid, 1,3-cyclopentadicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, diglycolic acid, itaconic acid, maleic acid and 2,5-norbornanedicarboxylic acid Dicarboxylic acids such as acids, dimethyl esters, diethyl esters, di-n-propyl esters, di-isopropyl esters, di-n-butyl esters, di-isobutyl esters, di-t-butyl esters, di-n of such dicarboxylic acids -Pentyl ester, di-isopentyl ester or di-n-hexyl ester It can be exemplified an ester-forming derivative such as Le. These aliphatic or alicyclic dicarboxylic acids or ester-forming derivatives thereof can be used alone or as a mixture of two or more.

As the aliphatic or alicyclic dicarboxylic acid component (a1), succinic acid or an alkyl ester thereof or a mixture thereof is particularly preferable, and an aliphatic polyester copolymer (A) having a low melting point (Tm) is obtained. Succinic acid may be the main component and adipic acid may be used in combination as a subcomponent. Aliphatic or alicyclic dihydroxy compound component (a2) The aliphatic or alicyclic dihydroxy compound component (a2), which is a component constituting the aliphatic polyester copolymer (A) according to the present invention, is not particularly limited. Usually, it is a branched or linear dihydroxy compound having 2 to 12 carbon atoms, preferably 4 to 6 carbon atoms if it is an aliphatic dihydroxy compound component, and 5 if it is an alicyclic dihydroxy compound component. And cyclic compounds having 10 to 10 carbon atoms.

Specific examples of the aliphatic or alicyclic dihydroxy compound component (a2) include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, and 1,4-butane. Diol, 1,5-pentanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3 -Propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 2,2,4-trimethyl-1,6-hexanediol, in particular ethylene glycol, 1,3-propanediol, 1,4 -Butanediol and 2,2-dimethyl-1,3-propanediol (neopentyl glycol); cyclopentanediol, 1,4-cyclo Xanthdiol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol and 2,2,4,4-tetramethyl-1,3-cyclobutanediol and diethylene glycol, triethylene Examples thereof include polyoxyalkylene glycols such as glycol and polyoxyethylene glycol, and polytetrahydrofuran, and particularly include diethylene glycol, triethylene glycol and polyoxyethylene glycol, or a mixture thereof or a compound having a different number of ether units. The aliphatic or cycloaliphatic dihydroxy compound component can also be a mixture of different aliphatic or cycloaliphatic dihydroxy compounds. As the aliphatic or alicyclic dihydroxy compound component (a2), 1,4-butanediol is preferable.

Bifunctional aliphatic hydroxycarboxylic acid component (a3) The bifunctional aliphatic hydroxycarboxylic acid component (a3), which is a component constituting the aliphatic polyester copolymer (A) according to the present invention, is not particularly limited. Examples thereof include compounds having a branched or linear divalent aliphatic group having 1 to 10 carbon atoms. Specific examples of the bifunctional aliphatic hydroxycarboxylic acid component (a3) include glycolic acid, L-lactic acid, D-lactic acid, D, L-lactic acid, 2-methyllactic acid, 3-hydroxybutyric acid, 4 -Hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-2-methylbutyric acid, 2-hydroxy-3-methylbutyric acid, hydroxypivalic acid, hydroxyisocaproic acid, Bifunctional aliphatic hydroxycarboxylic acid ester-forming derivatives such as hydroxycaproic acid and the like, such as methyl ester, ethyl ester, propyl ester, butyl ester and cyclohexyl ester of bifunctional aliphatic hydroxycarboxylic acid.

Among these, those containing lactic acid as a main component such as L-lactic acid, D-lactic acid, D, L-lactic acid are preferable, and those containing L-lactic acid as the main component are preferable. The aliphatic polyester copolymer (A) according to the present invention can be produced by various known methods. Specific polymerization methods are described, for example, in JP-A-8-239461 and JP-A-9-272789. In addition, the aliphatic / aromatic polyester (A) according to the present invention is manufactured and sold as GS Pla (trade name) by Mitsubishi Chemical Corporation, for example.

Polylactic acid (B) The polylactic acid (B) forming the first layer (I), the second layer (II) or the third layer (III) of the laminated film of the present invention is D-lactic acid (or L-lactic acid). Is preferably poly L-lactic acid (or D-lactic acid) containing 7 to 30% by weight, more preferably 8 to 25% by weight. Poly-L-lactic acid (or poly-D-lactic acid) having a D-lactic acid (or L-lactic acid) content of less than 7% by weight may impair the low-temperature heat sealability of the resulting polylactic acid biaxially stretched laminated film. On the other hand, when it exceeds 30% by weight, the moldability tends to be inferior. The D-lactic acid content in polylactic acid (B) is a value measured by using a gas chromatograph CP CYCLODX B 236M manufactured by Chrombac Co., Ltd. It is. The polylactic acid (B) preferably has a glass transition temperature (Tg) of less than 58 ° C, more preferably 50 to 57.5 ° C.

The weight average molecular weight of polylactic acid (B) is not particularly limited as long as it has film forming ability, but MFR (according to ASTM D-1238, load 2160 g, temperature 190 ° C.) is usually 0.1 to 100 g / 10 min. Preferably 1 to 50 g / 10 min, particularly preferably 2 to 10 g / 10 min are used. As a polymerization method of such polylactic acid (B), any known method such as condensation polymerization or ring-opening polymerization method can be employed. For example, in the condensation polymerization, polylactic acid having an arbitrary composition can be obtained by directly dehydrating condensation polymerization of L-lactic acid, D-lactic acid or a mixture thereof. In the polylactic acid (B) used in the present invention, an antioxidant, a weathering stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a slipping agent, light resistance are used as long as the object of the present invention is not impaired. You may mix | blend additives, such as a stabilizer, a ultraviolet absorber, a fluorescent brightening agent, an antibacterial agent, a nucleating agent, an inorganic compound, or an organic compound filler as needed.

Composition (D1) The composition (D1) constituting the first layer (I) of the laminated film of the present invention is 80 to 99% by weight, preferably 80 to 90% by weight, of the aliphatic polyester copolymer (A). , And 20 to 1% by weight, preferably 20 to 10% by weight of the polylactic acid (B) (the total of the aliphatic polyester copolymer (B) and the polylactic acid (C) is 100% by weight) Consists of. When the composition (D1) having an amount of polylactic acid (B) of less than 1% by weight is used for the first layer (I) of the laminated film, the second layer (II) comprising the composition (D2) described later On the other hand, the (aliphatic polyester composition of the first layer (I) of the laminated film comprising the composition (D1) in which the polylactic acid copolymer (B) exceeds 20% by weight. And polylactic acid are incompatible with each other and cause phase separation), resulting in a feeling of melody and haze remarkably worsening, and lowering the transparency as a polylactic acid biaxially stretched laminated film. (To use polylactic acid as a sealing layer) There is a risk that the heat seal strength may be reduced).

Composition (D2) The composition (D2) constituting the second layer (II) of the laminated film of the present invention is 1 to 20% by weight, preferably 10 to 20% by weight of the aliphatic polyester copolymer (A). And a composition of 99 to 20% by weight, preferably 90 to 80% by weight of the polylactic acid (B) (the total of the aliphatic polyester copolymer (B) and the polylactic acid copolymer (C) is 100% by weight) Is). When the composition (D2) in which the amount of the aliphatic polyester copolymer (A) is less than 1% by weight is used for the second layer (2) of the laminated film, the first composition (D1) comprising the above-described composition (D1). The layer (I) or the interlayer strength with the third layer (III) composed of the composition (D3) to be described later is reduced, and the film becomes brittle and cuts in the process of film formation and slitting, resulting in reduced efficiency. The heat seal strength may be reduced (because the layer is brittle), while the second layer (II) of the laminated film comprising the composition (D2) in which the aliphatic polyester copolymer (A) exceeds 20% by weight. (Because the aliphatic polyester composition and polylactic acid are incompatible with each other and cause phase separation), there is a possibility that a melamellar feeling is generated and the haze is remarkably deteriorated and the transparency is lowered.

Composition (D3) The composition (D3) constituting the third layer (III) of the laminated film of the present invention is the aliphatic polyester copolymer (A) 80 to 99% by weight, preferably 80 to 90% by weight. , And 20 to 1% by weight, preferably 20 to 10% by weight of the polylactic acid (B) (the total of the aliphatic polyester copolymer (B) and the polylactic acid (C) is 100% by weight) Consists of. When the composition (D3) in which the amount of polylactic acid (B) is less than 1% by weight is used for the third layer (III) of the laminated film, the second layer comprising the aliphatic polyester composition (D2) described above. On the other hand, the third layer (III) of the laminated film comprising the composition (D3) in which the polylactic acid copolymer (B) exceeds 20% by weight is likely to be (aliphatic). The polyester composition and polylactic acid are incompatible with each other and cause phase separation), resulting in a feeling of melamel and haze that is significantly deteriorated, lowering the transparency. Also, polylactic acid is brittle to use as a sealing layer, so the heat seal strength is low. There is a risk of becoming.

Each of the compositions (D1), (D2) and (D3) is composed of an aliphatic polyester copolymer (A) and a polylactic acid (B) in the above ranges, respectively, in a Henschel mixer, V-blender, ribbon blender, tumbler mixer, etc. And after mixing, it can be prepared by a single-screw extruder, a multi-screw extruder, a Banbury mixer, or the like. In the aliphatic polyester compositions (D1), (D2) and (D3) according to the present invention, the aliphatic polyester copolymer (A) and the polylactic acid (B) are separately used, or the composition (D1) ( In the production of D2) and (D3), an antioxidant, a weather resistance stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a slip agent, and light resistance are used as long as the object of the present invention is not impaired. You may mix | blend additives, such as a stabilizer, a ultraviolet absorber, a fluorescent brightening agent, an antibacterial agent, a nucleating agent, an inorganic compound, or an organic compound filler as needed.

Multilayer film The multilayer film of the present invention, the first layer (I) is composed of 80 to 99 wt% of the aliphatic polyester copolymer (A) and 20 to 1 wt% of the polylactic acid (B), The second layer (II) comprises 1 to 20% by weight of the aliphatic polyester copolymer (A) and 99 to 10% by weight of the polylactic acid (B), and the third layer (III) comprises the above-mentioned Each layer comprising 80 to 99% by weight of the aliphatic polyester copolymer (A) and 20 to 1% by weight of the polylactic acid (B) is laminated, and the first layer (I) and the second layer ( II) The total thickness of each layer is 100% of the total thickness of the first layer (I) and the second layer (II).
20% or more of the multilayer film having the first layer (I) / second layer (II) structure, or the first layer (I), the second layer (II), the third layer The thickness of each layer of the layer (III) is 20% or more of the total thickness (the total thickness of the first layer (I), the second layer (II), and the third layer (III) is 100%) A multilayer film having a constitution of a first layer (I) / a second layer (II) / a third layer (III), which is characterized by being.

Furthermore, when laminated with a polylactic acid biaxially stretched film and the first layer (I) as a sealant layer on the outer surface, it is excellent in transparency and heat seal strength of the present invention, and particularly suitable for pillow packaging and fusing sealing packaging. An axially stretched laminated film is obtained. The multilayer film has either a two-layer configuration of the first layer (I) / second layer (II) or a three-layer configuration of the first layer (I) / second layer (II) / third layer (III). However, a three-layer structure is preferable because the film is symmetric with respect to the second layer, so that there is little warpage. In the multilayer film comprising the first layer (I), the second layer (II) or the third layer (III) of the present invention, the first layer (I), the second layer (II) or the third layer (III) The thickness of each layer can be variously determined depending on the application. Usually, the thickness of the first layer (I) is in the range of 3 to 20 μm, preferably 5 to 10 μm, and the thickness of the second layer (II). Is in the range of 5 to 50 μm, preferably 10 to 30 μm. When the third layer (III) is used, the thickness of the third layer (III) is in the range of 3 to 20 μm, preferably 5 to 10 μm. .

The thickness of the entire multilayer film is usually in the range of 10 to 100 μm, preferably 20 to 50 μm in any case. In the multilayer film consisting of the first layer (I) / second layer (II), if the thickness of the first layer (I) is less than 3 μm, the heat seal strength may be reduced, and if it exceeds 20 μm There is a possibility that the haze of the layer is deteriorated, and if the second layer (II) is less than 5 μm, the ratio of the second layer (II) or the third layer (III) increases as a result, and the haze as a sealant film may be deteriorated. If the thickness exceeds 20 μm, the multilayer film becomes brittle, and there is a possibility that the film may be cut during film formation or slitting, or the heat seal strength may be reduced.

The same applies to the multilayer film in which the multilayer film is composed of the first layer (I) / second layer (II) / third layer (III), but the thickness of the third layer (III) is set to reduce the warpage of the film. It is preferable to be approximately equal to the first layer (I). Furthermore, when the thickness of the entire multilayer film is less than 10 μm, film formation, slitting and lamination are difficult, and when it exceeds 100 μm, the weight of the film increases, and the handiness as a product (packaging bag) may be impaired, and the cost may increase. . The multilayer film used in the present invention can be produced by various known methods. For example, the aliphatic polyester copolymer (A) and polylactic acid (B) constituting each of the first layer (I), the second layer (II), and the third layer (III) are blended in predetermined amounts. The multilayer film can be produced by coextrusion molding by directly feeding it into a film molding machine equipped with a multilayer die having two or more layers.

In addition, the aliphatic polyester copolymer (A) and the polylactic acid (B) constituting each of the first layer (I), the second layer (II), and the third layer (III) are each in a predetermined amount in advance. After blending, after melting and kneading to obtain compositions (D1), (D2), and (D3) which are raw materials of the first layer (I), the second layer (II), and the third layer (III) A multilayer film can be produced by coextrusion molding by introducing it into a film molding machine equipped with a multilayer die having two or more layers. Alternatively, after separately forming films comprising the composition (D1) of the first layer (I), the composition (D2) of the second layer (II), and the composition (D3) of the third layer (III) It can be laminated to produce a multilayer film. The multilayer film of the present invention is preferably unstretched. If it is a stretched film, heat seal strength and transparency may be reduced. Further, the multilayer film of the present invention has one surface, for example, corona treatment, flame treatment, in order to improve printability, vapor deposition, sputter film adhesion, or adhesion with the aforementioned multilayer film. Surface activation treatment is preferably performed by plasma treatment, undercoat treatment or the like.

Aromatic polyester (F)
The aromatic polyester copolymer (F) is an aromatic polyester containing an aromatic dicarboxylic acid having a sulfonic acid metal base as a nucleus substituent, and more specifically, an aromatic dicarboxylic acid, an aliphatic glycol, And an aromatic dicarboxylic acid having a sulfonic acid metal base as a nuclear substituent, and an aliphatic dicarboxylic acid or aliphatic hydroxycarboxylic acid added to the aromatic dicarboxylic acid as necessary, and a polycondensation reaction between these components. It is desirable. The preferred composition of the polyester resin is 30 to 49.9 mol% of units derived from an aromatic dicarboxylic acid component, 35 to 50 mol% of units derived from an aliphatic glycol component, and an aromatic having a sulfonic acid metal base as a substituent. 0.1 to 5 mol% of units derived from an aliphatic or aliphatic dicarboxylic acid component, and 0 to 30 mol% of units derived from an aliphatic dicarboxylic acid or aliphatic hydroxycarboxylic acid component (here, the total of all units) Is 100 mol%).
A polyester containing an aromatic dicarboxylic acid having a sulfonic acid metal base as a nuclear substituent as a copolymer component used in the present invention is basically formed by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol. In order to impart biodegradability, the polyester resin contains an aromatic dicarboxylic acid having a sulfonic acid metal base as a nuclear substituent as one of the copolymerization components. Further, it is a multi-component polyester resin in which an aliphatic dicarboxylic acid or an aliphatic hydroxycarboxylic acid is further added as a copolymerization component in order to impart or improve performance such as flexibility and biodegradability to the film. May be. Such resins are described in JP-A-5-507109, JP-A-6-505040, JP-A-6-505513, and the like.
Preferred such copolymers are aromatic dicarboxylic acid and aliphatic glycol as the main components, aromatic dicarboxylic acid having sulfonic acid metal base as a nucleus substituent, and aliphatic dicarboxylic acid or aliphatic hydroxycarboxylic acid as a secondary. It is a polyester obtained by allowing a polycondensation reaction to proceed between these components in addition to the components.
Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, and the like, and derivatives having ester forming ability such as dialkyl esters thereof can also be used. Among them, terephthalic acid or dimethyl terephthalate is preferably used. Further, two or more kinds of the aforementioned dicarboxylic acids may be used in combination.
Examples of the aliphatic glycol include alkylene glycols such as ethylene glycol, propylene glycol and butylene glycol, and oligomers thereof such as diethylene glycol, triethylene glycol, dipropylene glycol, and higher molecular weight polyalkylene glycol. These polyalkylene glycols can also be used. Further, two or more kinds of the aforementioned glycols may be used in combination. Since oligomers such as diethylene glycol have the effect of appropriately adjusting the mechanical properties, hydrolyzability or biodegradability of the polyester resin, it is possible to use alkylene glycols and polyalkylene glycols in combination. preferable. Among them, the combined use of ethylene glycol and diethylene glycol is desirable.
An aromatic dicarboxylic acid having a sulfonic acid metal base as a nuclear substituent is a compound in which a sulfonic acid metal base (—SO ₃ M) is bonded as a substituent to a benzene ring of an aromatic dicarboxylic acid such as phthalic acid or isophthalic acid. is there. Examples of the metal (M) include alkali metals such as lithium, sodium, and potassium, or alkaline earth metals such as magnesium and calcium. Preferable examples include a metal salt of 5-sulfo-isophthalic acid, a metal salt of 4-sulfo-isophthalic acid, and a metal salt of 4-sulfo-phthalic acid. This component is added for the purpose of imparting hydrolyzability and biodegradability to the aromatic polyester copolymer, and 5-sulfo-isophthalic acid sodium salt is particularly preferable because of its high effect. The aromatic dicarboxylic acid may be an alkyl ester and can be used, for example, in the form of dimethyl-5-sulfoisophthalic acid sodium salt.
Examples of the aliphatic dicarboxylic acid include azelaic acid, succinic acid, adipic acid, sebacic acid, and glutaric acid. Examples of the aliphatic hydroxycarboxylic acid include glycolic acid, hydroxyacetic acid, lactic acid, and caprolactone. can do. This aliphatic dicarboxylic acid or aliphatic hydroxycarboxylic acid lowers the glass transition temperature of the aromatic polyester copolymer, preferably lower than 70 ° C., or improves the hydrolyzability and biodegradability of the resin. It is added as a kind of copolymerization component for the purpose.
The polycondensation reaction between the components described above is carried out in the presence of a catalyst such as antimony oxide or germanium oxide at a high temperature of 200 ° C. or higher and under reduced pressure, whereby units derived from those components are randomly generated along the molecular chain. A distributed linear polyester resin can be obtained.
The content of units derived from each component in the polycondensed polyester resin is 30 to 49.9 units, preferably 37 to 48.7 mol%, derived from an aliphatic dicarboxylic acid component. Units of 35 to 50, preferably 40 to 49 mol%, 0.1 to 5, preferably 0.3 to 3 mol% of units derived from an aromatic dicarboxylic acid component having a sulfonic acid metal base as a substituent, And the unit derived from the aliphatic dicarboxylic acid or aliphatic hydroxycarboxylic acid component is 0 to 30, preferably 2 to 20 mol%. Here, the total of all units is 100 mol%.
In the preferred aromatic polyester copolymer, the unit derived from the terephthalic acid component is 30 to 49.9, preferably 37 to 48.7 mol%, and the unit derived from the ethylene glycol component is 15 to 48, preferably 20 ~ 45 mol%, unit derived from diethylene glycol component is 1 to 29, preferably 4 to 20 mol%, unit derived from aromatic dicarboxylic acid component having sulfonate metal base as substituent is 0.1 to 5, preferably Is 0.3 to 3 mol%, and the unit derived from the aliphatic dicarboxylic acid or aliphatic hydroxycarboxylic acid component is 0 to 30, preferably 2 to 20 mol%. Here, the total of all units is 100 mol%.
The aromatic polyester copolymer used in the present invention preferably has a weight average molecular weight in the range of 10,000 to 500,000. Moreover, it is preferable that the melt flow rate is based on ASTM D-1238, and the value measured under 220 degreeC and a 2160g load is 0.1-100 (g / 10min). When the molecular weight and the melt flow rate are within the above ranges, the melt viscosity suitable for extrusion molding is exhibited, and sufficient mechanical strength as a laminated film substrate layer is obtained.

Polylactic acid biaxially stretched laminate film The polylactic acid biaxially stretched laminate film obtained by laminating the multilayer film and the polylactic acid biaxially stretched film has excellent optical properties such as transparency and gloss, and rigidity, and is a multilayer film. As a sealant layer, low temperature heat sealability and heat seal strength are imparted without impairing optical properties. The total thickness of the polylactic acid biaxially stretched laminated film of the present invention is in the range of 15 to 200 μm, preferably 30 to 100 μm. If the thickness of the polylactic acid biaxially stretched laminated film is less than 15 μm, there is a risk of pinholes being formed when used as a packaging bag, and if it exceeds 200 μm, the packaging bag is bulky and the product (packaging bag) is not handy. In addition, the cost may increase. As a method of producing a polylactic acid biaxially stretched laminated film, a biaxially stretched film is produced in advance using polylactic acid, and a multilayer film is produced using the aliphatic polyester copolymer (A) and polylactic acid (B). A method of producing by casting and bonding using an adhesive (laminate method), or a composition (D1) and (D2) or a composition (D1), (D2) and (D) on one side of a polylactic acid biaxially stretched film Although the method of extruding and coating two or three layers of D3) (extrusion laminating method) can be used, a laminate method is preferable because printing, vapor deposition, or sputtering treatment can be performed on the multilayer film side.

Aromatic polyester biaxially stretched laminate film The aromatic polyester biaxially stretched laminate film obtained by laminating the multilayer film and the aromatic polyester biaxially stretched film is excellent in optical properties such as transparency and gloss, and rigidity. And since it has a multilayer film as a sealant layer, low-temperature heat sealability and heat seal strength are imparted without impairing optical properties. The total thickness of the aromatic polyester biaxially stretched laminated film of the present invention is in the range of 15 to 200 μm, preferably 30 to 100 μm. If the thickness of the aromatic polyester biaxially stretched laminated film is less than 15 μm, there is a risk of pinholes being used when used as a packaging bag. If the thickness exceeds 200 μm, the packaging bag is bulky, and the product (packaging bag) is not handy. There is a risk of damage and cost. As a method for producing an aromatic polyester biaxially stretched laminated film, a biaxially stretched film is produced in advance using an aromatic polyester (F), and an aliphatic polyester copolymer (A) and a polylactic acid (B) are produced. A method for producing a multilayer film by casting using an adhesive and laminating with an adhesive (laminate method), or a composition (D1) and (D2) or a composition (D1) on one side of a polylactic acid biaxially stretched film, A method of extruding and coating two or three layers of (D2) and (D3) (extrusion laminating method) can be used, but if it is a laminate method, printing, vapor deposition, or sputtering treatment can be performed on the multilayer film side. preferable.

Vapor Deposition, Sputtering The multilayer film of the present invention is one or more of aluminum oxide, aluminum, silicic acid, ITO in order to improve gas barrier properties, especially water vapor barrier properties when packaging rice crackers, dried foods, snacks, etc. Inorganic metals can be deposited or sputtered. Since the gas barrier property is improved while maintaining transparency and the cost is low, an aluminum oxide or silicic acid vapor deposition treatment is preferable. In addition, the multilayer film may be provided with a barrier performance by laminating with a polylactic acid biaxially stretched film or an aromatic polyester copolymer biaxially stretched film that has been subjected to vapor deposition or sputtering without performing the above treatment. . Moreover, when laminating a multilayer film and a polylactic acid biaxially stretched film or an aromatic polyester copolymer biaxially stretched film after vapor deposition or sputtering treatment, of course, in order to protect the vapor deposition film or the sputtered film, It is preferable that the vapor-deposited film or the sputtered surface be a laminated surface and not the outer surface of the packaging bag. The thickness of these vapor-deposited and sputtered layers is usually about 10 to 500 mm.

Pillow packaging film Polylactic acid biaxially stretched laminate film or aromatic polyester biaxially stretched laminate film obtained using the multilayer film of the present invention is the above polylactic acid biaxially stretched film or aromatic polyester biaxially stretched laminate film. It is prepared by laminating a multilayer film. Therefore, when used as a film for pillow packaging, since the polylactic acid biaxially stretched film or the aromatic polyester biaxially stretched laminated film is the outer surface, the resulting pillow packaging bag has excellent optical properties such as transparency and gloss, and rigidity, Further, since the multilayer film obtained from the compositions (D1) and (D2) or the compositions (D1), (D2) and (D3) is provided on one side, the one side can be heated at low temperature without impairing the optical properties. Since it has sealing properties and heat seal strength, it is excellent in pillow packaging suitability.

Film for fusing and sealing packaging When used as a film for fusing and packaging, polylactic acid biaxially stretched film or aromatic polyester biaxially stretched film is the outer surface, so the resulting fused and sealed packaging bag has optical properties such as transparency and gloss It has excellent rigidity and has a multilayer film obtained from the compositions (D1) and (D2) or the compositions (D1), (D2) and (D3) on one side, so that the optical properties are impaired. Since it has fusing heat seal strength, it is excellent in fusing seal packaging suitability.

Linear lactic acid copolymer polyester (E) The linear lactic acid copolymer polyester (E) that may be used in the second layer (II) of the multilayer film of the present invention has a weight average molecular weight of 15,000 to 10%. Polyester block comprising a polylactic acid block (e1) of 25 to 98% by weight, preferably 25 to 95% by weight, and a chain hydrocarbon and / or an alicyclic hydrocarbon containing a —COO— group (E2) A linear lactic acid-based copolyester composed of 2 to 75% by weight, preferably 5 to 75% by weight (the total of (e1) and (e2) is 100% by weight). The polylactic acid block (e1) is generally preferably composed of a lactide component formed by ring-opening polymerization of lactide, and is composed of a chain hydrocarbon and / or alicyclic hydrocarbon moiety containing a —COO— group. The polyester block (e2) is a polyester part derived from the raw material polyester, and is a constituent part composed of a chain hydrocarbon and / or an alicyclic hydrocarbon part containing a —COO— group. Such a linear lactic acid-based copolymer polyester (E) is generally an aliphatic polyester having a weight average molecular weight of 10,000 to 250,000 consisting of 25 to 98% by weight of lactide, an aliphatic dicarboxylic acid component and an aliphatic diol component. 2 to 75% by weight can be produced by a method of ring-opening polymerization and transesterification in the presence of a ring-opening polymerization catalyst.

Lactide is a compound obtained by cyclic dimerization of lactic acid, has a stereoisomer, L-lactide composed of L-lactic acid, D-lactide composed of D-lactic acid, and MESO-lactide composed of L-lactic acid and D-lactic acid. is there. A copolymer mainly composed of L-lactide or D-lactide is crystallized to obtain a high melting point. The linear lactic acid-based copolymer polyester (E) of the present invention can realize preferable resin characteristics by combining these three types of lactide. In the present invention, the linear lactic acid copolymer polyester (E) preferably contains 90% or more of L-lactide as a lactide in the total lactide.

Aliphatic polyester means what consists of an aliphatic dicarboxylic acid component and a diol component, It is preferable that it is high molecular weight, Specifically, it is 10,000-250,000 in a weight average molecular weight. In order to obtain a high molecular weight aliphatic polyester, the molar fraction of the aliphatic dicarboxylic acid component and the diol component is preferably about 1. Although it does not specifically limit as an aliphatic dicarboxylic acid component in aliphatic polyester, Especially, it is preferable that it is a C4-C14 aliphatic dicarboxylic acid component. Specific examples include succinic acid, adipic acid, azelaic acid, sebacic acid, brassic acid, cyclohexanedicarboxylic acid and the like. In addition, dimer acid and the like are also exemplified. The diol component is preferably a diol having 2 to 10 carbon atoms, specifically, ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexamethylene glycol, octanediol, neopentyl glycol, cyclohexanedimethanol, xylene glycol, Examples include diethylene glycol, triethylene glycol, dipropylene glycol, dibutanediol, 3-hydroxypivalyl pivalate, and hydrogenated bisphenol.

In the polymerization reaction, a ring-opening polymerization catalyst is generally used, and metals such as tin, zinc, lead, titanium, bismuth, zirconium, germanium, and their derivatives, which are also known as general ring-opening polymerization catalysts and transesterification catalysts, are used. In particular, metal organic compounds, carbonates, oxides and halides are preferred. Specifically, tin octoate, tin chloride, zinc chloride, zinc acetate, lead oxide, lead carbonate, titanium chloride, alkoxy titanium, germanium oxide, and zirconium oxide are suitable. Polylactide, aliphatic carboxylic acid and diol component are heated and melted in an extruder to initiate polymerization. The reaction temperature is generally above the melting point of lactide.

In the polymerization reaction, polylactide is subjected to ring-opening addition polymerization in a block form to the terminal OH group of the aliphatic polyester used for copolymerization, for example, to produce a block copolymer of A-BB-A-BBB-A type. Further, it is considered that the transesterification reaction between the polymers proceeds. It is considered that the lactic acid copolymer polyester produced by these ring-opening polymerization and transesterification reaction substantially maintains a linear structure.

Moreover, as a polyester block (e2) comprised from the chain | strand-shaped hydrocarbon and / or alicyclic hydrocarbon containing a -COO-group, the polyester block (e2 ') which consists of propylene glycol, succinic acid, or sebacic acid is used. Particularly preferred. The linear lactic acid-based copolymer polyester (E) of the present invention is desirably a resin having good flexibility, and preferably has a glass transition point of room temperature or higher and a melting point of 140 ° C. or higher. For the purpose of improving the transparency of the multilayer film, the second layer (II) of the multilayer film includes an aliphatic or alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional aliphatic. Aliphatic polyester copolymer (A) 1 to 20% by weight, polylactic acid (B) 94 to 65% by weight, linear lactic acid copolymer polyester (E) 5 to 15% by weight comprising the hydroxycarboxylic acid component (a3) It can mix | blend so that it may become a ratio (it is set as 100 weight% in total of (A), (B) and (E)).

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist. The raw materials used in Examples and Comparative Examples are as follows. (1) Aliphatic polyester copolymer (A) (i) Succinic acid / 1,4-butanediol / lactic acid / polyester copolymer (A-1) manufactured by Mitsubishi Chemical Co., Ltd., trade name: GS-Pla AD92W MFR (190 ° C, load 2160 g): 4.5 g / 10 min, melting point (Tm): 86.9 ° C, crystallization temperature (Tc): 40.4 ° C, (Tm)-(Tc): 45.5 ° C, density: 1.3 g / cm ³ . (Ii) Succinic acid / 1,4-butanediol / lactic acid / polyester copolymer (A-2), manufactured by Mitsubishi Chemical Corporation, trade name GS-Pla AZ91T MFR (190 ° C., load 2160 g): 4.5 g / 10 min , Melting point (Tm): 108.9 ° C., crystallization temperature (Tc): 68.0 ° C., (Tm)-(Tc): 40.9 ° C., density: 1.3 g / cm ³ . (2) Polylactic acid (B): D-lactic acid content: 12.6 wt%, MFR (temperature 190 ° C., load 2160 g): 2.6 g / 10 min, melting point (Tm): none, Tg: 56.9 ° C. Density: 1.3 g / cm ³ (3) Linear lactic acid-based copolymer polyester (E) Block copolymer of polylactic acid and poly (propylene succinate) Daime Ink Chemical Co., Ltd. Puramate PD-350 Weight average molecular weight: 2 60,000, Tm (° C) 139.7 ° C
(4) Sulfonate group-containing aromatic polyester (F):
Terephthalic acid 45 mol%, ethylene glycol 37 mol%, diethylene glycol 9 mol%, 5-sulfo-sodium isophthalate sodium 1 mol%, hydroxyacetic acid 8 mol%, density: 1.35 g / cm ³ , melting point (Tm): 200 ° C. , MFR (220 ° C., 2160 g load): 15 g / 10 min.

(5) Additive (i) Silica, manufactured by Fuji Silysia Chemical Co., Ltd., trade name: Cylicia 730 (particle size: 4 μm) (ii) erucamide, manufactured by Ciba Specialty Chemicals, Inc., trade name: ATMER SA1753 (iii) Polyethylene glycol, manufactured by Daiichi Kogyo Seiyaku , Product surface PEG4000 Various measurement methods in the present invention are as follows. (1) Optical characteristics It measured with both the laminated | multilayer film and the polylactic acid laminated film. Haze (HZ:%), parallel light transmittance (PT:%), and gloss (%) were measured using a haze meter 300A manufactured by Nippon Denshoku Industries Co., Ltd. The measured value is an average of 5 times. The gloss of the laminated film was measured on the stretched film side.

(2) Tensile test It measured with both the multilayer film and the polylactic acid laminated film. As a test piece, a strip-like film piece (length: 150 mm, width: 15 mm) was cut out from a polylactic acid biaxially stretched laminated film in the machine direction (MD) and the transverse direction (TD), and a tensile tester (Tensilon manufactured by Orientec Co., Ltd.) Using a universal testing machine RTC-1225), a tensile test was performed under the conditions of the distance between chucks: 100 mm and the crosshead speed: 300 mm / min (however, the Young's modulus was measured at 5 mm / min), and the strength at the breaking point (MPa) , Elongation (%) and Young's modulus (MPa) were determined. Elongation (%) was defined as a change in the distance between chucks. The measured value is an average of 5 times.

(3) Heat seal strength TP-701-B, manufactured by Tester Sangyo Co., Ltd., so that the laminated film faces are formed after the multilayer film and the polylactic acid biaxially stretched film are bonded to form a polylactic acid biaxially stretched laminated film. Using HEATSEALTESTER, heat sealing was performed at a predetermined temperature under conditions of a seal surface pressure of 1 kg / cm ² and a time of 0.5 seconds. The heating was performed only on the upper side. Next, a test piece having a width of 15 mm was cut out from the heat-sealed polylactic acid biaxially stretched laminated film and peeled off at a tensile rate of 300 mm / min using a tensile tester (Orientec Tensilon Universal Tester RTC-1225). The maximum strength was defined as heat seal strength (thermal fusion strength: N / 15 mm). (4) Oxygen permeability Based on JIS K7126, it measured on the conditions of 20 degreeC humidity 0% RH (relative humidity) using the oxygen-permeation measuring device (the MOCON company make, OXTRAN2 / 21 ML). (5) Moisture permeability (water vapor permeability)



It calculated | required based on JISZ0208. The film was collected to make a bag having a surface area of about 100 cm ² , and after putting an appropriate amount of calcium chloride, it was sealed. This was left in an atmosphere of 40 ° C. and 90% RH (relative humidity) for 3 days, and the moisture permeability (water vapor permeability) was determined from the weight increase.

Examples 1-3, Comparative Examples-1-10 < Manufacture of Aliphatic Polyester Composition (D)> As the aliphatic polyester used in the multilayer film, the raw materials and additives shown in Table 1 were used in Examples-1-3 , Comparative Example. -1 to 10 were blended and melt-kneaded at 180 ° C using a 40 mmφ single screw extruder to prepare each aliphatic polyester composition (D). <Manufacture of multilayer film> Examples-1 to 3 are 3 layers, Comparative Examples-1 to 10 are single layers, and a three-layer coextrusion sheet molding machine equipped with a multi-manifold T-die at the tip is used. -By adjusting the discharge rate so that the layer ratio is as described in 1 and extruding a coextruded (or single layer) sheet from a T-die heated to 200 ° C, it is rapidly cooled with a casting roll at 30 ° C. A three-layer (or single-layer) unstretched multilayer film having a thickness of 30 μm was prepared. Moreover, the corona treatment was performed on one side.

<Manufacture of polylactic acid biaxially stretched laminated film> A urethane adhesive (manufactured by Takeda Pharmaceutical Co., Ltd.) is applied to the corona-treated surface of a 20 μm thick polylactic acid biaxially stretched film (manufactured by Tosero Corp .: Palgreen LC). : Takelac A310 (60%) + Takelac A3 (5%) + Ethyl acetate (35%)) was applied at about 7 g / m ² and then dry laminated to obtain a polylactic acid biaxially stretched laminated film having a thickness of 50 to 55 μm. It was. The physical properties of the multilayer film and the obtained polylactic acid biaxially stretched laminated film were measured by the above methods. The measurement results are shown in Table 1.

The measurement result 1 compares the multilayer film, and the measurement result 2 compares the polylactic acid biaxially stretched laminated film. Example-1 and Comparative Examples-1 to 6 are systems comprising the same aliphatic polyester (A-1) and polylactic acid (B), and Example-1 has a three-layer structure with ratios shown in Table-1. Comparative Examples-1 to 6 are single layers. As in the comparative example, the polylactic acid (B) content in the single layer is 0 to 50% (Comparative Example-1 to 4), and the haze is 18 to 12% (multilayer film), 19 to 14% (polylactic acid biaxially stretched laminate) Film) and 6% (multilayer film) and 7% (polylactic acid biaxially stretched laminated film) of Example-1 are significantly worse. Moreover, when the amount of polylactic acid (B) is further increased to 80 to 100% (Comparative Examples-5 and 6) in the single layer as in the comparative example, the haze is 4 to 2% (multilayer film), 7 to 4% (poly However, the sealing strength when used as a polylactic acid biaxially stretched laminate film is greatly reduced to 10 N / 15 mm width or less, and cannot be used as a packaging film. In addition, Comparative Examples 4 to 6 having a single layer in which the amount of polylactic acid (B) is 50 to 100% have a breaking elongation in the MD direction of 3% or less by a tensile test, and film breakage occurs during film formation and slitting. Possibility is high and productivity is low.

In Example-1 and Comparative Example-4, the raw material is the same as that of aliphatic polyester (A): polylactic acid (B) = 50: 50. The benefits are obvious. In Example-3, the transparency is further improved by blending 10% of the copolymer (E-1) in the second layer of Example-1.

Example-2 is also the same, Example-2 and Comparative Examples-7 to 10 and 6 are the same system comprising aliphatic polyester (A-2) and polylactic acid (B), and Example-2 is a table- A three-layer structure with a ratio of 1 and Comparative Examples -7 to 10 and 6 are single layers. As in the comparative example, the amount of polylactic acid (B) in the single layer is 0 to 50% (Comparative Example -7 to 10), and the haze is 22 to 12% (multilayer film), 23 to 14% (polylactic acid biaxially stretched laminate) Film) and 10% of Example-2 (multilayer film) and 11% (polylactic acid biaxially stretched laminated film). Moreover, when the amount of polylactic acid (B) is further increased to 100% (Comparative Example-6) in the single layer as in the comparative example, the haze is 2% (multilayer film) and 4% (polylactic acid biaxially stretched laminated film). Although improved, the sealing strength when used as a polylactic acid biaxially stretched laminated film is greatly reduced to 10 N / 15 mm width or less, and becomes a level that cannot be used as a packaging film. In Example-2 and Comparative Example-10, the raw material is the same as aliphatic polyester (A-2): polylactic acid (B) = 50: 50. Is obvious. The multi-layer films of the examples all have small elongation at break. However, the polylactic acid biaxially stretched laminated film is significantly improved in strength by the polylactic acid biaxially stretched film, and has no practical problem.
Examples 4 to 11, Reference Examples 1 and 2
<Manufacture of Aliphatic Polyester Composition (D)> As the aliphatic polyester used for the multilayer film, the raw materials and additives shown in Table 2 were blended according to the formulation described in Example-4, and 180 mm using a 60 mmφ twin screw extruder. Each aliphatic polyester composition (D) was prepared by melt-kneading at ° C. <Manufacture of Multilayer Film> Using a three-layer coextrusion sheet forming machine having a multi-manifold T-die at the tip in the layer configuration described in Example-4, the discharge rate was adjusted so as to achieve the layer ratio described in Table-2. After adjusting and extruding a co-extruded (or single layer) sheet from a T-die heated to 200 ° C., it is cooled rapidly with a casting roll at 30 ° C., so that there is no three layer (or single layer) having a thickness of 30 μm. A stretched multilayer film was prepared. Further, the third layer surface (surface without additive) was subjected to corona treatment.

<Polylactic acid biaxially stretched film>
A polylactic acid biaxially stretched film (manufactured by Tosero Co., Ltd .: Pal Green LC # 25) (thickness: 25 μm, double-sided corona treatment) was used.
<Production of sulfonate group-containing aromatic polyester biaxially stretched film>
The sulfonate group-containing aromatic polyester (F) pre-dried in an oven is extruded at a temperature of 230 ° C. using a 60 mmφ extruder of a continuous biaxially stretched film molding machine (Brookner, sequential biaxially stretched film molding machine). Extruded from a 230 ° C T-die, quenched with a 30 ° C casting roll, biaxially stretched successively in the machine and transverse directions at a temperature of 55-80 ° C, heat set at 200 ° C for about 5 seconds, Corona treatment was performed on both surfaces to form a stretched film having a thickness of 25 μm.
<Vapor Deposition Process> Using an electron beam heating type vacuum vapor deposition apparatus, the vapor deposition process was performed while maintaining the inside of the vacuum vessel at a vacuum degree of 0.001 Torr or less. In the case of aluminum vapor deposition, aluminum was used as the vapor deposition source. In the case of alumina deposition, aluminum was used as a deposition source, and oxygen was further introduced to oxidize aluminum to alumina to form an alumina deposition film. However, Example-11 was tested using alumina itself as a deposition source.
<Multilayer film and biaxially stretched film>
Corona surface of polylactic acid biaxially stretched film or sulfonate group-containing aromatic polyester biaxially stretched film (deposited surface if vapor-deposited) corona surface of multilayer film as described above (deposited if vapor-deposited) The surface was coated with about 7 g / m ² of urethane adhesive (manufactured by Takeda Pharmaceutical: Takelac A310 (60%) + Takelac A3 (5%) + ethyl acetate (35%)), and then dry-laminated to give a thickness of 50 A laminate film having a thickness of ˜55 μm was obtained, and the physical properties of the laminate film were measured by the above-described method, and the measurement results are shown in Tables 4 to 6.

In the measurement result 3, the film is compared with each of the laminate, transparency, oxygen permeability, and water vapor permeability of the multilayer film and stretched film.
As is apparent from Table 4, Examples 4 to 11 in which the vapor deposition treatment was performed were significantly improved in oxygen permeability and water vapor permeability as compared to Reference Examples 1 and 2 in which no vapor deposition was performed, and were barriers such as food packaging. It turns out that it has reached the level where there is no problem even in the use where performance is necessary.
In particular, Examples-6 and 7 using a stretched aromatic polyester film are excellent in the gas barrier property because the gas barrier property inherent in the stretched aromatic polyester film is excellent.

(Table 5 and Table 6)

Since the multilayer film of the present invention has excellent optical properties and heat sealability, it can be instantly used for instant noodle foods such as ramen, udon, soba, fried noodles, yogurt, pudding by laminating with a polylactic acid biaxially stretched film. , Beverages desserts such as lactic acid bacteria beverages such as jelly, etc. Not limited to individual or multiple packaging films, aerosol products, interior products, CDs, general shrink packaging of magnetic tape products, cans and bottled beverages, It can be used for various packaging films such as seasoning and other integrated shrink packs, plastic containers, shelled shrink labels such as glass bottles, and bottle cap seals such as wine and whiskey.

In addition, the polylactic acid biaxially stretched laminated film can be used for pillow packaging and fusing seal packaging, has excellent transparency, gloss, rigidity, heat sealability on one side, and can withstand transportation. In addition, it can be used in all applications where overlap film made of polyolefin film is used, such as chocolates, gums, candy and other sweets, tobacco, cosmetics, etc., cassette tape, video It can be suitably used as a packaging film for box packaging, such as recording materials such as tapes, CDs, CDRs, DVDs, game software, and their integrated packaging materials. Furthermore, vapor barrier performance is improved by vapor deposition or sputtering of an inorganic metal on the stretched film or multilayer film of the present invention, and the quality retention period when used in food packaging becomes longer, and the use is expanded.

Claims (10)

  Aliphatic polyester copolymer (A) 80- consisting of aliphatic or alicyclic dicarboxylic acid component (a1), aliphatic or alicyclic dihydroxy compound component (a2) and bifunctional aliphatic hydroxycarboxylic acid component (a3) The first layer (I) of the composition (D1) comprising 99% by weight, 20% to 1% by weight of polylactic acid (B), and (the total of (A) and (B) is 100% by weight), aliphatic or 1-20% by weight of an aliphatic polyester copolymer (A) comprising an alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional aliphatic hydroxycarboxylic acid component (a3) A second layer (II) of a composition (D2) comprising polylactic acid (B) 99 to 80% by weight, (the total of (A) and (B) is 100% by weight), 1st layer (I), 2nd layer (I ) Is 20% or more of the total thickness (the total thickness of the first layer (I) and the second layer (II) is 100%). A multilayer film having a structure of I) / second layer (II).   Aliphatic polyester copolymer (A) 80- consisting of aliphatic or alicyclic dicarboxylic acid component (a1), aliphatic or alicyclic dihydroxy compound component (a2) and bifunctional aliphatic hydroxycarboxylic acid component (a3) The first layer (I) of the composition (D1) comprising 99% by weight, 20% to 1% by weight of polylactic acid (B), and (the total of (A) and (B) is 100% by weight), aliphatic or 1-20% by weight of an aliphatic polyester copolymer (A) comprising an alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional aliphatic hydroxycarboxylic acid component (a3) A second layer (II) of a composition (D2) comprising 99 to 80% by weight of polylactic acid (B) (100% by weight in total of (A) and (B)), aliphatic or cycloaliphatic Dicarboxylic acid component (a1 An aliphatic polyester copolymer (A) comprising an aliphatic or alicyclic dihydroxy compound component (a2) and a bifunctional aliphatic hydroxycarboxylic acid component (a3), 80 to 99% by weight, polylactic acid (B) 20 to 1 And a third layer (III) of a composition (D3) comprising (in total 100 parts by weight of (A) and (B)) is laminated in this order, and the first layer (I) The thickness of each of the second layer (II) and the third layer (III) is the total thickness (the total thickness of the first layer (I), the second layer (II), and the third layer (III)). The multilayer film having the structure of the first layer (I) / the second layer (II) / the third layer (III), characterized by being 20% or more of 100%).   3. The second layer (II) according to claim 1, wherein the second layer (II) comprises an aliphatic or alicyclic dicarboxylic acid component (a1), an aliphatic or alicyclic dihydroxy compound component (a2), and a bifunctional aliphatic hydroxycarboxylic acid component ( a3) aliphatic polyester copolymer (A) 1 to 20% by weight, polylactic acid (B) 94 to 65% by weight, and polylactic acid block (e1) 25 to 98% by weight, containing -COO- groups Polyester block (e2) composed of chain hydrocarbons and / or alicyclic hydrocarbons (75) to 2% by weight (the total of (e1) and (e2) is 100% by weight), Linear lactic acid copolymer polyester (E) having a weight average molecular weight of 15,000 to 100,000 (E) 5 to 15% by weight (the total of (A), (B) and (E) is 100% by weight) Characterized by The multilayer film according to claim 1 or 2. The polylactic acid (B) is poly L-lactic acid containing 7 to 30% by weight of D-lactic acid or poly D-lactic acid containing 7 to 30% by weight of L-lactic acid. The multilayer film of any one of Claims . Difunctional aliphatic hydroxycarboxylic acid component (a3) is a multilayer film according to any one of claims 1 to 4 is lactic acid. Aliphatic polyester copolymer (A) having a melting point (Tm) of 80 to 120 ° C., a crystallization temperature (Tc) of 35 to 75 ° C., and (Tm)-(Tc) of 35 to 55 ° C. the multilayer film according to any one of claims 1 to 5, characterized in that a polyester copolymer. The aluminum oxide in the multilayer film, aluminum, silicate, multilayer film according to any one of claims 1 to 6 or one or more inorganic metal is deposited or sputtered out of ITO.   A biaxially stretched film comprising a polylactic acid or an aromatic polyester copolymer (F) laminated on the multilayer film on which the inorganic metal according to claim 7 is deposited or sputtered. Laminate film. Aluminum oxide multilayer film according to any one of claims 1 to 7, aluminum, silicate, polylactic acid or aromatic polyester copolymer which any one or more inorganic metal of the ITO is deposited or sputtered A biaxially stretched laminate film, wherein a biaxially stretched film made of a polymer (F) is laminated. The aromatic polyester copolymer (F) is a polyester containing an aromatic dicarboxylic acid having a sulfonic acid metal base as a nucleus substituent as one copolymerization component, and includes an aromatic dicarboxylic acid, an aliphatic glycol, and a sulfonic acid metal base. It is a polyester obtained by adding an aromatic dicarboxylic acid having an aromatic substituent as an aromatic dicarboxylic acid and, if necessary, an aliphatic dicarboxylic acid or an aliphatic hydroxycarboxylic acid, and performing a polycondensation reaction between these components. The biaxially stretched laminate film according to claim 8 or 9 .