Deep-drawn packaging body and multi-layer film for deep-drawn packaging body

Abstract

To provide a deep drawn package having easy peel-ability and suppressed from cobwebbing.SOLUTION: A deep drawn package comprises a lid material and a bottom material having a recess, so as to be hermetically sealed by heat sealing of the lid material and the bottom material with a received object contained in the recess. At least one of the lid material and the bottom material at least has a base material layer (A) containing ethylenic resin (a1), a center layer (B) containing linear low-density polyethylene (b1) and butene-1 resin (b2), and a heat seal layer (C) containing low-density polyethylene (c1) and butene-1 resin (c2), in which the content of the butene-1 resin (c2) is 30 mass% or higher and 50 mass% or lower. The base material layer (A), the center layer (B) and the heat seal layer (C) are of a multi-layer film layered in order of (A), (B) and (C), so that the lid material and the bottom material can be heat sealed by the heat seal layer (C).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a deep-draw packaging product and a multilayer film for a deep-draw packaging product. [Background technology]

[0002] In recent years, with the increasing sophistication of packaging materials, vacuum deep drawing packaging for ham and sausages is required to not only satisfy the airtightness achieved by heat sealing, but also to have easy-peel properties that allow easy opening.

[0003] Regarding easy peel properties, the cohesive failure mechanism is an example of a peel mechanism. The cohesive failure mechanism is designed by blending a thermoplastic resin with an incompatible or partially compatible thermoplastic, and utilizes the difference in cohesive strength between the resins to cause cohesive failure within the sealant, rather than at the sealant interface. The cohesive failure mechanism is often used because it is easy to reduce the seal strength, but it has the problem of being prone to stringing when opened. Stringing is more likely to occur because the interlayer strength between adjacent layers decreases as the seal strength is reduced, and it has been difficult to achieve both weak seal strength and suppression of stringing.

[0004] To date, a lid material has been reported that is used for containers having a sealing portion covered with polyethylene resin and that comprises a base material and a sealant layer having a first thermoplastic resin layer and a second thermoplastic resin layer, as a lid material that can reduce the occurrence of stringing when opened without compromising ease of opening (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-065508 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, because deep-draw packaging has a wider seal width than other packaging, a weaker seal strength is required. In order to achieve both airtightness and easy-peelability, a heat seal strength of approximately 1N / 15mm to 2.5N / 15mm is required. However, in the past, it was difficult to prevent stringing with such a weak heat seal strength.

[0007] The present invention aims to solve the above-mentioned conventional problems and achieve the following object: That is, the present invention aims to provide a deep-draw package that has easy-peel properties and suppresses stringiness. [Means for solving the problem]

[0008] The present invention is based on the findings of the present inventors, and the means for solving the above problems are as follows. <1> A cover material and a base material having a recess, A deep-drawn package capable of housing and sealing an object to be housed in the recess by heat sealing the lid material and the base material, At least one of the lid material and the base material is A substrate layer (A) containing an ethylene-based resin (a1); A central layer (B) containing a linear low-density polyethylene (b1) and a butene-1 resin (b2); and a heat seal layer (C) containing a low-density polyethylene (c1) and a butene-1 resin (c2), the content of the butene-1 resin (c2) being 30% by mass or more and 50% by mass or less, a multilayer film in which the base layer (A), the core layer (B) and the heat seal layer (C) are laminated in the order of (A) / (B) / (C); The deep-draw packaging body is characterized in that the lid material and the base material can be heat-sealed by the heat-seal layer (C). <2> The content of the butene-1 resin (b2) in the intermediate layer (B) is 10% by mass or more and less than 30% by mass. <1> 2. The deep-drawn packaging body according to claim 1 . <3> 3. The deep drawn package according to claim 1, wherein the thickness of the heat seal layer (C) is 20% or less. <4> The total thickness of the intermediate layer (B) and the heat seal (C) is 10% or more and 30% or less. <1> from <3> 1. The deep-draw packaging body according to claim 1 . <5> The polyethylene (c1) in the heat seal layer (C) has a melt flow rate of 30 g / 10 min or more under measurement conditions of a temperature of 190° C. and a load of 2.16 kg. <1> from <4> 1. The deep-draw packaging body according to claim 1 . <6> The cover material or base material to be heat-sealed to the multilayer film is a resin film. <1> from <5> 1. The deep-draw packaging body according to claim 1 . <7> The easy peel strength between the lid material and the base material is 0.5 N / 15 mm width or more and 2.5 N / 15 mm width or less. <1> from <6> 2. The deep-drawn package according to claim 1 . <8> The above-mentioned products are for food packaging or medical use. <1> from <7> 1. The deep-draw packaging body according to claim 1 . <9> A substrate layer (A) containing an ethylene-based resin (a1); A central layer (B) containing a linear low-density polyethylene (b1) and a butene-1 resin (b2); a heat seal layer (C) containing a low-density polyethylene (c1) and a butene-1 resin (c2), the content of the butene-1 resin (c2) being 30% by mass or more and 50% by mass or less based on the total amount of resin components contained in the heat seal layer (C); The multilayer film for deep drawing packaging is characterized in that the base layer (A), the core layer (B) and the heat seal layer (C) are laminated in the order of (A) / (B) / (C). Effect of the Invention

[0009] According to the present invention, it is possible to solve the above-mentioned problems in the conventional technology and achieve the above-mentioned object, thereby providing a deep-drawn package having easy-peel properties and suppressing stringiness. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of the multilayer film for deep-draw packaging of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing another example of the multilayer film for deep-draw packaging of the present invention. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing an example of the deep draw packaging body of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (Deep-draw packaging) The deep drawn package of the present invention has a lid material and a base material having a recess, and is a deep drawn package that can accommodate an item in the recess and be sealed by heat sealing the lid material and the base material. At least one of the lid material and the base material is a multilayer film. The cover material may be the multilayer film and the base material may be another film, the base material may be the multilayer film and the cover material may be another film, or the cover material and the base material may be the multilayer film. The deep drawn packaging product is preferably for food packaging or medical use.

[0012] A "deep-drawn package" is a packaging form in which one of a pair of films used for a packaging container is deep-drawn to form a base material with a recess, and the item to be contained (also called the contents) is placed in the recess.The other film, which serves as a lid, is then placed over the film, and the air is either degassed or replaced with an inert gas, etc., and the contact points between the pair of films are heat-sealed. The deep drawing molding is a process in which a base material having a recess capable of containing an object is molded from a sheet-like film using a mold having a specific shape (for example, a shape corresponding to the object to be contained). This allows the manufacture of a deep drawing package that can fit the shape of the object to be contained, regardless of the shape of the object to be contained, such as food or medical products, and can hygienically seal the object to be contained. The shape of the recess and the seal width or area between the lid material and the base material in the deep-drawn packaging body vary depending on the shape and form of the contained item to be packaged and cannot be uniquely specified, but are not particularly limited and can be selected as appropriate depending on the intended application form.

[0013] The deep drawn packaging product is preferably for food packaging or medical use. The food products are not particularly limited and can be appropriately selected depending on the purpose. Examples include processed fish and egg products such as sausages, ham, tamagoyaki (rolled omelet), and kamaboko (fish cake), dairy products such as cheese, and boiled side dishes such as hamburger steak containing sauce or dressing. The medical product is not particularly limited and can be appropriately selected depending on the purpose. Examples of the medical product include masks, gauze, cotton swabs, and cotton balls.

[0014] <Multilayer film> The multilayer film has at least a base material layer (A), a central layer (B), and a heat seal layer (C), and is a multilayer film in which the base material layer (A), the central layer (B), and the heat seal layer (C) are laminated in the order of (A) / (B) / (C). The base material layer (A) is on the outside of the package, and the heat seal layer (C) is on the inside of the package, facing the contents or forming a heat seal surface with the other of the lid material and the base material. The heat seal layer (C) of the multilayer film makes it possible to heat seal the lid material and the base material of the deep drawn package. The multilayer film can be suitably used as the multilayer film for deep-draw packaging of the present invention. The multilayer film is preferably a coextruded multilayer film having at least a base layer (A), a central layer (B), and a heat seal layer (C). The multilayer film is preferably a multilayer film having an additional base layer (α) on the base layer (A) side, and laminated in the order of (α) / (A) / (B) / (C).

[0015] <<(A) Base material layer>> The substrate layer (A) contains an ethylene-based resin (a1) as a main resin component, and optionally contains other olefin-based resins. The substrate layer (A) may be a surface layer on which a packaging film can be printed.

[0016] -(a1) Ethylene-based resin- The ethylene resin (a1) is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include low-density polyethylene, medium-density polyethylene, and high-density polyethylene. Among these, low-density polyethylene is preferred, and linear low-density polyethylene is more preferred. These may be used alone or in combination of two or more.

[0017] The melt flow rate (MFR) of the ethylene-based resin is not particularly limited and may be appropriately selected depending on the purpose. However, under measurement conditions of a temperature of 190° C. and a load of 2.16 kg, the MFR is preferably from 1.0 g / 10 min to 50.0 g / 10 min, more preferably from 1.0 g / 10 min to 20.0 g / 10 min, even more preferably from 2.0 g / 10 min to 10.0 g / 10 min, and particularly preferably from 2.0 g / 10 min to 7.0 g / 10 min. The melt flow rate (MFR) is a value measured in accordance with JIS K7210 at 190° C. and a load of 2.16 kg (21.18 N). The density of the low density polyethylene is 0.900 g / cm 3 ~0.945g / cm 3 is preferred, and 0.915 g / cm 3 ~0.940g / cm 3 is more preferred.

[0018] The melting point of the low-density polyethylene is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 100° C. to 130° C., and more preferably 110° C. to 125° C. The melting point can be measured using a differential scanning calorimeter (DSC) (for example, DSC-7020 manufactured by Hitachi High-Tech Science Corporation).

[0019] The average thickness of the base layer (A) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably from 15 μm to 35 μm, more preferably from 20 μm to 30 μm. The thickness of the base layer (A) is not particularly limited and can be appropriately selected depending on the purpose. The ratio (%) of the average thickness of the intermediate layer (B) to the total thickness of the base layer (A), the central layer (B) and the heat seal layer (C) is preferably 90% or less, more preferably 20% to 90%, and even more preferably 50% to 80%.

[0020] <<(B) Central layer>> The central layer (B) contains a linear low-density polyethylene (b1) and a butene-1 resin (b2) as main resin components, and optionally contains other ethylene resins.

[0021] -(b1) Linear low-density polyethylene- The linear low-density polyethylene (b1) is not particularly limited and can be appropriately selected depending on the purpose. One type may be used alone, or two or more types may be used in combination.

[0022] The linear low-density polyethylene may be, for example, a polymer obtained by copolymerizing ethylene monomer as a main component with a comonomer as required, such as butene-1, hexene-1, octene-1, or 4-methylpentene. The content of the comonomer in the linear low-density polyethylene is preferably from 0 mol % to 20 mol %, and more preferably from 0.5 mol % to 15 mol %. The linear low-density polyethylene can be produced by a low-pressure radical polymerization method using a single-site catalyst.

[0023] The melt flow rate (MFR) of the linear low-density polyethylene (b1) is not particularly limited and can be appropriately selected depending on the purpose. However, under measurement conditions of a temperature of 190° C. and a load of 2.16 kg, it is preferably 0.5 g / 10 min to 20 g / 10 min, more preferably 1 g / 10 min to 15 g / 10 min, and particularly preferably 2 g / 10 min to 10 g / 10 min. The density of the linear low-density polyethylene (b1) is not particularly limited and can be appropriately selected depending on the purpose. 3 ~0.934g / cm 3 is preferred, and 0.890 g / cm 3 ~0.920g / cm 3 is more preferred.

[0024] The melting point of the linear low density polyethylene (b1) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably from 95°C to 120°C, more preferably from 100°C to 115°C.

[0025] -(b2) Butene-1 resin - The butene-1 resin (b2) is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include a homopolymer of butene-1 monomer, an ethylene-butene-1 copolymer or a propylene-butene-1 copolymer mainly composed of butene-1 monomer, etc. Among these, an ethylene-butene-1 copolymer is preferred. These may be used alone or in combination of two or more kinds. The content of the butene-1 monomer in the butene-1 based resin (b2) is preferably from 60 mol % to 100 mol %, and more preferably from 70 mol % to 100 mol %.

[0026] The melt flow rate (MFR) of the butene-1 resin (b2) is not particularly limited and can be appropriately selected depending on the purpose. However, under the measurement conditions of a temperature of 190° C. and a load of 2.16 kg, the MFR is preferably 0.5 g / 10 min to 20 g / 10 min, more preferably 1 g / 10 min to 15 g / 10 min, and even more preferably 2 g / 10 min to 10 g / 10 min. The density of the butene-1 resin (b2) is not particularly limited and can be appropriately selected depending on the purpose. 3 ~0.930g / cm 3 is preferred, and 0.900 g / cm 3 ~0.920g / cm 3 is more preferred.

[0027] The melting point of the butene-1 resin (b2) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 80°C to 135°C, more preferably 105°C to 130°C, and even more preferably 110°C to 125°C.

[0028] The content of the butene-1 resin (b2) is not particularly limited and can be appropriately selected depending on the purpose. However, it is preferably from 10% by mass to less than 30% by mass, and more preferably from 10% by mass to 20% by mass, based on the total amount of resin components contained in the intermediate layer (B). When the content is 10% by mass or more and less than 30% by mass, a gradient is generated between the content of the butene-1 based resin (c2) contained in the heat seal layer (C) and the content of the butene-1 based resin (b2) contained in the intermediate layer (B), thereby improving the adhesion between the layers, preventing delamination (so-called film residue), and enabling delamination by a cohesive failure mechanism.

[0029] The mass ratio (b2 / b1) of the butene-1 resin (b2) to the linear low-density polyethylene (b1) in the intermediate layer (B) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 / 90 to 30 / 70, more preferably 10 / 90 to 20 / 80.

[0030] The average thickness of the intermediate layer (B) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 4 μm to 12 μm, more preferably 5 μm to 10 μm, and even more preferably 6 μm to 8 μm. The thickness of the intermediate layer (B) is not particularly limited and can be appropriately selected depending on the purpose. The ratio (%) of the average thickness of the intermediate layer (B) to the total thickness of the base layer (A), the core layer (B) and the heat seal layer (C) is preferably 30% or less, more preferably 10% to 30%, and even more preferably 15% to 25%.

[0031] <<(C) Heat seal layer>> The heat seal layer (C) contains a low density polyethylene (c1) and a butene-1 resin (c2) as main resin components.

[0032] -(c1) Low density polyethylene- The low-density polyethylene (c1) is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include branched low-density polyethylene. Among these, branched low-density polyethylene obtained by homopolymerizing ethylene is preferred. These may be used alone or in combination of two or more kinds.

[0033] The melt flow rate (MFR) of the low-density polyethylene (c1) is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 10 g / 10 min or more, more preferably 20 g / 10 min or more, and even more preferably 30 g / 10 min or more under the measurement conditions of a temperature of 190° C. and a load of 2.16 kg. The upper limit is preferably 50 g / 10 min or less, more preferably 45 g / 10 min or less, and even more preferably 40 g / 10 min or less. It is preferable that the melt flow rate (MFR) is 30 g / 10 min or more, since the occurrence of stringiness can be further suppressed.

[0034] The density of the low-density polyethylene (c1) is not particularly limited and can be appropriately selected depending on the purpose. 3 ~0.935g / cm 3 is preferred, and 0.915 g / cm 3 ~0.935g / cm 3 is more preferred.

[0035] The melting point of the low-density polyethylene (c1) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably from 100°C to 125°C, more preferably from 105°C to 115°C.

[0036] -(c2) Butene-1 resin- The butene-1 resin (c2) is not particularly limited and may be selected from the same resins as the butene-1 resin (b2) according to the purpose. The butene-1 resin (b2) and the butene-1 resin (c2) may be the same or different.

[0037] The content of the butene-1 resin (c2) is from 30% by mass to 50% by mass, and more preferably from 35% by mass to 45% by mass, based on the total amount of resin components contained in the heat seal layer (C). The content of 30% by mass or more and 50% by mass or less is advantageous in that weak seal strength is exhibited, resulting in excellent easy peel properties. In addition, a gradient is generated between the content of the butene-1 resin (c2) contained in the heat seal layer (C) and the content of the butene-1 resin (b2) contained in the intermediate layer (B), which is advantageous in that the adhesion between layers is improved, interlayer peeling (so-called film residue) is prevented, and peeling can be achieved by a cohesive failure mechanism.

[0038] The mass ratio (c2 / c1) of the butene-1 resin (c2) to the low-density polyethylene (c1) in the heat seal layer (C) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 30 / 70 to 50 / 50, more preferably 35 / 65 to 45 / 55.

[0039] The average thickness of the heat seal layer (C) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably from 2 μm to 8 μm, more preferably from 3 μm to 6 μm, and even more preferably from 3.5 μm to 4.5 μm. The thickness of the heat seal layer (C) is not particularly limited and can be appropriately selected depending on the purpose, but the ratio (%) of the average thickness of the heat seal layer (C) to the total thickness of the base layer (A), the central layer (B) and the heat seal layer (C) is preferably 20% or less, more preferably 18% or less, and even more preferably 15% or less. The lower limit is preferably 5% or more, and more preferably 8% or more. When the thickness is 20% or less, it is advantageous in that weak seal strength is exhibited, resulting in excellent easy peel properties, and the occurrence of stringiness can be further suppressed.

[0040] The total thickness of the intermediate layer (B) and the heat seal layer (C) is not particularly limited and can be appropriately selected depending on the purpose, but the ratio (%) of the total thickness of the base layer (A), the central layer (B) and the heat seal layer (C) is preferably 10% to 30%. If the total thickness is 10% to 30%, it is advantageous in that it is more likely to undergo cohesive failure and has excellent easy peel properties.

[0041] <<(α) Additional base material layer>> The multilayer film may further include an additional base layer (α) on the base layer (A) side, and may be a multilayer film laminated in the order of (α) / (A) / (B) / (C). The additional base layer (α) may be a single layer or a plurality of layers. The plurality of additional base layers (α) may have the same composition or different compositions. The additional base material layer (α) may be extruded together with the base material layer (A), the central layer (B) and the heat seal layer to form a coextruded multilayer film laminated in the order of (α) / (A) / (B) / (C), or the additional base material layer (α) may be bonded to a multilayer film laminated in the order of (A) / (B) / (C) to form a laminate film laminated in the order of (α) / (A) / (B) / (C). In the case where the additional base material layer (α) is present, the additional base material layer (α) may be a surface layer on which printing of a packaging film can be provided.

[0042] The adhesion method for laminating the additional base layer (α) is not particularly limited and may be appropriately selected depending on the purpose. For example, dry lamination, wet lamination, non-solvent lamination, extrusion lamination, etc. may be mentioned. The additional base layer (α) is not particularly limited and can be appropriately selected depending on the purpose. For coextrusion, for example, polyolefin resins similar to the ethylene-based resin (a1) can be used. For laminate films, examples include unstretched polyester (CPET), unstretched nylon (CNY), unstretched polypropylene (CPP), unstretched polyethylene (CPE), unstretched polystyrene (CPS), expanded polystyrene (EPS), biaxially oriented polyester (OPET), biaxially oriented polypropylene (OPP), ethylene-vinyl alcohol copolymer (EVOH), coextruded biaxially oriented polypropylene, biaxially oriented ethylene-vinyl alcohol copolymer (EVOH), coextruded biaxially oriented polypropylene coated with polyvinylidene chloride (PVDC), biaxially oriented nylon, and aluminum foil can be used.

[0043] When the additional base layer (α) is present, the average thickness of the additional base layer (α) is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 μm to 500 μm, more preferably 12 μm to 300 μm.

[0044] <Other films> At least one of the lid material and the base material of the deep drawn packaging body is the multilayer film, and the other lid material or base material which is not the multilayer film is another film. The other film, which is a cover material or a base material to be heat-sealed to the multilayer film, is preferably a resin film. The material for the resin film is not particularly limited, and any known heat-sealable ethylene-based resin can be appropriately selected depending on the purpose.

[0045] The deep draw packaging of the present invention has a lid material and a base material having a recess, and an item to be contained can be placed in the recess and sealed by heat sealing the lid material and the base material. The method for producing the multilayer film is not particularly limited, and any known method can be appropriately selected depending on the purpose. For example, a coextrusion method, a lamination process, etc. can be mentioned. The co-extrusion method may, for example, be a method in which the base material layer (A), the core layer (B), and the heat seal layer (C) are extruded from a T-die at an extrusion temperature (e.g., 250°C) so that the thicknesses of the layers are in a predetermined ratio, cooled with a water-cooled metal cooling roll (e.g., 40°C), optionally subjected to a corona discharge treatment, wound up on a roll, and aged (e.g., for 24 hours) in an aging chamber (e.g., 40°C).

[0046] There are no particular limitations on the method for manufacturing the base material having the recess, and any known method can be selected as appropriate depending on the purpose. For example, there is a method (deep drawing molding) in which a mold having a specific shape (e.g., a shape corresponding to the object to be contained) is used to mold a base material having a recess capable of containing the object from a sheet-like film. The shape of the recess and the seal width or area between the lid material and the base material in the deep-drawn packaging body vary depending on the shape and form of the contents to be packaged and cannot be uniquely specified, but are not particularly limited and can be selected as appropriate depending on the intended application form.

[0047] There are no particular limitations on the method for heat-sealing the lid material and the base material, and any known method can be selected depending on the purpose. For example, there is a method in which the item to be contained is placed in the recess of the base material, the lid material is placed over the item, and the air is degassed or replaced with an inert gas or the like, while the contact portion of the lid material and the base material is heat-sealed. The heat sealing is not particularly limited and can be performed using a well-known deep drawing packaging machine depending on the purpose. The molding heating temperature and molding time in the heat sealing are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include 100°C to 150°C and 1.0 seconds to 5.0 seconds.

[0048] (Multilayer film for deep-draw packaging) The multilayer film for deep drawn packaging of the present invention has at least a base layer (A) containing an ethylene-based resin (a1), a central layer (B) containing a linear low-density polyethylene (b1) and a butene-1-based resin (b2), and a heat-seal layer (C) containing low-density polyethylene (c1) and a butene-1-based resin (c2) and having a content of the butene-1-based resin (c2) of 30% by mass or more and 50% by mass or less, and is a multilayer film in which the base layer (A), the central layer (B) and the heat-seal layer (C) are laminated in the order of (A) / (B) / (C). As the multilayer film for deep drawn packages of the present invention, the features explained in relation to the multilayer film for deep drawn packages of the present invention can be appropriately adopted.

[0049] The multilayer film 10 for deep drawn packaging of the present invention is a multilayer film consisting of a base layer (A) 1, a central layer (B) 2, and a heat seal layer (C) 3 laminated in the order of (A) / (B) / (C), for example, as shown in FIG. 1. 2, the multilayer film 10 for deep drawn packaging of the present invention may be a multilayer film further having an additional base material layer (α) 4 on the base material layer (A) 1 side, laminated in the order of (α) / (A) / (B) / (C). The additional base material layer (α) 4 may be a single layer or multiple layers. 3 is a schematic cross-sectional view showing an example of the deep drawn package of the present invention. The deep drawn package 100 of the present invention is a package having a lid material 20 and a base material 30 having a recess, and can be fitted to the shape of the contents 40 (e.g., ham, etc.). The deep drawn package 100 of the present invention may be in an embodiment in which the lid material 20 is a multilayer film 10 and the base material 30 having a recess is another film, in which the base material 30 having a recess is a multilayer film 10 and the lid material 20 is another film, or in which both the lid material 20 and the base material 30 are multilayer films 10. An embodiment in which the base material 30 is a multilayer film 10 is preferred. EXAMPLES

[0050] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0051] Example 1 <Preparation of multi-layer film for packaging> The resin for the surface layer (A layer) was linear low-density polyethylene (hereinafter referred to as "m-LLDPE"). MFR: 3.6 g / 10 min (190 °C, 21.18 N), density: 0.93 g / cm 3 The resin for the central layer (layer B) was 85 parts by mass of the same m-LLDPE as that for layer A, and 1-butene polymer (hereinafter referred to as "PB"; MFR: 4.0 g / 10 min (190°C, 21.18 N), density: 0.91 g / cm 3 As the resin for the heat seal layer (layer C), low-density polyethylene (hereinafter referred to as "LDPE"; MFR: 35 g / 10 min (190°C, 21.18 N), density: 0.92 g / cm 3 ) 60 parts by mass, and 40 parts by mass of the same PB as in the B layer were used. By coextrusion, the layers (A) / (B) / (C) were extruded from a T-die at an extrusion temperature of 250° C. so that the thicknesses of the layers (A) / (B) / (C) were 28 μm / 8 μm / 4 μm, and the resultant was cooled with a water-cooled metal cooling roll at 40° C., after which a corona discharge treatment was performed so that the wet tension of the resin layer (A) was 40 mN / m. The resultant was then taken up on a roll and aged in an aging chamber at 40° C. for 24 hours to obtain a multilayer film a for packaging of Example 1, which was a coextruded laminate film with a total thickness of 40 μm.

[0052] <Preparation of laminate film> A biaxially oriented polypropylene (thickness: 20 μm) serving as an additional base layer (α) was attached to the base layer (layer A) side of the multilayer film for packaging a by dry lamination to obtain a multilayer film for packaging b of Example 1, which is a laminate film 1. As the dry lamination adhesive, a two-component curing adhesive (polyester adhesive "LX500" and curing agent "KR-90S") manufactured by DIC Corporation was used.

[0053] <Production of deep-drawn packaging bodies> As shown in FIG. 3, a deep-draw package was produced in which the base material 30 having a recess was the multilayer film 10 and the cover material 20 was another film. A 16 μm thick PET sheet was used as the lid material and multilayer film for packaging 1b was used as the base material. The PET sheet was bonded to the heat seal layer (layer C) of multilayer film for packaging 1, and vacuum packaged using a deep draw packaging machine to produce the deep draw package of Example 1. The vacuum forming part of the deep drawing packaging machine is cylindrical with a diameter of 98 mm and a drawing depth of 5 mm. The size of the packed product is 170 mm long and 125 mm wide. The forming heating temperature is 138°C and the forming time is 2.0 seconds.

[0054] <Evaluation> The prepared multi-layer film b for packaging was evaluated as follows.

[0055] <<Easy peel>> The heat-sealed surface of the multilayer film b for packaging as the lid material or bottom material was overlapped with the linear low-density polyethylene surface of biaxially oriented polypropylene / biaxially oriented polyethylene terephthalate / linear low-density polyethylene (total thickness 60 μm, individual layer thickness 20 μm / 12 μm / 40 μm) as another resin film, and heat-sealed under the conditions of heat-sealing temperatures of 110° C., 120° C., 130° C., 140° C. and 150° C., sealing pressure of 0.2 MPa, and sealing time of 1 second. Next, the heat-sealed film was naturally cooled at 23° C. for 6 hours or more, and then cut into a 15 mm-wide strip to prepare a test piece. The test piece was subjected to 90° peeling at a speed of 300 mm / min using a tensile tester (manufactured by A&D Co., Ltd.) in a thermostatic room at 23° C. and 50% RH.

[0056] From the above results, the easy peel property was evaluated according to the following criteria. [Evaluation Criteria] ◯: Heat seal strength is 1N / 15mm or more and 2.5N / 15mm or less at all heat seal temperatures. ×: The heat seal strength is less than 1 N / 15 mm or more than 2.5 N / 15 mm at any heat seal temperature.

[0057] << Evaluation of stringiness >> The test pieces measured above were evaluated for stringiness according to the following evaluation criteria. [Evaluation Criteria] ◯: No stringiness was observed at all heat sealing temperatures. Δ: Some stringiness was observed at any of the heat sealing temperatures. ×: Stringiness was observed at any of the heat sealing temperatures.

[0058] Example 2 In Example 1, the conditions of extrusion by the coextrusion method were changed as follows to change the thickness of each layer (A) / (B) / (C) as shown in Table 1. In the same manner as in Example 1, except that, multilayer films a and b for packaging and deep drawn packaging bodies of Example 2 were produced and evaluated.

[0059] Example 3 In Example 1, except that the thickness of each layer (A) / (B) / (C) was changed as shown in Table 1, the multilayer films a and b for packaging and the deep drawn packaging body of Example 3 were produced in the same manner as in Example 1, and their evaluations were carried out.

[0060] Example 4 In Example 3, as shown in Table 1, the composition of the resin for the heat seal layer (layer C) was changed to 70 parts by mass of LDPE and 30 parts by mass of PB, but in the same manner as in Example 3, multilayer films a and b for packaging and deep-drawn packaging bodies of Example 4 were produced and evaluated.

[0061] Example 5 In Example 3, except that the thickness ratio of each layer (A) / (B) / (C) was changed as shown in Table 1, the multilayer films a and b for packaging and the deep drawn packaging body of Example 5 were produced in the same manner as in Example 3, and their evaluations were carried out.

[0062] Comparative Example 1 In Example 1, as shown in Table 2, except that 1-butene-based polymer (PB) was not used as the resin for the central layer (B layer), multilayer films a and b for packaging and deep-drawn packaging bodies of Comparative Example 1 were produced in the same manner as in Example 1, and their evaluations were carried out.

[0063] (Comparative Examples 2 to 3) In Example 1, as shown in Table 2, a 1-butene polymer (PB) was not used as the resin for the central layer (B layer), and LDPE (MFR: 35 g / 10 min (190° C., 21.18 N), density: 0.92 g / cm 3 was used as the resin for the heat seal layer (C layer). 3 ) with LDPE (MFR: 7g / 10min (190℃, 21.18N), density: 0.92g / cm 3 ) or LDPE (MFR: 2g / 10min (190℃, 21.18N), density: 0.933g / cm 3 ), multilayer films for packaging a and b and deep-draw packaging bodies of Comparative Examples 2 and 3 were produced in the same manner as in Example 1, and these were evaluated.

[0064] Comparative Example 4 In Example 3, except that the composition ratio of the resin for the heat seal layer (layer C) was changed as shown in Table 2, multilayer films a and b for packaging and deep-drawn packaging bodies of Comparative Example 4 were prepared in the same manner as in Example 3, and their evaluations were carried out.

[0065] Comparative Example 5 In Example 1, as shown in Table 2, a 1-butene-based polymer was used as the resin for the central layer (B layer) in the form of an ethylene-vinyl acetate copolymer (MFR: 2.5 g / 10 min (190° C., 21.18 N), density: 0.938 g / cm 3 ), multilayer films for packaging a and b and a deep-draw packaging body of Comparative Example 5 were produced in the same manner as in Example 1, and their evaluations were carried out.

[0066] Comparative Example 6 In Example 1, as shown in Table 1, the LDPE used as the resin for the heat seal layer (layer C) had an MFR of 7 g / 10 min (190° C., 21.18 N) and a density of 0.92 g / cm 3 Except for changing the LDPE, the multilayer films a and b for packaging and the deep-draw packaging body of Comparative Example 6 were produced in the same manner as in Example 1, and their evaluations were carried out.

[0067] [Table 1]

[0068] [Table 2] [Explanation of symbols]

[0069] 1 Base material layer (A) 2 Central layer (B) 3. Heat seal layer (C) 4 Additional base material layer (α) 10 Multilayer film (multilayer film for deep drawing packaging) 20 Lid material 30 Bottom material 40 Contents 100 Deep-drawn packaging

Claims

1. A cover material and a base material having a recess, A deep-drawn package capable of housing and sealing an object to be housed in the recess by heat sealing the lid material and the base material, At least one of the lid material and the base material is A substrate layer (A) containing an ethylene-based resin (a1); a central layer (B) containing a linear low-density polyethylene (b1) and a butene-1 resin (b2); and a heat seal layer (C) containing a low-density polyethylene (c1) and a butene-1 resin (c2), the content of the butene-1 resin (c2) being 30% by mass or more and 50% by mass or less, a multilayer film in which the base layer (A), the core layer (B) and the heat seal layer (C) are laminated in the order of (A) / (B) / (C); The thickness of the heat seal layer (C) is 20% or less, A deep-draw packaging body, characterized in that the lid material and the base material can be heat-sealed by the heat-seal layer (C).

2. The deep drawn packaging body according to claim 1, wherein the content of the butene-1 resin (b2) in the core layer (B) is 10% by mass or more and less than 30% by mass.

3. The deep drawn packaging body according to claim 1 or 2, wherein the thickness of the heat seal layer (C) is 18% or less.

4. The deep drawn packaging body according to any one of claims 1 to 3, wherein the total thickness of the core layer (B) and the heat seal (C) is 10% or more and 30% or less.

5. The low-density polyethylene (c1) in the heat seal layer (C) has a melt flow rate of 30 g / 10 min or more under measurement conditions of a temperature of 190° C. and a load of 2.16 kg.

6. 6. The deep draw packaging body according to claim 1, wherein the lid material or the base material that is heat sealed to the multilayer film is a resin film.

7. 7. The deep draw packaging body according to claim 1, wherein an easy peel strength between the lid material and the base material is 0.5 N / 15 mm width or more and 2.5 N / 15 mm width or less.

8. Further comprising an additional substrate layer (α), The deep drawn packaging body according to any one of claims 1 to 7, which is a multilayer film in which the additional base material layer (α), the base material layer (A), the central layer (B) and the heat seal layer (C) are laminated in the order of (α) / (A) / (B) / (C).

9. 9. The deep drawn package according to claim 1, which is for food packaging or medical packaging.

10. A deep drawn package having a lid material and a base material having a recess, the deep drawn package capable of containing and sealing an object in the recess by heat sealing the lid material and the base material, the deep drawn package being used as at least one of the lid material and the base material, A substrate layer (A) containing an ethylene-based resin (a1); a central layer (B) containing a linear low-density polyethylene (b1) and a butene-1 resin (b2); a heat seal layer (C) containing a low-density polyethylene (c1) and a butene-1 based resin (c2), the content of the butene-1 based resin (c2) being 30% by mass or more and 50% by mass or less based on the total amount of resin components contained in the heat seal layer (C); The base layer (A), the central layer (B) and the heat seal layer (C) are laminated in the order of (A) / (B) / (C), The thickness of the heat seal layer (C) is 20% or less, A multilayer film for deep drawing packaging, characterized in that the lid material and the base material can be heat sealed by the heat seal layer (C).

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