JP2006192806A - Polylactic acid-based stretched laminated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid-based stretched laminated film excellent in low temperature heat-sealing properties and sealing strength without damaging concealability, decorative properties and ultraviolet cutting-off properties being the characteristics of a polylactic acid-based stretched laminated film compounded with an inorganic filler and having biodegradability. <P>SOLUTION: The polylactic acid-based stretched laminated film is constituted by laminating a coating layer (II), which comprises an aliphatic polyester composition (D) of 97-5 mass% of a specific aliphatic polyester copolymer (B) and 3-95 mass% of a polylactic acid copolymer (C) [the sum total of (B) and (C) is 100 mass%], at least on one side of a base material layer (I) comprising polylactic acid compounded with fine particles of titanium oxide and fine particles of at least one kind of a component selected from the group consisting of calcium carbonate, barium sulfate, talc, silica, mica and kaolin and stretching the obtained laminate at least in a uniaxial direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a stretched laminated film in which a base layer is a system in which titanium oxide is blended with polylactic acid together with calcium carbonate and the like, and a composition of an aliphatic polyester copolymer and a polylactic acid copolymer is used as a coating layer. More specifically, the present invention relates to a stretched laminated film that has a concealing property, a cosmetic property, and an ultraviolet ray-cutting property as a milky white biodegradable film, is excellent in low-temperature heat-fusibility and heat-sealing strength, and is suitable for a packaging film.

  In order to facilitate the disposal of plastic films, biodegradable films have attracted attention, and various films have been developed. Such a biodegradable film undergoes hydrolysis or biodegradation in soil or water, and gradually collapses or decomposes of the film. Finally, the biodegradable film changes into 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.

As a method for improving the mechanical strength, durability and thickness accuracy of a polylactic acid stretched film, there is a method of blending polylactic acid with an inorganic filler and stretching (for example, see Patent Document 1). The stretched polylactic acid film thus obtained has a concealing property, a cosmetic property, and an ultraviolet ray cutting property in addition to the improvement of the mechanical strength. However, the film obtained does not have heat-fusibility (heat sealability) as it is.
On the other hand, as a method for imparting heat sealability to a polylactic acid biaxially stretched film, a biaxially stretched film 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 ( Japanese Patent Laid-Open No. 2001-219522) has been proposed, but the heat-sealing property is imparted, but the low-temperature heat-sealing property is insufficient. (Patent Document 2)

Japanese Patent No. 3380407 (Claim 1) JP 2001-219522 A (Claim 1, paragraph 0024, Examples 1 to 4)

  The present invention provides a stretched laminated film having excellent low-temperature heat sealability, sealing strength, and biodegradability without impairing the concealing properties, cosmetic properties, and UV-cutting properties that are characteristic of stretched laminated films containing an inorganic filler. The purpose is to provide.

That is, the present invention contains 3 to 20% by mass of titanium oxide fine particles and one or more fine particles selected from the group consisting of calcium carbonate, barium sulfate, talc, silica, mica and kaolin in a proportion of 5 to 40% by mass. On at least one surface of the base layer (I) made of the polylactic acid composition (A), the melting point (Tm) is 80 to 120 ° C., the crystallization temperature (Tc) is 35 to 75 ° C. and (Tm) − Aliphatic or cycloaliphatic dicarboxylic acid component (b1), aliphatic or cycloaliphatic dihydroxy compound component (b2) and bifunctional aliphatic hydroxycarboxylic acid component (b3) in which (Tc) is in the range of 35 to 55 ° C. Aliphatic polyester copolymer (B) 97 to 5% by mass and polylactic acid copolymer (C) 3 to 95% by mass
The coating layer (II) comprising the aliphatic polyester composition (D) (the sum of (B) and (C) is 100% by mass) is laminated and stretched at least in the uniaxial direction. The present invention relates to a stretched polylactic acid film characterized by the following.

  The polylactic acid-based stretched laminate film of the present invention has excellent low-temperature heat sealability, seal strength, and biodegradability without losing the concealment, cosmetic properties, and UV-cutting properties that are characteristic of stretched laminate films containing inorganic fine particles. And can be suitably used as a packaging film.

The polylactic acid-based stretched laminated film of the present invention is a polylactic acid obtained by laminating a coating layer (II) on at least one side of the base material layer (I), preferably on both sides, and stretching in at least a uniaxial direction, preferably a biaxial method. It is a system stretched laminated film. Below, base material layer (I) and coating layer (II) are demonstrated.
Base material layer (I)
The substrate layer (I) according to the present invention is composed of a polylactic acid composition (A) in which specific fine particles are blended. The fine particles to be blended are 3 to 20% by mass, preferably 5 to 15% by mass of titanium oxide fine particles, and 5 or more kinds of fine particles selected from the group consisting of calcium carbonate, barium sulfate, talc, silica, mica and kaolin. -40% by mass, preferably 10-30% by mass.

Titanium oxide is used to develop a white color. If the blending amount is less than 3% by mass, the obtained stretched film is insufficient in white color development and may have poor concealability.
One or more kinds of fine particles selected from the group consisting of calcium carbonate, barium sulfate, talc, silica, mica and kaolin are used to cause peeling at the interface with polylactic acid and to form voids.
If the proportion of fine particles other than titanium oxide is less than 5% by mass, voids are not sufficiently formed during stretching, and if it exceeds 30% by mass, the resulting stretched film may be brittle.
Moreover, the average particle diameter of titanium oxide is 0.1-1 micrometer, and 0.15-0.5 micrometer is especially suitable. If the thickness is less than 0.1 μm, handling may be poor and nonuniformity may occur during kneading. If the thickness is greater than 1 μm, the white color of the obtained stretched film may be insufficient and the concealability may be poor.

  The fine particles blended other than titanium oxide are one or more fine particles selected from the group consisting of calcium carbonate or barium sulfate, talc, silica, mica and kaolin. These average particle diameters are preferably 0.3 to 12 μm. If the average particle size is less than 0.3 μm, voids are not sufficiently formed during stretching, and if it is greater than 12 μm, the particles may aggregate and be clogged with the mesh of the extruder.

The polylactic acid used in the composition (A) of the polylactic acid base layer (I) has a D-lactic acid or L-lactic acid content of less than 5% by mass, preferably less than 3% by mass, and a melting point of 150 to 170. ° C, preferably in the range of 160-170 ° C. As such polylactic acid, in addition to D-lactic acid or L-lactic acid, as a comonomer copolymerizable with lactic acid, for example, 3-hydroxybutyrate, caprolactone, glycolic acid or the like may be copolymerized. . As polylactic acid, MFR (according to ASTM D-1238, load 2160 g, temperature 190 ° C.) is usually 0.1 to 100 g / 10 minutes, preferably 1 to 50 g / 10 minutes, particularly preferably 2 to 10 g / 10 minutes. Is used.

  As a polymerization method of these polylactic acids, 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.

Titanium oxide blended in the composition (A) of the titanium oxide base layer (I) is classified into anatase type, rutile type and brookite type from its crystal form, and any of these can be used. The average particle size is preferably 0.1 to 1 μm, more preferably 0.15 to 0.5 μm. Moreover, in order to make the dispersibility to polylactic acid a factory, what coated the surface with oxides, such as an alumina, a silica, and zinc oxide, or surface-treated with aliphatic polyol etc. can be used. Examples of commercially available products include Taipei [made by Ishihara Sangyo Co., Ltd., trade name], Tyton [made by Sakai Chemical Industry Co., Ltd., trade name] and the like.
One or more types of fine particles selected from the group consisting of calcium carbonate, barium sulfate, talc, silica, mica, and kaolin blended in the base material layer (I) will be described below.
Calcium carbonate Calcium carbonate can be used in the form of any of calsanite, aragonite, and vaterite, and those having an average particle size of 0.3 to 6 μm are preferably used. Examples of commercially available products include NCC [manufactured by Nitto Flour Chemical Co., Ltd., trade name], Sunlite [manufactured by Takehara Chemical Co., Ltd., trade name] and the like.

Barium sulfate barium sulfate is a precipitated barium sulfate produced from barite by a chemical reaction and having an average particle size of 0.1 to 2 μm. Examples of commercially available products include precipitated barium sulfate TH and precipitated barium sulfate ST (trade name, manufactured by Barite Industries Co., Ltd.).

Talc Talc is a hydrous magnesium silicate naturally occurring, average particle size can be used for 0.1 to 10 [mu] m. Examples of commercially available products include PK and LMS (manufactured by Fuji Talc Industrial Co., Ltd., trade name).
Silica Silica is a silicic acid obtained by natural or synthetic, can be used as the average particle size 1～12Myuemu. Examples of the commercially available products include siricia [manufactured by Fuji Silysia Chemical Co., Ltd., trade name], furex crystallite [manufactured by Tatsumori Co., Ltd., trade name] and the like.
Any of mica natural mica and synthetic mica can be used.

Kaolin Kaolin is a hydrous aluminum silicate produced in nature and having an average particle size of 0.5 to 10 μm can be used. A type from which water of crystallization has been removed can also be used. Examples of commercially available products include NN cation clay (manufactured by Tsuchiya Cationic Industry Co., Ltd., trade name), ASP, Satinton [manufactured by Engelhard Co., Ltd., trade name] and the like.
The composition (A) constituting the base material layer (I) is a method of mixing titanium oxide and other inorganic fine particles together with polylactic acid using a Henschel mixer, a V-blender, a ribbon blender, a tumbler mixer, etc. After mixing, it is obtained by a method of melt kneading with a single screw extruder, a multi-screw extruder, a Banbury mixer or the like.

Coating layer (II)
The coating layer (II) of the present invention comprises an aliphatic polyester composition (D) containing an aliphatic polyester copolymer (B) and a polylactic acid copolymer (C).
Aliphatic polyester copolymer (B)
The aliphatic polyester copolymer (B) has a melting point (Tm) of 80 to 120 ° C, preferably 80 to 115 ° C, and a crystallization temperature (Tc) of 35 to 75 ° C, preferably 37 to 73 ° C and (Tm). -(Tc) is a copolymer in the range of 30 to 55 ° C, preferably 35 to 50 ° C.
The aliphatic polyester copolymer (A) 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). Consists of.

When the melting point (Tm) of the aliphatic polyester copolymer (B) is less than 80 ° C., the melting point is too low to use the obtained film as a coating layer, and it is melted in the heat setting step after biaxial stretching, and then recrystallized. When doing so, the surface gloss may be lost and the gloss may decrease. Moreover, when used as a packaging film, there is a risk of stickiness and poor packaging suitability.
On the other hand, when the melting point (Tm) exceeds 120 ° C., the melting temperature at the time of heat-sealing becomes high, and the heat sealability may be deteriorated.
In addition, when the crystallization temperature (Tc) of the aliphatic polyester copolymer (B) is less than 35 ° C., the crystallization temperature is too low, and the stretched raw film of the laminated film containing the copolymer as a coating layer can be cast-molded. Even if it is to be obtained, it is not completely solidified at a normal cooling temperature (5 to 30 ° C.), and a film having a poor appearance cannot be obtained by transferring imprints such as a nip roll to the obtained stretched raw material or peeling off from the cooling roll easily. There is a risk of becoming.

Furthermore, when (Tm)-(Tc) of the aliphatic polyester copolymer (B) is less than 30 ° C., the resulting film may be inferior in transparency and heat sealability (particularly heat seal strength).
In such an aliphatic polyester copolymer (B), the content of the bifunctional aliphatic hydroxycarboxylic acid component (a3) is preferably 0.1 to 25 mol%, more preferably 1 to 10 mol% [aliphatic Or an 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 Aliphatic or cycloaliphatic dihydroxy compound component (a2) molar quantities are substantially equal, aliphatic or cycloaliphatic dicarboxylic acid component (a1), aliphatic or cycloaliphatic dihydroxy compound component (a2) and bifunctional aliphatic The total molar quantity of the 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 (B) 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 (b1)
The aliphatic or alicyclic dicarboxylic acid component (b1), which is a component constituting the aliphatic polyester copolymer (B) according to the present invention, is not particularly limited, but usually the aliphatic dicarboxylic acid component is 2 to 10%. It is a compound having 4 carbon atoms (including carbon of a carboxyl group), preferably 4 to 6 carbon atoms, and may be linear or branched. The alicyclic dicarboxylic acid component is usually preferably one having 7 to 10 carbon atoms, particularly 8 carbon atoms.
The aliphatic or alicyclic dicarboxylic acid component (b1) 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 (b1) 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-norbornane Dicarboxylic acids such as dicarboxylic 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-pentyl ester, di-isopentyl ester or di-n-hexyl It can be exemplified an ester-forming derivative such as ester.
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 (b1), succinic acid or an alkyl ester thereof or a mixture thereof is particularly preferable.

Aliphatic or alicyclic dihydroxy compound component (b2)
The aliphatic or alicyclic dihydroxy compound component (b2), which is a component constituting the aliphatic polyester copolymer (B), is not particularly limited, but usually 2 to 12 if it is an aliphatic dihydroxy compound component. In the case of a branched or linear dihydroxy compound having 4 to 6 carbon atoms, or an alicyclic dihydroxy compound component, a cyclic compound having 5 to 10 carbon atoms may be mentioned.
Specific examples of the aliphatic or alicyclic dihydroxy compound component (b2) 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 (b2), 1,4-butanediol is preferable.

Bifunctional aliphatic hydroxycarboxylic acid component (b3)
The bifunctional aliphatic hydroxycarboxylic acid component (b3), which is a component constituting the aliphatic polyester copolymer (B), is not particularly limited, but is usually a branched or linear chain having 1 to 10 carbon atoms. The compound which has a bivalent aliphatic group is mentioned.
Specific examples of the bifunctional aliphatic hydroxycarboxylic acid component (b3) 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.

  The aliphatic polyester copolymer (B) in 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. The aliphatic / aromatic polyester (A) according to the present invention is manufactured and sold as, for example, GS Pla (trade name) from Mitsubishi Chemical Corporation.

Polylactic acid copolymer (C)
The polylactic acid copolymer (C) according to the present invention is a copolymer of D-lactic acid and L-lactic acid containing 7 to 30% by mass, preferably 8 to 25% by mass of D-lactic acid.
When the content of D-lactic acid is less than 7% by mass, the low-temperature heat sealability of the resulting biaxially stretched film may be impaired. On the other hand, when the content exceeds 30% by weight, the moldability tends to be inferior.

The D-lactic acid content in the polylactic acid copolymer (C) is a value measured using a gas chromatograph CP CYCLODEX B 236M manufactured by Chromeback.
The polylactic acid copolymer (C) preferably has a glass transition temperature (Tg) of less than 58 ° C, more preferably 57.5 to 50 ° C.
The weight average molecular weight of the polylactic acid copolymer (C) is not particularly limited as long as it has a film-forming ability, but MFR (load 2160 g, temperature 190 ° C. according to ASTM D-1238) is usually 0.1 to 100 g / 10 minutes, preferably 1-50 g / 10 minutes, particularly preferably 2-10 g / 10 minutes are used.

Aliphatic polyester composition (D)
The aliphatic polyester composition (D) is 97 to 5% by mass, preferably 90 to 25% by mass, more preferably 85 to 55% by mass of the above-mentioned aliphatic polyester copolymer (B), and a polylactic acid copolymer. (C) 3 to 95% by mass, preferably 10 to 75% by mass, more preferably 15 to 45% by mass (total of aliphatic polyester copolymer (B) and polylactic acid copolymer (C) Is 100% by mass).
When the composition (D) in which the amount of the polylactic acid copolymer (C) is less than 3% by mass is used for the coating layer (II) of the laminated film, the base material layer (I) comprising the composition (A) And the coating layer (II) made of the composition (D) are inferior in adhesiveness, so that sufficient heat seal strength may not be obtained.

On the other hand, even if the composition in which the amount of the polylactic acid copolymer (C) exceeds 95% by mass is used for the coating layer (II) of the biaxially stretched laminated film, the low temperature sealing property and the sealing strength may not be improved.
When an aliphatic polyester composition in which the amount of the polylactic acid copolymer (C) in the composition (D) is in the range of 15 to 45% by mass is used for the coating layer (II), transparency, gloss, and low temperature heat are particularly good. A biaxially stretched laminated film having excellent sealing properties (low temperature heat fusion properties) and heat seal strength can be obtained.
The aliphatic polyester composition (D) is a method in which the aliphatic polyester copolymer (B) and the polylactic acid copolymer (C) are mixed in the above ranges by a Henschel mixer, a V-blender, a ribbon blender, a tumbler mixer, etc. Further, after mixing, it is obtained by a method of melt kneading with a single screw extruder, a multi-screw extruder, a Banbury mixer or the like.

In the aliphatic polyester composition (D) of the present invention, the aliphatic polyester copolymer (B) and the polylactic acid copolymer (C) are prepared separately or when the composition (D) is produced. Antioxidants, weathering stabilizers, antistatic agents, antifogging agents, antiblocking agents, slip agents, lightproof stabilizers, UV absorbers, fluorescent whitening agents, antibacterial agents that are usually used within the scope of the invention Further, additives such as a nucleating agent, an inorganic compound or an organic compound filler can be blended as necessary.
Moreover, the said additive can be mix | blended with a composition (A) as needed. For example, it is desirable to blend silica in the composition (D) at a ratio of 0 to 1% by mass.

Polylactic acid-based stretched laminated film The polylactic acid-based stretched laminated film of the present invention comprises a base material layer (I) comprising the composition (A) and a coating layer (II) comprising the composition (D) laminated on at least one surface thereof. And is a stretched laminated film stretched in at least a uniaxial direction, preferably a biaxial method. Stretching is preferably about 1.3 to 5 times at least for a uniaxial method.
Hereinafter, the polylactic acid biaxially stretched laminated film of the present invention will be described.
The polylactic acid biaxially stretched laminated film of the present invention has a coating layer (II) made of an aliphatic polyester composition (D) on at least one surface of a base material layer (I) made of a composition (A). The biaxially stretched laminated film. The biaxially stretched laminated film of the present invention has excellent concealability, cosmetic properties, and UV-cutting properties, and has a coating layer (II) obtained from the aliphatic polyester composition (D) on the surface, so that it can be heated at low temperature. It has sealability and seal strength.
The thickness of the base material layer (I) and the coating layer (II) of the polylactic acid-based biaxially stretched laminated film can be variously determined according to the application. Usually, the base layer (I) has a thickness of 5 to 500 μm, preferably 10 to 200 μm, and the coating layer (II) has a thickness of 0.1 to 10 μm, preferably 0.3 to 5 μm. The thickness of the axially stretched laminated film is in the range of 5 to 500 μm, preferably 10 to 200 μm.

Examples of the method for producing the polylactic acid biaxially stretched laminated film of the present invention include the following.
That is, a laminated sheet coextruded using the composition (A) of the base material layer (I) and the composition (D) of the coating layer (II) is converted into a known simultaneous biaxial stretching method or sequential biaxial stretching method. There is a method of forming a polylactic acid-based biaxially stretched laminated film by biaxial stretch molding such as.
The biaxial stretching conditions are the conditions under which the base material layer (I) can be stretched, for example, in the sequential biaxial stretching method, the longitudinal stretching temperature is in the range of 60 to 100 ° C., the stretching ratio is in the range of 2 to 6 times, It is desirable that the stretching temperature in the direction is 60 to 120 ° C. and the stretching ratio is in the range of 2 to 12 times.
Further, in the simultaneous biaxial stretching method, it is desirable that the stretching temperature is 60 to 120 ° C. and the stretching ratio is 2 to 12 times (4 to 150 times in terms of surface magnification).

After biaxial stretching, the heat shrinkage rate of the obtained biaxially stretched laminated film can be set within an arbitrary range, for example, 80 ° C. for 15 minutes by performing heat setting (heat treatment) under various conditions depending on the use of the biaxially stretched laminated film. The thermal contraction rate in the vertical direction under the conditions of 1 to 5%, the thermal contraction rate in the horizontal direction within the range of 5 to 10%, and the thermal contraction rate in the vertical direction under the conditions of 100 ° C. and 15 minutes to 5%. 15%, and the heat shrinkage rate in the lateral direction can be in the range of 10 to 20%.
As a method for producing a polylactic acid-based biaxially stretched laminated film, a biaxially stretched film is produced in advance using the composition (A) by the above method without stretching the coextruded laminated sheet, and then the biaxially stretched film. A method of extruding and coating the composition (D) on one side or both sides of the substrate layer (I) of the film (extrusion laminating method), or after obtaining a film made of the aliphatic polyester composition (D) in advance and then biaxially stretching The method of laminating with the film base layer (I) can be taken (the laminating method), but the method of stretching the co-extruded laminated sheet can be multi-layered in one step compared to the extruded laminating method, so the cost is low, and the laminating method The number of processing steps is small compared to the above, and the heat-sealing layer can be thinned to a thickness of, for example, 0.5 to 2 μm, which is preferable.

  In addition, after obtaining a biaxially stretched laminated film, heat treatment was not performed, or various heat treatment conditions were selected to suppress heat shrinkability of the polylactic acid-based biaxially stretched laminated film or heat shrinkability. A polylactic acid-based biaxially stretched laminated film can be obtained.

Film for Overlap Packaging The polylactic acid-based biaxially stretched laminated film of the present invention is suitable as an overwrapping film. Since the film for overlap packaging of the present invention has excellent concealability, cosmetic properties, and UV-cutting properties, and has a coating layer (II) obtained from the aliphatic polyester composition (D) on both surfaces, Both surfaces have low temperature heat sealability and heat seal strength.

  The overlap wrapping film of the present invention also has impact resistance that can withstand transportation, and therefore uses for which an overlap wrapping film made of a conventional polyolefin film is used, such as frozen food and chocolate, As a packaging film for box packaging such as gum, candy and other sweets, cosmetics and other luxury items, cassette tapes, videotapes, CDs, CDRs, DVDs, game software and other recording materials, and their integrated packaging materials It can be used suitably.

  The polylactic acid-based biaxially stretched laminated film of the present invention is not limited to the above-mentioned uses. For example, beverage desserts such as instant cup noodle foods such as ramen, udon, soba and fried noodles, and lactic acid bacteria beverages such as yogurt, pudding and jelly In addition to individual or multiple packaging films for cup foods, general shrink packaging for aerosol products and interior products, integrated shrink packs for cans, bottled drinks, seasonings, etc., and trunk shrink shrink labels for plastic containers, glass bottles, etc. It can be used for various packaging films such as bottle cap seals for wine and whiskey.

Next, an example explains the present invention.
The raw materials used in Examples and Comparative Examples are as follows.
(A) Polylactic acid (PLAC-A)
D-lactic acid content: 1.9% by mass, MFR (temperature 190 ° C., load 2160 g): 6.7 g / 10 min, melting point (Tm): 168.0 ° C., Tg: 59.8 ° C.
Density: 1.3 g / cm ³ .
(B) Calcium carbonate NCC410 manufactured by Nitto Flour Chemical Co., Ltd.
Specific surface area: 13,000 (cm ³ / g), average particle diameter: 1.71 (μm), specific gravity: 2.7
(C) Titanium oxide Ishihara Sangyo Co., Ltd. Taipaque PF739
Specific surface area: 10 (m ³ / g), average particle size: 0.21 (μm), specific gravity: 4.2
(D) Silica manufactured by Fuji Silysia Chemical Co., Ltd., trade name: Silysia 730 (average particle size: 3 μm)
(E) erucic acid amide Ciba Specialty Chemicals, trade name ATMER SA1753

(F) Aliphatic polyester copolymer (B)
(I) Succinic acid / 1,4-butanediol / lactic acid polyester copolymer (B-1)
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 (1.25) g / cm ³ .
(Ii) Succinic acid / 1,4-butanediol / polyester copolymer (B-2)
Product name Bionore # 1001 MFR (190 ° C., load 2160 g): 1.5 g / 10 minutes, melting point (Tm): 112.6 ° C., crystallization temperature (Tc): 86.8 ° C. Tm)-(Tc): 17.7 [deg.] C., density: 1.3 (1.26) g / cm < ³ >.
(G) Polylactic acid copolymer (PLAC-B):
D-lactic acid content: 12.6% by mass, 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

Various measurement methods in the present invention are as follows.
(1) Optical characteristics Using a Nippon Denshoku Industries Co., Ltd. haze meter 300A, haze (HZ:%), parallel light transmittance (PT:%) and gloss (%) were measured. The measured value is an average value of 5 times.
(2) Tensile test A strip-shaped film piece (length: 150 mm, width: 15 mm) is cut out from the film in the machine direction (MD) and the transverse direction (TD) as a test piece, and a tensile tester (Tensilon Universal made by Orientec) Using a testing machine RTC-1225), a tensile test was performed under the conditions of a chuck-to-chuck distance: 100 mm and a crosshead speed: 300 mm / min (however, Young's modulus was measured at 5 mm / min). Elongation (%) and Young's modulus (MPa) were determined. The elongation (%) was the change in the distance between chucks. The measured value is an average value of 5 times.

(3) Heat seal strength
After the heat-sealable layer surfaces of the polylactic acid-based biaxially stretched film are overlapped, they are sandwiched between 12 μm thick biaxially stretched polyethylene terephthalate films (trade name: Lumirror, manufactured by Toray Industries, Inc.) and TP-701-B manufactured by Tester Sangyo Co., Ltd. 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-fused 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 the heat fusion strength.

Example 1
<Manufacture of composition (A1) for base material layer (I)>
PLAC-A: calcium carbonate: titanium oxide was weighed in a ratio of 70:20:10 (mass%) and melt kneaded at 180 ° C. using a twin screw extruder to obtain a composition (A1).
<Manufacture of composition (D1) for coating layer>
B-1: PLAC-B was weighed at a ratio of 90:10 (mass%), and 100 parts by mass of this mixture was charged with silica having an average particle size of 3 μm (trade name: Silicia 730, manufactured by Fuji Silysia Chemical Co., Ltd.). .1 part by mass was added and melt-kneaded at 180 ° C. using a single screw extruder to obtain a composition (D1).
<Manufacture of stretched film>
Further, the composition (A1) and the composition (D1) were each extruded at 200 ° C. from a multi-manifold T-die at 200 ° C. using a single screw extruder, and the composition (A1) was extruded into the base material layer (I). Further, the composition (D1) was used as a two-layer / three-layer film as a coating layer on both sides of the base material layer (I).
The discharge amount of the molten resin was adjusted so that the coating layer / base material layer (I) / coating layer had a thickness ratio of 10/80/10.

  This melt-extruded co-extruded sheet (400 μm) is rapidly cooled with a casting roll at 30 ° C., stretched 3.0 times in the MD direction at a set temperature of 65 ° C., and then 3.0 times in the TD direction at 68 ° C. Stretching was performed. Furthermore, heat setting was performed at 165 ° C. in an atmosphere for 6 seconds to obtain a biaxially stretched laminated film having a total thickness of 45 μm (base layer 35 μm, coating layer 5 μm each). The evaluation results of the film are shown in Table 1.

Example 2, Comparative Examples 1-5
A biaxially stretched laminated film was formed in the same manner as in Example 1 except that the coating layer having the composition shown in Table 1 was used, and the physical properties were evaluated. The results are shown in Table 1.

As is clear from Table 1, the composition of (Tm)-(Tc): 40.9 ° C. polyester copolymer (B-1) and polylactic acid copolymer (PLAC-B) is used as the coating layer. (Examples 1 and 2), a biaxially stretched laminated film having excellent heat sealability is obtained.
On the other hand, when the polyester copolymer (B-1) simple substance is used as the coating layer (Comparative Example 1), the heat seal strength is inferior to the Examples. When the polylactic acid copolymer (PLAC-B) alone is used as the coating layer (Comparative Example 2), it is clear that the sealing start temperature is higher than that of the example, the sealing strength is lower, and the heat sealing property is inferior. It is.
Further, in the case of using the polyester copolymer (B-2) (Tm)-(Tc): 17.7 ° C. instead of the polyester copolymer (B-1) (Comparative Examples 3 to 5), Since the interlayer strength between the material layer and the coating layer is small, the heat seal strength is small and the heat sealability is clearly inferior. In particular, Comparative Example 3 using the polyester copolymer (B-2) alone had already peeled between the base material layer and the coating layer after stretching, and did not form a multilayer film body.

The polylactic acid-based stretched laminated film blended with the fine particles of the present invention is excellent in concealability, cosmetic properties, and UV-cutting properties, and has heat-sealing properties. Therefore, the packaging film is similar to a packaging film made of a conventional polyolefin film. Can be suitably used.
In addition, since the polylactic acid-based stretched laminated film of the present invention also has the biodegradability inherent to polylactic acid, used packaging materials can be used as compost even if non-packaged materials such as foods are attached. Garbage collection and disposal become easy.

Claims (6)

  3 to 20% by mass of fine particles of titanium oxide and polylactic acid containing 5 to 40% by mass of one or more fine particles selected from the group consisting of calcium carbonate, barium sulfate, talc, silica, mica and kaolin. On at least one side of the base material layer (I) comprising the composition (A), the melting point (Tm) is 80 to 120 ° C., the crystallization temperature (Tc) is 35 to 75 ° C., and (Tm) − (Tc) is 35 to 35 ° C. An aliphatic polyester copolymer comprising an aliphatic or cycloaliphatic dicarboxylic acid component (b1), an aliphatic or cycloaliphatic dihydroxy compound component (b2) and a bifunctional aliphatic hydroxycarboxylic acid component (b3) in the range of 55 ° C. Aliphatic polyester composition (D) (97% to 5% by mass of polymer (B) and 3 to 95% by mass of polylactic acid copolymer (C) (total of (B) and (C) is 100% by mass) is there. Consisting coating layer (II) is laminated, polylactic acid stretched laminate film characterized by comprising been stretched at least uniaxially.   The bifunctional aliphatic hydroxycarboxylic acid component (b3) constituting the aliphatic polyester copolymer (B) is contained in the copolymer (B) in a proportion of 0.1 to 25 mol% [However, aliphatic or An alicyclic dicarboxylic acid component (b1), an aliphatic or alicyclic dihydroxy compound component (b2), and a bifunctional aliphatic hydroxycarboxylic acid component (b3), an aliphatic or alicyclic dicarboxylic acid component (b1) and a fat The molar quantity of the aliphatic or alicyclic dihydroxy compound component (b2) is substantially equal, the aliphatic or alicyclic dicarboxylic acid component (b1), the aliphatic or alicyclic dihydroxy compound component (b2) and the bifunctional aliphatic The total molar quantity of the hydroxycarboxylic acid component (b3) is 100 mol%. 2. The polylactic acid-based stretched laminated film according to claim 1, wherein   The polylactic acid-based stretched laminated film according to claim 1 or 2, wherein the bifunctional aliphatic hydroxycarboxylic acid component (b3) is lactic acid.   The polylactic acid copolymer (C) is a copolymer of 7 to 30% by mass of D-lactic acid and 93 to 70% by mass of L-lactic acid (the total of D-lactic acid and L-lactic acid is 100% by mass). The polylactic acid-based stretched laminated film according to any one of claims 1 to 3, which is a coalescence.   The polylactic acid-based stretched laminated film according to any one of claims 1 to 4, wherein the base layer (I) has a coating layer (II) on both sides.   The laminated sheet obtained by co-extrusion forming the composition (B) and the composition (D) as a base layer (I) and a coating layer (II), respectively, is stretched at least in a uniaxial direction. A method for producing a polylactic acid-based stretched laminated film according to any one of 1 to 5.