JP4817857B2 - Polyamide resin laminated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated polyamide resin film having good heat sealability, appearance of a heat seal part when used as a packaging material, excellent in toughness, dimensional stability in the longitudinal direction and gas-barrier properties, and used suitably as high-speed automatic filling, bag-making. <P>SOLUTION: A laminated polyamide resin film has at least three layers including an aliphatic polyamide layer (a) and a saponified ethylene-vinyl acetate later (b) and, when held in a dry, hot atmosphere for 5 min, indicates thermal shrinkage factors of 0-1.5% at 140&deg;C in the longitudinal direction and 1.5-4.5% in the transverse direction and of 0-2% at 160&deg;C in the longitudinal direction and 2.5-7% in the transverse direction, respectively. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a polyamide-based resin laminated film that is suitably used for packaging materials such as foods, pharmaceuticals, and chemicals.

Conventionally, polyamide-based resin films are used alone or as laminates with other films for various packaging materials. For example, in order to improve gas barrier properties, they are laminated with various gas barrier resins. Has been done. In particular, in applications such as liquid-filled packaging, such polyamide-based resin laminated films are often used from the viewpoints of excellent oxygen gas barrier properties, flex resistance, transparency, heat resistance, toughness, and the like.
Such polyamide-based resin films are used for seasonings such as miso and soy sauce, water-containing foods such as soups and retort foods, or medicine packaging bags. When using this polyamide-based resin film as a packaging bag, a polyamide-based film laminate provided with a sealant layer is manufactured, the laminate is produced in a bag, and the contents are filled through the opening. Heat seal. At this time, since the packaging of the articles by the automatic filling machine is excellent in terms of simplicity and productivity, it is widely used for packaging of various articles including the above foods and beverages. In recent years, filling machines have been increased in speed and efficiency for the purpose of further improving productivity.

  However, in general, when a polyamide-based resin film is used and packaging is performed as described above, particularly when automatic filling and bag making are performed continuously at high speed, wrinkles are formed in the heat seal portion in parallel with the vertical direction, which is the film transfer direction. It occurred and there was a problem that the appearance was remarkably inferior. In addition, due to the generation of wrinkles, the contents are accumulated in the wrinkles, and there is a problem that a sealing failure or the like is likely to occur. In general, the polyamide-based resin film used for packaging has a lower shrinkage rate in order to avoid problems such as wrinkles and pattern displacement in the printing and laminating processes (for example, Patent Document 1). .

Japanese Patent Laid-Open No. 11-277698

However, using a conventional polyamide-based resin film, laminating a sealant, and performing automatic filling bag making of liquid soup, etc., particularly under high speed, when horizontal sealing is performed in a direction perpendicular to the film transfer direction, When the sealant melts and is then cooled and solidified, solidification shrinkage may occur, and at the same time, the polyamide resin film undergoes thermal shrinkage. At this time, when the heat shrinkage rate in the lateral direction is insufficient, the solidification shrinkage of the sealant cannot be absorbed, and wavy wrinkles are generated in the heat seal portion. Wavy wrinkles generated in the heat seal part significantly reduce the product value in terms of appearance, and further induce a seal failure, leading to leakage of contents and broken bags.
For example, in the film formed using the method of Patent Document 1, since the wrinkle improvement of the horizontal seal is insufficient and the contraction rate in the vertical direction is also large, the vertical pitch in the sealing machine Became unstable and the notch position for tearing the bag was shifted.

  The present invention solves the above-mentioned problems of the prior art, that is, the heat sealability when used as a packaging material and the appearance of the heat seal part are good, and it is excellent in toughness, longitudinal dimensional stability, and gas barrier properties. An object of the present invention is to provide a polyamide-based resin laminated film that can be suitably used as a high-speed automatic filling bag.

As a result of intensive studies to solve the above problems, the inventors of the present invention have at least three layers including (a) a layer made of an aliphatic polyamide and (b) a layer made of a saponified ethylene-vinyl acetate copolymer. It has been found that the above problems can be solved by a polyamide-based resin laminated film having a laminated structure and having a heat shrinkage rate in a specific range when held in a dry heat atmosphere. did.
That is, the present invention is a polyamide-based resin film having a laminated structure consisting of at least three layers including (a) a layer made of aliphatic polyamide and (b) a layer made of saponified ethylene-vinyl acetate copolymer, When held in a dry heat atmosphere for 5 minutes, the heat shrinkage rate at 140 ° C. is 0 to 1.5% in the vertical direction, 1.5 to 4.5% in the horizontal direction, and 160 ° C. Provides a polyamide-based resin laminated film having 0 to 2% in the vertical direction and 2.5 to 7% in the horizontal direction.

  According to the present invention, there is provided a polyamide-based resin laminated film having good heat sealability and heat seal portion appearance when used as a packaging material, and excellent in toughness, longitudinal dimensional stability, and gas barrier properties. Can do. Moreover, the above-mentioned characteristics when the resin film is used for high-speed automatic filling bag making, particularly wavy wrinkles in the heat seal portion can be improved extremely effectively.

The present invention is described in detail below.
The polyamide-based resin laminated film of the present invention has a laminated structure consisting of at least three layers including (a) a layer made of aliphatic polyamide and (b) a layer made of a saponified ethylene-vinyl acetate copolymer.
The layer (a) is made of an aliphatic polyamide as a main component.
Aliphatic polyamides include ring-opening polymers of cyclic lactams such as homopolymers of ε-caprolactam (nylon-6), polycondensates of aminocarboxylic acids, and dicarboxylic acids such as polyhexamethylene adipamide (nylon-66). Examples thereof include polycondensates of acids and diamines.
Among these aliphatic polyamides, ε-caprolactam homopolymer (nylon-6), polyhexamethylene adipamide (nylon-66) are available at low cost and can be smoothly stretched. ) Is preferred.
The aliphatic polyamide is preferably contained in the layer (a) in an amount of 60 to 100% by mass, more preferably 80 to 100% by mass, from the viewpoint of bending pinhole resistance, toughness and the like.

The layer (a) may contain 5-40% by mass of aromatic polyamide from the viewpoint of gas barrier properties and toughness.
The aromatic polyamide is not particularly limited, and examples thereof include resins containing 70 mol% or more of polyamide constituent units composed of xylylenediamine and an α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms in the molecular chain. Preferably mentioned.
Specifically, homopolymers such as polymetaxylylene adipamide, polymetaxylylene pimeramide, polymetaxylylene azelamide, polyparaxylylene azelamide, polyparaxylylene decanamide, metaxylylene / paraxylylene azamide Examples of the copolymer include a amide copolymer, a metaxylylene / paraxylylene pimeramide copolymer, a metaxylylene / paraxylylene azeramide copolymer, and a metaxylylene / paraxylylene sepacamide copolymer.

Other polyamide constituents include nylon salts of diamines and dicarboxylic acids, lactams such as ε-caprolactam, ω-aminocarboxylic acids such as ε-aminocarboxylic acid, and the like.
The diamines that are the components of the nylon salt include aliphatic diamines such as hexamethylene diamine and 2,2,4-trimethylhexamethylene diamine, heterocycles or heteroatoms such as piperazine bispropylamine and neopentylglycol bispropylamine. Dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, azelaic acid and sebacic acid, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and cyclic such as 1,4-cyclohexanedicarboxylic acid. Examples thereof include aliphatic dicarboxylic acids.

(A) When the polyamide which comprises a layer is a mixture containing the said aliphatic polyamide and aromatic polyamide, it is preferable that this mixture is a homogeneous mixed composition of aliphatic polyamide and aromatic polyamide.
Various additives such as a lubricant, an antistatic agent, an antioxidant, an antiblocking agent, a stabilizer, a dye, a pigment, and inorganic fine particles can be added to these raw material polyamide and polyamide mixed composition.

The layer (b) is made of a saponified ethylene-vinyl acetate copolymer (hereinafter referred to as “EVOH”) for the purpose of imparting gas barrier properties and aroma retention. The EVOH is not particularly limited as long as it is produced by a conventionally known method.
Among these EVOHs, those having an ethylene content in the range of 25 to 38 mol%, preferably 29 to 35 mol%, and having a saponification degree of 95 mol% or more, preferably 98 mol% or more. Is suitable.
When the ethylene content is in the range of 25 to 38 mol%, the melt extrudability at the time of melt extrusion becomes good, and the oxygen gas barrier property is not lowered. Moreover, when the saponification degree of EVOH is 95 mol% or more, oxygen gas barrier properties and moisture resistance are good.
In addition to the saponified product of ethylene and vinyl acetate binary copolymer, the EVOH includes a small amount of an α-olefin such as propylene, isobutene, α-octene, α-dodecene and α-octadecene as a copolymer component; Saturated carboxylic acids, or salts thereof, partial alkyl esters, fully alkyl esters, nitriles, amides, anhydrides; unsaturated sulfonic acids, salts thereof, and the like may be included. A mixture of thermoplastic resins such as polyolefin, polyester and polyamide may be used.
The EVOH content in the (b) layer is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, from the viewpoints of gas barrier properties and aroma retention.
In addition, various additives such as a lubricant, an antistatic agent, an antioxidant, an antiblocking agent, a stabilizer, a dye, a pigment, and inorganic fine particles can be added to the layer (b).

The polyamide-based resin laminated film of the present invention can contain, for example, 0.5 to 10% by mass of the bending-resistant pinhole improving material in at least one of the above-mentioned (a) layer and (b) layer. Bending resistance can be improved. As content of a bending-resistant pinhole improvement material, Preferably it is 1-7 mass%.
As the aliphatic polyamide or EVOH containing the bending pinhole resistance improving material, the aliphatic polyamide or EVOH and the bending pinhole resistance improving material are dry blended at a predetermined ratio, and the dry blended product is extruded using an extruder. Any of the pellets after melting may be used.
Examples of the bending-resistant pinhole improving material include polyolefins, polyamide elastomers, and polyester elastomers.

  Examples of the polyolefins include those containing 50 mass% or more of polyethylene units and / or polypropylene units in the main chain, and may be graft-modified with maleic anhydride or the like.

  The polyamide elastomers belong to polyamide block copolymers such as polyether amide and polyether ester amide, and examples of the amide component include nylon-6, nylon-66, nylon-12, and the like, and ether components Examples thereof include polyoxytetramethylene glycol, polyoxyethylene glycol, polyoxy-1,2-propylene glycol and the like.

Examples of the polyester elastomers include polyether ester elastomers combining polybutylene terephthalate and polytetramethylene glycol, and polyester ester elastomers combining polybutylene terephthalate and polycaprolactone.
These bending-resistant pinhole improving materials may be used alone or in combination of two or more.

The layer structure of the polyamide-based laminated film of the present invention is not particularly limited as long as the layer structure includes at least three layers including the (a) layer and the (b) layer. For example, (a) / (b ) / (A), (b) / (a) / (b) are preferred. Further, an adhesive layer may be further provided between the above layers.
The thickness of each layer is preferably 50 to 97% of the total layer for the layer (a) and 50 to 3% of the total layer for the layer (b) from the viewpoint of strength, gas barrier properties, and aroma retention.
The total thickness of the polyamide-based resin laminated film of the present invention is preferably 10 to 40 μm. When the thickness of the film is within this range, a film sufficient for packaging use can be obtained from the viewpoint of balance between oxygen gas barrier property and bending pinhole resistance, wear resistance, and suitable for soft packaging use. . The thickness of the entire film is more preferably 12 to 30 μm, still more preferably 12 to 25 μm.

The polyamide-based resin laminated film of the present invention has a heat shrinkage rate of 140 ° C. in the vertical direction of 0 ° C. when held in a dry heat atmosphere for 5 minutes in order to improve the appearance of the heat seal portion during heat sealing. -1.5%, preferably 0-1.0%, 1.5-4.5% in the transverse direction, preferably 2.0-4.0%, and the heat shrinkage at 160 ° C. in the longitudinal direction 0 to 2%, preferably 0.5 to 1.5%, and 2.5 to 7%, preferably 3.0 to 5.0% in the lateral direction.
About the polyamide-type resin laminated film of this invention, when a horizontal seal | sticker is performed, a sealant will melt | dissolve and will cause solidification shrinkage | contraction when it cools and solidifies after that. At the same time, the polyamide-based resin laminated film undergoes heat shrinkage. At this time, if the heat shrinkage rate in the vertical direction and the horizontal direction is within the above range, the solidification shrinkage of the sealant can be absorbed and no wrinkles are generated in the heat seal portion.
In the present invention, the dry heat atmosphere means, for example, conditions of a temperature of 140 to 160 ° C. and a relative humidity of 0 to 2% RH.

When the thermal contraction rate in the vertical direction at 140 ° C. exceeds 1.5% when held in a dry heat atmosphere for 5 minutes, the toughness such as laminating strength and the dimensional stability are inferior. In addition, when the thermal shrinkage rate in the lateral direction at 140 ° C. is less than 1.5%, the shrinkage rate in the seal temperature range is insufficient, and it is impossible to follow the solidification shrinkage of the sealant at the time of sealing. If it exceeds 4.5%, the shrinkage rate is too large, and the appearance of the heat seal portion is deteriorated.
Moreover, when the thermal contraction rate in the vertical direction at 160 ° C. exceeds 2%, the toughness such as the laminar strength and the dimensional stability are inferior. Also, if the thermal shrinkage rate in the lateral direction is less than 2.5%, the shrinkage rate in the seal temperature range is insufficient, and the solidification shrinkage of the sealant at the time of sealing cannot be followed. In the case of exceeding, the shrinkage rate is too large, the appearance of the heat seal part is deteriorated, and troubles such as wrinkles and pattern displacement in the printing and laminating processes occur.
The thermal shrinkage at 140 ° C. or 160 ° C. is a value obtained by the following method.
That is, a film test piece is cut into a width of 120 mm and a length of 120 mm, and a line of about 100 mm is drawn on the sample in the longitudinal (MD) direction and the transverse (TD) direction. This sample is allowed to stand for 24 hours in an atmosphere of 23 ° C. and 50% RH, and the reference line is measured. The measured length is defined as a length F before the heat treatment. This sample was hung in a hot air dryer maintained at 140 ° C. or 160 ° C., heated for 5 minutes, and then allowed to stand in an atmosphere of 23 ° C. and 50% RH for 30 minutes. Let it be the length G after.
The heat shrinkage rate is calculated by [(F−G) / F] × 100 (%).
With the above method, each shrinkage rate in the MD direction and TD direction was measured at n = 5, and the average value was defined as the heat shrinkage rate.

  The polyamide-based resin laminated film of the present invention can be produced by various methods, but for example, it is preferably produced by the following method. That is, a substantially amorphous and unoriented film (hereinafter referred to as “unstretched film”) is usually produced by a coextrusion method using polyamide-based resin and EVOH as raw materials. The unstretched film is produced, for example, by melting the above raw material with 1 to 5 extruders, extruding from a flat die or an annular die, and then rapidly cooling to obtain a flat or annular unstretched film. A coextrusion method can be employed.

Next, the above-mentioned unstretched film is usually 2.5 to at least in one direction from the viewpoint of stretching effect, film strength, etc. in the film flow direction (longitudinal direction) and in a direction perpendicular to the film direction (transverse direction). The film is stretched 5 times, preferably 2.6 to 4.0 times in the longitudinal and lateral biaxial directions.
As the biaxial stretching method, any conventionally known stretching method such as tenter-type sequential biaxial stretching, tenter-type simultaneous biaxial stretching, tubular simultaneous biaxial stretching, and the like can be adopted. For example, in the case of the tenter type sequential biaxial stretching method, the unstretched film is heated to a temperature range of 50 to 110 ° C., and stretched 2.6 to 3.5 times in the longitudinal direction by a roll type longitudinal stretching machine, Then, it can manufacture by extending | stretching 2.6 to 4.0 time in a horizontal direction within the temperature range of 60-140 degreeC with a tenter type horizontal extending | stretching machine. Moreover, in the case of the tenter type simultaneous biaxial stretching and the tubular type simultaneous biaxial stretching method, for example, in the temperature range of 60 to 130 ° C., it is manufactured by stretching 2.5 to 5 times in each axial direction simultaneously in the longitudinal and lateral directions. can do.

  It is preferable that the stretched film stretched by the above method is subsequently heat-set. Dimensional stability at room temperature can be imparted by heat setting. In this case, the treatment temperature is preferably in the range of 210 to 225 ° C, more preferably 210 to 220 ° C. If the heat setting temperature is within the above range, the heat setting is sufficiently performed, the stress at the time of stretching is relaxed, and a sufficient lamination strength is maintained. Moreover, sufficient mechanical strength, impact resistance and pinhole resistance of the film can be obtained, and an excellent film free from troubles such as breakage and whitening of the film surface can be obtained.

  During the heat setting, relaxation is preferably performed in the lateral direction, preferably in the range of 0 to 15%, more preferably 3 to 10%. By relaxing, the stress of crystallization shrinkage due to heat fixation can be relaxed. If the relaxation rate is within the above range, the film is sufficiently relaxed and uniformly relaxed in the lateral direction of the film, so that the lateral shrinkage rate becomes uniform and a film having excellent room temperature dimensional stability can be obtained. Further, since relaxation is performed following the shrinkage of the film, there is no fluttering in the film, no fluttering in the tenter, and no breakage of the film.

After the relaxation, it is preferably cooled to a temperature of 140 to 200 ° C., more preferably 160 to 200 ° C., and preferably 2 to 9%, more preferably 3 to 7%, and further preferably 4 to 7% at that temperature. It is preferable to carry out re-lateral stretching in the range described above.
If the re-lateral stretching temperature is within the above range, an appropriate stress at the time of stretching can be obtained and uniform stretching can be performed, so that the shrinkage rate in the lateral direction becomes uniform. In addition, heat setting is not applied after stretching, and the transverse shrinkage tends to be developed.
Further, if the re-lateral stretching ratio is within the above range, a sufficient transverse shrinkage rate to follow the solidification shrinkage of the sealant is obtained, the heat seal part has a good appearance, and an appropriate shrinkage rate is obtained. Thus, troubles such as wrinkles and pattern displacement can be prevented in the printing and laminating processes.
The polyamide-based resin laminated film formed by the above method is cooled and wound by a conventional method.

The polyamide-based resin laminated film of the present invention can be produced by the above-described method. Further, the laminate obtained by forming a sealant layer is subjected to further processing for packaging material applications such as high-speed automatic filling packaging bags. be able to.
As the resin for forming the sealant layer, polyethylene resin films such as metallocene LL (LL: linear low density polyethylene), LL, low density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), polypropylene, etc. (PP), block copolymer PP with ethylene, random copolymer PP with ethylene, polypropylene resin such as metallocene PP, ionomer resin, ethylene-ethyl acrylate copolymer (EEA) resin, ethylene-methyl acrylate copolymer Examples thereof include a polymer (EMA) resin, an ethylene-methacrylic acid copolymer (EMAA) resin, and an ethylene-methyl methacrylate copolymer (EMMA) resin.
Examples of the method for forming the sealant layer include a dry laminating method, a PE sand laminating method, and an extrusion laminating method.

  When the sealant layer is laminated on the polyamide-based resin laminated film of the present invention, the peel strength between the film and the sealant layer (hereinafter referred to as peel strength after lamination) is preferably 450 g / 15 mm or more. If it is in this range, a sufficient pouch-proof strength can be obtained with a liquid-filled pouch. The peel strength after lamination is more preferably 500 g / 15 mm or more. Here, the peel strength after lamination is specifically a value obtained by the measurement method described later.

  By applying a polyvinylidene chloride resin-based gas barrier coating agent to the polyamide-based resin laminated film of the present invention, a laminated film with improved gas barrier properties and excellent moisture resistance can be obtained. Moreover, it can be set as a laminated body by laminating | stacking various single layer or laminated | multilayer film by the dry lamination method, PE sand lamination method, the extrusion lamination method, etc.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
In the following examples, the obtained film was evaluated by the following method.
The evaluation results in each example etc. are shown in Table 1.

1) Heat Shrinkage A film test piece is cut into a width of 120 mm and a length of 120 mm, and a line of about 100 mm is drawn on the sample in the longitudinal (MD) direction and the transverse (TD) direction. This sample is allowed to stand for 24 hours in an atmosphere of 23 ° C. and 50% RH, and the reference line is measured. The measured length is defined as a length F before the heat treatment. This sample was hung in a hot air dryer maintained at 140 ° C. or 160 ° C., heated for 5 minutes, and then allowed to stand in an atmosphere of 23 ° C. and 50% RH for 30 minutes. Let it be the length G after.
The heat shrinkage rate is calculated by [(F−G) / F] × 100 (%).
With the above method, each shrinkage rate in the MD direction and TD direction was measured at n = 5, and the average value was defined as the heat shrinkage rate.

2) Breaking Stretched polyamide films were produced continuously, and whether or not stable film formation for 1 hour or more was possible at the tenter outlet of the tenter type stretching machine was visually evaluated according to the following criteria.
○: Stable film formation ×: Breakage occurred

3) Peel strength after laminating One side of the formed polyamide resin laminate film is corona treated to a wetting index of 500 μN (50 dyn) or higher, and TM-329 manufactured by Toyo Morton Co., Ltd. as an adhesive is used as a curing agent. CAT-8B manufactured by Toyo Morton Co., Ltd. and ethyl acetate as a diluent solvent were mixed at 13.8% by mass, 13.8% by mass, and 72.4% by mass, respectively, and after gravure coating, dried at 70 ° C. Ethyl acetate was removed to make the adhesive coating amount 3 g / m ² . Further, a metallocene LL (“TUX TCS” manufactured by Tosello Co., Ltd.) having a thickness of 50 μm was bonded as a sealant by dry lamination at 90 ° C., and then aging was performed at 40 ° C. for 24 hours.

  The layer between the polyamide resin laminated film dry-laminated by the above method and the sealant is peeled off with tweezers using water or ethanol. When the peeled portion becomes about 1 cm, a rappy tape (cemedine 18 mm width) is adhered in the longitudinal direction of the film so as to cover the peeled portion. The film with the rappy tape is cut into strips with a width of 15 mm and a length of 100 mm in a direction perpendicular to the flow direction, and the peeled portion is expanded to about 50 mm while applying water. Both sides of the film from which the moisture had been removed were gripped with an autograph (Toyo Seiki) chuck and pulled at a speed of 50 mm / min. The initial peak value was measured at n = 5, and the average value was defined as the peel strength after lamination (g / 15 mm).

4) Side seal appearance evaluation As a high-speed automatic filling machine, NT-Dangan Type III manufactured by Taisei Ramick Co., Ltd. was used to create a water-filled bag using the polyamide-based resin laminated film dry-laminated in 2) above. The filling conditions are as follows.
Size: Length 80mm x Width 75mm
Filling speed: 20 m / min
Vertical sealing temperature: 180 ° C
Horizontal seal temperature: 140 ° C
Filling liquid amount: 20g
Filling liquid temperature: 80 ° C
Vertical seal width: 10mm
Horizontal seal width: 14mm
Appearance evaluation is to visually evaluate the state of wavy wrinkles occurring in the horizontal seal part, ◎ is the state without wrinkles, ○ is a state where there is no practical problem, △ is a poor appearance, and the seal is insufficiently foamed The case where a defect occurred was evaluated as “x” and evaluated in the following order.
(Good) ← ◎>○>△> × → (Evil)

5) Stability of the seal in the vertical direction (print pitch deviation)
The following printing test evaluation as a positional deviation evaluation was performed. Using a three-color gravure printing machine (manufactured by Modern Machinery), blue and red of gravure ink "Univia A" manufactured by Dainippon Ink & Chemicals, Inc. White was subjected to gravure printing (speed 50 m / min, drying temperature 120 ° C.) continuously in three colors, and visual appearance and print displacement were visually evaluated according to the following criteria.
○: Print pitch misalignment is 1 mm or less ×: Print pitch misalignment is 2 mm or more Δ: Print pitch misalignment is between ◯ and × The print pitch misalignment is easily misaligned in the vertical direction during filling seal, Practicality is reduced.
6) Gas barrier property Based on JIS K 7126 (Method B) isobaric method, the oxygen permeability (cc / m ² · d · atm) of the polyamide resin film was measured.

Example 1
(A) Nylon-6 (manufactured by Mitsubishi Chemical Engineering Plastics, Novamid 1022C6) is used as the polyamide layer, and (b) Soarnol DC3203FB (manufactured by Nippon Synthetic Chemical Industry, (Ethylene content 32 mol%), (a) / (b) / (a) co-extruded as a laminated film consisting of three layers, closely adhered to a 30 ° C. cast roll, and each thickness was ( a) An unstretched laminated film having a ratio of 40% / (b) 20% / (a) 40% was obtained.
The obtained unstretched laminated film was stretched three times in the machine direction by a roll-type stretcher under the condition of 60 ° C., and then the end of the longitudinally stretched film was held with a tenter clip, and was 100 ° C. in a tenter oven. The film was stretched 3.5 times in the transverse direction under the above conditions, heat-set at 215 ° C., relaxed 7% in the transverse direction, cooled to 180 ° C., and re-stretched 5%.
The film after re-lateral stretching is cooled to room temperature, both end portions corresponding to the gripping portion of the clip are trimmed, the trimmed product portion is wound up in a roll shape, the outer layer is 6 μm, and the inner layer is 3 μm ( A polyamide-based resin laminated film having a three-layer configuration of a) / (b) / (a) and a total thickness of 15 μm was obtained. The evaluation results of the film are shown in Table 1.

Examples 2-5
A polyamide-based resin laminated film was produced in the same manner as in Example 1 except that the production conditions of the film were as shown in Table 1, and evaluated in the same manner as in Example 1. The results are shown in Table 1.
Comparative Examples 1 and 2
Regarding the film production conditions, the heat setting temperature is set as shown in Table 1, and a polyamide-based resin laminated film was produced in the same manner as in Example 1 except that re-lateral stretching was not performed. And evaluated. The results are shown in Table 1.
Comparative Examples 3 and 4
Regarding the production conditions of the film, a polyamide-based resin laminated film was produced in the same manner as in Example 1 except that the re-lateral stretching ratio was as shown in Table 1, and evaluated in the same manner as in Example 1. The results are shown in Table 1.
Comparative Examples 5 and 6
A polyamide-based resin laminated film was produced in the same manner as in Example 1 except that the relateral stretching temperature was as shown in Table 1 with respect to the film production conditions. The resulting film was evaluated only for breakage. The heat shrinkage rate and the like could not be measured because a stable sample could not be obtained. The results are shown in Table 1.

  The polyamide-based resin laminated film of the present invention is suitably used as a packaging material that continuously seals and fills liquids such as foods, pharmaceuticals, and chemicals, particularly as a packaging material for liquids such as liquid soups and seasonings. . Moreover, it is used suitably for the high-speed automatic filling of the said liquid substance.

Claims (4)

  A polyamide-based resin film having a laminated structure composed of at least three layers including (a) a layer made of aliphatic polyamide and (b) a layer made of saponified ethylene-vinyl acetate copolymer, in a dry heat atmosphere When held for 5 minutes, the heat shrinkage rate at 140 ° C. is 0 to 1.5% in the vertical direction, 1.5 to 4.5% in the horizontal direction, and the heat shrinkage rate at 160 ° C. is 0 in the vertical direction. A polyamide-based resin laminate film of ˜2% and 2.5 to 7% in the transverse direction.   The polyamide-based resin laminated film according to claim 1, wherein a peel strength between the sealant layer and the sealant layer when laminated is 450 g / 15 mm or more.   After stretching, the film is heat-set at 210-225 ° C., relaxed in the range of 0-15% in the transverse direction during the heat setting, then cooled to a temperature of 140-200 ° C., and 2-9% at the temperature The polyamide-based resin laminated film according to claim 1, which is obtained by performing re-lateral stretching in the range described above.   The polyamide-based resin laminated film according to any one of claims 1 to 3, which is used for high-speed automatic filling bags.