JP6375974B2 - Easy tear multilayer sealant film and packaging material - Google Patents

Description

  The present invention relates to an easily tearable multilayer sealant film and a packaging material. More specifically, the present invention relates to an easily tearable multilayer sealant film that has excellent tearability in the longitudinal direction and lateral direction, and also has high transparency, high gloss, and high interfacial strength. And a packaging material using the same.

Laminate films mainly used for food packaging films and the like are laminated with films having different properties to make use of their respective characteristics to constitute a packaging material having desired performance.
In general, the laminate film is a base film used as a surface substrate of a laminate film such as OPP, PET, ONy, a sealant film used as an inner surface of a film as a heat seal material, and a base film and a sealant film depending on applications. And a film of an intermediate substrate (barrier sand film) used for the purpose of blocking oxygen, water vapor, light, and the like.
Usually, the sealant film used is often a single-layer film blended with a weldable polyethylene resin because of its ease of use and the advantage of being weldable at low temperatures.
On the other hand, in food packaging materials, etc., hand tearability that can be easily opened by hand is required. Even if an easily tearable biaxially stretched OPP film or the like is used for the base film of the base material, packaging is possible. There was a problem that in the portion of the sealant film constituting the material, the resin was stretched and the tearability was poor.
As described above, a sealant film used for a packaging material or the like is required to satisfy both heat sealability and easy tearability. In response to such demands, attempts have been made to impart easy tearability, heat sealability, and the like by using a polypropylene resin and a cyclic olefin resin. For example, a coextruded multilayer film composed of an outer layer made of polypropylene resin, an intermediate layer made of a mixture of 10-30% by weight of cyclic olefin resin and polyethylene resin, and an inner layer made of polyethylene resin (see Patent Document 1). Proposed.
However, these films are excellent in heat sealability, but in any case, sufficient tearability has not yet been obtained. Moreover, since low-density polyethylene is used as the main component for the intermediate layer and laminated with the outer-layer polypropylene resin, there is a concern that the heat seal strength may be reduced due to the low interfacial adhesive strength between the two layers. From such a point of view, there is a problem in using the packaging material for easy tear opening that can be easily opened by hand.
Therefore, it is excellent in the tearability in the longitudinal direction and the transverse direction, and further in the balance of the tearability in the longitudinal direction and the transverse direction, and is required for a packaging film having high rigidity, high gloss, high transparency, heat sealability, etc. An easily tearable film suitable for a packaging material having both properties has been desired.

JP 2010-234660 A

  An object of the present invention is to provide an easily tearable multilayer sealant film having excellent longitudinal and lateral tearability, high transparency and high gloss, and sufficient interfacial strength, and a packaging material using the same. is there.

  By laminating a polypropylene resin layer having a specific melting point obtained from a metallocene catalyst and a polyethylene resin layer containing a cyclic olefin resin in a multilayer film in which a polypropylene resin and a polyethylene resin are laminated, I found out that the problem can be solved. These findings have been further studied and the present invention has been completed.

  That is, according to the first invention of the present invention, an outer layer (A) comprising a resin composition mainly composed of a polypropylene resin (a1) having a laminated structure of at least three layers and a melting point of 130 ° C. or less. ), An intermediate layer (B) comprising a resin composition containing 10 to 90% by weight of the linear polyethylene resin (b1) and 10 to 90% by weight of the cyclic olefin resin (b2), and a melting point of 130 ° C. There is provided an easily tearable multilayer sealant film having an inner layer (C) made of a resin composition containing as a main component a polypropylene resin (c1) as described below.

According to the second invention of the present invention, in the first invention, the polypropylene resin (a1) and the polypropylene resin (c1) are ethylene / propylene / random copolymers obtained by using a metallocene catalyst. An easily tearable multilayer sealant film is provided.

According to the third invention of the present invention, in the first or second invention, the density of the polyethylene resin (b1) measured in accordance with JIS K7112 is 0.895-0.970 g / cm. ³ is an easily tearable multilayer sealant film, characterized in that it is a linear polyethylene.

  According to the fourth invention of the present invention, in the first to third inventions, the resin composition of the intermediate layer (B) further comprises a low density polyethylene resin (b3) obtained by a high pressure radical polymerization method. An easily tearable multilayer sealant film characterized by containing 3 to 25% by weight is provided.

  According to the fifth invention of the present invention, in the first to fourth inventions, the cyclic olefin resin (b2) is a norbornene copolymer having a glass transition temperature Tg of 60 ° C. or higher. An easily tearable multilayer sealant film characterized by being a resin is provided.

  According to a sixth invention of the present invention, in the first to fifth inventions, the Elmendorf tear strengths of the MD and TD of the film are both 10 N / mm or less. A sealant film is provided.

  According to the seventh invention of the present invention, in the first to sixth inventions, the outer layer (A) has a glossiness of 70% or more at an incident angle of 20 ° measured with reference to JIS Z8741. An easily tearable multilayer sealant film is provided.

  Further, according to the eighth invention of the present invention, in the first to seventh inventions, in the film specimen having a width of 15 mm and a thickness of 50 μm in accordance with JIS Z1713, the lower bar temperature is 60 ° C. and the upper bar temperature is 160 ° C. An easily tearable multilayer sealant film having a heat seal strength of at least 17 N / 15 mm is provided.

  According to the ninth invention of the present invention, in the first to eighth inventions, the polyethylene resin (a2) and / or the polyethylene resin (c2) are respectively applied to the outer layer (A) and / or the inner layer (C). An easily tearable multilayer sealant film characterized by containing 1 to 40% by weight is provided.

  According to the tenth invention of the present invention, in the first to ninth inventions, there is provided an easily tearable multilayer sealant film in which PET and nylon are bonded to the outer layer (A) as a base material.

  According to the easily tearable multilayer sealant film and packaging material of the present invention, in the first invention, the main component is a polypropylene resin (a1) having a laminated structure of at least three layers and having a melting point of 130 ° C. or less. An intermediate layer comprising an outer layer (A) comprising a resin composition comprising 10 to 90% by weight of a linear polyethylene resin (b1) and 10 to 90% by weight of a cyclic olefin resin (b2). By having the layer (B) and the inner layer (C) made of a resin composition whose main component is a polypropylene resin (c1) having a melting point of 130 ° C. or less, the value of the tear strength in the longitudinal and transverse directions is small. Not only is it easy to tear, it also has a good balance of tear strength in both directions, as well as excellent rigidity, transparency and gloss.

In addition, according to the second invention, the polypropylene resin of the inner and outer layers is an ethylene / propylene / random copolymer obtained with a metallocene catalyst, so that the interface strength with the intermediate layer is excellent, Excellent transparency, gloss and low temperature heat sealability.

Further, according to the third invention, since the density of the polyethylene resin in the intermediate layer is a linear polyethylene having a density of 0.895 to 0.970 g / cm ³ , the interface strength with the inner and outer layers is excellent.

  Further, according to the fourth invention, the resin composition of the intermediate layer (B) further contains 3 to 25% by weight of the low density polyethylene resin (b3) obtained by the high pressure radical polymerization method. Excellent tearability.

  According to the fifth invention, the cyclic olefin-based resin is a norbornene-based copolymer having a glass transition temperature Tg of 60 ° C. or higher, so that it is not only excellent in tearability but also in close contact with the outer layer and the inner layer. Excellent in properties.

Further, according to the sixth aspect of the present invention, the Elmendorf tear strength of the MD and TD of the film is 10 N / mm or less, so that it is excellent in easy tearability.

Further, according to the seventh aspect of the present invention, the glossiness of the outer layer is 70% or more, so that the glossiness is excellent.

Further, according to the eighth aspect of the present invention, the heat seal strength is 17 N / 15 mm or more, so that the interface strength is excellent.

According to the ninth aspect of the present invention, the interfacial strength with the intermediate layer is excellent by containing 1 to 40% by weight of the polyethylene resin in the outer layer and / or the inner layer.

FIG. 1 is a diagram showing a layer structure of an easily tearable multilayer sealant film in the present invention.

Hereinafter, the easily tearable multilayer sealant film and the packaging material of the present invention will be described in detail for each item.
The present invention has inner and outer layers made of a resin composition mainly composed of a polypropylene resin having a laminated structure of at least three layers and a melting point of 130 ° C. or less, 10 to 90% by weight of polyethylene resin and cyclic It has the intermediate | middle layer which consists of a resin composition containing 10 to 90 weight% of olefin resin.
Moreover, the packaging material of this invention uses the said easily tearable multilayer sealant film, It is characterized by the above-mentioned.

1. Layers constituting easy tearable multilayer sealant film (1) Outer layer (A)
The outer layer (A) in the easily tearable multilayer sealant film of the present invention is characterized by comprising a resin composition mainly composed of a polypropylene resin (a1) having a melting point of 130 ° C. or lower.
Preferably, it is an ethylene / propylene / random copolymer obtained with a metallocene catalyst having a linear molecular structure with a melting point of 130 ° C. or lower. When the melting point exceeds 130 ° C., not only transparency and glossiness are lacking, but also sufficient interface strength with the intermediate layer may not be obtained. The lower limit of the melting point is not particularly limited, but is usually preferably 110 ° C. or higher, more preferably 115 ° C. or higher and 128 ° C. or lower.
Furthermore, the melting point difference between the polypropylene resin (a1) and the linear polyethylene resin (b1) of the intermediate layer is preferably 50 ° C. or less. When the melting point difference exceeds 50 ° C., the adhesion between the intermediate layer and the outer layer may be lowered.
The ethylene / propylene / random copolymer obtained with the metallocene catalyst preferably has a glossiness of 70% or more measured at an incident angle of 20 ° in accordance with JIS Z8741.
Such a propylene resin having a melting point of 130 ° C. or lower is a special one having an extremely low melting point among general propylene resins having a melting point of 150 ° C. or higher, but a method for producing such a polymer is already known. For example, as a linear ethylene / propylene / random block copolymer obtained from these metallocene catalysts, for example, “Wintech” (registered trademark) series made by Nippon Polypro Co., Ltd. is sold. Of these, commercially available products that satisfy the desired physical properties may be purchased and used.
The melting point as used in the field of this invention means the melting point measured by the method normally used as a physical property measuring method of polypropylene resin or polyethylene resin. For example, the melting point can be measured as an endothermic peak based on melting of the crystal by DSC measurement. For example, using a differential scanning calorimeter (DSC6200 manufactured by Seiko Instruments Inc.), a sample piece made into a sheet is packed in a 5 mg aluminum pan, heated from 50 ° C. to 200 ° C. at a heating rate of 100 ° C./min. After maintaining for 10 minutes, the temperature is lowered to 40 ° C. at 10 ° C./minute, crystallized, held for 1 minute, and then calculated as the maximum melting peak temperature when the temperature is raised to 200 ° C. at 10 ° C./minute.
As resin used for an outer layer (A), you may use other resin together in the range which does not impair the effect of this invention other than a polypropylene resin (a1). In the present invention, the “main component” specifically means that 60% by weight or more, preferably 80% by weight or more of the resin component constituting the outer layer (A) is the polypropylene resin (a1). Means.
As another resin added to the outer layer (A), for example, a polyethylene resin (a2) is further contained in the resin composition constituting the outer layer in an amount of 1 to 40% by weight.
As the polyethylene-based resin (a2), in addition to the same resin as the linear polyethylene-based resin (b1) used for an intermediate layer described later, high-density polyethylene, low-density polyethylene by high-pressure radical polymerization method, or the like can be used. .

(2) Intermediate layer (B)
The intermediate layer (B) in the easily tearable multilayer sealant film of the present invention contains 10 to 90% by weight of the linear polyethylene resin (b1) and 10 to 90% by weight of the cyclic olefin resin (b2). It consists of things. More preferably, it consists of 40 to 60% by weight of the linear polyethylene resin (b1) and 40 to 60% by weight of the cyclic olefin resin (b2). If the cyclic olefin-based resin is less than 40% by weight, it is not preferable because sufficient tearability may not be obtained.
(A) Polyethylene resin (b1)
The linear polyethylene resin (b1) used to form the intermediate layer (B) is a copolymer of ethylene and α-olefin, which is polymerized by a metallocene catalyst, Ziegler catalyst, Phillips catalyst, or the like. Although it may be any, the density is 0.895-0.970 g / cm ³ and it is necessary to be linear polyethylene. Since the molecular structure is linear, there is an advantage that sufficient interface strength with the inner and outer layers can be obtained. More preferably, it is a low / medium density linear polyethylene having a density of 0.895 to 0.950 g / cm ³ . Alternatively, linear high-density polyethylene having a density of more than 0.950 g / cm 3 and 0.970 g / cm 3 is preferable. In the present invention, the density is a value measured according to JIS K7112.

Moreover, it is preferable that the melt index (MI) of a polyethylene-type resin (b1) is 0.1-30 g / 10min in 190 degreeC. More preferably, it is 0.5-4.0 g / 10min. When MI is less than 0.1 g / 10 min, melt flowability is poor, extrusion film processing becomes difficult, motor load increases, and there is a risk that the transparency of the film may be lowered, which is not preferable. . On the other hand, if it exceeds 30 g / 10 minutes, the melt viscosity is too low, and the film-forming stability during extrusion may be lowered, which is not preferable.
In the present invention, the melt index (MI) is a melt index value measured according to JIS K7210. In the present specification, hereinafter, MI is also referred to as MFR.

  The linear polyethylene resin (b1) used in the present invention is specifically as follows. That is, the α-olefin copolymerized with ethylene is copolymerized in an amount of 0.1 to 15 mol%, preferably 0.5 to 10 mol%, particularly preferably 0.5 to 5 mol%. The α-olefin is usually an α-olefin having 3 to 8 carbon atoms, specifically, propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, 4-methylpentene-1 can be mentioned.

(B) Cyclic olefin resin (b2)
Examples of the cyclic olefin resin (b2) used in the intermediate layer (B) of the easily tearable film of the present invention include a norbornene polymer, a vinyl alicyclic hydrocarbon polymer, and a cyclic conjugated diene polymer. . Among these, norbornene-based polymers are preferable. The norbornene polymer includes a ring-opening polymer of a norbornene monomer (hereinafter also referred to as “COP”), a norbornene copolymer obtained by copolymerizing a norbornene monomer and an α-olefin such as ethylene. And the like (hereinafter also referred to as “COC”). COP and COC hydrogenated products can also be used.

  As the COC, linear monomers such as α-olefins such as ethylene, propylene, butene-1, pentene-1, hexene-1, heptene-1 and octene-1 and cyclic monomers such as tetracyclododecene and norbornene And a cyclic olefin copolymer obtained from the above. More specifically, the above-mentioned linear monomer, monocycloalkene having 3 to 20 carbon atoms, bicyclo [2.2.1] -2-heptene (norbornene), and derivatives thereof, tricyclo [4.3.0.12. , 5] -3-decene and derivatives thereof, tetracyclo [4.4.1.0.2, 5.17,10] -3-dodecene and derivatives thereof, pentacyclo [6.5.1.13, 6.02 , 7.09,13] -4-pentadecene and derivatives thereof, pentacyclo [7.4.0.12,5.19,12.08,13] -3-pentadecene and derivatives thereof, pentacyclo [8.4. .12, 5.19, 12.08, 13] -3-hexadecene and derivatives thereof, pentacyclo [6.6.1.13, 6.02, 7.09,14] -4-hexadecene and derivatives thereof, hexacycline [6.6.1.13, 6.110, 13.02, 7.09,14] -4-heptadecene and its derivatives, heptacyclo [8.7.0.12,9.14,7.111,17 .03, 8.012, 16] -5-eicosene and the like and derivatives thereof, heptacyclo [8.7.0.13, 6.110, 17.112, 15.02, 7.011, 16] -4-eicosene And its derivatives, heptacyclo [8.8.0.12,9.14,7.111,18.03,8.012,17] -5-heneicosene and its derivatives, octacyclo [8.8.0.12, 9.14, 7.111, 18.113, 16.03, 8.012, 17] -5-docosene and its derivatives, nonacyclo [10.9.1.14, 7.113, 20.115, 18. 02, 10.03 .012,21.014,19] -5-pentacosene and a cyclic olefin copolymer comprising a copolymer of a cyclic olefin of the derivatives. The linear monomer and the cyclic monomer can be used alone or in combination of two or more. Moreover, such a cyclic olefin copolymer can be used individually or in combination. Further, the COP and COC may be used in combination with the cyclic olefin resin (b1). In that case, different performances of COP and COC can be imparted.

  In the present invention, the cyclic olefin resin (b2) is preferably COC for reasons of dispersibility in polyethylene. The COC is preferably an ethylene / cyclic olefin copolymer in which the linear monomer is ethylene. Furthermore, the cyclic monomer is preferably norbornene or the like.

In the present invention, the ethylene / cyclic olefin copolymer preferably has an ethylene / cyclic olefin content of 15 to 40/85 to 60 by weight. More preferably, it is 30-40 / 70-60. If the ethylene content is less than 15% by weight, the rigidity becomes too high, and the inflation moldability and bag making suitability are deteriorated. On the other hand, if ethylene is 40% by weight or more, sufficient easy tearability and rigidity cannot be obtained. A content ratio within this range is preferable because the rigidity, tearability, processing stability, and impact strength of the film are improved.
Furthermore, the ethylene / cyclic olefin copolymer preferably has a glass transition point of 60 ° C. or higher. More preferably, it is 70 degreeC or more. When the content of the cyclic olefin is below the above range, the glass transition point becomes below the above range, for example, the barrier property of the fragrance component is lowered, sufficient rigidity cannot be obtained, and high speed packaging machine is suitable. There is a risk of being inferior. On the other hand, when the content of the cyclic olefin exceeds the above range, the glass transition point becomes too high, and the melt moldability of the copolymer and the adhesiveness with the olefin resin may be lowered, which is not preferable.
In addition, the weight average molecular weight of the cyclic olefin resin (b2) is preferably 5,000 to 500,000, more preferably 7,000 to 300,000.

  It is preferable that 20 to 70 weight% of cyclic olefin resin (b2) is contained on the basis of the whole easily tearable multilayer film. More preferably, it is 20 to 50% by weight. If it is less than 20% by weight, it is not preferred because sufficient tearability cannot be obtained. On the other hand, if it is more than 70% by weight, the rigidity becomes too high and the inflation moldability and bag making suitability are deteriorated.

  As a commercial product that can be used as the cyclic olefin resin (b2), examples of the ring-opening polymer (COP) of the norbornene monomer include “ZEONOR” manufactured by Nippon Zeon Co., Ltd. Examples of the copolymer (COC) include “Appel” manufactured by Mitsui Chemicals, Inc. and “TOPAS” manufactured by Polyplastics. In the present invention, the TOPAS grade 8007 is preferred because the content ratio of the norbornene-based monomer is in the above-mentioned range and the workability and the like.

(C) Other ingredients
As the resin used for the intermediate layer (B), in addition to the linear polyethylene-based resin (b1) and the cyclic olefin-based resin (b2), the intermediate layer may be composed of other resins within a range not impairing the effects of the present invention. In the resin composition to be used, you may use together in the range of 1 to 30 weight%.
Examples of the other resin include a low-density polyethylene-based resin (b3) obtained by a high-pressure radical polymerization method, and 1 to 30% by weight, preferably 2 to 25% by weight, is contained in the resin composition of the intermediate layer. A characteristic aspect is mentioned.

(3) Inner layer (C)
Like the outer layer (A), the inner layer (C) in the easily tearable multilayer sealant film of the present invention is composed of a resin composition whose main component is a polypropylene resin (c1) having a melting point of 130 ° C. or lower. And
As the resin to be used, the same resin as the polypropylene resin (a1) described in the section of the outer layer (A) can be used, but the same resin as the resin of the outer layer (A) may be used or different. A resin may be used.
Furthermore, the melting point difference between the polypropylene resin (c1) and the intermediate layer polyethylene resin (b1) is preferably 50 ° C. or less, and if the melting point difference exceeds 50 ° C., the adhesion between the intermediate layer and the inner layer may be reduced. There is.
As the resin used for the inner layer (C), in addition to the polypropylene resin (c1), other resins may be used in combination as long as the effects of the present invention are not impaired. In the present invention, the “main component” specifically means that 60% by weight or more, preferably 80% by weight or more of the resin component constituting the inner layer (C) is a polypropylene resin (c1). Means.
As other resin added to the inner layer (C), for example, a polyethylene resin (c2) is further contained in the resin composition constituting the inner layer in an amount of 1 to 40% by weight.
As the polyethylene-based resin (c2), in addition to the same resin as the linear polyethylene-based resin (b1) used for the intermediate layer, high-density polyethylene, low-density polyethylene by high-pressure radical polymerization, or the like can be used.

  In the present invention, the outer layer (A), the intermediate layer (B) and the inner layer (C) include an antifogging agent, an antistatic agent, a heat stabilizer, a nucleating agent, an antioxidant, a lubricant, an antiblocking agent, and a release agent. Components such as an agent, an ultraviolet absorber and a colorant can be added within a range that does not impair the object of the present invention. In particular, the outer layer (A) and the inner layer (C) preferably have a friction coefficient of 1.5 or less, more preferably 1.2 or less in order to impart processing suitability during film forming and packaging suitability of the filling machine. It is preferable to add a lubricant or an antiblocking agent to (A) and the inner layer (C) as appropriate.

2. Easily tearable multilayer sealant film The easily tearable multilayer sealant film of the present invention comprises a specific outer layer (A) / specific intermediate layer (B) / specific inner layer (C) as described above. is there. In FIG. 1, the schematic of the cross section of an example of the easily tearable multilayer sealant film of this invention is shown. Reference numeral 1 denotes an outer layer (A), 2 denotes an intermediate layer (B), and 3 denotes an inner layer (C).
The total thickness of the easily tearable multilayer sealant film is preferably 10 to 150 μm. If the thickness of the multilayer film is 30 μm or more, excellent secondary formability can be obtained. Moreover, in the range whose thickness of a multilayer film is 50-80 micrometers, it can be used as a bag-shaped packaging material which heat-sealed inner layers (C).

  Moreover, it is preferable that the thickness of the intermediate | middle layer (B) in the easily tearable multilayer sealant film of this invention is 20 to 70% on the basis of the whole easily tearable multilayer sealant film. More preferably, it is 20 to 50%. That is, the outer layer (A) / intermediate layer (B) / inner layer (C) can have a thickness of 1: 0.5: 1 to about 1: 4: 1. If the intermediate layer (B) is thinner than 20%, it is not preferable because sufficient tearability cannot be obtained. On the other hand, if it is thicker than 70%, the rigidity becomes too high and the inflation moldability and bag making suitability are deteriorated. If the intermediate layer (B) is within this range, it is preferable because it is excellent in easy tearing and is advantageous in terms of cost, and the transparency, tearing property and pinhole resistance of the easy tearing multilayer sealant film are improved. .

  Although it does not specifically limit as a manufacturing method of the easily tearable multilayer sealant film of this invention, For example, the polypropylene resin (a1) used for an outer layer (A), and the cyclic olefin resin (b2) used for an intermediate | middle layer (B) And / or the linear polyethylene-based resin (b1) and the polypropylene-based resin (c1) used for the inner layer (C) are heated and melted in different extruders, respectively, such as a co-extrusion multilayer die method or a feed block method. Examples thereof include a coextrusion method in which the layers are laminated in the order of (A) / (B) / (C) in a molten state by a method and then formed into a film shape by inflation, T-die / chill roll method, or the like. This coextrusion method is preferable because the thickness ratio of each layer can be adjusted relatively freely, and a multilayer film excellent in hygiene and cost performance can be obtained.

  The easily tearable film of the present invention preferably has an Elmendorf tear strength measured in accordance with JIS K7128-2 of 10 N / mm or less in the longitudinal and transverse directions, respectively. More preferably, it is 7 N / mm or less.

3. Packaging Material Although the easily tearable multilayer sealant film of the present invention can be used alone, it can be used as a packaging material usually in the form of a laminate laminated on a substrate.
Examples of the packaging material include packaging bags and packaging containers used for foods, medicines, medical instruments, industrial parts, miscellaneous goods, magazines and the like.
As the base material used, metal foil such as aluminum foil, metal vapor deposited film, paper, polyester film such as polyethylene terephthalate, olefin film such as polyethylene and polypropylene, polyamide film such as nylon 6 and nylon 6,6, Examples thereof include a single-layer or multi-layer polymer film having excellent gas barrier properties such as an ethylene-vinyl alcohol copolymer and polyvinylidene chloride. The polymer film may be biaxially stretched, uniaxially stretched, or unstretched. The substrate can be used in combination of not only one type but also two or more types.

The packaging material may be produced by directly extruding and laminating the resin composition of the sealant film to the base material in the form of a film, or by dry laminating the above-described sealant film to the base material via an anchor coating agent.
When obtaining a transparent type packaging material, examples of the layer structure include a laminated structure such as a polyamide film / sealant film and a polyethylene terephthalate / sealant film.
When a retort pouch containing aluminum foil is obtained, the layer structure is, for example, a laminated structure of aluminum foil / sealant film, polyethylene terephthalate film / aluminum foil / sealant film, polyethylene terephthalate film / polyamide film / aluminum foil / sealant film, etc. Can be illustrated.

The base material is laminated on the outer layer (A) of the easily tearable multilayer sealant film of the present invention, and the inner layer (C) is heated by overlapping the inner layers (C) as a heat seal layer when formed into a bag. A packaging bag is formed by sealing.
For example, after cutting out two packaging materials into the desired size of the packaging bag, overlapping them and heat-sealing three sides to form a bag, the contents were filled from one side that was not heat-sealed. Then, it can be used as a packaging bag by heat sealing. Moreover, it can also be used in the form of pillow packaging using a single packaging material. Furthermore, it is also possible to form a packaging bag by heat-sealing an inner layer (C) and another heat-sealable film. At that time, as another film to be used, a film such as LDPE or EVA having relatively low mechanical strength can be used.

  In the packaging material using the easily tearable multilayer sealant film of the present invention, any tear such as V-notch, I-notch, perforation, micro-porosity, etc. is used for the seal portion in order to weaken the initial tear strength and improve the opening property. Preferably, the start is formed. Therefore, this laminate film can be used in an automatic packaging device for solids such as snacks and bread, powders, or liquid materials.

  In addition, the packaging container includes a deep-drawn molded product (a bottom material having an opening at the top) obtained by secondary molding of the laminate of the easily tearable multilayer sealant film and the substrate of the present invention, A typical example is the bottom material of a blister pack. The lid material for sealing the bottom material is not particularly limited as long as it can be heat-sealed with the bottom material, but since the lid material and the bottom material can be simultaneously torn and opened, the easily tearable laminate of the present invention is covered. It is preferable to use it as a material.

Examples of the secondary forming method include a vacuum forming method, a pressure forming method, and a vacuum / pressure forming method. Among these, vacuum forming is preferable because a film or sheet can be formed in-line on a packaging machine and filled with the contents.
This container is suitably used for packaging instant noodles, miso, jelly, pudding, snacks and the like.

Examples of the present invention and comparative examples are shown below, but the present invention is not limited to these examples.
In addition, the physical property evaluation method, film forming method, and resin used in Examples and Comparative Examples are as follows.

1. Physical property evaluation method <Glossiness>
Measured with the following equipment and conditions with reference to JIS Z8741.
Apparatus: UGV-4D manufactured by Suga Test Instruments Co., Ltd.
Incident light angle: 20 °
Measurement environment: temperature 23 ° C, humidity 50%
<Haze>
Based on JIS K7136, it measured with the following apparatus and conditions.
Apparatus: Murakami Color Research Laboratory Co., Ltd. Haze meter HM-150 type Measurement environment: Temperature 23 ° C, humidity 50%
<Elmendorf tear strength>
With reference to JIS K7128-2, Elmendorf tear strength was evaluated using the following apparatus. In addition, MD is a flow direction (MD: Machine Direction), and TD is a value in the vertical direction (TD: Transverse Direction).
Equipment: Digital Elmendorf Tear Tester Model SA (manufactured by Toyo Seiki Seisakusho Co., Ltd.)
Measurement environment: temperature 23 ° C, humidity 50%
<Measurement of heat seal strength>
With reference to JIS Z1713, measurement was performed using the following apparatus.
<Heat seal>
Apparatus: Heater tester upper heater temperature manufactured by Tester Sangyo Co., Ltd. Temperature: 160 ° C
Lower heater temperature: 60 ° C
Seal pressure: 0.2 MPa
Sealing time: 1 sec
Seal width: 5mm
Base material: PET (12 μm)
<Measurement of heat seal strength>
Apparatus: Tensilon universal testing machine manufactured by Orientec Co., Ltd. Test piece width: 15 mm
Tensile speed: 500 mm / min
Distance between chucks: 50mm

2. T-die film forming method A T-die film was formed using the following forming apparatus and forming conditions.
Molding machine: 3-layer T-die film molding machine (Placo)
Die width: 550mm
Lip width: 1.0mm
Take-off speed: 10 m / min
Extrusion amount: 15 kg / hr
Chill roll temperature: 40 ° C
Processing temperature: 220 ° C
Thickness: 50 μm
Layer ratio: 1: 1: 1

3. Inflation film forming method An inflation film was formed using the following forming apparatus and forming conditions.
Molding machine: 3-layer inflation molding machine (Placo)
Die diameter: φ200mm
Lip width: 3.0mm
Take-off speed: 20 m / min
Extrusion amount: 60 kg / hr
Processing temperature: inner and outer layers 190 ° C, intermediate layer 195 ° C
Thickness: 50 μm
Layer ratio: 1: 1: 1
Blow ratio: 2.0
4). Raw material polypropylene resin (a1), polypropylene resin (c1)
PP-1: manufactured by Nippon Polypro Co., Ltd., trade name Wintech, grade name WFX4TA, MFR = 7.0 g / 10 min, density = 0.90 g / cm ³ , melting point Tm = 125 ° C.
PP-2: manufactured by Nippon Polypro Co., Ltd., trade name: Novatec PP, grade name: FB3B, MFR = 7.5 g / 10 min, density = 0.90 g / cm ³ , melting point Tm = 161 ° C.
Polyethylene resin (b1)
LLDPE: manufactured by Nippon Polyethylene Co., Ltd., trade name Novatec LL, grade name UF320, MFR = 0.9 g / 10 min, density = 0.922 g / cm ³
HDPE: manufactured by Nippon Polyethylene Co., Ltd., trade name: Novatec HD, grade name: HY444, MFR = 1.1 g / 10 min, density = 0.95 g / cm ³
LDPE: manufactured by Nippon Polyethylene Co., Ltd., trade name: Novatec LD, grade name: LF440B, MFR = 2.8 g / 10 min, density = 0.925 g / cm ³
Cyclic olefin resin (b2)
COC: Polyplastics Co., Ltd., trade name TOPAS8007F-500, MVR (190 ℃ , 2.16kg) = 2.0cm 3/10 min, density = 1,010kg / ^{m 3,} a glass transition temperature Tg = 78 ° C.

(Example 1, Comparative Examples 1-3)
Using the resin described above, a T-die film having a thickness of 50 μm and a layer ratio of 1: 1: 1 was obtained according to the formulation shown in Table 1. The evaluation results are shown in Tables 1 and 2.

(Example 2, Example 3)
Using the resin described above, an inflation film having a thickness of 50 μm and a layer ratio of 1: 1: 1 was obtained according to the formulation shown in Table 1. The evaluation results are shown in Tables 1 and 2.

<About heat seal strength measurement in multilayer film>
In Table 1, #: Edge breakage is a fracture mode derived from the fracture of the test film, which means that high seal strength can be secured. That is, it means that the interface strength between the layers is sufficiently large.
In Table 1, *: delamination is a destructive form derived from delamination between layers constituting the test film, meaning that sufficient seal strength cannot be ensured.
That is, it means that the interface strength between each layer is weak.

(Evaluation)
As is clear from Tables 1 and 2, Comparative Example 1 satisfies the easy tearability of MD and TD, and the interface strength between the intermediate layer and the inner and outer layers, but the appearance is insufficient. Although the interface strength and appearance of the layer and the inner and outer layers are satisfactory, the easy tearability of MD and TD is insufficient, and in Comparative Example 3, the easy tearability and appearance of MD and TD are satisfactory. In Example 1, Example 2 and Example 3 according to the present invention, the interfacial strength between MD and TD, the interfacial strength between the intermediate layer and the inner and outer layers, It has become clear that it has all the appearances and is particularly suitable as an easy tear film used as a packaging material.

1 Outer layer (A)
2 Intermediate layer (B)
3 Inner layer (C)

Claims (8)

An outer layer (A) comprising a resin composition mainly composed of a polypropylene resin (a1) having a laminated structure of at least three layers and a melting point of 130 ° C. or less; and a linear polyethylene resin (b1). An intermediate layer (B) comprising a resin composition containing 40 to 90% by weight and 10 to 60 % by weight of a cyclic olefin resin (b2), and a polypropylene resin (c1) having a melting point of 130 ° C. or lower as main components. possess an inner layer (C) made of a resin composition,
The Elmendorf tear strengths of MD and TD of the film are both 10 N / mm or less, and in accordance with JIS Z1713, the film specimen having a width of 15 mm and a thickness of 50 μm has a lower bar temperature of 60 ° C. and an upper bar temperature of 160 ° C. An easily tearable multilayer sealant film having a heat seal strength of 17 N / 15 mm or more .   The easily tearable multilayer sealant film according to claim 1, wherein the polypropylene resin (a1) and the polypropylene resin (c1) are an ethylene / propylene / random copolymer obtained with a metallocene catalyst. The polyethylene resin (b1) is, according to claim 1 or 2, wherein the density is measured in accordance with JIS K7112 is a linear polyethylene which is a 0.895~0.970g / cm ³ Easy tear multilayer sealant film.   The resin composition of the intermediate layer (B) further contains 3 to 25% by weight of a low density polyethylene resin (b3) obtained by a high pressure radical polymerization method. The easily tearable multilayer sealant film as described.   5. The olefin resin according to claim 1, wherein the cyclic olefin resin (b2) is a cyclic olefin resin that is a norbornene copolymer having a glass transition temperature Tg of 60 ° C. or higher. Tearable multilayer sealant film. The easily tearable multilayer sealant film according to any one of claims 1 to 5 , wherein the outer layer (A) has a glossiness of 70% or more at an incident angle of 20 ° measured according to JIS Z8741. The outer layer (A) and / or inner layer (C), any of the claims 1-6, further characterized by containing each from 1 to 40% by weight of polyethylene resin (a2) and / or polyethylene resin (c2) An easily tearable multilayer sealant film according to claim 1. On the outer layer of the easily tearable multilayer sealant film of claim 1~ 7 (A), packaging material, characterized in that bonding the PET film or a nylon film as a substrate.

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