JP2005144726A - Laminated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated film having sufficient easy tear properties imparted thereto only by altering a crystalline resin to be laminated without largely changing the film forming conditions of a crystalline polylactic acid or a laminated film having solvent resistance not achieved heretofore only by a single layer of a polylactic acid resin. <P>SOLUTION: This laminated film is composid of a layer A based on a crystalline polylactic acid polymer A with a glass transition temperature Tg(A) and a melting point Tm(A) and a layer B based on a crystalline resin composition B with a glass transition temperature Tg(B) and a crystallization temperature Tc(B) and characterized in that the relation between Tg(A), Tm(A), Tg(B) and Tc(B) is Tg(A) ≥ Tg(B) and Tm(A) ≥ Tc(B), the crystal melting calorie (ΔHm) of the film in DSC temperature rising measurement is 15 J/g or above and a layered constitution is at least 3 layers including A/B/A or B/A/B. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a laminated film, and more specifically, a packaging film imparted with excellent hand cutting property, that is, easy-opening property by laminating crystalline polylactic acid and a crystalline resin composition, or solvent resistance and printability. Further, the present invention relates to a film for industrial materials to which processability is imparted.

  Conventionally, plastic waste has been mainly treated by incineration or landfill. However, problems such as generation and discharge of harmful by-products due to incineration, reduction of landfill sites, and environmental pollution due to illegal dumping have become apparent. As social concerns about such plastic waste disposal problems increase, research and development of biodegradable plastics that are decomposed by enzymes and microorganisms has been actively carried out. Has been. Recently, polylactic acid is an example of a biodegradable aliphatic polyester that has been particularly actively researched and developed.

  Polylactic acid is a polymer obtained by producing lactic acid using starch obtained from corn, potatoes, etc. as a raw material, and by chemical synthesis, and is excellent in mechanical properties, heat resistance, and transparency among aliphatic polyesters. Therefore, research and development for the purpose of developing various molded products such as films, sheets, tapes, fibers, ropes, non-woven fabrics, and containers have been actively conducted. However, since polylactic acid is hard and brittle in an unstretched sheet (non-oriented state), a thin film was not practical for packaging. On the other hand, although the physical properties can be greatly improved by stretching and orienting the sheet, polylactic acid has a relatively low glass transition temperature compared to aromatic resins represented by PET and the like. As a functional resin that can be changed to PET because of its large thermal deformation and rigidity reduction as described above, low intermolecular force because it does not have an aromatic ring, and inferior to PET in heat resistance, solvent resistance, etc. The current situation is that it has not expanded significantly.

  On the other hand, there are several examples of making use of the characteristics of polylactic acid to try to impart functionality to the polylactic acid film by lamination. For example, a technique for laminating a low melting point polymer and a high melting point polylactic acid into two layers to impart heat sealability is disclosed (for example, Patent Documents 1 to 3).

  Further, a technique is disclosed in which a low melting point or amorphous polylactic acid is laminated on the inner layer, and a high melting point polylactic acid is laminated on the outer layer, and heat treatment is performed at a temperature of a low melting point or higher to provide hand tearability, that is, easy tearing (for example Patent Document 4). However, when grades with different melting points of low-melting polylactic acid are used, not only the problem of requiring changes in the heat treatment temperature for each grade and precise heat treatment temperature control is required, but also low melting point, non-crystalline polylactic acid. Since lactic acid has low crystallinity and is likely to be blocked, there is a problem that handling property and operability are lowered. Furthermore, a technique of laminating a crystalline polylactic acid layer as a solvent resistant layer and an amorphous polylactic acid layer as an ink receiving layer is disclosed (for example, Patent Documents 5 to 6). However, the solvent resistance of the crystalline polylactic acid layer is inferior to the solvent resistance of aromatic resins typified by PET and the like, and its performance is inadequate. It was.

As described above, although a polylactic acid film was laminated, an attempt was made to impart high functionality that is not found in a polylactic acid single layer, that is, easy tearing or solvent resistance, but in terms of handling properties, productivity, and performance. In fact, the technology related to the laminated film having a high potential has not been achieved yet.
JP-A-8-323946 (paragraphs [0001] to [0015]) JP 2002-273845 A (paragraphs [0001] to [0006]) JP 2003-80655 A (paragraphs [0001] to [0009]) JP 2001-191407 A (paragraphs [0001] to [0007]) JP 2002-103550 A (paragraphs [0007] to [0038]) JP 2003-94586 A (paragraphs [0004] to [0016])

  SUMMARY OF THE INVENTION An object of the present invention is to provide a laminated film or a polylactic acid-based resin that has been provided with sufficient tearability only by changing the crystalline resin to be laminated without greatly changing the film forming conditions of crystalline polylactic acid. The object of the present invention is to provide a laminated film imparted with solvent resistance that could not be achieved by a single layer alone.

In order to solve the above problems, the laminated film of the present invention mainly has the following configuration. That is,
A layer mainly composed of crystalline polylactic acid polymer A having glass transition temperature Tg (A) and melting point Tm (A), and crystal having glass transition temperature Tg (B) and crystallization temperature Tc (B) A laminated film composed of a B layer mainly composed of a conductive resin composition B, wherein the relationship between Tg (A), Tm (A), Tg (B) and Tc (B) is
Tg (A) ≧ Tg (B) and Tm (A) ≧ Tc (B)
The heat of crystal fusion (ΔHm) of the film in DSC temperature rise measurement is 15 J / g or more, and the layer structure is A / B / A or 3 layers including B / A / B. A laminated film characterized by
It is.

  The laminated film of the present invention is a laminated film provided with sufficient tearability or solvent resistance only by changing the crystalline resin to be laminated without greatly changing the film forming conditions of crystalline polylactic acid. The present invention relates to a packaging material that requires excellent easy-openability, or a film for industrial materials that requires solvent resistance, printability, and processing suitability. Furthermore, the laminated film of the present invention has an advantage that biodegradability in a natural environment is higher than that of a conventional plastic and is relatively easily decomposed in a natural environment after use. The aliphatic polyester resin of the present invention greatly contributes to solving environmental problems related to industry and plastic waste.

  The layer A of the laminated film of the present invention is mainly composed of a crystalline polylactic acid polymer A having a glass transition temperature Tg (A) and a melting point Tm (A). What is the crystalline polylactic acid polymer A? L-lactic acid and / or D-lactic acid as a main component, and the lactic acid-derived component in the polymer is 70% by weight or more, and homopolylactic acid substantially consisting of L-lactic acid and / or D-lactic acid is Preferably used. The glass transition temperature Tg (A) of the crystalline polylactic acid-based polymer in the present invention is a sample rapidly quenched from a molten state in a DSC (Differential Scanning Calorimetry) measurement at −50 ° C. in a nitrogen atmosphere. This is the glass transition temperature observed when measured at a heating rate of 20 ° C./min after holding for 5 minutes, and the melting point Tm (A) is the minimum point of the endothermic curve obtained from the DSC curve (ie, the differential value). Is a peak temperature indicating a point at which becomes 0). When two or more types of peak temperatures exist, the highest temperature side is defined as Tm (A). For example, when uniform homopolylactic acid is used as the polylactic acid polymer, homopolylactic acid having an optical purity of 70% or more may be used. Alternatively, depending on the application when used as a film, two or more types of homopolylactic acid having different optical purities may be used in combination for the purpose of imparting or improving a required function. It is also possible to use crystalline homopolylactic acid in combination. In this case, the proportion of amorphous homopolylactic acid may be determined within a range that does not impair the effects of the present invention. In general, the higher the optical purity of homopolylactic acid, the higher the melting point. For example, poly L-lactic acid having an optical purity of 98% or more has a melting point of about 170 ° C. In this case, it is preferable that at least one of the polylactic acid polymers to be used contains polylactic acid having an optical purity of 95% or more.

  The polylactic acid production method includes a two-stage lactide method in which L-lactic acid, D-lactic acid, and DL-lactic acid (racemic) are used as raw materials to once generate lactide, which is a cyclic dimer, and then ring-opening polymerization is performed. A one-step direct polymerization method in which the raw material is directly subjected to dehydration condensation in a solvent is known. In the present invention, when homopolylactic acid is used, it may be obtained by any production method. However, in the case of a polymer obtained by the lactide method, the lactide contained in the polymer is vaporized at the time of molding, for example, melted. At the time of film formation, it causes cast drum contamination and film surface smoothness deterioration, so that the content of lactide contained in the polymer before the melt film formation is preferably 0.3% by weight or less. Further, in the case of the direct polymerization method, there is substantially no problem caused by lactide, so that it is more preferable from the viewpoint of film forming property. The weight average molecular weight of the polylactic acid polymer (A) in the present invention is usually at least 50,000, preferably 80,000 to 300,000, and more preferably 100,000 to 200,000. When the average molecular weight is in such a range, the strength physical properties in the case of a film can be made excellent.

  The crystalline polylactic acid-based polymer in the present invention may be a copolymerized polylactic acid obtained by copolymerizing other monomer components having ester forming ability in addition to L-lactic acid and D-lactic acid. Examples of copolymerizable monomer components include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid, and other hydroxycarboxylic acids, as well as ethylene glycol, propylene glycol, and butane. Compounds containing a plurality of hydroxyl groups in the molecule such as diol, neopentyl glycol, polyethylene glycol, glycerin, pentaerythritol or derivatives thereof, succinic acid, adipic acid, sebacic acid, fumaric acid, terephthalic acid, isophthalic acid, 2 , 6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium sulfoisophthalic acid and the like, or compounds containing a plurality of carboxylic acid groups in the molecule. In addition, as a copolymerization component of a polylactic acid-type polymer (A), it is preferable to select the component which has biodegradability.

  The layer B of the laminated film of the present invention is mainly composed of the crystalline resin composition B having a glass transition temperature Tg (B), a crystallization temperature Tc (B), and a melting point Tm (A). The glass transition temperature Tg (B) of the product B is a temperature increase rate of 20 ° C./min after holding the sample rapidly cooled from the molten state in a nitrogen atmosphere at −50 ° C. for 5 minutes in the DSC measurement as described above. This is the glass transition temperature observed when the measurement is performed, and the crystallization temperature Tc (B) is a peak temperature indicating the maximum point of the exothermic curve obtained from the DSC curve (that is, the point at which the differential value becomes 0). The melting point Tm (B) is a peak temperature indicating the minimum point of the endothermic curve obtained from the DSC curve (that is, the point at which the differential value becomes 0). When two or more types of peak temperatures exist, the highest temperature side is defined as Tc (B) and Tm (B).

The stretching of the thermoplastic resin is generally performed at a temperature not lower than the glass transition point of the resin and not higher than the crystallization temperature. As an example of stretching of crystalline polylactic acid, the glass transition temperature of crystalline polylactic acid having an optical purity of 98% or more and a melting point of about 170 ° C. is about 60 ° C., and the crystallization temperature is about 130 ° C. Therefore, it is known that the stretching temperature is in the range of 60 to 130 ° C, preferably in the range of 70 to 100 ° C. Regarding the heat treatment temperature after stretching, it is generally carried out at an arbitrary temperature not lower than the glass transition temperature and not higher than the melting point, preferably in the range of 100 to 150 ° C. The laminated film of the present invention is characterized by being capable of imparting various properties such as various easy tear properties and solvent resistance without greatly changing the film formation conditions of crystalline polylactic acid. The relationship between Tg (A), Tm (A), Tg (B) and Tc (B)
Tg (A) ≧ Tg (B) and Tm (A) ≧ Tc (B)
It is necessary to become. When Tg (A) <Tg (B), it is difficult to form a film under the stretching condition of the crystalline polylactic acid polymer A, that is, the stretching condition of the laminated film is newly set to a condition equal to or higher than Tg (B). The necessity to set arises and it is not preferable from the surface of productivity. Also, when Tm (A) <Tc (B), the crystallization of the crystalline resin B does not proceed sufficiently at the heat treatment temperature of the crystalline polylactic acid polymer A when the heat treatment is performed after stretching the laminated film. The characteristic properties obtained by the present invention, that is, easy tearability and solvent resistance cannot be imparted, which is not preferable.

  The laminated film of the present invention is characterized in that various characteristics can be imparted by the crystalline resin composition B laminated on the B layer. Moreover, as a mechanism which can provide various characteristics with the resin laminated | stacked on B layer, it can be demonstrated by the following concepts about the case where easy tear property and solvent resistance are provided, for example.

[Disclosure of concept and technology for imparting easy tearability]
When a crystallizable film is crystallized in a non-oriented state, the brittleness increases and the elongation of the film decreases, making it very easy to cut. On the other hand, crystallizing after orienting the film makes it possible to greatly improve the physical properties and to obtain a film having strength, elongation and heat resistance. Further, although the relationship between the stretching conditions and the orientation state is not uniquely determined, when the stretching temperature is set to a temperature significantly higher than the glass transition temperature of the crystalline resin, the orientation of the film tends to be reduced. This is presumed to be due to the fact that the movement of the molecular chain starting at or above the glass transition temperature increases as the temperature rises, and that orientation is relaxed even when stretched. That is, when the film is stretched and crystallized at a temperature that greatly exceeds the glass transition temperature, it becomes a non-oriented state and a film having a small elongation can be obtained.

  Accordingly, the inventors of the present invention pay attention to the above, and a crystalline polylactic acid-based polymer A and a crystalline resin composition having a glass transition temperature Tg (B) lower than the glass transition temperature Tg (A) of A. By laminating B and stretching at a temperature equal to or higher than Tg (A), that is, a temperature greatly exceeding Tg (B), the A layer is oriented and crystallized, and functions as a layer that retains strength, elongation, and heat resistance. The B layer is hardly oriented and functions as a layer with reduced elongation of the film, and it is found that a laminated film imparted with an easy tear property by the effect of both layers is disclosed and disclosed herein.

  From the above viewpoint, Tg (A) ≧ Tg (B) +10 is more preferable, and Tg (A) ≧ Tg (B) +20 is further preferable.

  In addition, as one of methods for determining the presence or absence of easy tearing, there is a method of relatively calculating the load applied to the film when the film is cut. Specifically, in accordance with JIS K7161 and JIS K7127, 23 ° C. It is the method of calculating | requiring from the value of the product of the film breaking strength (MPa) and the film thickness (micrometer) obtained by the test done on tension | pulling speed 300mm / min conditions using a Tensilon universal testing machine. The smaller the product of the breaking strength and the thickness, the smaller the load applied to the film at the time of breaking, that is, the film can be broken with a small load and has an easy tear property. From this viewpoint, the product of the breaking strength and the thickness is preferably 3000 or less, more preferably 2500 or less, and particularly preferably 2000 or less.

[Disclosure of concept and technology for imparting solvent resistance]
Conventionally, plastic processed films and sheets are often printed with printing inks using hydrocarbon solvents such as toluene, xylene, ethyl acetate, acetone, methyl ethyl ether, etc. If soaked by deformation, swelling, etc., the printability may be deteriorated and the beauty after printing may be impaired. This tendency becomes particularly remarkable when the film is not crystallized or when an aliphatic polymer having no aromatic ring is used. For example, even when a polylactic acid film is used, the crystallized polylactic acid film has much better solvent resistance than the amorphous polylactic acid film. Even when a crystalline polymer was used, an aromatic film represented by PET or the like was superior in solvent resistance compared to a polylactic acid film. This is presumed to be due to the fact that the aromatic ring has excellent solvent resistance to the solvent. That is, the solvent resistance can be remarkably improved by the resin having an aromatic ring.

  Accordingly, the inventors of the present invention pay attention to the above and have a crystalline polylactic acid-based polymer A, a glass transition temperature Tg (B) lower than the glass transition temperature Tg (A) of A, and an A layer. A laminated film provided with excellent solvent resistance that is difficult to express only by the A layer by laminating the crystalline resin composition B having superior solvent resistance and stretching at a temperature of Tg (A) or higher. Is disclosed and disclosed herein.

  One method for determining the presence or absence of solvent resistance is to observe changes in film haze before and after the solvent treatment. Specifically, a solvent such as toluene, xylene, ethyl acetate, acetone, methyl ethyl ether is dropped on the film, and then the film surface is wiped off with a gauze under a constant pressure, and the haze increase on the film surface is observed. is there. The better the solvent resistance, the lower the haze rise after solvent treatment. From this viewpoint, the haze increase before and after the treatment is preferably 5% or less, more preferably 3% or less, and particularly preferably 1% or less.

  The laminated film of the present invention needs to have a heat of crystal melting (ΔHm) of 15 J / g or more in DSC temperature rise measurement. If it is less than 15 J / g, the crystallization of the film becomes insufficient, and the above-described excellent easy tearing and solvent resistance cannot be imparted. In this respect, ΔHm is preferably 20 J / g or more, and more preferably 30 J / g or more.

  Furthermore, the layer structure of the laminated film of the present invention needs to be three or more layers including A / B / A or B / A / B. When the layer structure is only two layers of A / B, the above-described easy tearing and solvent resistance are insufficient, which is not preferable. Whether A / B / A or B / A / B is adopted can be appropriately determined depending on the required film properties. For example, in the case of imparting easy tearability, it is possible to adopt a configuration in which a layer retaining strength, elongation and heat resistance is an outer layer, that is, an A / B / A configuration, and in the case of imparting solvent resistance. Further, it is possible to adopt a configuration in which a layer having solvent resistance is an outer layer, that is, a B / A / B configuration. The film configuration is not limited to this, and a new layer for adding new functions such as slipperiness, adhesiveness, tackiness, heat resistance, and weather resistance to the outermost layer may be added to the laminated configuration. Good. For example, when the C layer and D layer having different resin or additive compositions are laminated on the A layer and B layer, C / A / B / A, C / B / A / B, D / A / 4 layers such as B / A, D / B / A / B, C / A / B / A / C, C / B / A / B / C, D / A / B / A / D, D / B Examples include five layers such as / A / B / D, C / A / B / A / D, and C / B / A / B / D. Furthermore, if necessary, it may be a multi-layered structure with more than five layers, and the thickness ratio of each layer can also be set arbitrarily.

  The laminated film of the present invention is characterized in that various characteristics can be imparted by the crystalline resin composition B laminated on the B layer. Examples of the crystalline resin composition B laminated on the B layer include compositions made of various thermoplastic resins such as polyolefins, polyamides, polyesters, etc., but the A layer mainly comprises the crystalline polylactic acid polymer A. From the viewpoint of improving the interlaminar adhesion, that is, the interlaminar affinity, a polyester resin composition is preferable. Further, from the viewpoint of imparting easy tearability, it is more preferably a resin composition containing a polyester obtained by polycondensation of a diol and a dicarboxylic acid component or a resin composition containing a polylactic acid-based polymer as a main component. From the viewpoint of sufficiently promoting the crystallization of the layer and imparting solvent resistance, the dicarboxylic acid particularly preferably contains an aromatic dicarboxylic acid component. In addition, it is preferable that the resin composition B of this invention has biodegradability. From the above viewpoints, the resin composition B is a resin composition mainly composed of a hydroxycarboxylic acid polymer such as a polylactic acid polymer, or an aromatic such as terephthalic acid, isophthalic acid, phthalic acid, or naphthalenedicarboxylic acid. Dicarboxylic acid components and / or aliphatic dicarboxylic acid components such as oxalic acid, malonic acid, succinic acid, adipic acid, etc. are converted into ethylene glycol, propylene glycol, 1,4-butanediol 1,6-hexanediol, 1,4- An aliphatic or aromatic-aliphatic polyester polycondensed with a diol component such as cyclohexanediol is preferably used.

  In addition, the laminated film of the present invention is preferably used after being stretched because at least the A layer is oriented and crystallization can be promoted while maintaining transparency. The draw ratio is preferably 1.1 times or more in at least uniaxial direction, and more preferably 1.1 to 10 times in at least uniaxial direction. For example, the stretching conditions of the film can be adjusted appropriately according to the desired heat shrinkage characteristics, dimensional stability, strength, elastic modulus, etc., and can be carried out by any method. For example, the stretching temperature is the glass transition of the resin used. It is preferable to carry out at a temperature above the crystallization temperature in terms of stretchability and transparency. The draw ratio is preferably arbitrarily selected from the range of 1.1 times to 10 times in the longitudinal direction and the width direction, respectively. In particular, the draw ratio may be the same in the longitudinal direction or the width direction, and is the same. May be. In addition, when the draw ratio of a uniaxial direction exceeds 10 times, a drawability will fall, the fracture | rupture of a film will occur frequently and the stable drawability may not be acquired. Depending on conditions such as stretching temperature and stretching (deformation) speed, non-uniform stretching may occur, and the preferred stretching ratio in the uniaxial direction is preferably 2 times or more, and more preferably 2.5 times or more. For example, the draw ratio in the case of forming a biaxially stretched film is preferably 4 times or more, more preferably 7 times or more, as an area ratio that is an area ratio of the film before and after stretching.

  In addition, when imparting solvent resistance to the laminated film, it is preferable to crystallize the B layer in addition to the A layer, and it is more preferable to crystallize while maintaining the transparency. It is particularly preferable to satisfy both properties and crystallization. Transparent crystallization at the time of stretching makes it difficult to be immersed in a solvent. The method of transparent crystallization at the time of stretching is to adjust Tg (A) and Tg (B) as close as possible within the range satisfying Tg (A) ≧ Tg (B), and to set the stretching temperature to Tg (A). The temperature is adjusted as low as possible within the range (specifically, the stretching temperature is preferably Tg (A) + 30 ° C. or lower, more preferably Tg (A) + 25 ° C. or lower, particularly preferably Tg (A) + 20 ° C. or lower). And a method of selecting a crystalline resin composition B having high transparent crystallinity at the time of stretching, etc. Among these, Tg (A) is within the range satisfying Tg (A) ≧ Tg (B). ) And Tg (B) are particularly preferably adjusted to the closest possible range, more specifically, preferably Tg (B) ≦ Tg (A) ≦ Tg (B) +25, more preferably Tg (B) ≦. Tg (A) ≦ Tg (B) +20 Particularly preferably may be selected to Tg (B) ≦ Tg (A) crystalline resin composition B satisfying ≦ Tg (B) +15. The criterion for judging that the A layer and the B layer are transparently crystallized is, for example, that when the DSC temperature rise measurement of the film after film formation is performed, the crystallization peak is not observed at the first temperature rise. Only the melting peak is observed and the film haze can be determined to be 10% or less, and more simply, the laminated film after film formation has a Tm (A) of Tc (B) or more. It can be judged from the fact that the film haze before and after being left undisturbed after being left in an oven set at an arbitrary temperature for 1 hour or longer.

  In addition, when using the laminated film of the present invention, including when not accompanied by stretching, for example, together with an inorganic nucleating agent such as talc or an organic nucleating agent such as erucic acid amide, as in the case of oriented crystallization during stretching, In some cases, crystallization of the A layer or the B layer can be promoted.

  In the laminated film of the present invention, it is necessary to laminate a B layer mainly composed of the crystalline resin composition B having a glass transition temperature of Tg (A) ≧ Tg (B), but Tg (A) ≧ In order to achieve Tg (B), a plasticizer may be used. In this case, even if the crystalline resin itself used does not satisfy Tg (A) ≧ Tg (B), Tg (A) ≧ Tg (B This is particularly preferable because the range of resins that can be used is widened.

  As the plasticizer contained in the crystalline resin composition B, a phthalic acid type, a polyester type, a polyether type, a polyether ester type, or a known one can be used, and the addition amount is appropriately set according to the Tg (B) for which the amount to be added is required. However, when the crystalline resin composition B uses a polyester resin composition whose main component is a polylactic acid polymer, one or more polylactic acid segments having a molecular weight of 1,500 or more in one molecule It is preferable to use a plasticizer having polyether-based and / or polyester-based segments. In this case, the polylactic acid segment of the plasticizer is incorporated into the crystal formed from the polylactic acid polymer as the base material, thereby causing the plasticizer molecule to be anchored to the base material. Volatilization, exudation, and extraction (bleed out) can be sufficiently suppressed. Further, the molecular weight of the polylactic acid segment in the plasticizer is usually less than 10,000. When the molecular weight is 10,000 or more, the plasticizing efficiency is lowered, and it may be difficult to impart practical flexibility.

  In addition, the laminated | multilayer film of this invention may contain components other than having mentioned above in the range which does not impair the effect of this invention. For example, various known plasticizers, antioxidants, UV stabilizers, anti-coloring agents, matting agents, deodorants, flame retardants, weathering agents, antistatic agents, mold release agents, antioxidants, ion exchange agents Alternatively, inorganic fine particles or organic compounds may be added as necessary as coloring pigments. Known plasticizers include, for example, phthalate esters such as diethyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, di-1-butyl adipate, di-n-octyl adipate, di-n-butyl sebacate , Aliphatic dibasic acid esters such as di-2-ethylhexyl azelate, phosphate esters such as diphenyl-2-ethylhexyl phosphate and diphenyloctyl phosphate, tributyl acetylcitrate, tri-2-ethylhexyl acetylcitrate , Hydroxy polycarboxylic acid esters such as tributyl citrate, fatty acid esters such as methyl acetylricinoleate and amyl stearate, polyhydric alcohol esters such as glycerin triacetate and triethylene glycol dicaprylate, epoxidized soybean oil, Epo Shi linseed oil fatty acid butyl ester, epoxy plasticizers such as epoxy stearic octyl, polyester plasticizers such as polypropylene glycol sebacic acid ester, polyalkylene ether, ether ester type, and the like acrylate. From the viewpoint of safety, it is preferable to use a plasticizer that is approved by the US Food and Drug Administration (FDA). Examples of the antioxidant include hindered phenols and hindered amines. Color pigments include inorganic pigments such as carbon black, titanium oxide, zinc oxide, iron oxide, cyanine, styrene, phthalocyanine, anthraquinone, perinone, isoindolinone, quinophthalone, and quinocridone. Organic pigments such as thioindigo can be used. In addition, when adding inorganic fine particles for the purpose of improving the slipperiness and blocking resistance of a molded product, for example, silica, colloidal silica, alumina, alumina sol, kaolin, talc, mica, calcium carbonate, etc. are used. be able to. The average particle diameter is not particularly limited, but is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm, and most preferably 0.08 to 2 μm.

  Furthermore, the A layer or the B layer of the laminated film of the present invention contains a resin other than those described above within a range not impairing the effects of the present invention for the purpose of reducing the melt viscosity or improving the biodegradability. May be. Examples of the resin other than those described above include polyglycolic acid, poly (3-hydroxybutyrate), poly (3-hydroxybutyrate · 3-hydroxyvalerate), polycaprolactone, ethylene glycol, 1,4-butanediol, and the like. And aliphatic dihydroxy acids such as succinic acid and adipic acid, and polyglycolic acid.

  The laminated film of the present invention can be obtained by an existing melt molding method, and will be described below as an example, particularly including a method for imparting easy tearability and solvent resistance.

  The film can be obtained by an existing stretched film manufacturing method such as an inflation method, a sequential biaxial stretching method, or a simultaneous biaxial stretching method. In the production of films by the sequential biaxial stretching method and the simultaneous biaxial stretching method, after sufficiently drying the crystalline polylactic acid polymer A and the crystalline resin composition B, supply A and B to separate extruders. And it can be extruded by a known method such as guiding to a three-layer T die die and melt extrusion into a sheet, but the temperature of the extruder, polymer piping, die, etc. is preferably 250 ° C. or less, preferably 240 ° C. or less. Further preferred is 230 ° C. or less. The residence time from when the crystalline polylactic acid polymer A and the crystalline resin composition B are melted in the extruder until they are discharged from the die is preferably 20 minutes or less, and preferably 10 minutes or less. More preferably, it is more preferably 5 minutes or less. The extruded sheet-like melt is brought into close contact with a casting drum and cooled and solidified to obtain an unstretched film. The unstretched film obtained by this method is continuously stretched in at least one direction, and then stretched in a direction perpendicular to the first-stage stretching direction as necessary.

  In order to impart easy tearability, a crystalline resin composition B having Tg (B) as described above that is significantly lower than Tg (A) is selected, and at a temperature equal to or higher than Tg (A), preferably Tg + 10 ° C. or higher. It is preferable that the orientation of the B layer is kept small by stretching at a temperature of.

  Moreover, in order to provide solvent resistance, as described above, a crystalline resin composition in which Tg (A) and Tg (B) are as close as possible within a range satisfying Tg (A) ≧ Tg (B). It is preferable that the product B is selected and stretched at a temperature equal to or higher than Tg (A) to transparently crystallize the A layer and the B layer.

  Subsequent to stretching or after winding, the layers A and B are subjected to heat treatment for a longer period of time of 10 seconds or longer at a temperature range of Tc (B) or higher and Tm (A), preferably higher temperature of 100 ° C. or higher. It is preferable to keep the crystallinity of the layer sufficiently large.

  Furthermore, after forming into a film, various surface treatments may be applied for the purpose of improving printability, laminate suitability, coating suitability, and the like. Examples of surface treatment methods include corona discharge treatment, plasma treatment, flame treatment, acid treatment, etc., and any method can be used, but continuous treatment is possible, and equipment for existing film forming equipment is used. Corona discharge treatment can be exemplified as the most preferable because of its easy installation and simple processing.

  The thickness of the film of the present invention is not particularly limited, and may be set to an appropriate thickness depending on performance required according to the application, for example, solvent resistance, easy tearability, strength, transparency, biodegradation speed, price, and the like. Usually, it is 5 μm or more and 1 mm or less, and a range of 5 μm or more and 200 μm or less is particularly preferred.

  The laminated film of the present invention preferably has a film haze value of 0.2 to 15%. The film haze value is evaluated by the method described in the Examples, and refers to a value obtained by converting the actual measured value when the film thickness is 10 μm by proportional calculation. In particular, in the use of a solvent-resistant laminated film, especially a film for a printing substrate, a film haze value of 0.2 to 15% is preferable because it can be used without impairing the beauty of the printed matter. A preferable range of the film haze value is 0.2 to 10%, and a more preferable range is 0.2 to 5%. Moreover, it is preferable that it is 15% or less also in an actual measured value. Furthermore, in applications where a certain level of concealment is required, such as garbage bags or agricultural multi-films, or where it is preferable that the light transmittance is low or the absorption rate of sunlight is high, for example, coloring pigments, etc. It is good to add.

  The laminated film of the present invention is a laminated film that retains excellent easy tearability or solvent resistance, which is not practically found in a single layer of polylactic acid film, and therefore can be used in a wider field than before. For example, it can be used for packaging materials such as pressure-sensitive adhesive tapes, medicine packaging, etc. where cellophane has been used in the past, or for industrial materials such as various films, sheets, and synthetic papers that require surface treatment with organic solvents such as printing. Raru.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by a following example. The physical properties and evaluation results in the examples are values measured and judged by the following methods and standards.

(1) Film forming property The film forming property at the time of forming a laminated film was judged according to the following criteria.

○: A laminated film was stably obtained without blocking, sticking and tearing in the extruder or during stretching. ×: Blocking, sticking and tearing occurred in the extruder or during stretching, and the laminated film was stable. Could not get.

(2) Heat of crystal melting of laminated film The amount of heat absorbed by the laminated film was 20 ° C. after 5 mg of sample was held at −50 ° C. for 5 minutes in a nitrogen atmosphere using a differential scanning calorimeter RDC220 manufactured by Seiko Denshi Kogyo Co., Ltd. It was determined from the measurement at a heating rate of 1 minute.

(3) Breaking strength of laminated film [MPa]
A film sample was cut into a longitudinal direction of 150 mm and a width direction of 10 mm, and conditioned for 24 hours in an atmosphere of a temperature of 23 ° C. and a humidity of 65% RH in advance. This sample was subjected to a tensile test under the conditions of an initial length of 50 mm and a tensile speed of 300 mm / min using a Tensilon universal tester UTC-100 type (Orientec Co., Ltd.) in an atmosphere of 23 ° C. according to JIS K7161 and JIS K7127. The strength at break was determined. The test was performed 5 times in total, and the average value was defined as the breaking strength.

(4) Easy tear property evaluation The easy tear property evaluation of the laminated film was judged according to the following criteria from the product of the film sample thickness and the break strength obtained in (3).

○: Product of thickness and breaking strength is 2500 or less Δ: Product of thickness and breaking strength is 2500 to 3000
X: The product of thickness and breaking strength exceeds 3000.

(5) Film haze value [%]
As an index of transparency of the laminated film sample, the haze value of the film sample whose thickness was measured in advance was measured using a haze meter HGM-2DP type (manufactured by Suga Test Instruments Co., Ltd.). The measurement was performed 5 times per level, and the film haze value [%] was determined as a conversion value when a film having a thickness of 10 μm was obtained from the average value of the 5 measurements.

(6) Film thickness The film thickness was measured according to JIS C2111 using a dial gauge type micrometer.

(7) Presence / absence of transparent crystallization The presence / absence of transparent crystallization of the laminated film was determined according to the following criteria by performing DSC measurement and film haze measurement of the film sample according to (2) and (5).

○: No crystallization peak is observed at the first temperature rise, only a melting peak is observed, and the film haze is 10% or less. X: Other than above (8) Solvent resistance evaluation Solvent resistance evaluation of laminated film Is a process of wiping the surface of the film 5 times under a load of 200 g using a cotton gauze after dropping 5 ml of ethyl acetate on a laminated film previously cut into 30 mm × 50 mm. From the increase in film haze after treatment, Judged by criteria.

○: Haze increase value after treatment is 5% or less ×: Haze increase value after treatment exceeds 5%.

The polylactic acid-based polymer A and crystalline resin used in this example were obtained as follows.
[Polylactic acid polymer]
<P1 (high melting point polylactic acid)>
0.1 parts by weight of octylate and 0.1 parts by weight of lauryl alcohol are mixed with 100 parts by weight of L-lactide, and polymerized in a reaction vessel equipped with a stirrer at 190 ° C. for 15 minutes in a nitrogen atmosphere. After chipping with a shaft kneading extruder, solid-phase polymerization was performed in a nitrogen atmosphere at 140 ° C. for 3 hours to obtain a polylactic acid polymer P1. When DSC measurement was performed on P1, P1 had crystallinity, a glass transition temperature of 62 ° C., and a melting point of 172 ° C.

<P2 (low melting point polylactic acid)>
A mixture of 92 parts by weight of L-lactide and 8 parts by weight of DL-lactide was mixed with 0.1 parts by weight of tin octylate and 0.1 parts by weight of lauryl alcohol, and in a reaction vessel equipped with a stirrer at 190 ° C. in a nitrogen atmosphere. Polymerization was carried out for 3 hours, and further chipped with a biaxial kneading extruder to obtain a polylactic acid polymer P2. When DSC measurement was performed on P2, P2 exhibited crystallinity, and had a glass transition temperature of 58 ° C and a melting point of 149 ° C.

<P3 (amorphous polylactic acid)>
0.1 part by weight of octylate and 0.1 part by weight of lauryl alcohol are mixed with 65 parts by weight of L-lactide and 35 parts by weight of DL-lactide, and the mixture is stirred at 190 ° C. in a nitrogen atmosphere in a reaction vessel equipped with a stirrer. Polymerization was carried out for 3 hours, and further chipped with a biaxial kneading extruder to obtain a polylactic acid polymer P3. When DSC measurement was performed on P3, P3 did not exhibit crystallinity at a glass transition temperature of 58 ° C., and no crystallization temperature and melting point were observed.

[Crystalline resin]
<P4 (isophthalic acid copolymerized PET)>
To a mixture of 90 parts by weight of dimethyl terephthalate, 10 parts by weight of dimethyl isophthalate, and 60 parts by weight of ethylene glycol, 0.09 part by weight of magnesium acetate and 0.03 part by weight of antimony trioxide are added, and the temperature is raised by a conventional method. Then, a transesterification reaction was performed. Next, 0.026 part by weight of trimethyl phosphate is added to the transesterification reaction product, and then transferred to a polycondensation reaction layer. Next, the reaction system was gradually depressurized while being heated and heated, and polymerization was conducted at 290 ° C. under a reduced pressure of 1 mmHg by a conventional method to obtain P4. When DSC measurement was performed on P4, P4 exhibited crystallinity, and had a glass transition temperature of 72 ° C, a crystallization temperature of 182 ° C, and a melting point of 230 ° C.

<P5 (PPT)>
To a mixture of 100 parts by weight of dimethyl terephthalate and 80 parts by weight of trimethylene glycol, 0.09 part by weight of magnesium acetate and 0.03 part by weight of diantimony trioxide are added, and the temperature is raised by a conventional method to carry out a transesterification reaction. I did it. Next, 0.026 part by weight of trimethyl phosphate was added to the transesterification reaction product, and then transferred to a polycondensation reaction layer. Subsequently, the reaction system was gradually depressurized while being heated and heated, and polymerization was performed at 270 ° C. under a reduced pressure of 1 mmHg by a conventional method to obtain P5. When DSC measurement was performed on P5, P5 exhibited crystallinity, and had a glass transition temperature of 50 ° C., a crystallization temperature of 74 ° C., and a melting point of 230 ° C.

<P6 (succinic acid copolymerized PET1)>
To a mixture of 76 parts by weight of dimethyl terephthalate, 24 parts by weight of dimethyl succinate and 60 parts by weight of ethylene glycol, 0.09 parts by weight of magnesium acetate and 0.03 parts by weight of antimony trioxide are added, and the temperature is raised by a conventional method. Then, a transesterification reaction was performed. Next, 0.026 part by weight of trimethyl phosphate was added to the transesterification reaction product, and then transferred to a polycondensation reaction layer. Subsequently, the reaction system was gradually depressurized while being heated and heated, and polymerization was conducted at 260 ° C. under a reduced pressure of 1 mmHg by a conventional method to obtain P7. When DSC measurement was performed on P5, P7 exhibited crystallinity, and had a glass transition temperature of 42 ° C., a crystallization temperature of 137 ° C., and a melting point of 200 ° C.

<P7 (succinic acid copolymerized PET2)>
To a mixture of 84 parts by weight of dimethyl terephthalate, 16 parts by weight of dimethyl succinate and 60 parts by weight of ethylene glycol, 0.09 parts by weight of magnesium acetate and 0.03 parts by weight of antimony trioxide are added, and the temperature is raised by a conventional method. Then, a transesterification reaction was performed. Next, 0.026 part by weight of trimethyl phosphate was added to the transesterification reaction product, and then transferred to a polycondensation reaction layer. Subsequently, the reaction system was gradually depressurized while being heated and heated, and polymerization was carried out at 260 ° C. under a reduced pressure of 1 mmHg by a conventional method to obtain P6. When DSC measurement was performed on P5, P6 exhibited crystallinity, and had a glass transition temperature of 57 ° C., a crystallization temperature of 134 ° C., and a melting point of 210 ° C.

[Plasticizer]
<Plasticizer (S1)>
0.07 part by weight of tin octylate is mixed with 71 parts by weight of polyethylene glycol having an average molecular weight of 10,000 and 29 parts by weight of L-lactide, and polymerization is carried out at 190 ° C. for 60 minutes in a nitrogen atmosphere in a reaction vessel equipped with a stirrer. Thus, a block copolymer S1 of polyethylene glycol and polylactic acid having a polylactic acid segment having an average molecular weight of 2,000 was obtained.

(Example 1)
A mixture of 100 parts by weight of high melting point polylactic acid (P1) dried under reduced pressure at 100 ° C. for 6 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is used as a crystalline polylactic acid polymer A It was. 17 parts by weight of high melting point polylactic acid (P1) and 28 parts by weight of plasticizer (S1) dried under reduced pressure at 100 ° C. for 6 hours under a high vacuum of 10 torr, and non-dried under reduced pressure at 50 ° C. for 48 hours under a high vacuum of 10 torr. A mixture of 55 parts by weight of crystalline polylactic acid (P3) and 0.3 parts by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Co., Ltd. was subjected to melt kneading using a twin-screw kneading extruder with a cylinder temperature of 200 ° C. After homogenization, chips were formed to obtain a crystalline resin composition B. The composition B was dried under reduced pressure at 80 ° C. for 24 hours under a vacuum of 5 torr, and then the crystalline polylactic acid polymer A was fed to a single screw extruder A with a screw system of 30 mm and a cylinder temperature of 200 ° C. The product B is fed to a single screw extruder B with a screw system of 50 mm set at a cylinder temperature of 190 ° C., led to a three-layer T die die set at a die temperature of 200 ° C., extruded into a film, and cooled on a drum at 5 ° C. An unstretched film was produced by applying an electrostatic force to the film. At this time, the extrusion amounts of the extruders A and B were adjusted so that A / B / A was 2/6/2. After continuously stretching 3.0 times in the longitudinal direction between heating rolls at 85 ° C., the obtained uniaxially stretched film is gripped with a clip and guided into a tenter, and heated in a temperature of 75 ° C. and 3 in the lateral direction. The film was stretched by a factor of 0 and fixed in the width direction at 140 ° C. for 20 seconds to obtain a laminated film having a thickness of 25 μm. At this time, it was possible to obtain a laminated film with extremely stable extrusion and stretching conditions. The evaluation results of the obtained film are shown in Table 1.

(Example 2)
A laminated film was obtained in the same manner as in Example 1 except that the laminated film thickness was 40 μm. At this time, it was possible to obtain a laminated film with extremely stable extrusion and stretching conditions. The evaluation results of the obtained film are shown in Table 1.

(Example 3)
A mixture of 100 parts by weight of high melting point polylactic acid (P1) dried under reduced pressure at 100 ° C. for 6 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is used as a crystalline polylactic acid polymer A It was. 59 parts by weight of high melting point polylactic acid (P1) and 14 parts by weight of plasticizer (S1) dried under reduced pressure at 100 ° C. for 6 hours under a high vacuum of 10 torr, and non-dried under reduced pressure for 48 hours at 50 ° C. under a high vacuum of 10 torr. A mixture of 27 parts by weight of crystalline polylactic acid (P3) and 0.3 parts by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is supplied to a twin-screw kneading extruder with a cylinder temperature of 200 ° C. and melt-kneaded. After homogenization, chips were formed to obtain a crystalline resin composition B. The composition B was dried under reduced pressure at 80 ° C. for 24 hours under a vacuum of 5 torr, and then the crystalline polylactic acid polymer A was fed to a single screw extruder A with a screw system of 30 mm and a cylinder temperature of 200 ° C. The product B is fed to a single screw extruder B with a screw system of 50 mm set at a cylinder temperature of 190 ° C., led to a three-layer T die die set at a die temperature of 200 ° C., extruded into a film, and cooled on a drum at 5 ° C. An unstretched film was produced by applying an electrostatic force to the film. At this time, the extrusion amounts of the extruders A and B were adjusted so that A / B / A was 2/6/2. After continuously stretching 3.0 times in the longitudinal direction between heating rolls at 85 ° C., the obtained uniaxially stretched film is gripped with a clip and guided into a tenter, and heated in a temperature of 75 ° C. and 3 in the lateral direction. The film was stretched by a factor of 0 and fixed in the width direction at 140 ° C. for 20 seconds to obtain a laminated film having a thickness of 25 μm. At this time, it was possible to obtain a laminated film with extremely stable extrusion and stretching conditions. The evaluation results of the obtained film are shown in Table 1.

Example 4
A mixture of 100 parts by weight of high melting point polylactic acid (P1) dried under reduced pressure at 100 ° C. for 6 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is used as a crystalline polylactic acid polymer A It was. Crystalline resin composition B was a mixture of succinic acid copolymerized PET1 (P6) dried under reduced pressure at 120 ° C. for 5 hours and 0.3 part by weight of hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corporation. The crystalline polylactic acid polymer A is applied to a single screw extruder A with a screw system of 30 mm set at a cylinder temperature of 200 ° C., and the crystalline resin composition B is applied to a single screw extruder B with a screw system of 50 mm set at a cylinder temperature of 250 ° C. The film was fed to a three-layer T-die die set at a base temperature of 240 ° C., extruded into a film shape, and electrostatically cast on a drum cooled to 5 ° C. to prepare an unstretched film. At this time, the extrusion amounts of the extruders A and B were adjusted so that A / B / A was 2/6/2. After continuously stretching 3.0 times in the longitudinal direction between heating rolls at 85 ° C., the obtained uniaxially stretched film is gripped with a clip and guided into a tenter, and heated in a temperature of 75 ° C. and 3 in the lateral direction. The film was stretched by a factor of 0 and fixed in the width direction at 140 ° C. for 20 seconds to obtain a laminated film having a thickness of 25 μm. At this time, it was possible to obtain a laminated film with extremely stable extrusion and stretching conditions. The evaluation results of the obtained film are shown in Table 1.

(Comparative Example 1)
A mixture of 100 parts by weight of high melting point polylactic acid (P1) dried under reduced pressure at 100 ° C. for 6 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is used as a crystalline polylactic acid polymer A It was. The crystalline polylactic acid polymer A was fed to a single screw extruder A with a screw system of 30 mm set at a cylinder temperature of 200 ° C., led to a T die die set at a die temperature of 200 ° C., extruded into a film shape, and cooled to 5 ° C. An unstretched film was produced by electrostatic application casting on a drum. After continuously stretching 3.0 times in the longitudinal direction between heating rolls at 85 ° C., the obtained uniaxially stretched film is gripped with a clip and guided into a tenter, and heated in a temperature of 75 ° C. and 3 in the lateral direction. The film was heat-treated at 140 ° C. for 20 seconds while being stretched by 0.times. And fixed in the width direction to obtain a single-layer film having a thickness of 25 μm. At this time, a single layer film could be obtained with very stable extrusion and stretching conditions. The evaluation results of the obtained film are shown in Table 1.

(Comparative Example 2)
A single layer film was obtained in the same manner as in Example 1 except that the thickness of the laminated film was 40 μm. At this time, a single layer film could be obtained with very stable extrusion and stretching conditions. The evaluation results of the obtained film are shown in Table 1.

(Comparative Example 3)
A mixture of 100 parts by weight of high melting point polylactic acid (P1) dried under reduced pressure at 100 ° C. for 6 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is used as a crystalline polylactic acid polymer A It was. A mixture of isophthalic acid copolymerized PET (P4) dried under reduced pressure at 130 ° C. for 5 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Co. was used as the crystalline resin composition B. The crystalline polylactic acid polymer A is applied to a single screw extruder A with a screw system of 30 mm set at a cylinder temperature of 200 ° C., and the crystalline resin composition B is applied to a single screw extruder B with a screw system of 50 mm set at a cylinder temperature of 250 ° C. The film was fed to a three-layer T-die die set at a base temperature of 240 ° C., extruded into a film shape, and electrostatically cast on a drum cooled to 5 ° C. to prepare an unstretched film. At this time, the extrusion amounts of the extruders A and B were adjusted so that A / B / A was 2/6/2. Attempts were made to continuously stretch in the longitudinal direction at a preheating temperature of 85 ° C. and in the transverse direction at a preheating temperature of 75 ° C., but the film was broken and a laminated film could not be obtained.

(Comparative Example 4)
A mixture of 100 parts by weight of high melting point polylactic acid (P1) dried under reduced pressure at 100 ° C. for 6 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is used as a crystalline polylactic acid polymer A It was. A mixture of 100 parts by weight of amorphous polylactic acid (P3) dried under reduced pressure at 50 ° C. for 48 hours under a high vacuum of 10 torr and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corporation It was set as the composition B which is the raw material of a layer. The crystalline polylactic acid polymer A was fed to a single screw extruder A with a screw system of 30 mm set at a cylinder temperature of 200 ° C, and the composition B was fed to a single screw extruder B with a screw system of 50 mm set at a cylinder temperature of 190 ° C. Then, the film was led into a two-layer T-die die set at a die temperature of 200 ° C., extruded into a film shape, and casted electrostatically on a drum cooled to 5 ° C. to prepare an unstretched film. At this time, the extrusion amounts of the extruders A and B were adjusted so that A / B was ½. After continuously stretching 3.0 times in the longitudinal direction between heating rolls at 85 ° C., the obtained uniaxially stretched film is gripped with a clip and guided into a tenter, and heated in a temperature of 75 ° C. and 3 in the lateral direction. The film was stretched by a factor of 0 and fixed in the width direction at 140 ° C. for 20 seconds to obtain a laminated film having a thickness of 25 μm. At this time, the blocking and adhesion of the composition B were very much observed in the extruder and during stretching, and the film could not be formed stably. The evaluation results of the obtained film are shown in Table 1.

(Comparative Example 5)
A mixture of 100 parts by weight of high melting point polylactic acid (P1) dried under reduced pressure at 100 ° C. for 6 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is used as a crystalline polylactic acid polymer A It was. A mixture of 100 parts by weight of low melting point polylactic acid (P2) dried under reduced pressure at 60 ° C. for 48 hours under a high vacuum of 10 torr and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corporation was crystallized. Resin composition B. The crystalline polylactic acid polymer A was fed to a single screw extruder A with a screw system of 30 mm set at a cylinder temperature of 200 ° C, and the composition B was fed to a single screw extruder B with a screw system of 50 mm set at a cylinder temperature of 190 ° C. Then, the film was led to a three-layer T-die die set at a base temperature of 200 ° C., extruded into a film shape, and electrostatically cast on a drum cooled to 5 ° C. to prepare an unstretched film. At this time, the extrusion amounts of the extruders A and B were adjusted so that A / B / A was 2/6/2. After continuously stretching 3.0 times in the longitudinal direction between heating rolls at 85 ° C., the obtained uniaxially stretched film is gripped with a clip and guided into a tenter, and heated in a temperature of 75 ° C. and 3 in the lateral direction. The film was stretched by a factor of 0 and fixed in the width direction at 140 ° C. for 20 seconds to obtain a laminated film having a thickness of 25 μm. At this time, it was possible to obtain a laminated film with stable extrusion and stretching. The evaluation results of the obtained film are shown in Table 1.

(Comparative Example 6)
A mixture of 100 parts by weight of low melting point polylactic acid (P2) dried under reduced pressure at 60 ° C. for 48 hours under a high vacuum of 10 torr and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corporation was crystallized. Polylactic acid polymer A. A mixture of 100 parts by weight of amorphous polylactic acid (P3) dried under reduced pressure at 50 ° C. for 48 hours under a high vacuum of 10 torr and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corporation It was set as the composition B which is the raw material of a layer. The crystalline polylactic acid polymer A was fed to a single screw extruder A with a screw system of 30 mm set at a cylinder temperature of 200 ° C, and the composition B was fed to a single screw extruder B with a screw system of 50 mm set at a cylinder temperature of 190 ° C. Then, the film was led to a three-layer T-die die set at a base temperature of 200 ° C., extruded into a film shape, and electrostatically cast on a drum cooled to 5 ° C. to prepare an unstretched film. At this time, the extrusion amounts of the extruders A and B were adjusted so that A / B / A was 2/6/2. After continuously stretching 3.0 times in the longitudinal direction between heating rolls at 85 ° C., the obtained uniaxially stretched film is gripped with a clip and guided into a tenter, and heated in a temperature of 75 ° C. and 3 in the lateral direction. After stretching by a factor of 0, an attempt was made to heat-treat at 140 ° C. for 20 seconds with the film fixed in the width direction, but the film was broken and a laminated film could not be obtained.

(Example 5)
A mixture of 100 parts by weight of high melting point polylactic acid (P1) dried under reduced pressure at 100 ° C. for 6 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is used as a crystalline polylactic acid polymer A It was. Crystalline resin composition B was a mixture of succinic acid copolymerized PET1 (P6) dried under reduced pressure at 130 ° C. for 5 hours and 0.3 part by weight of hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corporation. The crystalline polylactic acid polymer A is applied to a single screw extruder A with a screw system of 50 mm set at a cylinder temperature of 200 ° C., and the crystalline resin composition B is applied to a single screw extruder B with a screw system of 30 mm set at a cylinder temperature of 250 ° C. The film was fed to a three-layer T-die die set at a base temperature of 240 ° C., extruded into a film shape, and electrostatically cast on a drum cooled to 5 ° C. to prepare an unstretched film. At this time, the extrusion amounts of the extruders A and B were adjusted so that B / A / B was 2/6/2. After continuously stretching 3.0 times in the longitudinal direction between heating rolls at 85 ° C., the obtained uniaxially stretched film is gripped with a clip and guided into a tenter, and heated in a temperature of 75 ° C. and 3 in the lateral direction. The film was stretched by a factor of 0 and fixed in the width direction at 140 ° C. for 20 seconds to obtain a laminated film having a thickness of 25 μm. At this time, it was possible to obtain a laminated film with extremely stable extrusion and stretching conditions. The evaluation results of the obtained film are shown in Table 2.

(Example 6)
A mixture of 100 parts by weight of high melting point polylactic acid (P1) dried under reduced pressure at 100 ° C. for 6 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is used as a crystalline polylactic acid polymer A It was. Crystalline resin composition B was a mixture of succinic acid copolymerized PET2 (P7) dried under reduced pressure at 130 ° C. for 5 hours and 0.3 part by weight of hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corporation. The crystalline polylactic acid polymer A is applied to a single screw extruder A with a screw system of 50 mm set at a cylinder temperature of 200 ° C., and the crystalline resin composition B is applied to a single screw extruder B with a screw system of 30 mm set at a cylinder temperature of 250 ° C. The film was fed to a three-layer T-die die set at a base temperature of 240 ° C., extruded into a film shape, and electrostatically cast on a drum cooled to 5 ° C. to prepare an unstretched film. At this time, the extrusion amounts of the extruders A and B were adjusted so that B / A / B was 2/6/2. After continuously stretching 3.0 times in the longitudinal direction between heating rolls at 85 ° C., the obtained uniaxially stretched film is gripped with a clip and guided into a tenter, and heated in a temperature of 75 ° C. and 3 in the lateral direction. The film was stretched by a factor of 0 and fixed in the width direction at 140 ° C. for 20 seconds to obtain a laminated film having a thickness of 25 μm. At this time, it was possible to obtain a laminated film with extremely stable extrusion and stretching conditions. The evaluation results of the obtained film are shown in Table 2.

(Example 7)
A mixture of 100 parts by weight of high melting point polylactic acid (P1) dried under reduced pressure at 100 ° C. for 6 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is used as a crystalline polylactic acid polymer A It was. Crystalline resin composition B was a mixture of PPT (P5) dried under reduced pressure at 130 ° C. for 5 hours and 0.3 part by weight of hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corporation. The crystalline polylactic acid polymer A is applied to a single screw extruder A with a screw system of 50 mm set at a cylinder temperature of 200 ° C., and the crystalline resin composition B is applied to a single screw extruder B with a screw system of 30 mm set at a cylinder temperature of 250 ° C. The film was fed to a three-layer T-die die set at a base temperature of 240 ° C., extruded into a film shape, and electrostatically cast on a drum cooled to 5 ° C. to prepare an unstretched film. At this time, the extrusion amounts of the extruders A and B were adjusted so that B / A / B was 2/6/2. After continuously stretching 3.0 times in the longitudinal direction between heating rolls at 85 ° C., the obtained uniaxially stretched film is gripped with a clip and guided into a tenter, and heated in a temperature of 75 ° C. and 3 in the lateral direction. The film was stretched by a factor of 0 and fixed in the width direction at 140 ° C. for 20 seconds to obtain a laminated film having a thickness of 25 μm. At this time, it was possible to obtain a laminated film with extremely stable extrusion and stretching conditions. The evaluation results of the obtained film are shown in Table 2.

(Comparative Example 7)
A single layer film was prepared in the same manner as in Comparative Example 1. The evaluation results of the obtained film are shown in Table 2.

(Comparative Example 8)
A mixture of 100 parts by weight of high melting point polylactic acid (P1) dried under reduced pressure at 100 ° C. for 6 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is used as a crystalline polylactic acid polymer A It was. A mixture of isophthalic acid copolymerized PET (P4) dried under reduced pressure at 130 ° C. for 5 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Co. was used as the crystalline resin composition B. The crystalline polylactic acid polymer A is applied to a single screw extruder A with a screw system of 50 mm set at a cylinder temperature of 200 ° C., and the crystalline resin composition B is applied to a single screw extruder B with a screw system of 30 mm set at a cylinder temperature of 250 ° C. The film was fed to a three-layer T-die die set at a base temperature of 240 ° C., extruded into a film shape, and electrostatically cast on a drum cooled to 5 ° C. to prepare an unstretched film. At this time, the extrusion amounts of the extruders A and B were adjusted so that B / A / B was 2/6/2. After continuously stretching 3.0 times in the longitudinal direction between heating rolls at 85 ° C., the obtained uniaxially stretched film is gripped with a clip and guided into a tenter, and heated in a temperature of 75 ° C. and 3 in the lateral direction. The film was stretched by a factor of 0 and fixed in the width direction at 140 ° C. for 20 seconds to obtain a laminated film having a thickness of 25 μm. Attempts were made to continuously stretch in the longitudinal direction at a preheating temperature of 85 ° C. and in the transverse direction at a preheating temperature of 75 ° C., but the film was broken and a laminated film could not be obtained.

(Comparative Example 9)
A mixture of 100 parts by weight of high melting point polylactic acid (P1) dried under reduced pressure at 100 ° C. for 6 hours and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corp. is used as a crystalline polylactic acid polymer A It was. A mixture of 100 parts by weight of amorphous polylactic acid (P3) dried under reduced pressure at 50 ° C. for 48 hours under a high vacuum of 10 torr and 0.3 part by weight of a hindered phenol antioxidant “Irganox 1010” manufactured by Ciba Geigy Corporation It was set as the composition B which is the raw material of a layer. The crystalline polylactic acid polymer A is fed to a single screw extruder A with a screw system of 50 mm set at a cylinder temperature of 200 ° C., and the composition B is fed to a single screw extruder B with a screw system of 30 mm set at a cylinder temperature of 200 ° C. Then, the film was led to a three-layer T-die die set at a base temperature of 200 ° C., extruded into a film shape, and electrostatically cast on a drum cooled to 5 ° C. to prepare an unstretched film. At this time, the extrusion amounts of the extruders A and B were adjusted so that B / A / B was 2/6/2. After continuously stretching 3.0 times in the longitudinal direction between heating rolls at 85 ° C., the obtained uniaxially stretched film is gripped with a clip and guided into a tenter, and heated in a temperature of 75 ° C. and 3 in the lateral direction. The film was stretched by a factor of 0 and fixed in the width direction at 140 ° C. for 20 seconds to obtain a laminated film having a thickness of 25 μm. At this time, very much blocking and adhesion of the composition B were observed in the extruder, and the film formation could not be performed stably. The evaluation results of the obtained film are shown in Table 2.

  The present invention can be applied to various packaging materials, various industrial materials, films for various industrial materials, and the like, but the application range is not limited thereto.

Claims (13)

A layer mainly composed of crystalline polylactic acid polymer A having glass transition temperature Tg (A) and melting point Tm (A), and crystal having glass transition temperature Tg (B) and crystallization temperature Tc (B) A laminated film composed of a B layer mainly composed of a conductive resin composition B, wherein the relationship between Tg (A), Tm (A), Tg (B) and Tc (B) is
Tg (A) ≧ Tg (B) and Tm (A) ≧ Tc (B)
The heat of crystal fusion (ΔHm) of the film in DSC temperature rise measurement is 15 J / g or more, and the layer structure is A / B / A or 3 layers including B / A / B. A laminated film characterized by The laminated film according to claim 1, wherein the laminated film is obtained by stretching at least 1.1 times in a uniaxial direction. The laminated film according to claim 1 or 2, wherein ΔHm is 30 J / g or more. The laminated film according to claim 1, further satisfying Tg (A) ≧ Tg (B) +10. The laminated film according to claim 1, further satisfying Tg (A) ≦ Tg (B) +25. 6. The laminated film according to claim 1, wherein the crystalline resin composition B is a polyester resin composition. The laminated film according to claim 6, wherein the polyester resin composition is a composition containing a polyester obtained by polycondensation of a diol component and a dicarboxylic acid component. The laminated film according to claim 7, wherein the dicarboxylic acid component includes an aromatic dicarboxylic acid component. The laminated film according to claim 6, wherein the polyester resin composition is a polyester resin composition containing a polylactic acid-based polymer as a main component. The laminated resin according to claim 1, wherein the crystalline resin composition B contains a plasticizer. The laminated film according to any one of claims 1 to 10, wherein a film haze value is 0.2 to 10%. The laminated film according to any one of claims 1 to 11 is stretched at a temperature of Tg (A) + 10 ° C or higher and subjected to a heat treatment in a temperature range of Tc (B) or higher and Tm (A) or lower to form the B layer. A laminated film obtained by crystallizing and having a product of film breaking strength (MPa) and thickness (μm) obtained by a tensile test at 23 ° C. of the film of 3000 or less. The laminated film according to any one of claims 1 to 11, wherein the B layer is transparently crystallized, and the film is made of at least one organic solvent selected from toluene, xylene, ethyl acetate, acetone, and methyl ethyl ketone. A laminated film having a film haze increase value of 5% or less after treatment.