JP2008074008A - Polyamide-based multilayer stretched film - Google Patents

Abstract

The present invention relates to a polyamide having excellent dimensional stability, aroma retention, moisture proofing, and better pinhole resistance while maintaining the excellent toughness and gas barrier properties characteristic of a polyamide-based multilayer film. A multi-layer stretched film is provided.
A polyamide-based multilayer laminate having at least five layers of a crystalline polyester layer / modified polyester elastomer layer / aliphatic polyamide layer / modified polyester elastomer layer / crystalline polyester layer is 2.5 to 4.5 times in the longitudinal direction, transverse direction. A multilayer stretched film obtained by biaxially stretching 2.5 to 5 times, the total thickness of the multilayer stretched film is 10 to 50 μm, and the thickness of each layer constituting the multilayer stretched film is a crystalline polyester. The present invention relates to a polyamide-based multilayer stretched film in which the layer is 0.5 to 15 μm, the aliphatic polyamide layer is 5 to 40 μm, the modified polyester elastomer layer is 0.5 to 3 μm, and the thickness of the polyamide layer in the multilayer stretched film is 30 to 95%.
[Selection figure] None

Description

  The present invention relates to a polyamide-based multilayer stretched film used for packaging foods and the like.

  Conventionally, a polyamide-based multilayer film containing a nylon resin has been widely used in various fields as a film having gas barrier properties, toughness, pinhole resistance and the like.

  Although this polyamide-based multilayer film has the excellent characteristics as described above, for example, when used for packaging films for foods, etc., the odor of the contents leaks or the packaging film absorbs moisture by contact with water. There was a problem that the dimensions of the change. This is not preferable because it leads to deterioration of contents and a decrease in commercial value.

  Therefore, the packaging film is required to have high fragrance retention, moisture absorption dimensional stability, moisture resistance, and the like. Furthermore, when used as a packaging film for more severe boil processing or retort processing, higher moisture resistance, moisture absorption dimensional stability, and thermal dimensional stability are required.

In addition, polyamide-based multilayer films are distributed in the market as packaging films for foods, etc., but pinholes may occur due to wear during transportation, transportation, etc., and the excellent gas barrier properties of the multilayer films are due to the pinholes. The result was disturbed. Therefore, a packaging film excellent in toughness and particularly excellent in abrasion resistance is desired from the market.
Japanese Patent Laid-Open No. 08-118569 JP 11-322974 A

  The present invention is a polyamide-based multilayer stretch having excellent dimensional stability, fragrance retention, moisture proofing and better pinhole resistance while maintaining the excellent toughness and gas barrier properties that are characteristic of the polyamide-based multilayer film. The object is to provide a film.

  As a result of intensive studies to solve the above problems, the inventor of the present invention has a five-layer film of crystalline polyester layer / modified polyester elastomer layer / aliphatic polyamide layer / modified polyester elastomer layer / crystalline polyester layer. As a result, the adhesion between the crystalline polyester layer and the aliphatic polyamide layer becomes strong, and by stretching each layer to a predetermined thickness, toughness, gas barrier properties, dimensional stability, aroma retention, moisture resistance And it discovered that the polyamide-type multilayer stretched film excellent in all the pinhole resistance was obtained. Based on this knowledge, the present invention was completed by further research.

  That is, the present invention provides the following polyamide-based multilayer stretched film.

  Item 1. A polyamide-based multilayer laminate having at least 5 layers of crystalline polyester layer / modified polyester elastomer layer / aliphatic polyamide layer / modified polyester elastomer layer / crystalline polyester layer is 2.5 to 4.5 times in the vertical direction and 2.5 to 5 in the horizontal direction. It is a multilayer stretched film obtained by biaxially stretching twice, the total thickness of the multilayer stretched film is 10-50 μm, the thickness of each layer constituting the multilayer stretched film is 0.5- A polyamide-based multilayer stretched film having a thickness of 15 μm, an aliphatic polyamide layer of 5-40 μm, a modified polyester elastomer layer of 0.5-3 μm, and an aliphatic polyamide layer thickness of 30-95% in the multilayer stretched film.

  Item 2. A polyamide-based multilayer laminate having at least 7 layers of crystalline polyester layer / modified polyester elastomer layer / aliphatic polyamide layer / gas barrier layer / aliphatic polyamide layer / modified polyester elastomer layer / crystalline polyester layer is longitudinally 2.5 to 4.5. A multilayer stretched film obtained by biaxially stretching 2.5 to 5 times in the transverse direction, the total thickness of the multilayer stretched film is 10 to 50 μm, and the thickness of each layer constituting the multilayer stretched film is The crystalline polyester layer is 0.5 to 15 μm, the aliphatic polyamide layer is 2 to 20 μm, the modified polyester elastomer layer is 0.5 to 3 μm, the gas barrier layer is 1 to 10 μm, and the thickness ratio of the aliphatic polyamide layer in the multilayer stretched film is 30-95% polyamide multilayer stretched film.

  The polyamide-based multilayer stretched film of the present invention has excellent toughness, gas barrier properties, dimensional stability, fragrance retention, moisture resistance, and more pinhole resistance. Therefore, it is suitably used as a packaging film.

The present invention is described in detail below.
I. Polyamide-based multilayer stretched film The polyamide-based multilayer stretched film of the present invention is a multilayer film having at least five layers of crystalline polyester layer / modified polyester elastomer layer / aliphatic polyamide layer / modified polyester elastomer layer / crystalline polyester layer, The thickness of each layer is in a predetermined range. The multilayer film has at least seven layers of crystalline polyester layer / modified polyester elastomer layer / aliphatic polyamide layer / gas barrier layer / aliphatic polyamide layer / modified polyester elastomer layer / crystalline polyester layer, and the thickness of each layer is predetermined. It is the range of these. The modified polyester elastomer is also referred to as “modified TPEE”.

Crystalline polyester layer The crystalline polyester layer contains a crystalline polyester as a main component. Examples of the crystalline polyester include polyethylene terephthalate (PET), polyethylene terephthalate / isophthalate, and polybutylene terephthalate. Polyethylene terephthalate is preferable from the viewpoint of thermal dimensional stability, aroma retention, and heat resistance. . Note that, if necessary, a resin compatible with the crystalline polyester may be contained, but the PET is preferably 50% by weight or more based on the weight of the crystalline polyester layer.

  Since the crystalline polyester layer is usually the outermost layer, it may contain a lubricant as required. The lubricant is not particularly limited as long as it can reduce the dynamic friction coefficient of the surface of the crystalline polyester layer that is the outermost layer, and examples thereof include inorganic filler particles, bisamide compounds, and mixtures thereof.

  In addition, although it has two crystalline polyester layers in this invention, the kind and compounding ratio of crystalline polyester may be the same or different. In general, from the viewpoint of simplicity of multilayer film production, it is preferable to use crystalline polyesters of the same kind and the same blending ratio.

Aliphatic polyamide layer The aliphatic polyamide layer contains an aliphatic polyamide as a main component. The aliphatic polyamide is an essential component, but may contain other polyamide components (for example, an aromatic polyamide) as long as the object of the present invention can be achieved.

Examples of the aliphatic polyamide include aliphatic nylon and copolymers thereof. Specifically, polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecanamide (nylon-11), polylauryllactam ( Nylon-12), polyethylenediamine adipamide (nylon-2,6), polytetramethylene adipamide (nylon-4,6), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene Bacamide (nylon-6,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), polydecamethylene adipamide (nylon-10,8) , Caprolactam / lauryl lactam copolymer (nylon-6 / 12), caprolactam / ω-aminononanoic acid copolymer Body (nylon -6/9), caprolactam / hexamethylene diammonium adipate copolymer (nylon-6 / 6,6), lauryl lactam / hexamethylene diammonium adipate copolymer (nylon-12 / 6,6), Ethylenediamine adipamide / hexamethylenediammonium adipate copolymer (nylon-2,6 / 6,6), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon-6,6 / 6) 10), ethyleneammonium adipate / hexamethylene diammonium adipate / hexamethylene diammonium sebacate copolymer (nylon-6 / 6, 6/6, 10), etc., among which two or more fats Can be mixed with polyamid polyamide Yes.

  Preferred aliphatic polyamides include nylon-6, nylon-6,6, nylon-6 / 6,6 (copolymer of nylon 6 and nylon 6,6), more preferably nylon-6, nylon- 6/6, 6 and particularly preferably nylon-6. As the two or more kinds of aliphatic polyamides, a combination of nylon-6 and nylon-6 / 6,6 (weight ratio of about 50:50 to 95: 5) is preferable.

  Moreover, as an aromatic polyamide which is another polyamide component, for example, aromatic diamines such as metaxylenediamine and paraxylenediamine, and adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, etc. Examples thereof include crystalline aromatic polyamides obtained by polycondensation reaction with dicarboxylic acid or a derivative thereof. A crystalline aromatic polyamide such as polymetaxylene adipamide (MXD-nylon) is preferable. Specific examples include S-6007 and S-6011 (both manufactured by Mitsubishi Gas Chemical Co., Inc.).

  Alternatively, an amorphous aromatic polyamide (amorphous nylon) obtained by a polycondensation reaction between an aliphatic diamine such as hexamethylenediamine and a dicarboxylic acid such as terephthalic acid or isophthalic acid or a derivative thereof can be used. Preferred is a copolymer of hexamethylene diamine-terephthalic acid-hexamethylene diamine-isophthalic acid. Specific examples include Sealer PA (Mitsui / DuPont Polychemical Co., Ltd.) and the like.

  Preferred combinations of aliphatic polyamide and aromatic polyamide include a combination of nylon-6 and MXD-nylon, and a combination of nylon-6 and amorphous aromatic polyamide (amorphous nylon).

  The polyamide contains an aliphatic polyamide (particularly nylon-6) as a main component, and the aliphatic polyamide in the polyamide is about 80 to 100% by weight, preferably about 83 to 95% by weight, more preferably 85 to 90% by weight. About% is contained. In addition, the polyamide contains about 0 to 20% by weight of aromatic polyamide, preferably about 5 to 17% by weight, more preferably about 10 to 15% by weight.

Modified polyester elastomer layer (modified TPEE layer)
The modified TPEE layer functions as an adhesive layer that strengthens the adhesion between the crystalline polyester layer and the aliphatic polyamide layer, and the peel strength after adhesion of both is dramatically improved.

  The modified TPEE is obtained by modifying a saturated polyester thermoplastic elastomer containing a polyalkylene ether glycol segment with an unsaturated carboxylic acid or a derivative thereof. Specifically, it is obtained by modifying a saturated polyester thermoplastic elastomer having a polyalkylene ether glycol segment content of 58 to 73% by weight with an unsaturated carboxylic acid or a derivative thereof in the presence of a radical generator. It is a modified polyester elastomer. Since a reactive group is introduced by graft reaction and terminal addition reaction of unsaturated carboxylic acid or its derivative, chemical bondability and hydrogen bondability with various resins are improved.

  The saturated polyester thermoplastic elastomer is a block copolymer composed of a soft segment containing a polyalkylene ether glycol segment and a hard segment containing a polyester, and the content of the polyalkylene ether glycol segment is the polyester elastomer. It is about 58 to 73% by weight.

  Examples of the polyalkylene ether glycol constituting the soft segment include polyethylene glycol, poly (1,2 and 1,3-propylene ether) glycol, poly (tetramethylene ether) glycol, poly (hexamethylene ether) glycol, and the like. It is done. The polyalkylene ether glycol has a number average molecular weight of 400 to 6000.

  As unsaturated carboxylic acid or its derivative (s), unsaturated carboxylic acid, such as acrylic acid, maleic acid, fumaric acid, its acid anhydride, its ester, or its metal salt is mentioned, for example.

  Examples of the radical generator include peroxides such as t-butyl hydroperoxide and cumene hydroperoxide, and azo compounds such as 2,2′-azobisisobutyronitrile (AIBN).

  The blending ratio of each component is 0.01 to 30 parts by weight of the unsaturated carboxylic acid or a derivative thereof and 0.001 to 3 parts by weight of the radical generator with respect to 100 parts by weight of the saturated polyester thermoplastic elastomer.

  The method for preparing modified TPEE can be carried out as described in JP-A-2002-155135. MFR (JIS K7210 conformity, 230 degreeC, 2.16 kg) of the modified polyester-type elastomer obtained is 40-300 (g / 10min).

  Specifically, Primalloy AP-IF203 (Mitsubishi Chemical Corporation) and the like are exemplified.

  The above-mentioned modified TPEE layer has good adhesiveness, and is suitable for food packaging film applications where contact with high-temperature water such as boil treatment or retort treatment is assumed.

In polyamide-based multilayer stretched film comprising a gas barrier layer of at least seven layers, the resin constituting the gas barrier layer, an ethylene - vinyl alcohol copolymer (EVOH), and aromatic polyamide and the like. The inclusion of the gas barrier layer, the gas barrier property is remarkably improved.

  EVOH is not particularly limited, but has an ethylene content of 55 mol% or less (preferably 20 to 50 mol%, more preferably 29 to 44 mol%) and a saponification degree of vinyl acetate component of 90 mol% or more (preferably 95 mol% or more) is preferably used.

  EVOH includes a small amount of an α-olefin such as propylene, isobutene, α-octene, α-dodecene, α-octadecene, etc .; an unsaturated carboxylic acid or a derivative thereof (in the range not adversely affecting the effects of the present invention). For example, it may contain a comonomer such as a salt, a partial alkyl ester, a complete alkyl ester, a nitrile, an amide, an anhydride); an unsaturated sulfonic acid or a salt thereof.

  The melt index (MI) of EVOH is preferably 0.5 to 50 g / 10 min (210 ° C., 2160 g load), more preferably 1 to 35 g / 10 min (same as above). If the MI is 0.5 g / 10 min (same as above) or higher, the melt extrusion is not hindered. On the other hand, if the MI is 50 g / 10 min (same as above) or less, the deterioration of the film forming property is suppressed. it can.

  Examples of preferable EVOH include SG464B, DC3203FB, DT2903B (all manufactured by Nippon Synthetic Chemical Co., Ltd.) and the like.

  Examples of aromatic polyamides include polycondensation of aromatic diamines such as metaxylenediamine and paraxylenediamine with dicarboxylic acids such as adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, and isophthalic acid, or derivatives thereof. Examples thereof include crystalline aromatic polyamides obtained by the reaction. An aromatic nylon such as polymetaxylene adipamide (MXD-nylon) is preferable. Examples of the aromatic nylon include S-6007 and S-6011 (both manufactured by Mitsubishi Gas Chemical Co., Ltd.).

The gas barrier layer, a further effect does not adversely affect the scope of the present invention, aliphatic amides, modified ethylene vinyl acetate copolymer, may contain other components such as methacrylic acid copolymer ionomer. When containing other components in the gas barrier layer, the content of this component is usually 15 parts by weight or less relative to 100 parts by weight EVOH or aromatic polyamide, preferably preferably about 1.0 to 7.5 parts by weight .

  The total thickness of the polyamide-based multilayer stretched film of the present invention is about 10 to 50 μm, preferably about 15 to 40 μm. In such a range, the film productivity and the unit sales price are preferable.

  In the 5-layer film, the thickness of each layer is as follows: crystalline polyester layer (0.5-15 μm) / modified TPEE layer (0.5-3 μm) / aliphatic polyamide layer (5-40 μm) / modified TPEE layer (0.5-3 μm) / crystalline A polyester layer (0.5 to 15 μm) is preferable.

  In the 7-layer film, the thickness of each layer is as follows: crystalline polyester layer (0.5-15 μm) / modified TPEE layer (0.5-3 μm) / aliphatic polyamide layer (2-20 μm) / gas barrier layer (1-10 μm) / aliphatic polyamide Layer (2 to 20 μm) / modified TPEE layer (0.5 to 3 μm) / crystalline polyester layer (0.5 to 15 μm) is preferable. By setting the thickness of the aliphatic polyamide layer within this range, it is preferable that the pinhole resistance is excellent.

  In any of the 5-layer film and the 7-layer film, the total thickness of the aliphatic polyamide layer is about 30 to 95%, preferably about 40 to 90% with respect to the total thickness of the polyamide-based multilayer stretched film.

In seven-layer film, the thickness of the gas barrier layer may be about 2-50% of the total thickness of the polyamide-based multilayer stretched film. If it is this range, desired gas-barrier property can be provided to a film.

In the multilayer stretched film of the present invention, by setting each layer thickness within the above range, it is possible to obtain a film excellent in all of toughness, gas barrier property, dimensional stability, aroma retention, moisture resistance and pinhole resistance. it can.
II. Manufacture of a polyamide-type multilayer stretched film The polyamide-type multilayer stretched film of the present invention is coextruded on a chill roll in which cooling water circulates from a T die so as to be in the order of each layer to obtain a flat multilayer film. The obtained film was stretched longitudinally 2.5 to 4.5 times by a roll stretching machine at 50 to 100 ° C., for example, and further stretched to 2.5 to 5 times by a tenter stretching machine in an atmosphere at 90 to 150 ° C., and subsequently the same tenter. Can be obtained by heat treatment in an atmosphere of 100 to 240 ° C. The multilayer film of the present invention may be uniaxially stretched or biaxially stretched (simultaneous biaxial stretching, sequential biaxial stretching), and the obtained multilayer stretched film may be subjected to a corona discharge treatment on both surfaces or one surface if necessary. Can also be applied.
III. Features of the polyamide-based multilayer stretched film The polyamide-based multilayer stretched film of the present invention produced as described above has excellent toughness, gas barrier properties, dimensional stability, aroma retention, moisture resistance and more pinhole resistance. Have. Therefore, it is suitably used as a packaging film.

The polyamide-based multilayer stretched film of the present invention is excellent in abrasion resistance due to bending. Specifically, the number of pinholes generated in a gelboflex test at normal temperature (23 ° C.) × 1,000 times is 8/300 cm ² or less, further 6/300 cm ² or less, especially 5/300 cm ² or less. It has the characteristics. Evaluation of pinholes by bending is as described in Test Example 1.

  In addition, it has excellent wear resistance due to repeated contact. This “abrasion resistance by repeated contact” is evaluated by the method described in Examples described later.

  Specifically, the multilayer film is mounted on a conical aluminum jig, and the apex of the conical shape is brought into contact with the cardboard through the multilayer stretched film. Next, load 10 to 120 g on the jig, slide at a speed of 2700 mm / min and a moving distance of 45 mm under the condition of humidity 65% RH, and the number of sliding times until the pinhole is opened. Count (see, for example, FIG. 1). The occurrence of pinholes is determined by dripping the penetrating solution where the top of the jig hits the film. Under such measurement conditions, in the multilayer stretched film of the present invention, when the load is 63 g, the number of sliding times until the pinhole is opened is 500 times or more, preferably 750 times or more, more preferably 1000 times or more. If it is less than 500 times, the wear resistance is low and pinholes are likely to occur due to repeated wear during actual transportation.

  The polyamide-based multilayer stretched film of the present invention has excellent interlayer strength. A film is cut out with a width of 10 mm, and a T-peel test is performed at a speed of 200 mm / min at 23 ° C. × 65% RH at the interface between the crystalline polyester layer and the aliphatic polyamide layer. In this case, the peel strength (N / cm) is 1.0 N / cm or more, preferably 1.5 N / cm or more.

  Since the polyamide-based multilayer stretched film of the present invention has the above characteristics, it is suitably used as a packaging film. A sealing film is laminated on one surface of the polyamide-based multilayer stretched film to produce a packaging film. This is formed into a bag shape with the outermost layer facing outward, and the sealing layer surfaces are heat-sealed and processed into a bag shape to produce a packaging bag.

  Here, the sealing layer may be a resin film having heat sealing properties, and examples thereof include polyolefins such as LLDPE, LDPE, CPP, and EVA. As a method of laminating the polyamide-based multilayer film and the seal layer, a known method can be adopted. Also, a known method can be adopted as a heat sealing method.

  The obtained packaging bag is filled with the contents to obtain a package. The contents to be packaged are not particularly limited, but in particular, water-based foods such as soups, rice cakes, and pickles, heavy foods such as rice cakes, winners, and seasonings, shampoos, rinses, body soaps for refilling, The effect of the present invention is remarkably exhibited when packaging a heavy liquid such as a detergent.

  Examples of the form of the packaging bag include a bag-like form such as a three-side seal form, an envelope form, a closet form, and a flat bottom form, a spout pouch, a refill pouch, and the like.

  Furthermore, since the multilayer film of the present invention has high transparency, it is easy to visually check the contents when packaged.

  Next, the present invention will be described in more detail with reference to the following examples and comparative examples, but is not limited thereto.

Example 1
The polyester resin “Belpet-EFG6C” (manufactured by Bell Polyester Products) is used as the first layer and the fifth layer, and the adhesive resin “Primalloy AP-IF203” (Mitsubishi Chemical Corporation) is used as the second layer and the fourth layer. Used as the third layer, 85 parts by weight of polyamide resin nylon-6 “UBE nylon-1022FDX23” (manufactured by Ube Industries), 15 weight of amorphous nylon “sealer PA” (manufactured by Mitsui DuPont Polychemical Co., Ltd.) Part of the resin was used.

  The resin constituting each layer is coextruded on a chill roll in which cooling water circulates from a T die so that the first layer / second layer / third layer / fourth layer / fifth layer are arranged in order, A five-layer film was obtained. This 5-layer film was longitudinally stretched 2.7 times by a 65 ° C roll stretcher, then stretched 4.2 times by a tenter stretcher at 110 ° C atmosphere, and further in an atmosphere at 210 ° C by the same tenter. Was then heat-treated to obtain a 5-layer stretched film having a thickness of 15 μm. The thickness of each layer is as described in Table 1.

Examples 2-3
A 5-layer film was produced in the same manner as in Example 1, except that the thickness of each layer was changed as described in Table 1.

Example 4
Other than using nylon-6 / 6,6 “UBE nylon-5034B” (Ube Industries) instead of the third layer amorphous nylon “Sealer PA” (Mitsui / DuPont Polychemical) Produced a 5-layer stretched film in the same manner as in Example 1. See Table 1.

Example 5
The polyester resin “Belpet-EFG6C” (manufactured by Bell Polyester Products) is used as the first layer and the seventh layer, and the adhesive resin “Primalloy AP-IF203” (Mitsubishi Chemical Corporation) is used as the second layer and the sixth layer. Made of polyamide resin nylon-6 “UBE nylon-1022FDX23” (manufactured by Ube Industries), nylon-6 / 6,6 “UBE nylon-5034B” A resin containing 15 parts by weight of Ube Industries, Ltd.) was used, and a barrier resin “S-6011” (Mitsubishi Gas Chemical Co., Ltd.) was used as the fourth layer.

  Chill rolls in which cooling water circulates from the T dice so that the resin constituting each layer is in the order of first layer / second layer / third layer / fourth layer / fifth layer / sixth layer / seventh layer The film was coextruded to obtain a flat seven-layer film. This seven-layer film was longitudinally stretched 2.7 times by a 65 ° C. roll stretching machine, then transversely stretched 4.2 times by a 110 ° C. atmosphere tenter stretching machine, and further in a 210 ° C. atmosphere by the same tenter. And a seven-layer stretched film having a thickness of 15 μm was obtained. The thickness of each layer is as described in Table 1.

Examples 6-7
A seven-layer stretched film was produced in the same manner as in Example 5 except that the thickness of each layer was changed as described in Table 1.

Comparative Examples 1-2
90 parts by weight of polyamide resin nylon-6 “UBE nylon-1022FDX23” (manufactured by Ube Industries) instead of five layers of resin, nylon-6 / 6,6 “UBE nylon-5034B” (manufactured by Ube Industries) ) A single-layer stretched film (thickness 15 μm and 25 μm) was produced in the same manner as in Example 1 except that a single-layer resin composed of a resin containing 10 parts by weight was used.

Comparative Example 3
Instead of 5 layers of resin, the first and third layers are polyamide resin nylon-6 “UBE nylon-1022FDX23” (manufactured by Ube Industries), 90 parts by weight, nylon-6 / 6,6 “UBE nylon- 5034B "(manufactured by Ube Industries, Ltd.) Example 1 except that a resin compounded with 10 parts by weight was used, and the barrier resin" S-6011 "(manufactured by Mitsubishi Gas Chemical Co., Ltd.) was used as the second layer. Similarly, a single layer stretched film was produced. The thickness of each layer is as described in Table 1.

Comparative Example 4
Other than using polyester elastomer (TPEE) “Hytrel 4275” (manufactured by Toray DuPont) instead of adhesive resin “Primalloy AP-IF203” (manufactured by Mitsubishi Chemical Corporation) as the second and fourth layers A 5-layer stretched film was produced in the same manner as in Example 1. See Table 1.

Comparative Example 5
Implemented except that polyamide elastomer (TPAE) “Pebax 5533” (manufactured by Arkema) was used in place of the adhesive resin “Primalloy AP-IF203” (manufactured by Mitsubishi Chemical Corporation) as the second and fourth layers. A 5-layer stretched film was produced in the same manner as in Example 1. See Table 1.

Test example 1
About the polyamide-type multilayer stretched film obtained in Examples 1-7 and Comparative Examples 1-5, it measured about the test item shown below. The results are shown in Tables 2-6.
[Interlaminar strength test]
The film was cut out with a width of 10 mm and peeled off at the interface between the crystalline polyester layer and the aliphatic polyamide layer. Table 2 shows the results of a T-shaped peel test conducted at a speed of 200 mm / min under the condition of 23 ° C. × 65% RH.

It can be seen that the multilayer stretched film using the modified polyester elastomer as the adhesive resins of Examples 1 to 7 has excellent interlayer strength. On the other hand, the multilayer film using unmodified polyester elastomer and unmodified polyamide elastomer as the adhesive resins of Comparative Examples 4 and 5 resulted in insufficient interlayer strength.
[Thermal dimensional stability test]
A sample of MD × TD = 100 mm × 100 mm was heat-treated, and the shrinkage after the treatment was measured. The boil treatment shows the shrinkage (%) after 98 ° C. × 60 minutes, and the retort treatment shows the shrinkage (%) after 121 ° C. × 30 minutes. See Table 3.

It turns out that Examples 1-7 have a small shrinkage rate by heat processing and excellent dimensional stability as compared with Comparative Examples 1 and 2 which are polyamide single layer films. On the other hand, Comparative Examples 4 and 5 provided with an adhesive layer had insufficient interlayer strength, resulting in delamination during retort processing.
[Hygroscopic dimensional stability test]
A sample of MD × TD = 100 mm × 100 mm was subjected to moisture absorption treatment, and the shrinkage after the treatment was measured. Water treatment indicates normal temperature (23 ° C.) water × shrinkage rate (%) after 10 seconds, and storage under high humidity indicates shrinkage rate (%) after storage at 40 ° C. × 90% RH × 1 week. See Table 4.

It can be seen that Examples 1 to 7 are less stretched in film and superior in dimensional stability even in water treatment and storage under high humidity as compared with Comparative Examples 1 to 3.
[Scent retention]
Small sachets (3 cm × 8 cm) were prepared with each film, filled with 5 ml each of vinegar (rice vinegar, brewed vinegar) and sealed. This was sealed in a glass jar. The vinegar odor after 3 days was evaluated by sensory evaluation according to the following rank (n = 6). The average value is shown in Table 5.

sensory evaluation:
5: Not smelling at all 4: Smelling slightly 3: Smelling a little 2: Smelling 1: Smelling strongly [Dampproof]
Small sachets (3 cm × 8 cm) were prepared with each film, filled with 5 ml each of vinegar (rice vinegar, brewed vinegar) and sealed. This was sealed in a glass jar. The weight reduction rate (%) of the contents after 5 days was measured. The results are shown in Table 5.

  Since the above-mentioned measurement is affected by the thickness of the film, it was measured only with a film having a thickness of 15 μm.

It can be seen that Examples 1, 2 and 5 are superior to Comparative Examples 1 and 3 in terms of excellent fragrance retention, little change in weight of the contents, and excellent moisture resistance.
[Tensile strength and tensile elongation]
Measured according to JIS K-7127. The results are shown in Table 6.
[Evaluation of pinhole by bending]
Evaluation of the pinhole property by bending was performed using a gelbo flex tester manufactured by RIKEN. In this method, a film made in a cylindrical shape with a folding diameter of 150 mm and a length of 300 mm is attached to a Gelboflex tester, and a 62.5 cm linear horizontal motion at a twist angle of 440 ° is performed 1000 times under normal temperature (23 ° C) conditions. After the repetition, the number of pinholes is examined by using an osmotic solution. Note that the number of pinholes was measured at a location of 300 cm ^{2 in} the center portion of the sample that was twisted and bent. The number of pinholes was measured for three samples, and the average value is shown in Table 6.
[Evaluation of pinholes by repeated contact]
A film is attached to a jig made of aluminum with a cone shape using tape or the like, and the apex of the cone-shaped jig is placed on the cardboard through the film (for KOKUYO Campus, for fine puss, 430g / m ² ). The vertex R was set to a sliding direction R = 0.1 to 1.0 mm, and a direction R = 0.1 to 1.0 mm perpendicular to the sliding direction. Next, a load of 63 g was placed on the jig. The jig was slid in parallel with the cardboard at a speed of 2700 mm / min and a moving distance of 45 mm under the condition of a humidity of 65%, and the number of sliding times until a pinhole was formed was counted. The occurrence of pinholes was determined based on whether or not the penetrating solution was dropped onto the film where the top of the jig had hit and permeated on white paper. For eight samples, the number of sliding until a pinhole was formed was measured, and the average value was calculated. The results are shown in Table 6.

  FIG. 1 shows a schematic diagram of the measuring apparatus. FIG. 2 shows an example of a conical aluminum jig.

  In addition, since the thickness of the film affects the wear strength, it was measured only with a film having a thickness of 15 μm.

  The pinhole resistance by bending and the pinhole resistance by repeated contact are excellent in the examples, whereas the pinhole resistance by bending is excellent in the comparative example, but the pinhole resistance by repeated contact is not sufficient. I understand that.

The schematic diagram of the measuring apparatus used for evaluation of the pinhole which generate | occur | produces by repeated contact is shown. It is a figure which shows an example of a cone-shaped aluminum jig.

Claims (2)

  A polyamide-based multilayer laminate having at least 5 layers of crystalline polyester layer / modified polyester elastomer layer / aliphatic polyamide layer / modified polyester elastomer layer / crystalline polyester layer is 2.5 to 4.5 times in the vertical direction and 2.5 to 5 in the horizontal direction. It is a multilayer stretched film obtained by biaxially stretching twice, the total thickness of the multilayer stretched film is 10-50 μm, the thickness of each layer constituting the multilayer stretched film is 0.5- A polyamide-based multilayer stretched film having a thickness of 15 μm, an aliphatic polyamide layer of 5-40 μm, a modified polyester elastomer layer of 0.5-3 μm, and an aliphatic polyamide layer thickness of 30-95% in the multilayer stretched film.   A polyamide-based multilayer laminate having at least 7 layers of crystalline polyester layer / modified polyester elastomer layer / aliphatic polyamide layer / gas barrier layer / aliphatic polyamide layer / modified polyester elastomer layer / crystalline polyester layer is longitudinally 2.5 to 4.5. A multilayer stretched film obtained by biaxially stretching 2.5 to 5 times in the transverse direction, the total thickness of the multilayer stretched film is 10 to 50 μm, and the thickness of each layer constituting the multilayer stretched film is The crystalline polyester layer is 0.5 to 15 μm, the aliphatic polyamide layer is 2 to 20 μm, the modified polyester elastomer layer is 0.5 to 3 μm, the gas barrier layer is 1 to 10 μm, and the thickness ratio of the aliphatic polyamide layer in the multilayer stretched film is Polyamide-based multilayer stretched film that is 30 to 95%.

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