JP2013001024A - Stretched film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stretched film which is excellent in stretching properties during film forming and gas barrier properties, quietness, pinhole resistance, and low thermal shrinkage properties as physical properties and has strong interlayer adhesive strength as a whole and large cost merits.SOLUTION: The stretched film has a polylactic acid-based resin layer and a polyamide-based resin layer, and is stretched in at least one direction. An adhesive resin is contained in at least one of the resin layers.

Description

  The present invention has excellent stretchability during film formation, and excellent physical properties such as gas barrier properties, quietness, pinhole resistance, chemical resistance, and low heat dissipation, and has a large adhesion strength and cost merit as a whole film. It relates to film.

  Polyamide resins have high crystallinity and melting point, and are therefore used as heat-resistant molded products. Moreover, since it has gas-barrier property, pinhole resistance, chemical resistance, and quietness as a film use, it is suitable for the film for food packaging, for example. However, since many polyamide-based resins are petroleum-derived materials, their use is problematic from the viewpoint of exhaustion of petroleum resources and carbon dioxide emission. Therefore, it is required to replace them with plant / biological materials.

  A typical plant-derived alternative material candidate is a polyester resin composition containing a lactic acid monomer as a main component, that is, a polylactic acid resin. Polylactic acid-based resin can produce lactic acid, which is a monomer, at low cost by fermentation using microorganisms using biomass such as corn as a raw material, and has a melting point as high as about 170 ° C. and can be melt-molded. Therefore, it is promising as an alternative to fossil raw material-based resins. However, polylactic acid-based resins have many problems when used as food packaging films in which polyamide-based resins are suitably used due to lack of heat resistance, flexibility, gas barrier properties, and quietness.

  In order to improve these drawbacks, a multilayer film containing a layer mainly composed of a polyamide resin and a layer mainly composed of a polylactic acid resin is formed, thereby taking advantage of the excellent physical properties of the polyamide resin, It has been devised to increase the plant / biological origin of the film as a whole. In this case, since the adhesive strength between the polylactic acid-based resin layer and the polyamide-based resin layer is small, measures are taken by providing a layer made of an adhesive resin between them.

  Patent Document 1 discloses a configuration in which a polylactic acid resin is an inner layer and an outer layer is a polyamide resin layer through an adhesive resin layer as an embodiment of a multilayer film that can be easily opened and sealed. ing.

  Patent Document 2 discloses a configuration in which an adhesive resin layer is provided between a polylactic acid resin layer and a polyamide resin layer as one form of a multilayer film containing a polylactic acid resin mainly used as a shrinkable tube. ing.

  In Patent Document 3, as one form of a deep drawing film excellent in film stiffness, gloss / transparency and deep drawing moldability, an outer polylactic acid resin layer and an inner heat seal layer are used. In the meantime, a configuration having a layer made of a polyamide-based resin is disclosed.

JP 2006-213053 A Special table 2009-535236 gazette JP 2008-55902 A

  In past studies represented by the above-mentioned patent documents, an adhesive resin layer is present between the polylactic acid-based resin layer and the polyamide-based resin layer in order to develop the adhesiveness between them. Then, as a method for forming a multilayer film having such a structure, a polylactic acid resin film and a polyamide resin film are separately formed in advance and then bonded together through an adhesive resin. It has been done. However, in this case, since the process of film formation and adhesion is required, the resulting film is expensive. Furthermore, since this method does not allow the laminated film to be stretched as a single piece, it eliminates the disadvantages of each resin film by integral stretching (for example, reducing the heat shrinkage rate for polylactic acid resin films and improving stretchability for polyamide resin films). ) Cannot be done.

  As another method, in order to form a multilayer film having such a structure in a one-step process, an extruder dedicated to the adhesive resin is prepared, and the shape of the feed block and the like is specially designed and executed. There is something. However, similarly to the above method, the labor and cost required for film production are greatly increased as compared with the case of forming a laminated film without an adhesive resin layer. In addition, there are problems such as difficulty in adjusting the film lamination ratio and the number of laminations, and adjusting the melt viscosity and stretchability of each component.

  The present invention solves such a conventional problem, thereby improving various drawbacks of the polylactic acid resin film and the polyamide film alone.

  In order to solve the above problems, the present invention proposes the following configurations. That is, the stretched film has a polylactic acid resin layer and a polyamide resin layer, and the polylactic acid resin layer and / or the polyamide resin layer contains an adhesive resin.

  The present invention is a stretched film having a laminated structure in which stretchability during film formation and physical properties are excellent in gas barrier properties, quietness, pinhole resistance, chemical resistance, low thermal shrinkage, and the cost advantage of the entire film is large. It is about. And by containing adhesive resin in the structural component of a layer, it is possible to express the adhesive strength between layers easily. The film of the present invention can be suitably used as a general industrial film or a packaging material film.

  The stretched film in the present invention has a polylactic acid resin layer and a polyamide resin layer, and the polylactic acid resin layer and / or the polyamide resin layer contains an adhesive resin.

  The number of layers of the stretched film in the present invention is not limited as long as it has at least a polylactic acid-based resin layer and a polyamide-based resin layer. It does not matter. Further, a resin layer different from the polylactic acid resin layer and the polyamide resin layer may be present. However, increasing the number of layers complicates the configuration of the extruder, feed block, etc. during film formation, so judging from the labor and cost, the number of layers is preferably 2 to 7, more preferably 2 5, more preferably 2 to 3.

  In the stretched film of the present invention, the configuration in which the polylactic acid-based resin layer is at least one of the outermost layers includes an amorphous polylactic acid-based resin described later as a polylactic acid-based resin in the polylactic acid-based resin layer. This is a preferred form because the heat sealability is exhibited. Here, the heat sealability is a property for filling and packaging the contents and taking the form of a bag, and the adhesive layer is bonded by melting and pressure bonding by heating. In the stretched film of the present invention, when at least one of the outermost layers is a polylactic acid-based resin layer and the polylactic acid-based resin in the polylactic acid-based resin layer contains an amorphous polylactic acid-based resin, Since the outer layer has heat sealability, the process can be simplified and thinned compared to the case where a heat seal layer is provided by extrusion lamination or a heat seal layer is provided by dry lamination, thereby reducing costs and environmental impact. It is preferable from the viewpoint of reduction.

  When at least one of the outermost layers is a polylactic acid resin layer for the purpose of developing heat sealability, and the polylactic acid resin in the polylactic acid resin layer contains an amorphous polylactic acid resin, In 100% by mass of the polylactic acid resin in the lactic acid resin layer, the amorphous polylactic acid resin is preferably 30% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, Preferably they are 80 mass% or more and 100 mass%.

  In addition, the stretched film of the present invention has a polyamide resin layer as both outermost layers. When the stretched film of the present invention is a biaxially stretched film, the polylactic acid resin layer is present on the surface layer. In comparison, since the adhesion to the roll during roll stretching is suppressed, the film-forming property is improved, and the heat setting temperature can be increased, so the heat shrinkage rate of the resulting film is reduced. This is a preferable mode from the viewpoint that it becomes possible.

  In the stretched film of the present invention, when the plant-derived polyamide resin described later is not used as the polyamide-based resin in the polyamide-based resin layer, the higher the content of the polylactic acid-based resin, the more the plant-derived degree as the whole film. It is preferable because it improves. On the other hand, such a preference does not exist when using a plant-derived polyamide resin. However, when the plant-derived polyamide resin is more expensive than the polylactic acid resin, the higher the content of the polylactic acid resin layer, the higher the content of the polylactic acid resin layer.

  The polylactic acid-based resin layer in the stretched film of the present invention means a layer in which all the components of the layer contain the most polylactic acid-based resin in mass (in the layer, the polylactic acid-based resin is a main component). means). In the polylactic acid-based resin layer, components other than the polylactic acid-based resin (referred to as subcomponents) can be contained in the polylactic acid-based resin layer within a range not exceeding the content ratio of the polylactic acid-based resin. . From the viewpoint of stable film formation, the polylactic acid-based resin layer is preferably composed of 70% by mass or more and 100% by mass or less of components other than the polylactic acid-based resin (various additions) Agent) is 0% by mass to 30% by mass.

  The polylactic acid resin refers to a polymer polymerized using lactic acid as a main structural unit (monomer component). In addition, lactic acid is the main structural unit means that the lactic acid unit is 50 mol% or more and 100 mol% or less when the total of the structural units of the polymer is 100 mol%. From the viewpoint of extrusion characteristics, when the total of the structural units of the polymer is 100 mol%, the lactic acid unit is preferably 60 mol% or more and 100 mol% or less, more preferably 80 mol% or more and 100 mol% or less.

  The polylactic acid-based resin may contain a component (copolymerization component) other than lactic acid as a constituent unit. Examples of components other than lactic acid include ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, and octanediol. Glycol compounds such as nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, pentaerythritol, bisphenol A, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, oxalic acid, Adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, bis (p-carboxyl Nyl) methane, anthracene dicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium isophthalic acid and other dicarboxylic acids, glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, Examples thereof include hydroxycarboxylic acids such as hydroxycaproic acid and hydroxybenzoic acid, and lactones such as caprolactone, valerolactone, propiolactone, undecalactone, and 1,5-oxepan-2-one.

  In the present invention, for applications requiring heat resistance, it is preferable to use a polylactic acid resin having a high optical purity of lactic acid units as the polylactic acid resin. That is, in one polylactic acid resin layer, among 100 mol% of total lactic acid units in the polylactic acid resin, L-form lactic acid units are contained in an amount of 80 mol% to 100 mol%, or D-form lactic acid units are 80 mol%. Preferably, it is contained in an amount of from 100 mol% to 100 mol%, more preferably from 90 mol% to 100 mol% of L-lactic acid units, or from 90 mol% to 100 mol% of D-lactic acid units. It is particularly preferable that the L-form lactic acid unit is contained in an amount of 95 mol% to 100 mol%, or the D-form lactic acid unit is contained in an amount of 95 mol% to 100 mol%, and the L-form lactic acid unit is contained in an amount of 98 mol% to 100 mol%. % Or less, or D-form lactic acid units are most preferably contained in an amount of 98 mol% to 100 mol%.

  In the present invention, for applications requiring heat resistance, it is preferable to use a polylactic acid stereocomplex as the polylactic acid resin. Examples of the method for forming the polylactic acid stereocomplex include the following. That is, in one polylactic acid-based resin layer, L-lactic acid units are 90 mol% or more and 100 mol% or less of 100 mol% of all lactic acid units, preferably 95 mol% from the viewpoint of forming a more efficient stereocomplex. More preferably, poly-L-lactic acid in which 98 mol% or more is composed of L-lactic acid units, and D-lactic acid units of 90 mol% to 100 mol% of 100 mol% of all lactic acid units are more efficient. From the viewpoint of forming a simple stereocomplex, the method preferably comprises 95 mol% or more and 100 mol% or less, more preferably 98 mol% or more and 100 mol% or less comprising poly-D-lactic acid composed of D-form lactic acid units. is there.

  As another method for forming a polylactic acid stereocomplex, in one polylactic acid-based resin layer, poly-L-lactic acid (poly-L-lactic acid segment) and poly-D-lactic acid (poly-D-lactic acid segment) are used. The thing using the block copolymer which consists of can also be mentioned. This method is preferable because a polylactic acid stereocomplex can be easily formed.

  In the present invention, the polylactic acid stereocomplex may be used alone, or the polylactic acid stereocomplex and poly-L-lactic acid or poly-D-lactic acid may be used in combination. Poly-L-lactic acid and poly-D-lactic acid refer to those in which 50 mol% or more of 100 mol% of all lactic acid units is an L-form lactic acid unit or a D-form lactic acid unit.

  In addition, when it is necessary to impart heat sealability to the polylactic acid-based resin layer, it is preferable that the layer contains an amorphous polylactic acid-based resin. Amorphous polylactic acid resin is melted when it is subjected to differential scanning calorimetry (DSC) at a heating rate of 20 ° C./min after leaving the resin for 1 hour under heating at 100 ° C. It means a polylactic acid resin that does not show a peak. As an amorphous polylactic acid-based resin, D-form random copolymer poly-L-lactic acid can be preferably used from the viewpoint of cost. In this case, the D form copolymerization ratio is preferably 10 mol% to 20 mol%, and more preferably 12 mol% to 18 mol%, from the viewpoint of low crystallinity and cost.

  As a method for producing the polylactic acid-based resin, a known polymerization method can be used, and a direct polymerization method from lactic acid, a ring-opening polymerization method via lactide, or the like can be used.

  The molecular weight and molecular weight distribution of the polylactic acid resin are not particularly limited as long as it can be substantially extruded, but the weight average molecular weight (Mw) is usually 10,000 to 500,000, preferably It is 40,000 to 300,000, more preferably 80,000 to 250,000. The weight average molecular weight here refers to the molecular weight in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography. If the weight average molecular weight is less than 10,000, the molded product (stretched film) becomes extremely brittle and may not be suitable for practical use. If the weight average molecular weight exceeds 500,000, the melt viscosity is too high and extrusion is often difficult, and the surface of the film may be roughened.

  The melting point of the polylactic acid-based resin is preferably 120 ° C. or higher, more preferably 150 ° C. or higher, from the viewpoint of heat resistance, unless heat sealability is required. The upper limit is not particularly limited, but is usually 190 ° C. An amorphous polylactic acid resin that does not exhibit a melting point can also be used, but from the viewpoint of the mechanical properties of the stretched film, it is usually preferable to use a crystalline polylactic acid resin. An exception is when the above-mentioned heat sealability is required. In that case, an amorphous polylactic acid resin is preferably used.

  In addition, as a method for measuring the melting point of the polylactic acid-based resin, a method using a differential scanning calorimeter (DSC) can be mentioned. In this case, it is preferable to sufficiently crystallize the resin to be measured in advance under heating.

  In addition, it is preferable that the polylactic acid-based resin layer contains a polyamide-based resin from the viewpoints of improving crystallinity and moisture resistance and improving adhesive strength between layers. As the polyamide resin contained in the polylactic acid resin layer, the same resins as those suitable for the polyamide resin described later can be preferably exemplified.

  Furthermore, on the film-forming process, if the film edges and the like to be removed are reused as the recovered material to the most important layer in the mass ratio among the layers constituting the present invention, the production cost of the film can be reduced. preferable.

  When a subcomponent such as a polyamide-based resin is present in the polylactic acid-based resin layer, it is also preferable to add a compatibilizer as a subcomponent to the polylactic acid-based resin layer in order to improve the compatibility. As a compatibilizing agent contained in the polylactic acid resin layer, an acrylic resin introduced with a polar group, a styrene resin introduced with a polar group, a polyolefin resin introduced with a polar group, and a polyolefin resin introduced with a polar group -A block copolymer of polystyrene resin or the like can be preferably used.

  When using a polyamide-based resin as a subcomponent in the polylactic acid-based resin layer and a compatibilizer as another subcomponent, from the viewpoint of heat resistance, 100% by mass of all the components constituting the polylactic acid-based resin layer It is preferable to contain 56 mass% or more and 99 mass% or less of resin, 0.5 mass% or more and 24 mass% or less of subcomponents, such as a polyamide-type resin, and 0.5 to 20 mass% of compatibilizers.

  The polyamide-based resin layer in the stretched film of the present invention means a layer containing the largest amount of polyamide resin in all the components of the layer (meaning that the polyamide-based resin is the main component in the layer). . Components other than the polyamide-based resin in the polyamide-based resin layer (referred to as subcomponents) can be contained in the polyamide-based resin layer within a range not exceeding the content of the polyamide-based resin as the main component. . From the viewpoint of stable film formation, the polyamide-based resin layer is preferably composed of 70% by mass to 100% by mass of the polyamide-based resin in all components of 100% by mass, and other components (such as various additives) than the polyamide resin. A certain subcomponent is 0% by mass or more and 30% by mass or less.

  For polyamide resins, for example, aliphatic polyamide resins such as poly (hexamethylene adipamide) (polyamide 6,6), poly (hexamethylene sebacamide) (polyamide 6,10), poly (heptamethylenepimelami) (Polyamide 7,7), poly (octamethylene suberamide) (polyamide 8,8), poly (hexamethylene azelamide) (polyamide 6,9), poly (nonamethylene azelamide (polyamide 9,9), Poly (decamethylene azeramid) (polyamide 10,9), poly (tetramethylenediamine-co-oxalic acid) (polyamide 4,2), polyamide of n-dodecanedioic acid and hexamethylenediamine (polyamide 6,12) , Polyamides of dodecamethylenediamine and n-dodecanedioic acid (polyamides 12 and 12), Li (4-aminobutyric acid) (polyamide 4), poly (6-aminohexanoic acid) (polyamide 6), poly (7-aminoheptanoic acid) (polyamide 7), poly (8-aminooctanoic acid) (polyamide 8) , Poly (9-aminononanoic acid) (polyamide 9), poly (10-aminodecanoic acid) (polyamide 10), poly (11-aminoundecanoic acid) (polyamide 11), and poly (12-aminododecanoic acid) (polyamide 12) )) Or a copolymer of two or more of these, and a mixture thereof.For example, as an aromatic polyamide-based resin, poly (tetramethylenediamine-co-isophthalic acid) ( Polyamide 4, I), Polyhexamethylene isophthalamide (Polyamide 6, I), Polyhexamethylene tetraphthal Amides (polyamide 6, T), poly (2,2,2-trimethylhexamethylene terephthalamide), poly (m-xylylene adipamide) (polyamide MXD, 6), poly (p-xylylene adipamide) , Poly (hexamethylene terephthalamide), poly (dodecamethylene terephthalamide), a homopolymer such as polyamide MXD, I, a copolymer with two or more thereof, and a mixture thereof. Examples thereof include a copolymer comprising two or more of the above-mentioned aliphatic polyamide-based resin and aromatic polyamide-based resin, and a mixture thereof.

  In addition, as a polyamide-type resin in a polyamide-type resin layer, although an aliphatic polyamide-type resin and an aromatic polyamide-type resin can be used, in this invention, an aliphatic polyamide-type resin is preferable. This is because the former is better in compatibility with the polylactic acid-based resin and adhesiveness with the polylactic acid-based resin layer.

  In addition, the use of an aliphatic polyamide-based resin made from plant-derived materials as the polyamide-based resin in the polyamide-based resin layer increases the plant-derived degree of the entire film, so it is compared with other aliphatic polyamide-based resins. It is particularly preferable. Examples thereof include polyamide 4,10, polyamide 6,10, polyamide 10,10, polyamide 11, and polyamide 4 derived from glutamic acid, which are aliphatic polyamide resins using a raw material derived from castor oil. In particular, polyamides 10, 10, polyamide 11, and polyamide 4 have a plant-derived degree of 100% on a carbon atom basis, so that the plant-derived degree when laminated with a polylactic acid resin is increased, which is more preferable. Furthermore, the polyamide 11 has a melting point of about 190 ° C., which is close to that of the polylactic acid resin, compared to other polyamide resins, so that it is easy to form a film integrally with the polylactic acid resin, and has low impact resistance and low resistance. Since it is excellent in moisture absorption, it is especially preferable.

  Moreover, it is preferable that the polyamide-based resin layer contains a polylactic acid-based resin as a subcomponent of the polyamide-based resin from the viewpoint of improving the adhesive strength between the layers. Preferred examples of the polylactic acid resin that can be used as a subcomponent of the polyamide resin layer include the same resins as those suitable for the polylactic acid resin.

  In the polyamide resin layer, when a minor component such as a polylactic acid resin is present in the polyamide resin, it is also preferable to add a compatibilizer as a minor component to the polyamide resin layer in order to improve the compatibility. As the compatibilizing agent contained in the polyamide resin layer, an acrylic resin introduced with a polar group, a styrene resin introduced with a polar group, a polyolefin resin introduced with a polar group, a polyolefin resin introduced with a polar group- A block copolymer of polystyrene resin or the like can be preferably used.

  In the polyamide resin layer, when a polylactic acid resin or a compatibilizing agent is used as a subcomponent of the polyamide resin, from the viewpoint of heat resistance, the polyamide resin is 56% by mass in 100% by mass of all components of the polyamide resin layer. It is preferable to contain 99% by mass or less, 0.5% by mass to 24% by mass of the polylactic acid resin, and 0.5% by mass to 20% by mass of the compatibilizer.

  In the present invention, the method for producing the polyamide-based resin is not particularly limited, and a known method can be used.

  The stretched film of the present invention has a polylactic acid resin layer and a polyamide resin layer, and it is important that the polylactic acid resin layer and / or the polyamide resin layer contains an adhesive resin. As the adhesive resin used in this case, an adhesive strength sufficient to sufficiently bond adjacent layers (preferably 20 g / 15 mm width to 400 g / 15 mm width, more preferably 30 g / 15 mm width to 400 g / 15 mm width) Examples include ethylene / vinyl acetate copolymers, ethylene / (meth) acrylic acid ester copolymers, polyolefin resins containing polar groups, and polar groups. An acrylic resin, a styrene resin containing a polar group, a polyolefin resin-polystyrene block copolymer containing a polar group, and the like.

  The content of the adhesive resin contained in the polylactic acid resin layer and / or the polyamide resin layer is 0.5% by mass or more and 30% by mass in 100% by mass of all the components in each layer containing the adhesive resin. The following is preferable, and it is more preferably 1% by mass or more and 20% by mass or less. When the content of the adhesive resin in 100% by mass of all components in each layer containing the adhesive resin is less than 0.5% by mass, it is slightly inferior to sufficiently exhibit the adhesive strength between layers, 30 If it exceeds mass%, the viscosity at the time of extrusion may be excessively increased.

  The adhesive resin contained in the polylactic acid-based resin layer and / or the polyamide-based resin layer preferably has a 5% heat loss temperature of 230 ° C. or higher as determined by thermogravimetry from the viewpoint of extrusion stability. Preferably it is 240 degreeC or more.

  When an ethylene / vinyl acetate copolymer is used as the adhesive resin, when the total amount of the ethylene / vinyl acetate copolymer is 100% by mass, the vinyl acetate component content is 25% by mass or more and 55% by mass. It is preferable that it is less than. The remaining component excluding the vinyl acetate component in the ethylene / vinyl acetate copolymer is an ethylene component. The content of the vinyl acetate component is more preferably in the range of 28% by mass to 50% by mass, with 30% by mass to 45% by mass when the total amount of the ethylene / vinyl acetate copolymer is 100% by mass. More preferably, it is particularly preferably 34% by mass to 41% by mass.

  When ethylene / (meth) acrylic acid ester copolymer is used as the adhesive resin, when the total amount of ethylene / (meth) acrylic acid ester copolymer is 100% by mass, inclusion of (meth) acrylic acid ester component The amount is more preferably 30% by mass or more, and further preferably in the range of 30% by mass to 50% by mass. In addition, the remaining components except the (meth) acrylic acid ester component in the ethylene / (meth) acrylic acid ester copolymer are ethylene components.

  The adhesive resin is preferably a resin containing at least one functional group selected from an acid anhydride group such as a maleic anhydride group, an amino group, an imino group, and a glycidyl group. Or it is more preferable that it is resin containing a glycidyl group.

  Examples of the resin containing a maleic anhydride group and / or a glycidyl group include an ethylene / (meth) acrylic acid ester copolymer obtained by block copolymerization of a monomer containing a maleic anhydride group and / or a monomer containing a glycidyl group. Since it is excellent in compatibility with the polylactic acid resin layer and the polyamide resin layer, it can be suitably used as an adhesive resin. The content of the functional group (maleic anhydride group and / or glycidyl group) in the resin containing a maleic anhydride group and / or glycidyl group is 1% by mass to 20% by mass in 100% by mass of the resin. Preferably, it is 2 mass%-10 mass% more preferably. When the content of maleic anhydride group and / or glycidyl group is less than 1% by mass in 100% by mass of the resin containing maleic anhydride group and / or glycidyl group, the adhesiveness is remarkably lowered, and 20% by mass is reduced. This is because the extrusion stability is difficult.

  Examples of ethylene / (meth) acrylic acid ester copolymer obtained by block copolymerization of a monomer containing a maleic anhydride group and / or a monomer containing a glycidyl group include “Bondaine (registered trademark)”, “ Rotada (registered trademark) ".

  Further, the stretched film of the present invention has the most compact configuration when the polylactic acid resin layer and the polyamide resin layer are directly laminated without any other layer, and further, one of the two layers or Since the adhesive strength between layers is increased by the adhesive resin contained in both, it is a preferable configuration. In addition, it is more preferable that the adhesive resin is contained in both the polylactic acid resin layer and the polyamide resin layer because the interlayer adhesive force further increases.

  Adhesive resin in one layer selected from the group consisting of a polylactic acid resin layer and a polyamide resin layer when the polylactic acid resin layer and the polyamide resin layer are directly laminated without any other layers Is a resin containing maleic anhydride groups, and when the adhesive resin in the other layer selected from the above group is a resin containing glycidyl groups, maleic anhydride groups and Since a reaction takes place with the glycidyl group, it is effective in improving adhesiveness and is a preferred form.

  It is preferable that the polylactic acid resin layer and / or the polyamide resin layer contain a stretching aid from the viewpoints of improving the stretching ratio and improving productivity by suppressing breakage and improving the surface smoothness.

  As the stretching aid contained in the polylactic acid-based resin layer, polyester, a block copolymer of polyester and polylactic acid, a block copolymer of polyether and polylactic acid, polyolefin acrylate, and the like are preferably used.

  Polyesters acting as stretching aids include polybutylene terephthalate, polypropylene terephthalate, polybutylene sebacate, polybutylene succinate, polybutylene succinate / terephthalate, polybutylene adipate / terephthalate, polybutylene succinate / adipate, polypropylene sebacate Aromatic and / or aliphatic polyesters such as polypropylene succinate, polypropylene succinate / terephthalate, polypropylene adipate / terephthalate, and polypropylene succinate / adipate can be preferably used. Among these, polybutylene adipate / terephthalate and polybutylene succinate / adipate are particularly effective for improving stretchability.

  From the viewpoint of compatibility with the polylactic acid resin, the weight average molecular weight of the stretching aid is preferably 2,000 to 200,000, more preferably 5,000 to 150,000, and particularly preferably 10,000 to 100. , 000. In addition, a weight average molecular weight here means the molecular weight which measured with the chloroform solvent by the gel permeation chromatography (GPC), and was calculated by the polymethylmethacrylate conversion method.

  The block copolymer of polyester and polylactic acid is a block copolymer comprising a polyester segment and a polylactic acid segment, and the block copolymer of polyether and polylactic acid is a polyether segment and a polylactic acid A block copolymer comprising segments. The content of the polylactic acid segment is preferably 5% by mass or more and 60% by mass or less in the total amount of 100% by mass of these block copolymers. In the block copolymer of polyester and polylactic acid and the block copolymer of polyether and polylactic acid, if the content of the polylactic acid segment exceeds 60% by mass, the effect of improving stretchability may be lowered. Further, when the content of polylactic acid is less than 5% by mass, the bleed-out resistance is slightly lowered. Furthermore, in order to efficiently exhibit the bleed-out suppressing effect, it is preferable to have one or more polylactic acid segments having a weight average molecular weight of 1,500 to 200,000 in one molecule of the block copolymer. The presence of the polylactic acid segment improves compatibility with the polylactic acid resin.

  Examples of the polyester segment in the block copolymer of polyester and polylactic acid include polybutylene terephthalate, polypropylene terephthalate, polybutylene sebacate, polybutylene succinate, polybutylene succinate / terephthalate, polybutylene adipate / terephthalate, polybutylene adipate / Succinate, polypropylene sebacate, polypropylene succinate, polypropylene succinate / terephthalate, polypropylene adipate / terephthalate, polypropylene adipate / succinate and the like can be preferably used.

  As the polyether segment in the polyether / polylactic acid block copolymer, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol / polypropylene glycol copolymer and the like can be preferably used.

  It is preferable to contain 0.1-20 mass% of content of extending | stretching adjuvant with respect to 100 mass% of all the components of the layer containing this. The content is more preferably 0.2 to 10% by mass, particularly preferably 0.5 to 5% by mass.

  As long as the effects of the present invention are not impaired, each layer may contain various additives. Specifically, each layer includes an anti-blocking agent, a stabilizer (antioxidant, ultraviolet absorber, etc.), a lubricant (alkyl carboxylic acid amide, stearate, etc.), an antistatic agent (alkyl sulfonate, alkyl fatty acid). Salts, alkyl fatty acid esters, etc.), colorants including dyes and pigments, anti-coloring agents, matting agents, antibacterial agents, deodorants, flame retardants, weathering agents, ion exchange agents, tackifiers, antifoaming agents, A crystal nucleating agent and the like can be contained.

  Anti-blocking agents are particles added to the surface resin for the purpose of imparting irregularities to the film surface in order to suppress blocking between films and improve film handling properties, such as agglomerated silica, colloidal silica, and aluminosilicate. Inactive particles such as cross-linked PMMA, cross-linked polystyrene, and calcium carbonate can be used, and agglomerated silica, colloidal silica, and aluminosilicate are particularly preferable.

  As the antistatic agent, a known cationic system, anionic system, zwitterionic system, or nonionic system can be used, and any of a method of coating on the film surface and a method of kneading the resin component can be used. However, in the case of kneading with a resin component, use of an ionic antistatic agent may be unfavorable because decomposition occurs during kneading of the polylactic acid resin component, and in that case, a nonionic antistatic agent is preferably used. . Examples of the nonionic antistatic agent include polyhydric alcohols such as (poly) ethylene glycol, (poly) propylene glycol, glycerin and sorbit and / or fatty acid esters thereof.

  In the stretched film of the present invention, when the polylactic acid resin layer and the polyamide resin layer are directly laminated without interposing other layers, between the adjacent polylactic acid resin layer and the polyamide resin layer. The adhesive strength is preferably 20 g / 15 mm width or more and 400 g / 15 mm width or less, more preferably 30 g / 15 mm width or more and 400 g / 15 mm width or less. When the adhesive strength is less than 20 g / 15 mm width, the layers are easily separated during film formation, processing, and use as a packaging material, which makes handling difficult.

  In the stretched film of the present invention in which the polylactic acid resin layer and the polyamide resin layer are directly laminated without any other layer, the adhesive strength between the adjacent polylactic acid resin layer and the polyamide resin layer is Is 20 g / 15 mm width or more and 400 g / 15 mm width or less, the above-mentioned preferable one is selected as the adhesive resin contained in the polylactic acid resin layer and / or the polyamide resin layer, or the adhesive resin Increasing the content in a preferable range can be mentioned.

For practical use as a packaging film, the stretched film of the present invention preferably has a water vapor barrier property of 100 g / m ² · day or less, more preferably 80 g / m ² · day or less. The lower limit of the water vapor barrier property of the stretched film of the present invention is preferably small, but in practice, it is difficult to make it less than 0.1 g / m ² · day, and it can be applied as a packaging film. because even in terms sufficient if the order of 0.1g ^/ m 2 · day, the lower limit is considered to 0.1g ^/ m 2 · day or so. When the water vapor barrier property is particularly required, it can be dealt with by increasing the thickness of the polyamide resin layer.

  The thickness of the stretched film of the present invention is not particularly limited, but is preferably 1 to 500 μm, more preferably 3 to 100 μm, and more preferably 5 to 50 μm. The thickness of each layer is not particularly limited, but the inner layer is preferably 30% or more of the total thickness, and the outermost layer preferably does not exceed the thickness of the inner layer. Specifically, the inner layer is preferably 30 to 98% and the outermost layer is preferably 0.5 to 30% with respect to the entire thickness of the stretched film of the present invention.

  Although it is important that the stretched film of the present invention is at least stretched, it is preferably a biaxially stretched embodiment. This is because the film is biaxially oriented by biaxial stretching, and as a result, the gas barrier properties, strength, and interlayer adhesion strength are improved. The biaxial stretching method is not particularly limited, and examples thereof include a sequential biaxial stretching method, a simultaneous biaxial stretching method, and a combination thereof.

  The stretched film of the present invention preferably has a heat shrinkage of 10% or less when heat-treated at 120 ° C. for 15 minutes. When the heat shrinkage rate exceeds 10%, the film may be greatly shrunk by heat generated in processing steps such as printing, laminating, coating, bag making, vapor deposition, etc., and handling properties may be inferior. The upper limit of the heat shrinkage value is more preferably 5% or less, and still more preferably 3% or less. In order to reduce the heat shrinkage rate, it can be achieved by adopting a configuration in which a crystalline polylactic acid resin layer or a polyamide resin layer is an outermost layer and / or controlling the heat setting temperature in the production process. preferable. In addition, although the heat shrinkage rate of the product of the present invention does not have a lower limit, it is presumed that the limit for stable production is about -2%. The most desirable value is 0%.

  The stretched film of the present invention preferably has a breaking strength of 50 MPa or more, and more preferably 80 MPa or more. When the breaking strength is less than 50 MPa, troubles such as tearing may occur in processing steps such as printing, laminating, coating, bag making, and vapor deposition. In order to set the breaking strength to 50 MPa or more, the plane orientation of the film is controlled by biaxially stretching the film of the present invention and controlling the stretching temperature and magnification in the stretching process and the heat setting temperature in the heat setting process. The method achieved by

  The stretched film of the present invention is preferably produced using a resin made from plant and biological materials. This is because the use of petroleum-derived materials leads to depletion of petroleum resources and an increase in carbon dioxide emissions. The degree of biomass of the entire stretched film is preferably 25% or more, more preferably 50% or more, further preferably 80% or more, and most preferably 90% or more. In order to increase the degree of biomass, it is preferable to use a part of polyamide resin such as polylactic acid resin and polyamide 11 which are biomass-derived materials, and increase their use ratio. Further, in order to increase the degree of biomass while reducing the cost of the stretched film, it is particularly preferable to increase the amount of polylactic acid resin that is relatively inexpensive.

  The stretched film of the present invention desirably has high chemical resistance from the viewpoints of printability, fragrance retention, and content protection. In order to improve chemical resistance, it is desirable to increase the lamination ratio of the layer made of polyamide resin having higher chemical resistance than the polylactic acid resin, or to make it the outermost layer of the stretched film. The lamination ratio means the ratio of the thickness of each layer.

  Although the method for producing the stretched film of the present invention is specifically described below, the method is not limited to this.

  Feed block installed on the top of the multi-layer laminated die or die by supplying the resin composition forming each layer to each extruder, removing foreign substances and leveling the extrusion amount through filters and gear pumps in different paths Alternatively, the resin composition constituting each layer in the short pipe within the manifold is merged and laminated, then discharged into a sheet form from the die, and brought into close contact with the casting drum by an air knife or electrostatic application method and allowed to cool and solidify. Let it be a stretched film. Next, the sheet is preheated by passing through a roll, and subsequently passed between rolls having a difference in peripheral speed, stretched in the longitudinal direction, and immediately cooled to room temperature. Subsequently, the stretched film is guided to a tenter, stretched, and then heat-fixed while being relaxed in the width direction. Or you may extend | stretch by the method of extending | stretching a longitudinal direction and the width direction simultaneously, and may extend | stretch by the method of combining extending | stretching of a longitudinal direction and the extending | stretching of the width direction in multiple times.

  The stretching conditions of the stretched film of the present invention are preferably matched to the polylactic acid resin. This is because the thermal decomposition temperature of the polylactic acid-based resin is lower than that of the polyamide-based resin, and the successive biaxial stretching of the polyamide-based resin is usually difficult, but the configuration of the present invention enables the stretching. Because. That is, the stretching temperature in the longitudinal direction is preferably 70 to 110 ° C., more preferably 80 ° C. to 100 ° C., and the stretching ratio is preferably 2.5 to 4.2 times. The stretching temperature in the width direction is preferably 70 to 110 ° C, more preferably 80 to 100 ° C, and the stretching ratio is preferably 2.5 to 4.0 times.

  When a stretching aid is used in any layer of the stretched film, the above-described temperature and stretching conditions can be expanded. For example, from the viewpoint of mechanical properties of the film, the stretching temperature in the longitudinal direction is preferably 60 to 100 ° C., and the stretching ratio is preferably 3.0 to 5.0 times. Furthermore, the stretching temperature in the width direction is preferably 70 to 100 ° C., and the stretching ratio is preferably 2.5 to 10.0 times.

  In addition, the temperature for heat setting and relaxation is preferably 120 to 180 ° C., more preferably 125 to 175 ° C., and further preferably 130 to 170 ° C. in terms of suppressing the heat shrinkage rate of the film after stretching. Is preferably 2 to 15%, more preferably 3 to 10%, still more preferably 3 to 8%. Then, it is cooled.

  In addition, when both outermost layers are made of a polyamide-based resin layer, it becomes possible to suppress roll adhesion during stretching and to increase the heat setting temperature as described above. Can be adopted. This makes it possible to reduce the heat shrinkage rate of the film.

  The film of the present invention can be more suitably used by providing a gas barrier layer. The gas barrier layer can be provided by a technique such as coating, vapor deposition, or lamination, but a vapor deposition layer made of metal or metal oxide is more preferable because it does not depend on humidity and can exhibit excellent barrier properties with a thin film.

  The metal or metal oxide used for the vapor deposition layer is preferably a metal or metal oxide made of aluminum, aluminum oxide, silicon oxide, cerium oxide, calcium oxide, diamond-like carbon film, or a mixture thereof. . In particular, vapor deposition of aluminum or a metal oxide of aluminum is more preferable because it is excellent in economy and gas barrier performance.

  In addition, as a method for producing a thin film vapor deposition layer, a vacuum vapor deposition method, an EB vapor deposition method, a sputtering method, a physical vapor deposition method such as an ion plating method, and various chemical vapor deposition methods such as plasma CVD can be used. From the viewpoint of safety, the vacuum deposition method is particularly preferably used.

When providing a vapor deposition layer, in order to improve the adhesiveness of a vapor deposition layer, it is preferable to perform pre-processing by methods, such as a corona discharge process, in advance to a vapor deposition surface. Processing strength when subjected to corona treatment is preferably 5~50W · min / ^{m 2,} more preferably 10~45W · min / ^{m 2.} Moreover, it is preferable from a viewpoint of the adhesive improvement with a vapor deposition layer to perform not only in air | atmosphere but the atmosphere at the time of performing a corona treatment in nitrogen, a carbon dioxide gas / nitrogen mixed gas, etc. Furthermore, surface treatment such as gas treatment, plasma treatment, alkali treatment, electron beam radiation treatment, etc. may be performed as necessary.

  If the surface to be deposited is smooth, the gas barrier property is good. In addition, additives such as the above-mentioned anti-blocking agents and stabilizers may bleed out on the film surface and become vapor deposition defects, leading to a decrease in barrier properties. Therefore, it is important to adjust the content appropriately.

  Moreover, a vapor deposition layer can obtain higher gas barrier property by using together with a coating layer. In other words, if a coating layer is formed by applying an anchor coating agent in-line or off-line in advance on a stretched film, the deposited layer formed on the coating layer becomes a highly adherent layer, which is effective for improving gas barrier properties. is there. If an overcoat agent is applied on the vapor deposition layer, defects in the vapor deposition layer are complemented and gas barrier properties are improved. As the coating layer, polyvinylidene chloride, polyvinyl alcohol, polyethylene-vinyl alcohol, acrylic, polyester, polyurethane, and polyester-polyurethane resin are preferably used. The coating layer can contain various subcomponents as long as the effect is not impaired. The thickness of the coating layer is not particularly limited, but is preferably 0.01 μm to 3 μm.

The stretched film of the present invention having a vapor deposition layer made of a metal or metal oxide preferably has a water vapor barrier property of 2.0 g / m ² · day or less, more preferably 1.0 g / m ² · day or less. preferable. It is preferred that the smaller the lower limit value, practically is difficult to less than 0.01 g ^/ m 2 · day, also 2 · day about 0.01 g ^/ m in the viewpoint of the application as a packaging film Is sufficient, the lower limit is considered to be about 0.01 g / m ² · day.

The oxygen barrier property of the stretched film of the present invention having a vapor deposition layer made of a metal or metal oxide is preferably 40 cc / m ² · day · atm or less, more preferably 20 cc / m ² · day · atm or less. preferable. The lower limit is preferably smaller, but in practice, it is difficult to make the lower limit less than 0.01 cc / m ² · day, and from the viewpoint of application as a packaging film, about 0.01 cc / m ² · day. Is sufficient, the lower limit is considered to be about 0.01 cc / m ² · day.

  Although the use of the stretched film of the present invention is not particularly limited, it can be particularly suitably used as a packaging material. Therefore, the package which contains the stretched film of this invention in the structure is the suitable use.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereby.

Each physical property and characteristic was measured and evaluated by the following methods.
[Stretching film forming property]
During film formation by sequential biaxial stretching, while a 300 m film was collected, ○ (good) indicates that a stable film was formed, △ (good) indicates that surface roughness was confirmed visually, and tearing frequently occurred during the film formation. Things were evaluated as x (impossible).
[Adhesive strength]
One side of a # 60 biaxially oriented polypropylene film was subjected to corona treatment, and an adhesive (AD503 / cat10 / ethyl acetate = 20: 1: 20 manufactured by Toyo Morton Co., Ltd.) was applied to the surface. Subsequently, a corona treatment was performed on one surface of the sample, the treated surface and the above-described adhesive surface were bonded, and an aging treatment was performed at 40 ° C. for 48 hours. The film was measured for load when peeled under the following conditions using a tensile tester manufactured by British Scientific Instruments Seisakusho. The number of measurements was 3 times, and the average value was evaluated.
<Peeling conditions>
Film width: 15mm
Peeling speed: 200 mm / min Peeling accuracy: 90 ° peeling [thermal shrinkage]
A sample was cut into a rectangle having a length of 200 mm and a width of 10 mm in the longitudinal direction of the film. Marks were drawn at intervals of 150 mm, a 3 g weight was suspended, and heat treatment was performed in a hot air oven heated to 120 ° C. for 15 minutes. The distance between the marked lines after the treatment was measured, and the heat shrinkage rate was measured from the change from before the treatment. The number of measurements was five, and the average value was evaluated.
[Heat sealability]
The 15 mm wide films were heat sealed under the following conditions.
<Heat seal conditions>
Pressure: 2 kg / cm ² , Temperature: 140 ° C., Time: 1 second, Seal width: 10 mm
<Evaluation>
Without HS: Peeling by hand is possible HS: Peeling by hand is impossible [Water vapor barrier property]
Water vapor barrier property (moisture permeability: g / (m ² · day)) according to the method defined in method A of JIS Z0208 (1976) in a constant temperature and humidity device set to conditions of temperature 25 ° C. and humidity 90% RH Was measured. Moreover, the measurement was performed twice and the average value was evaluated.
[Strength at break]
Measurement was performed in an atmosphere of a temperature of 23 ° C. and a humidity of 65% RH using TENSILON UCT-100 manufactured by Orientec. A sample was cut into a rectangle 150 mm long × 10 mm wide in the longitudinal direction of the film. The measurement was performed according to the method defined in JIS-K7127 (1999). Moreover, the measurement was performed 5 times and the average value was evaluated.
[Biomass degree]
The biomass degree of the raw material in which all the carbon atoms constituting the resin are plant-derived is 100%, and the case where all the carbon atoms are derived from petroleum is 0%. ) Was multiplied by the biomass value of the film.
[chemical resistance]
Three drops of chloroform were dropped on one surface of the film and left for 10 seconds. In the case where no perforation occurred at the dropped site, three drops of chloroform were dropped from the opposite side of the film to the site and left for 10 seconds in the same manner. The presence or absence of perforations and the change in thickness after a series of treatments were evaluated.
<Evaluation>
×: There is a hole △: No hole, thickness reduction ○: No hole, thickness unchanged [raw material]
The following materials were used.

Polylactic acid resin (1) (abbreviation in the table is 4032D) (“4032D” manufactured by Natureworks, 1.4% D form, melting point 168 ° C.)
Polylactic acid resin (2) (abbreviation in the table is 4060D) (“4060D” manufactured by Natureworks, D-form 12% amorphous)
Polyamide resin (1) (abbreviation in the table is polyamide 11) ("Rilsan" BECNO TL: polyamide 11 manufactured by Arkema)
Polyamide resin (2) (abbreviation in the table shall be polyamide 12) ("Rilsan" AESN TL: polyamide 12 manufactured by Arkema)
Adhesive resin (1) (abbreviation in the table is Bondine) ("Bondaine" TX8030 manufactured by Arkema: ethylene / acrylic ester / maleic anhydride terpolymer resin)
Adhesive resin (2) (abbreviation in the table shall be rotada.) (Arkema "Rotada" AX8900: ethylene / acrylic ester / glycidyl methacrylate copolymer resin)
Adhesive resin (3) (The abbreviation in the table is Lotoril.) (Arkema “Lotril” 20MA08: ethylene / methyl acrylate copolymer resin)
Example 1
As the polylactic acid-based resin layer, 95 parts by mass of the polylactic acid-based resin (1) and 5 parts by mass of the adhesive resin (1) are supplied to the extruder 1 and melted at a temperature of 220 ° C., while the polyamide-based resin layer As above, 95 parts by mass of polyamide resin (1) and 5 parts by mass of adhesive resin (1) are supplied to another extruder-2 and melted at a temperature of 240 ° C. Layer / polyamide-based resin layer / polylactic acid-based resin layer = 1: 8: 1 so as to be extruded and formed into a sheet shape, and using a wire-like electrode having a diameter of 0.5 mm on a casting drum at a temperature of 25 ° C. It was wound while applying electrostatic force and cooled and solidified into a sheet.

The sheet was preheated at 80 ° C. with a roll, stretched 3.0 times in the longitudinal direction at 85 ° C. with a roll, and immediately cooled to 40 ° C. Next, the stretched sheet is guided to a tenter, preheated to a temperature of 85 ° C., subsequently stretched 3.0 times in the width direction at a temperature of 90 ° C., and then at a temperature of 150 ° C. while giving 5% relaxation in the width direction. After heat treatment, it was cooled and wound up to obtain a stretched film.
(Example 2)
Film formation was performed in the same manner as in Example 1 except that the laminated structure was polyamide-based resin layer / polylactic acid-based resin layer / polyamide-based resin layer = 1: 8: 1, and the heat treatment temperature was 165 ° C. A stretched film was obtained.
(Example 3)
Except that the raw material supplied to Extruder-2 was 95 parts by mass of the polyamide-based resin (1) and 5 parts by mass of the adhesive resin (2), film formation was performed in the same manner as in Example 2 to obtain a stretched film.
Example 4
Except that the raw material supplied to Extruder-2 was 100 parts by mass of the polyamide-based resin (1), film formation was performed in the same manner as in Example 2 to obtain a stretched film.
(Example 5)
Except that the raw material supplied to Extruder-2 was 95 parts by mass of the polyamide-based resin (1) and 5 parts by mass of the adhesive resin (3), film formation was performed in the same manner as in Example 2 to obtain a stretched film.
(Example 6)
The raw material supplied to Extruder-1 is 95 parts by mass of polylactic acid resin (1) and adhesive resin (3), and the raw material supplied to Extruder-2 is 95 parts by mass of polyamide resin (1) and adhesive. A stretched film was obtained by carrying out film formation in the same manner as in Example 2 except that the amount of the resin (3) was changed to 5 parts by mass.
(Example 7)
A stretched film was obtained by performing film formation in the same manner as in Example 2 except that 95 parts by mass of the polyamide-based resin (2) and 5 parts by mass of the adhesive resin (1) were supplied to the extruder-2.
(Example 8)
Except that the raw material supplied to Extruder-1 was 95 parts by mass of polylactic acid resin (2) and 5 parts by mass of adhesive resin (1), film formation was performed in the same manner as in Example 1 to obtain a stretched film. .
(Comparative Example 1)
Made in the same manner as in Example 2 except that the raw material supplied to the extruder-1 was 100 parts by mass of the polylactic acid resin (1) and the raw material supplied to the extruder-2 was 100 parts by mass of the polyamide resin (1). The film was formed to obtain a stretched film.
(Comparative Example 2)
Under the conditions of Example 2, the sheet-like cooled and solidified product obtained by winding around a casting drum was collected as it was without being stretched to obtain an unstretched film.
(Comparative Example 3)
The raw material supplied to the extruder-1 is 100 parts by mass of the polylactic acid resin (1), the raw material supplied to the extruder-2 is 100 parts by mass of the polylactic acid resin (1), and the structure is a single film of polylactic acid resin Then, the same as Example 1 except that the preheating temperature for longitudinal stretching was 70 ° C., the stretching temperature was 75 ° C., the preheating temperature for transverse stretching was 70 ° C., the stretching temperature was 75 ° C., and the heat treatment temperature was 140 ° C. Film formation was performed to obtain a film.
(Comparative Example 4)
The raw material supplied to the extruder-1 is 100 parts by mass of the polyamide resin (1), the raw material supplied to the extruder-2 is 100 parts by mass of the polyamide resin (1), and the configuration is a single film of the polyamide resin. Formed a film in the same manner as in Example 2 to obtain a film.

  As shown in Table 1, it can be seen that the film of the present invention is excellent in stretch film-forming properties, processability, gas barrier properties, chemical resistance, and biomass degree.

  The film of the present invention contains a polylactic acid resin, maintains the physical properties of the current polyamide film, and is excellent in film forming suitability, and can be suitably used as a packaging film. However, the application is not limited to this.

Claims (9)

  A stretched film having a polylactic acid resin layer and a polyamide resin layer, wherein the polylactic acid resin layer and / or the polyamide resin layer contains an adhesive resin.   2. The stretched film according to claim 1, wherein the polylactic acid resin layer and the polyamide resin layer are directly laminated without interposing another layer.   The stretched film according to claim 1 or 2, wherein the adhesive resin is a resin containing a maleic anhydride group and / or a glycidyl group. The polylactic acid resin layer and the polyamide resin layer are directly laminated without any other layers.
The adhesive resin in one layer selected from the group consisting of a polylactic acid resin layer and a polyamide resin layer is a resin containing a maleic anhydride group, and the adhesive resin in another layer selected from the above group Is a resin containing a glycidyl group, The stretched film according to claim 1.   The stretched film according to claim 1, wherein the polyamide-based resin is an aliphatic polyamide-based resin.   The stretched film according to claim 1, wherein the polyamide-based resin is polyamide 11.   The stretched film according to claim 1, wherein both outermost layers are polyamide-based resin layers.   At least one of the outermost layers is a polylactic acid resin layer, and the polylactic acid resin in the polylactic acid resin layer contains an amorphous polylactic acid resin. The stretched film in any one of. The polylactic acid resin layer and the polyamide resin layer are directly laminated without any other layers.
The stretching according to any one of claims 1 to 8, wherein the adhesive strength between the adjacent polylactic acid resin layer and the polyamide resin layer is 20 g / 15 mm width or more and 400 g / 15 mm width or less. the film.