JP7026526B2 - Laminates for packaging bags and packaging bags - Google Patents

Description

The present invention relates to a laminate for a packaging bag and a packaging bag.

As a constituent material of a packaging bag for enclosing and transporting liquid articles such as foods, paints, cosmetics, and pharmaceuticals, a laminated body for a packaging bag composed of a laminated body of a plurality of films is known.

For example, Patent Document 1 describes a laminate material in which a biaxially stretched polypropylene film layer, an oxygen barrier layer, and a sealant layer are laminated in this order, and the laminate material is 2 of the medical infusion pack. It is explained that it is suitable as a next packaging material.

Patent Document 2 describes a polyethylene-based resin composition composed of linear low-density polyethylene and high-pressure low-density polyethylene, and a bag-in-box inner container formed from the resin composition.

In addition, Patent Document 3 describes a method of manufacturing a packaging bag containing contents by using a vertical bag-making filling machine. The method of Patent Document 3 is a step of heat-welding both edges of a long film to form a tubular film having a vertical sealing portion formed by the heat welding, and a step of forming a tubular film having facing inner surfaces of the tubular film. In the width direction, there is a step of heat welding leaving a part so as to form an opening, a step of charging the packaged material (contents) into the tubular film from the opening, and an opening after the packaged material is charged. The portion includes a step of heat welding the facing inner surfaces of the tubular films in the width direction.

Japanese Unexamined Patent Publication No. 2006-7509 Japanese Unexamined Patent Publication No. 11-166081 Japanese Patent Application Laid-Open No. 2002-234504

Pinholes are unlikely to occur in the packaging bag for packaging liquid articles and the laminate material that composes the packaging material when stresses such as twisting, drop impact, and friction on bent parts are applied. Desired. The reason is as follows.

When a packaging bag containing contents is produced from a packaging bag laminate, the method described in Patent Document 3 is specifically performed as follows, for example. The laminate for packaging bags is formed into a long film and wound into a roll. The wound laminate material is, for example, unwound in the horizontal direction, then twisted by 90 ° to change the direction in the vertical direction, and is supplied to the vertical bag-making filling machine from above. At this time, pinholes may occur due to the stress of twisting the laminate material.

The laminate for packaging bags supplied to the bag-making filling machine is formed into a tubular body having an opening by sealing (for example, heat-sealing) one end or both ends of the side in the length direction, and further, the end side of the film. After the opening is sealed and formed into a bag shape, for example, a liquid article (packaged object) is injected from the opening. After injecting the liquid article, the opening of the tubular body is sealed and further cut at the sealed portion to form a packaging bag containing the contents. This content packaging bag falls to the floor after being cut. At the time of this drop, a drop impact is applied to the packaging bag, and the stress may cause pinholes.

The obtained packaging bags containing the contents are packed in several cardboard boxes, for example, and transported to the consumption area by, for example, railroads, trucks, aircraft, and the like. Vibration during transportation may cause friction between the packaging bag and the wall of another packaging bag or packaging cardboard box that is packed adjacently, and the stress may cause pinholes. In particular, the liquid article as the content may shake due to vibration during transportation and push up a part of the laminate material from the inside of the packaging bag, resulting in wrinkles or folds in the laminate material. When the bent portion of the wrinkle or fold is rubbed, pinholes are more likely to occur.

Therefore, a packaging bag for packaging a liquid article and a laminate material constituting the packaging bag are particularly required to have a high degree of pinhole resistance against stress.

An object of the present invention is to provide a laminated body for a packaging bag in which pinholes are unlikely to occur even when stress such as twisting, a drop impact, and friction on a bent portion is applied, and a packaging bag composed of the laminate. Is.

The present invention is as follows.

<< Aspect 1 >> A laminate having a base material layer and a sealant layer.
The substrate layer contains a nylon film or a polyester film and contains.
The sealant layer has a tensile elastic modulus of 350 MPa or less according to JIS K 7127 and a tear strength of 6.0 N or more according to JIS K 7128.
Laminate for packaging bags.
<< Aspect 2 >> The laminate according to << Aspect 1 >>, wherein the sealant layer has a tensile elastic modulus of 100 MPa or more and 300 MPa or less.
<< Aspect 3 >> The laminate according to << Aspect 1 >> or << Aspect 2 >>, wherein the sealant layer has a tear strength of 6.5 N or more and 15.0 N or less.
<< Aspect 4 >> The laminate according to any one of << Aspect 1 >> to << Aspect 3 >>, wherein the sealant layer is composed of a polyolefin film containing linear low-density polyethylene.
<< Aspect 5 >> The laminate according to any one of << Aspect 1 >> to << Aspect 4 >>, wherein the base material layer contains a nylon film.
<< Aspect 6 >> The laminate according to any one of << Aspect 1 >> to << Aspect 5 >>, wherein the base material layer has a tensile elastic modulus of 1,000 MPa or more according to JIS K 7127.
<< Aspect 7 >> The laminate according to any one of << Aspect 1 >> to << Aspect 6 >>, which further has a surface layer, and has a surface layer, a base material layer, and a sealant layer in this order.
<< Aspect 8 >> The laminate according to << Aspect 7 >>, wherein the surface layer is composed of a polyolefin film containing polypropylene.
<< Aspect 9 >> A packaging bag in which the laminate according to any one of << Aspect 1 >> to << Aspect 8 >> is formed into a bag shape.
The packaging bag according to << Aspect 10 >><< Aspect 9 >>
The contents sealed in the packaging bag and
Packing bag with contents, including.
<< Aspect 11 >> The packaging bag containing the contents according to << Aspect 10 >>, wherein the contents are liquid articles.

According to the present invention, there is provided a laminate material in which pinholes are unlikely to occur even when twisting, a drop impact, friction on a bent portion, or the like is applied, and a packaging bag made of the same.

FIG. 1 is a schematic cross-sectional view showing an example of the configuration of the laminated body of the present invention. FIG. 2 is a schematic cross-sectional view showing another example of the configuration of the laminated body of the present invention.

<< Laminated body >>
An example of the structure of the laminated body for a packaging bag of the present invention is shown in FIG. The laminated body for a packaging bag of the present invention is
A packaging bag laminate (10) having a base material layer (1) and a sealant layer (2).
The base material layer (1) contains a nylon film and contains.
The sealant layer (2) has a tensile elastic modulus of 350 MPa or less according to JIS K 7127 and a tear strength of 6.0 N or more according to JIS K 7128.

The tensile modulus in the present specification is a value when tested in accordance with JIS K 7127.

The tear strength in the present specification is a value when tested in accordance with the Elmendorf tear method described in JIS K 7128 Part 2. However, the measurement result is not assigned by the thickness of the test piece, and the average value of the measured tear strength itself is adopted.

The laminate for packaging bags of the present invention has improved pinhole resistance by using a base material layer containing a nylon film or a polyester film in combination with a sealant layer having a tensile elastic modulus and tear strength in the above ranges. There is.

Nylon film is suitable as a packaging bag material for liquid articles such as foods because it has excellent oxygen blocking properties and high toughness. Further, polyester films, particularly polybutylene terephthalate films, are excellent in aroma retention and also have high toughness, and are therefore used as packaging materials for liquid articles such as foods having a high fragrance. However, both nylon and polyester have a high melting point, and it is difficult to seal them with a single film. In addition, these films are hard and easily cracked when stress is applied. Therefore, in order to impart sealing properties and stress resistance to the packaging material in addition to oxygen blocking property or fragrance retaining property, a base material layer containing a nylon film or a polyester film and a lower melting point than these are used. It is used by laminating a sealant layer made of a soft material.

Here, in the laminated body for packaging bags of the present invention, a material having a tensile modulus of elasticity according to JIS K 7127 of 350 MPa or less and a tear strength of JIS K 7128 of 6.0 N or more is selected as the sealant layer. Use.

A tensile elastic modulus of 350 MPa or less means that it is easily elastically deformed even by a small stress. When a sealant layer that is easily deformed elastically by stress is used, the stress applied to the laminated body is relaxed by the deformation of the sealant layer, and the stress applied to the base material layer is reduced, whereby the pin resistance of the laminated body is reduced. It is considered that the hole property is improved.

A tear strength of 6.0 N or more means that when a minute crack that does not reach a pinhole is generated, the resistance to the expansion of the crack is large. Therefore, if a sealant layer having a tear strength of 6.0 N or more is used, even when minute cracks are generated in the laminated body (particularly the base material layer), the cracks are difficult to expand, so that pinholes are formed in the entire laminated body. It is considered that it is less likely to occur and the packaging bag is prevented from leaking (breaking bag).

Therefore, in the present invention, the base material layer containing the nylon film or the polyester film is combined with the sealant layer having a tensile elastic modulus of 350 MPa or less according to JIS K 7127 and a tear strength of 6.0 N or more according to JIS K 7128. By using this film, a laminate for packaging bags, which is excellent in oxygen blocking property or fragrance retaining property and toughness, and exhibits extremely improved pinhole resistance, can be obtained.

Another example of the structure of the laminated body for a packaging bag of the present invention is shown in FIG. In this case, the laminate for the packaging bag of the present invention is
A package having a surface layer (3) in addition to the base material layer (1) and the sealant layer (2), and having the surface layer (3), the base material layer (1), and the sealant layer (2) in this order. It may be a laminated body for a bag (20), and here,
The base material layer (1) contains a nylon film or a polyester film, and contains.
The sealant layer (2) has a tensile elastic modulus of 350 MPa or less according to JIS K 7127 and a tear strength of 6.0 N or more according to JIS K 7128.

Hereinafter, each layer constituting the packaging bag laminate of the present invention will be described in order.

<Base material layer>
The base material layer is a layer containing a nylon film or a polyester film. The polyester film may be, for example, a polybutylene terephthalate (PBT) film or the like.

In the laminate for packaging bags of the present invention, the base material layer may be relatively hard because an extremely high degree of pinhole resistance is imparted by the use of the sealant layer specified in the present invention. The substrate layer in the present invention may have a tensile elastic modulus according to JIS K 7127, for example, 500 MPa or more, 800 MPa or more, 1,000 MPa or more, 1,500 MPa or more, 2,000 MPa or more, or 2,500 MPa or more. .. On the other hand, if the base material layer is excessively hard, it may cause inconvenience in the manufacture and use of the packaging bag. In order to avoid this, the tensile elastic modulus of the base material layer is, for example, 10,000 MPa or less. Alternatively, it may be 5,000 MPa or less.

For the same reason as described above, the tear strength of the substrate layer in the present invention may be relatively small. The substrate layer in the present invention has a tear strength according to JIS K 7128, for example, 5.0 N or less, 3.0 N or less, 1.0 N or less, 0.50 N or less, 0.30 N or less, or 0.10 N or less. It may be there. On the other hand, in order to avoid inconvenience in handling, the tear strength of the base material layer may be, for example, 0.01 N or more, 0.03 N or more, or 0.05 N or more.

When the tensile elastic modulus and the tear strength of the base material layer are different in the MD direction and the TD direction, respectively, it is preferable to satisfy the above requirements in one direction of MD or TD, and in both the MD and TD directions. It is more preferable to meet the above requirements.

The nylon film or polyester film in the base material layer of the laminate for packaging bags of the present invention may be either a stretched film or a non-stretched film. When, for example, a nylon film is used as the base material layer in the packaging bag material, a non-stretched nylon film has been preferable in the prior art. However, in the laminate of the present invention, a stretched nylon film can be applied in addition to the unstretched nylon film, and it is preferable to use the stretched nylon film. The stretching may be either uniaxial stretching or biaxial stretching. The stretching method in the case of biaxial stretching is arbitrary, and for example, a nylon film stretched by tubular biaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, or the like may be used.

The base material layer may be a single layer or a multi-layer. The multilayer may be composed of a plurality of films selected from a nylon film and a polyester film, or may be a combination of these films and other films. The other film may be, for example, an ethylene-vinyl acetate copolymer or the like. The base material layer in the present invention is typically a single layer of a nylon film or a polyester film having the above-mentioned preferable properties, or a multilayer in which two or more layers selected from such a nylon film and a polyester film are laminated. It may be there.

The base material layer may have a barrier layer on one side or both sides thereof. The barrier layer may be, for example, a thin-film deposition layer containing silica, alumina, or the like.

The thickness of the base material layer is, for example, 5 μm or more, 8 μm or more, in order to ensure the protection of the contents of the packaging bag, impart the necessary toughness to the laminate and the packaging bag, and ensure good handleability. It may be 10 μm or more, 12 μm or more, or 15 μm or more, and may be, for example, 50 μm or less, 40 μm or less, 30 μm or less, or 20 μm or less. In the prior art, in order to improve the pinhole resistance of the laminate and the packaging bag, the thickness of the base material layer is designed to be thick, specifically, the base material layer exceeds 20 μm, typically about 25 μm. Was heavily used. However, in the laminate for packaging bags of the present invention, by using the base material layer in combination with the sealant layer specified in the present invention, the expected performance can be exhibited even when the base material layer is thin, for example, 20 μm or less. Typically, it may be about 15 μm.

<Sealant layer>
The sealant layer may have a tensile elastic modulus of 350 MPa or less according to JIS K 7127 and a tear strength of 6.0 N or more according to JIS K 7128, and may have a heat-sealing property.

In order to sufficiently elastically deform the sealant layer when stress is applied to the packaging bag laminate to relieve the stress and reduce the stress applied to the base material layer, the tensile elastic modulus of the sealant layer is set. It may be 350 MPa or less, 300 MPa or less, 250 MPa or less, 200 MPa or less, or 150 MPa or less. On the other hand, in order to ensure the handleability as a laminated body, the tensile elastic modulus of the sealant layer may be 100 MPa or more, 110 MPa or more, 120 MPa or more, 130 MPa or more, 140 MPa or more, 160 MPa or more, 180 MPa or more, or 200 MPa or more. .. The tensile elastic modulus of the sealant layer may typically be 100 MPa or more and 300 MPa or less.

When minute cracks occur in the laminate, the tear strength of the sealant layer is 6.0 N or more, 6.5 N or more, 7.0 N or more, in order to sufficiently increase the resistance to the expansion of the cracks. It may be 7.5 N or more, or 8.0 N or more. On the other hand, considering the manufacturing cost or availability, the tear strength of the sealant layer does not need to be excessively high, for example, 15.0N or less, 12.0N or less, 10.0N or less, 9.5N or less, 9.0N. It may be less than or equal to or less than 8.5N. The tear strength of the sealant layer may typically be 6.5 N or more and 15.0 N or less.

When the tensile elastic modulus and the tear strength of the sealant layer are different in the MD direction and the TD direction, respectively, it is preferable to satisfy the above requirements in one direction of MD or TD, and the above in both the MD and TD directions. It is more preferable to meet the requirements of.

The sealant layer may include, for example, a layer made of a thermoplastic resin.

Examples of the thermoplastic resin constituting the sealant layer include polypropylene (PP), ethylene-vinyl acetate copolymer (EVA), ionomer resin, ethylene-acrylic acid copolymer (EAA), and ethylene-methacrylic acid copolymer. (EMAA), polyethylene and the like can be mentioned. Polyethylene is preferable, and specific examples thereof include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and the like. One or more of the following may be used. The sealant layer is preferably made of a polyolefin film containing LLDPE, and more preferably made of an LLDPE film, from the viewpoint of imparting good low-temperature heat-sealing properties, processability, and the like.

The sealant layer may be a single layer composed of one resin layer or a laminated body composed of a plurality of resin layers. When the sealant layer is a laminate composed of a plurality of resin layers, the resins constituting each layer may be the same or different from each other.

The thickness of the sealant layer is, for example, 30 μm or more, 40 μm or more, 50 μm or more, or from the viewpoint of sufficiently increasing the pinhole resistance by protecting the base material layer and ensuring the sealing property when it is used as a packaging bag. It may be 60 μm or more. However, the sealant layer does not have to be excessively thick, and its thickness may be, for example, 200 μm or less, 180 μm or less, 160 μm or less, 140 μm or less, or 120 μm or less.

<Surface layer>
The surface layer optionally used in the laminated body for packaging bags of the present invention is a layer that is laminated on the surface of the base material layer opposite to the sealant layer to protect the base material layer. .. That is, in the laminated body for packaging bags of the present invention, the base material layer is protected by the sealant layer, and the generation of pinholes due to stress is suppressed. However, when the laminate in which the base material layer is arranged on the outermost surface is molded into a packaging bag, stress on the packaging bag is directly applied to the relatively hard base material layer, and there is a complete concern about the occurrence of pinholes. Will not be wiped out. Therefore, by further arranging the surface layer on the laminate for packaging bag of the present invention to have the surface layer, the base material layer, and the sealant layer in this order, the base material layer is formed by the surface layer and the sealant layer. It protects from both sides to further improve pinhole resistance.

The surface layer is preferably a layer made of a soft resin rather than a base material layer, and may include, for example, a layer made of a thermoplastic resin.

The thermoplastic resin constituting the surface layer may be, for example, a polyolefin such as polypropylene (PP) or polyethylene; or a polyester such as polyethylene terephthalate. When the surface layer is a layer composed of a polyolefin such as unstretched PP, uniaxially stretched PP, biaxially stretched PP, and high density polyethylene (HDPE), the resulting packaging bag has pinhole resistance to bending. It will be expensive. When the surface layer is composed of a polyolefin film containing polypropylene, the pinhole resistance to bending and friction is high, which is preferable. In particular, when the surface layer is a biaxially stretched PP film, pinhole resistance to bending and friction is high. It is more preferable because it has extremely high properties. In some cases, the laminate for packaging bags of the present invention does not have a surface layer other than the polyolefin film containing polypropylene.

The thickness of the surface layer may be, for example, 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more, but does not need to be excessively thick, for example, 50 μm or less, in order to ensure the protection of the base material layer. It may be 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

<< Manufacturing method of laminated body >>
The laminated body for a packaging bag of the present invention may be produced by laminating the base material layer and the sealant layer, or the surface layer, the base material layer, and the sealant layer in this order by any method as described above. .. Specifically, for example, after forming each layer constituting the packaging bag laminate of the present invention separately, these may be laminated by dry laminating, wet laminating, hot melt laminating or the like; the packaging bag of the present invention. After forming a part of the layers constituting the laminate for use, another layer may be formed on this layer by extrusion laminating; each layer constituting the laminate for packaging bag of the present invention is formed by coextrusion. It may be done; a combination of these methods may be used.

《Packaging bag》
The packaging bag of the present invention may be configured by forming the laminate for the packaging bag of the present invention into a bag shape. As a method for forming the laminate for packaging bag of the present invention into a bag shape, specifically, for example, two laminates are prepared, the sealant layers are opposed to each other so as to face inward, and the peripheral edge of the sealant layer is sealed. It may be molded by It may be formed into a tubular shape, and the tubular body may be cut into an appropriate size and then molded by sealing both ends of the cut. The seal in these methods may be, for example, a heat seal.

《Packaging bag with contents》
The packaging bag containing the contents of the present invention includes the packaging bag of the present invention as described above and the contents sealed in the packaging bag.

The contents of the packaging bag containing the contents may be a liquid article. The liquid article may be, for example, food, pharmaceuticals, cosmetics, paints and the like. Foods include, for example, beverages, edible oils, soups, creams, liquid seasonings (eg, soy sauce, vinegar, noodle soup, warishita, mirin, Worcestershire sauce, ketchup, tabasco, sweeteners, etc.). Pharmaceuticals include, for example, injections, infusions, infusions, perfusates, decoctions and the like. Cosmetics include, for example, shampoos, conditioners, hair styling products (eg, hair water, hair liquids, greases, etc.) and the like. The paint includes, for example, paint, varnish, oil stain and the like.

<Example 1>
(1) Manufacture of laminate for packaging bag Nylon film as a base material layer (manufactured by Kojin Film & Chemicals Co., Ltd., product number "RX # 15", thickness 15 μm) and LLDPE film as a sealant layer (Tamapoli Co., Ltd.) ), Part number "TS200", thickness 70 μm) were bonded together using a dry laminator so that the MD directions of the two were aligned to produce a film-shaped laminate for packaging bags.

Table 1 shows the characteristics of each layer used here.

(2) Evaluation of the laminated body for packaging bag (2-1) Bending test The laminated body for packaging bag obtained in (1) above was cut out into a rectangular shape having an MD direction of 210 mm and a TD direction of 286 mm. The cut-out laminate for packaging bags is formed into a cylinder with the sealant layer side inside and the MD direction in the height direction, and the axial direction of the cylinder is horizontal to the fixed head and movable head of the Gelboflex tester manufactured by Toyo Seiki Seisakusho Co., Ltd. I fixed it so that it would be. Then, a bending test was conducted under the following conditions in accordance with the US military specification standard MIL-B-131D, and the number of pinholes after bending 1,000 times was examined.

(Bending test conditions)
The movable head of the tester was rotated by 440 ° while moving 88.9 mm in the direction of the fixed head, and then further moved by 63.5 mm without rotating, and then these movements were reversed to the original. A series of movements to return to the position was regarded as one cycle, and the bending test was repeated a predetermined number of times at a speed of 40 cycles / minute.

This bending test was performed on three laminated samples. Table 2 shows the bending test results of each sample.

(2-2) Transport test Using a bag-making filling machine "ONPACK2530" manufactured by Orihiro Co., Ltd., a packaging bag made of the packaging bag laminate obtained in (1) above is filled with 1 kg of water and sealed. In addition, a vertical pillow type packaging bag containing contents having a length of 300 mm and a width of 150 mm was manufactured. Six of the obtained packaging bags containing the contents were packed in cardboard boxes having a length of 340 mm, a width of 245 mm, and a height of 100 mm. At this time, three cardboard boxes in which three pieces were arranged so that the long sides of the vertical pillows of adjacent packaging bags were in contact with each other were stacked and packed.

The pre-packed cardboard box was set in a transport packaging tester "BF-100UT" manufactured by IDEX Co., Ltd., and a transport test was conducted under the condition of an acceleration of 3.5 G. The device was stopped every 20 minutes of the test time (transportation distance: equivalent to 1,000 km), and the number of packaging bags in which the bag was broken (leakage occurred) was examined. The number of samples used in the test was 18 (for 3 cardboard boxes) up to 1,000 km, and 6 (for 1 cardboard box) thereafter. The results are shown in Table 4.

<Examples 2 to 6 and Comparative Examples 1 and 2>
(1) Production of Laminate for Packaging Bag A laminate for packaging bag was produced in the same manner as in Example 1 except that the LLDPE films shown in Table 1 were used as the sealant layer. Table 1 shows the characteristics of each layer used here (the sealant layer is a value for a product having a thickness of 70 μm).

(2) Evaluation of the laminated body for packaging bag (2-1) Bending test Using the laminated body for packaging bag obtained above, a bending test was performed in the same manner as in Example 1. The results are shown in Table 2. In addition, for the laminated bodies of Examples 4 to 6, the number of bendings was continued up to 2,000 times, and the number of pinholes after bending 2,000 times was also examined. The results are shown in Table 3.

(2-2) Transport test Using the laminates for packaging bags obtained in Examples 2, 3 and 5, and Comparative Example 1, a transport test was conducted in the same manner as in Example 1. At this time, in the transport test in Example 5, the number of samples up to a transport distance of 1,000 km was set to 42 (7 cardboard boxes). The evaluation results are shown in Table 4.

<Example 7>
(1) Manufacture of laminate for packaging bag PP film as surface layer (manufactured by Futamura Chemical Co., Ltd., product number "FOR # 20", thickness 20 μm) and nylon film as base material layer (Kojin Film & Chemicals (Kojin Film & Chemicals) MD of each layer manufactured by Tamapoli Co., Ltd., product number "RX # 15", thickness 15 μm) and LLDPE film as a sealant layer (manufactured by Tamapoli Co., Ltd., product number "TS200:", thickness 70 μm). A film-shaped laminate for packaging bags was manufactured by laminating in the order described above so that the directions match. Table 1 shows the characteristics of each layer used here.

(2) Evaluation of Laminate for Packaging Bag The laminate for packaging bag obtained above was evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 2 and 4.

<Examples 8 to 10>
A laminate for packaging bags was produced in the same manner as in Example 5, except that the films shown in Table 1 were used as the surface layer and the sealant layer, respectively, and a bending test and a transportation test were performed.

Table 1 shows the characteristics of each layer used here. The evaluation results are shown in Tables 2 and 4.

With reference to Tables 1-4, the following can be understood.

In a laminate for packaging bags having a base material layer and a sealant layer, a base material layer made of nylon and a sealant layer made of LLDPE having a tensile elastic modulus of more than 350 MPa and / or a tear strength of less than 6.0 N are provided. In the laminated bodies of Comparative Examples 1 and 2 used, pinholes may occur after bending 1,000 times when the bending test based on MIL-B-131D was performed. On the other hand, the laminates for packaging bags of Examples 1 to 6 using the sealant layer made of LLDPE having a tensile elastic modulus of 350 MPa or less and a tear strength of 6.0 N or more were subjected to a bending test under the same conditions. No pinholes occurred after 1,000 bends (see Tables 1 and 2).

Looking at Examples 4 to 6 in which the thickness of the sealant layer was changed, there was no substantial effect on the bending resistance when the thickness of the sealant layer was at least 40 μm or more and 100 μm or less, and in the bending test under the above conditions. No pinholes were generated after 1,000 bends, and very few pinholes were generated after 2,000 bends (see Table 3).

Further, in the packaging bag containing the contents obtained from the laminate of Comparative Example 1, in the transportation test, 4 out of 18 test bags were broken at a transportation distance equivalent to 1,000 km, whereas the packaging bag was carried out. The content-containing laminates of Examples 1 to 3 and 5 showed excellent transport resistance.

The laminate for packaging bags of Examples 7 to 10 having a surface layer further and having a surface layer, a base material layer, and a sealant layer in this order had pinholes after being bent 1,000 times in the bending test under the above conditions. It did not occur and showed excellent transport resistance in the transport test of the packaging bag containing the contents.

1 Base material layer 2 Sealant layer 3 Surface layer 10, 20 Laminate for packaging bag

Claims (10)

A laminate having a surface layer, a base material layer , and a sealant layer in this order .
The surface layer is composed of a polyolefin selected from uniaxially stretched polypropylene, biaxially stretched polypropylene, and high-density polyethylene.
The substrate layer contains a nylon film or a polyester film and contains.
The sealant layer has a tensile elastic modulus of 130 MPa or more and 350 MPa or less according to JIS K 7127, and a tear strength conforming to JIS K 7128 of 6.0 N or more and 12.0 N or less in both MD and TD directions .
Laminate for packaging bags. The laminate according to claim 1, wherein the sealant layer has a tensile elastic modulus of 160 MPa or more and 300 MPa or less. The laminate according to claim 1 or 2, wherein the sealant layer has a tear strength of 6.5 N or more and 15.0 N or less in both the MD and TD directions . The laminate according to any one of claims 1 to 3, wherein the sealant layer is composed of a polyolefin film containing linear low-density polyethylene. The laminate according to any one of claims 1 to 4, wherein the base material layer contains a nylon film. The laminate according to any one of claims 1 to 5, wherein the base material layer has a tensile elastic modulus of 1,000 MPa or more according to JIS K 7127. The laminate according to any one of claims 1 to 6, wherein the surface layer is composed of a polyolefin film containing biaxially stretched polypropylene. A packaging bag in which the laminate according to any one of claims 1 to 7 is molded into a bag shape. The packaging bag according to claim 8 and
The contents sealed in the packaging bag and
Packing bag with contents, including. The packaging bag containing the contents according to claim 9 , wherein the contents are liquid articles.

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