JP2016117160A - Sealant film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealant film which has excellent straight cutting properties in only one direction and has excellent low-temperature sealability.SOLUTION: In a sealant film in which at least a first resin layer, a second resin layer and a third resin layer are sequentially laminated, the first resin layer and the third resin layer are an outermost surface layer of the sealant film and are layers formed of polyethylene-based resins. The second resin layer is a layer formed of a mixed resin of polyethylene-based resin and cyclic polyolefin. A thickness of the second resin layer is 1/10 to 1/3 of a total thickness of the sealant film. The sealant film contains 3.0-25 mass% of the cyclic polyolefin based on a total mass of the sealant film.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sealant film for packaging material, which is not laminated with a base film having a straight cut property, but itself has a straight cut property in one direction, a packaging material comprising the sealant film, and The present invention relates to a package and a method for producing a sealant film.

Packaging materials used for packaging bags for foods, chemicals, pharmaceuticals, etc. have straight cuts in one direction so that when they are torn by hand, they can be cut straight and easily so that they can be opened easily. It is demanded.
As such a straight cut packaging material, a packaging material in which a base film having a straight cut property in one direction and a sealant film are laminated is known (Patent Document 1).

  However, in this type of straight cut packaging material, the base film is limited to a specific film having straight cut characteristics and base material properties, and a wide variety of other films cannot be selected. Or when using the film which does not have rectilinear cutting property as a base material, in addition to this base film and sealant film, it is necessary to laminate | stack the special film for providing further rectilinear cutting property. In this case, as the film thickness increases, the cutting performance decreases, so it is necessary to provide a further means for compensating for this, for example, a notch. In addition, there is a problem that so-called stringing, in which the resin remains in a fibrous form on the release surface, is likely to occur.

  In order to solve these problems, a straight cutting property is provided by placing a laser or a perforation in a packaging material composed of a base material film and a sealant film that do not have a straight cutting property. However, there are various restrictions on the specifications because the sealing performance and various functionalities are impaired, and additional dedicated facilities for lasers and perforations are required.

In order to solve this problem, it has been studied to impart a straight cut property to the sealant film itself (Patent Document 2).
However, since the conventional straight cut sealant films are mainly composed of a propylene-based resin, there is a problem that the low-temperature sealability is inferior.

International Publication WO2004 / 020309 Pamphlet JP 2011-162667 A

  In view of the above problems, an object of the present invention is to provide a sealant film that is excellent in straight cut ability in only one direction and excellent in low-temperature sealability.

  As a result of various studies, the inventors of the present application are sealant films in which at least a first resin layer, a second resin layer, and a third resin layer are laminated in order. The resin layer is the outermost layer of the sealant film and is a layer made of a polyethylene resin, and the second resin layer is a layer made of a mixed resin of a polyethylene resin and a cyclic polyolefin, The thickness of the resin layer is 1/10 to 1/3 of the thickness of the entire sealant film, and the cyclic polyolefin is contained in an amount of 3.0 to 25% by mass based on the mass of the entire sealant film. Has found that the above-mentioned purpose is achieved.

The present invention is characterized by the following points.
(1) A sealant film in which at least a first resin layer, a second resin layer, and a third resin layer are sequentially laminated, and the first resin layer and the third resin layer are made of a sealant film. The outermost layer is a layer made of polyethylene resin, the second resin layer is a layer made of a mixed resin of polyethylene resin and cyclic polyolefin, and the thickness of the second resin layer is a sealant The above-mentioned sealant film, which is 1/10 to 1/3 of the thickness of the entire film and contains 3.0 to 25% by mass of the cyclic polyolefin based on the mass of the entire sealant film.
(2) The polyethylene resin constituting the first resin layer and the third resin layer is an ethylene / α-olefin copolymer polymerized using a single site catalyst, and the second resin layer The sealant film according to the above (1), wherein the polyethylene resin in the mixed resin constituting the polymer is an ethylene / α-olefin copolymer polymerized using a multi-site catalyst.
(3) including an intermediate layer made of a thermoplastic resin between the first resin layer and the second resin layer and / or between the second resin layer and the third resin layer, The sealant film according to (1) or (2).
(4) The sealant film according to any one of (1) to (3), which is co-extruded.
(5) A package comprising a packaging material having the sealant film according to any one of (1) to (4) as a heat seal layer.
(6) A method for producing a sealant film in which at least a sealant film in which at least a first resin layer, a second resin layer, and a third resin layer are sequentially laminated is coextruded by an inflation method. The resin layer and the third resin layer are the outermost layers of the sealant film and are layers made of polyethylene resin, and the second resin layer is made of a mixed resin of polyethylene resin and cyclic polyolefin. And the thickness of the second resin layer is 1/10 to 1/3 of the thickness of the entire sealant film, and the cyclic polyolefin is 3.0 to 25 mass based on the mass of the entire sealant film. %, A method for producing a sealant film.

  Since the sealant film of the present invention is excellent in the straight cut property only in one direction, when used as a sealant layer of the package, it can impart easy tearability to the package. Moreover, since the main component of a sealant film is polyethylene, it is excellent also in low temperature sealing property.

It is a schematic sectional drawing which shows an example about the layer structure of the sealant film of this invention. It is a schematic sectional drawing which shows another example about the layer structure of the sealant film of this invention. It is a front view which shows a pillow packaging bag. It is a graph which shows an Elmendorf tear test result.

The above-described present invention will be described in more detail below.
<1> Layer Configuration of Sealant Film of the Present Invention FIGS. 1 and 2 are schematic cross-sectional views showing an example of a layer configuration of the sealant film of the present invention.
As shown in FIG. 1, the sealant film of the present invention has a basic structure of three layers of a first resin layer 1, a second resin layer 2, and a third resin layer 3. Here, the 1st resin layer 1 and the 3rd resin layer 3 are located in the outermost layer of a sealant film, and are layers which consist of a polyethylene-type resin. Moreover, the 2nd resin layer 2 is a layer which is located between the 1st resin layer and the 3rd resin layer, and consists of a mixed resin of polyethylene-type resin and cyclic polyolefin.

  Moreover, as shown in FIG. 2, an intermediate layer 4 made of a thermoplastic resin may be provided between the first resin layer 1 and the second resin layer 2 as desired. Similarly, an intermediate layer 5 made of a thermoplastic resin may be provided between the second resin layer 2 and the third resin layer 3 as desired. Each of the intermediate layers 4 and 5 may have a single layer structure or a multilayer structure made of the same or different thermoplastic resins.

In one embodiment of the present invention, a symmetrical layer structure with the second resin layer as the center can prevent curling after film formation.
By laminating the base material on the surface of the sealant film of the present invention on the first resin layer side by an arbitrary method, a packaging material having excellent straight cut property in only one direction can be obtained.

<2> Polyethylene resin forming the first and third resin layers As the polyethylene resin forming the first and third resin layers, high-density polyethylene (HDPE, density 0.940 g / cm ³ or more), Medium density polyethylene (MDPE, density 0.925 or more and less than 0.940 g / cm ³ ), low density polyethylene (LDPE), linear low density polyethylene (LLDPE, copolymer of ethylene and α-olefin), and these Can be mentioned.

In the present invention, low-density polyethylene (LDPE) is a high-pressure ethylene homopolymer, and linear low-density polyethylene (LLDPE) is typified by a multisite catalyst or metallocene catalyst typified by a Ziegler-Natta catalyst. These are copolymers of ethylene and α-olefin polymerized using a single site catalyst, all of which have a density of less than 0.925 g / cm ³ . As an α-olefin which is a comonomer of LLDPE, an α-olefin having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-nonene, 4-methylpentene, etc. , And mixtures thereof.

  By using polyethylene (PE), better low-temperature sealability can be obtained compared to polypropylene (PP). In particular, by using LLDPE, excellent low temperature sealing properties can be obtained. Moreover, since it can be used also for uses other than light packaging like snacks, for example, the use of packaging materials for refills, such as a shampoo, a use application can be expanded.

In the present invention, the density of LLDPE forming the first resin layer is preferably 0.910 to 0.925 g / cm ³ , and more preferably 0.915 to 0.923 g / cm ³ . And the density of LLDPE which forms a 3rd resin layer becomes like this. Preferably it is 0.910-0.925g / cm < ³ >, More preferably, it is 0.910-0.920g / cm < ³ >. Note that the third resin layer is the outermost layer of the packaging material, that is, the innermost layer of the package.

  In addition, in each layer which comprises the sealant film of this invention, a well-known additive can be mix | blended as needed in the range which does not impair the effect of this invention. Examples of such additives include lubricants, antiblocking agents, water repellents, antioxidants, heat stabilizers, antistatic agents and the like.

<3> Mixed resin for forming the second resin layer The polyethylene resin suitably used in the mixed resin for forming the second resin layer is as described for the first and third resin layers. The same polyethylene-type resin is mentioned.
In order to increase the interlayer adhesive strength between adjacent resin layers, it is preferable to use the same polyethylene resin as the polyethylene resin forming the adjacent resin layer.

In particular, when the first and third resin layers are made of LLDPE, high interlayer adhesion strength can be obtained by using LLDPE in the same manner.
More preferably, the polyethylene resin forming the first and third resin layers is LLDPE polymerized using a single site catalyst, and the polyethylene resin in the mixed resin forming the second resin layer The resin is LLDPE polymerized using a multi-site catalyst.

  LLDPE polymerized with a metallocene catalyst has higher strengths such as tensile strength, tear strength, and yield strength than those polymerized using a multi-site catalyst. Therefore, the first and third resin layers are made of LLDPE having higher strength, and the second resin layer is made of LLDPE having lower strength and cyclic polyolefin, so that the first and third resin layers The strength difference from the second resin layer is further increased. As a result, the sealant film of the present invention is further improved in straight-cut property, but also has increased strength as a film and is excellent in workability.

In the present invention, the density of LLDPE forming the second resin layer is preferably 0.910 to 0.925 g / cm ³ , and more preferably 0.915 to 0.920 g / cm ³ .
Here, a single site catalyst (including a metallocene catalyst, so-called Kaminsky catalyst) has a feature that the active sites are uniform (single site). This single-site catalyst is a catalyst composed of a metallocene transition metal compound and an organoaluminum compound, and is sometimes used while being supported on an inorganic substance.

  In the present invention, examples of the metallocene transition metal compound include, for example, transition metals selected from group IVB [titanium (Ti), zirconium (Zr), hafnium (Hf)], cyclopentadienyl group, substituted cyclopentadienyl. A group, an indenyl group, a substituted indenyl group, a tetrahydroindenyl group, a substituted tetrahydroindenyl group, a fluoronyl group or a substituted fluorenyl group, or two of these groups are covalently bridged In addition to the above, hydrogen atom, oxygen atom, halogen atom, alkyl group, alkoxy group, aryl group, acetylacetonate group, carbonyl group, nitrogen molecule, oxygen molecule, Lewis base, substituent containing silicon atom And those having a ligand such as an unsaturated hydrocarbon.

  In addition, examples of the organoaluminum compound include alkylaluminum, chain-like or cyclic aluminoxane, and the like. Here, examples of the alkylaluminum include triethylaluminum, triisobutylaluminum, dimethylaluminum chloride, diethylaluminum chloride, methylaluminum dichloride, ethylaluminum dichloride, dimethylaluminum fluoride, diisobutylaluminum hydride, diethylaluminum hydride, ethylaluminum sesquichloride, and the like. Can be mentioned.

  The chain or cyclic aluminoxane is produced by bringing alkyl aluminum into contact with water. For example, it can be obtained by adding alkylaluminum at the time of polymerization and adding water later, or by reacting crystallization water of a complex salt or adsorbed water of an organic / inorganic compound with alkylaluminum.

On the other hand, the cyclic polyolefin preferably used in the mixed resin forming the second resin layer includes a ring-opening metathesis polymer (COP) obtained by polymerizing a cyclic olefin by a metathesis ring-opening polymerization reaction, and a cyclic olefin and an α-olefin. Copolymers with (chain olefins), that is, cyclic olefin copolymers (COC) are included.
As the cyclic olefin, any cyclic hydrocarbon having an ethylenically unsaturated bond and a bicyclo ring can be used, particularly those having a bicyclo [2.2.1] hept-2-ene (norbornene) skeleton. preferable.

Specifically, bicyclo [2.2.1] hept-2-ene and derivatives thereof, tricyclo [4.3.0.1 ^2.5 ] -3-decene and derivatives thereof, tricyclo [4.4.0.1 ^2.5] -3-undecene and derivatives thereof, tetracyclo [4.4.0.1 ^2.5 .1 ^7.10] -3-dodecene and derivatives thereof, pentacyclo ^{[6.5.1.1 3.6 .0 2.7 .0 9.13]} - 4 pentadecene and its derivatives, pentacyclo ^{[7.4.0.1 2.5 .1 9.12 .0 8.13]} -3- pentadecene and its derivatives, pentacyclo ^{[6.5.1.1 3.6 .0 2.7 .0 9.13]} - 4,10 penta decadiene and its derivatives, pentacyclo ^{[8.4.0.1 2.5 .1 9.12 .0 8.13]} -3- hexadecene and it derivatives, and the like, without limitation. The cyclic olefin may have a polar group such as an ester group, a carboxyl group, and a carboxylic anhydride group as a substituent.

As the α-olefin copolymerized with the cyclic olefin, ethylene, an α-olefin having 3 to 20 carbon atoms can be used, and specifically, ethylene, propylene, 1-butene, 1-pentene, 3-methyl. Examples include -1-butene, 1-hexene, 4-methyl-1-pentene, and preferably ethylene.
In the present invention, the production of the ring-opening metathesis polymer is not particularly limited as long as it is a known ring-opening metathesis polymerization reaction, and can be produced by ring-opening polymerization of the above cyclic olefin using a polymerization catalyst. .

In the production of the cyclic olefin copolymer, 25 to 45 mol% of α-olefin and 55 to 75 mol% of cyclic olefin are randomly polymerized using a single site catalyst such as a metallocene catalyst or a multisite catalyst. Is made by
Ring-opening metathesis polymer and a cyclic olefin copolymer are preferably used in the present invention, some are commercially available, for example, Nippon Zeon Co., Ltd. of "ZEONOR ^(R)" and manufactured by Polyplastics Co., Ltd., "TOPAS ^{(R )} "And the like.

<4> Content of cyclic polyolefin The sealant film of the present invention is provided with a second resin layer that is relatively brittle compared to other layers in a multilayer structure composed of a polyethylene resin having high mechanical strength. is there. The second resin layer includes a predetermined amount of cyclic polyolefin and has desirable anisotropy when it is subjected to inflation coextrusion molding with another layer at a predetermined layer thickness. Thereby, the sealant film of the present invention is different from the breaking elongation E ₁ measured in one direction of the film and the breaking elongation E ₂ measured in the direction perpendicular to the film, and is excellent in only one direction. Shows cutting properties.

  Therefore, the sealant film of the present invention can be combined with various base films such as polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA) such as nylon, and constitute a wide variety of packaging materials. Therefore, the usage can be expanded.

  In a particularly preferred embodiment, the sealant film of the present invention exhibits excellent straight cut performance when torn in the TD direction perpendicular to the MD direction, which is the transport direction during film formation. By showing the straight cut property excellent in the TD direction, for example, it can be suitably used as a sealant film for a packaging material constituting a pillow packaging bag.

  An example of a pillow packaging bag is shown in FIG. The pillow packaging bag 10 is formed from, for example, an unrolled end portion after unrolling a roll made of a packaging material in which a sealant film is laminated on at least a base film to form a palm seal portion 13 and a bottom seal portion 11. It can be produced by filling the contents and closing the opening to form the top seal portion 12.

  Even if the sealant film of the present invention is not provided with easy opening means such as a half cut line formed by laser processing or a cutter, or easy opening means such as notches and scars, the width direction of the pillow packaging bag ( Easy tearability can be imparted in the lateral direction in FIG.

  Specifically, the mixed resin forming the second resin layer is a blend resin of 50 to 85% by mass of polyethylene resin and 15 to 50% by mass of cyclic polyolefin. More preferably, it is a blend of 50 to 80% by mass of a polyethylene resin and 20 to 50% by mass of a cyclic polyolefin, and more preferably a blend of 60 to 80% by mass of a polyethylene resin and 20 to 40% by mass of a cyclic polyolefin. is there. Further, the cyclic polyolefin contained in the second resin layer is blended at a content of 3.0 to 25% by mass, preferably 3.0 to 12.5, based on the mass of the entire sealant film. It is blended in the second resin layer so as to be 3.5% by mass, more preferably 3.5 to 10% by mass.

Furthermore, the thickness of the second resin layer is a ratio of 1/10 to 1/3, more preferably 1/8 to 1/4, with respect to the thickness of the entire sealant film.
By setting the content ratio of the cyclic polyolefin and the thickness of the second resin layer within the above ranges, a sealant film excellent in straight-cut property, impact resistance, and sealing property in only one direction can be obtained. When there is too much content rate of cyclic polyolefin, a sealing performance and impact resistance may be impaired. Further, if the second resin layer is too thin, it is difficult to obtain a straight cut property. On the other hand, if the second resin layer is thick and the other layers are too thin, the desired seal strength and film strength may not be obtained. Within the above range of the present invention, the straight cut property tends to be further improved by reducing the thickness of the second resin layer and increasing the concentration of the cyclic polyolefin in the second resin layer.

<5> Layer thickness In the present invention, the total thickness of the sealant film and the thickness of each layer are, for example, a total thickness of the sealant film of 20 to 125 μm, more preferably, in order to obtain high straight cut property and desired seal strength. 40-80 μm. Moreover, about the thickness of each layer, the thickness of the 1st resin layer is 3-50 micrometers, respectively, for example, Preferably it is 5-20 micrometers. And the thickness of the 2nd resin layer is 3-25 micrometers, for example, Preferably it is 3-10 micrometers. And the thickness of the 3rd resin layer is 3-50 micrometers, for example, Preferably it is 5-30 micrometers.

  In one aspect of the present invention, when an intermediate layer is provided between the first resin layer and the second resin layer, the thickness of the intermediate layer is, for example, 2 to 30 μm. By sandwiching an intermediate layer made of a thermoplastic resin, curling of the film after film formation can be prevented, or adhesion between layers can be further improved. The same applies when an intermediate layer is provided between the second resin layer and the third resin layer.

<6> Thermoplastic resin that forms the intermediate layer The thermoplastic resin that forms the intermediate layer is an arbitrary thermoplastic resin having adhesiveness between the first or third resin layer and the second resin layer. Good.
As such a thermoplastic resin, for example, polyethylene resins similar to those described for the first to third resin layers can be used alone or in admixture of two or more. Since high adhesiveness can be obtained, a polyethylene resin is particularly preferable.

  By providing the intermediate layer, a desired interlayer adhesive strength can be easily achieved. Further, by selecting the configuration of the intermediate layer, it can be controlled to prevent the film after film formation from curling in either direction.

<7> Breaking elongation The sealant film of the present invention has directionality in breaking elongation. That is, in the present invention, the breaking elongation E ₁ measured in one direction of the film is different from the breaking elongation E ₂ measured in the direction orthogonal thereto, and the ratio of E ₁ and E ₂ is specified. It is in the range.
Specifically, in the sealant film of the present invention, the value of E ₁ / E ₂ is in the range of 0.1 to 0.4, more preferably 0.12 to 0.38. If the value of E ₁ / E ₂ is less than 0.1, the balance of the orientation of the film becomes worse, and the strength such as impact resistance of the film is remarkably lowered. On the other hand, if the value of E ₁ / E ₂ is larger than 0.4, a sealant film having excellent straight cut ability only in one direction cannot be obtained.

Further, among the breaking elongations E ₁ and E ₂ , the smaller breaking elongation E ₁ is 100 to 300%, more preferably 110 to 280%. When E ₁ is less than 100%, good film forming properties cannot be obtained. On the other hand, if E ₁ is larger than 300%, a sealant film excellent in straight cut ability only in one direction cannot be obtained.

In the present invention, the elongation at break is a tensile test conducted in accordance with JIS Z1702. A strip-shaped test piece having a width of 15 mm is drawn with two marked lines at a distance between marked lines of 50 mm, and the test piece breaks. It is calculated from the distance between the marked lines at the time of breaking (cutting) when a tensile load is applied. Specifically, it is a value represented by the following formula:
E = (L−L ₀ ) / L ₀ × 100
E: Elongation at break (%)
L: Distance between marked lines at break (mm)
L ₀ : Distance between marked lines before test (mm)
In a preferred embodiment of the present invention, the smaller elongation at break E ₁ is the elongation at break E _MD when a tensile load is applied in the MD direction, which is the conveying direction when the sealant film is formed, and the larger elongation at break. E ₂ is the elongation at break E _TD when a tensile load is applied in the TD direction, which is a direction orthogonal to the MD direction.

<8> Production The sealant film of the present invention can be suitably produced by melting the resin forming each layer and co-extruding it by an inflation method.
In the inflation method, each molten resin is coextruded from an extruder through a circular die into a cylindrical shape, and a refrigerant such as air is blown into the cylindrical molten resin to expand it to a predetermined size, and then wound around a roll. Take it into a film.

  In the inflation method, first, in the heating and melting step, each resin as a raw material is supplied from a hopper, and this is heated and melted in an extruder. The obtained molten resin is sent to an annular die installed at the tip of the extruder while being adjusted to a temperature suitable for extrusion (extrusion temperature) by a heater / blower. Next, in the inflation step, the molten resin is extruded from the annular die into a cylindrical shape. At this time, air is sent into the cylindrical molten resin from below to expand the diameter of the cylinder to a predetermined size, and cooling air is sent from below to the outside of the cylinder. This expanded cylindrical body is called a bubble.

  Next, the bubble is folded into a film shape by a guide plate and a pinch roll, and wound up at the winding-up part. The folded film may be wound up in a cylindrical shape, or may be wound after removing both ends of the tube with a slitter or the like and separating them into two films.

  The resin extruded from the annular die is tensioned in both the film forming flow direction (MD direction) and the radial direction of the cylinder (TD direction), but it is cooled by applying more tension in the film forming flow direction. Occasionally, the shrinkage difference between the polyethylene resin and the cyclic polyolefin in the flow direction becomes larger, the elongation at break in the MD direction becomes smaller, and it is considered that the straight cut property and the easy tear property in the TD direction (lateral direction) are exhibited. . However, if too much tension is applied in the film-forming flow direction, the film cannot withstand its own weight during inflation film formation, and the film is cut. Therefore, the die temperature and the discharge amount are adjusted so that a suitable tension is applied.

  Specifically, in a normal inflation method, in the extrusion step, the raw material resin is melted and extruded at a die temperature that is at least 90 ° C. higher than its melting point. Therefore, for example, in the case of LLDPE, it is heated and melted at around 200 ° C. and is formed by extrusion from an annular die. If the die temperature is too low, the melt viscosity of the resin becomes high, and it is easy to cause problems such as the generation of fish eyes due to poor kneading of the resin (defective appearance), and film breakage due to the generation of fish eyes. That is generally not done much.

  However, this die temperature is set to be lower by about 10 to 15 ° C. than usual, for example, each resin is melt-extruded at a die temperature of about 160 to 180 ° C., and the melt viscosity is slightly increased to control the tension. Becomes easier. Furthermore, the tension can be controlled by adjusting the discharge amount of the molten resin.

  In one embodiment of the present invention, the heating and melting temperature of the mixed resin forming the second resin layer is set higher than the heating and melting temperature of the resin forming the other layers, for example, 5 to 20 ° C. By setting the temperature higher by 15 ° C., the polyethylene resin and the cyclic polyolefin can be kneaded more uniformly.

<9> Reason for exhibiting straight cut performance excellent only in one direction The reason why the sealant film of the present invention exhibits a straight cut performance excellent only in one direction is considered as follows. That is, it is considered that the second resin layer has a so-called sea-island structure in which the polyethylene resin becomes the sea and the cyclic polyolefin becomes the island in the plane direction. When the sealant film is formed, when the molten resin is extruded and then cooled, the cyclic polyolefin contracts in a direction in which a stronger tension is applied (for example, the MD direction), so that the polyolefin resin and the cyclic polyolefin It is considered that a straight cut property excellent only in a direction perpendicular to the gap (for example, the TD direction) is exhibited because a gap is formed between the gaps and the portion where the gap is formed becomes brittle.

<10> Application to packaging material By laminating any surface of the first and third resin layers of the sealant film of the present invention facing an arbitrary base material, it is possible to cut straightly in one direction. An excellent packaging material can be obtained, and a packaging body can be formed using the packaging material.
As the base material, various plastic films that can be used as a base material for ordinary packaging materials can be used.

  Specifically, a plastic film made of polyethylene terephthalate (PET), polypropylene (PP), polyamide (PA) such as nylon, or the like can be used. Or the multilayer film which laminated | stacked two or more of these plastic films may be sufficient. In the case of a multilayer film, each layer may have the same composition or a different composition.

These plastic films may be stretched in a uniaxial or biaxial direction. In addition, paper or the like can also be used as the base material. Furthermore, you may make it laminate | stack an intermediate | middle layer between a base material and the sealant film of this invention.
In this invention, when using a plastic film as a base material, in order to express suitable tearability, the thickness becomes like this. Preferably it is 9-80 micrometers, More preferably, it is 12-50 micrometers, More preferably, 12- 25 μm.

When a plastic film is used as the substrate, the plastic film may be subjected to pretreatment such as corona treatment, ozone treatment, and frame treatment on the surface on which the sealant film of the present invention is laminated. Moreover, you may provide printing layers, such as a character, a figure, a symbol, and a design, on a base material.
Lamination of the sealant film and the substrate of the present invention can be appropriately performed by an arbitrary method, for example, a sandwich lamination method or a dry lamination method.

  Also, using the packaging material obtained above, the sealant film of the present invention is laminated with the surfaces facing each other, for example, a pillow seal type (joint-sealed seal type), a standing pouch type, a side seal type, a two-way seal Various types of packaging bags are heat-sealed by heat sealing forms such as molds, three-side seal types, four-side seal types, envelope-sealed seal types, pleated seal types, flat bottom seal types, square bottom seal types, gusset types, etc. be able to.

In the above, as a heat sealing method, for example, a known method such as a bar seal, a rotary roll seal, a belt seal, an impulse seal, a high frequency seal, and an ultrasonic seal can be used.
The packaging bag made of the packaging material can be suitably used for chemical products, pharmaceuticals, quasi-drugs, cosmetics, light packaging of foods, heavy bags, liquid or large-capacity free-standing bags, etc. .
Next, the present invention will be specifically described with reference to examples.

[Example 1]
(1) LLDPE polymerized by metallocene catalyst (Co. Prime Polymer Co. Evolue ^(R) SP2020, density ^{= 0.916g / cm 3, MI =} 2.3g / 10 min) 97 wt% and the slip agent masterbatch ( Ube Maruzen Polyethylene Co., Ltd. M425, erucamide 2% by mass containing master batch, density 0.920 g / cm ³ , MI = 4.0 g / 10 min) 3% by mass, And the synthetic resin 1 which forms a 3rd resin layer and an intermediate | middle layer was prepared (layer density 0.916g / cm < ³ >).
(2) Ziegler-Natta catalyst was polymerized using LLDPE ((Ltd.) manufactured by Prime Polymer Co. Ultra Zekkusu ^(R) 2021L, density ^{0.920g / cm 3, MI = 2.0g} / 10 min) and 70 wt%, Secondly, 30% by mass of a cyclic olefin copolymer (TOPAS ^(R) 8007F-500 manufactured by Polyplastics Co., Ltd., density 1.020 g / cm ³ , MI = 2.1 g / 10 min) was sufficiently kneaded. Synthetic resin 2 for forming a resin layer was prepared (layer density: 0.948 g / cm ³ ).

(3) First resin layer (7.5 μm) / second resin layer (5.0 μm) / intermediate layer A using the synthetic resin 1 and the synthetic resin 2 prepared in the above (1) and (2) The film was coextruded by an inflation method so as to have a layer structure of (12.5 μm) / intermediate layer B (5.0 μm) / third resin layer (10.0 μm).
The synthetic resin 1 forming the first and third resin layers and the intermediate layers A and B is from the cylinder to the annular die and is melt-kneaded at 160 to 170 ° C. to form the resin layer of the die 2. Was melt-kneaded from a cylinder to an annular die at 160 to 180 ° C., and these were combined and co-extruded from a 170 ° C. annular die at a discharge rate of 140 kg / h to produce the sealant film of the present invention.
(4) The above-obtained sealant film of the present invention is subjected to a tensile test in accordance with JIS Z1702, and the breaking elongation in the MD direction and the TD direction is obtained using Orientec Co., Ltd. “RTC-1210A”. It was. Each test was performed three times, and the average value was calculated. The breaking elongation E _{MD in} the MD direction was 120%, the breaking elongation E _{TD in the} TD direction was 790%, and E _MD / E _TD = 0. .15.

[Example 2]
(1) As synthetic resin 3 for forming the first and third resin layers, LLDPE polymerized with a Ziegler-Natta catalyst (Novatec ^™ UF320 manufactured by Nippon Polyethylene Co., Ltd., density = 0.922 g / cm ³ , MI = 0. 9 g / 10 min) was prepared.
(2) As synthetic resin 4 forming the second resin layer, LLDPE polymerized with a Ziegler-Natta catalyst (Novatec ^™ UF320, manufactured by Nippon Polyethylene Co., Ltd., density = 0.922 g / cm ³ , MI = 0.9 g / 10) Min) A mixed resin of 80% by mass and 20% by mass of a cyclic olefin copolymer (TOPAS ^(R) 8007F-500 manufactured by Polyplastics Co., Ltd.) was prepared.
(3) The first resin layer (10 μm) / second resin layer (10 μm) / third resin layer (20 μm) using the synthetic resin 3 and synthetic resin 4 prepared in (1) and (2) above. The film was coextruded by an inflation method so as to obtain the layer structure of) to produce the sealant film of the present invention.

The melting temperature, the die temperature, and the discharge amount of the resin were the same as in Example 1.
(4) The above-obtained sealant film of the present invention is subjected to a tensile test in accordance with JIS Z1702, and the breaking elongation in the MD direction and the TD direction is obtained using Orientec Co., Ltd. “RTC-1210A”. It was. Each test was performed three times, and the average value was calculated. The breaking elongation E _{MD in} the MD direction was 180%, the breaking elongation E _{TD in the} TD direction was 790%, and E _MD / E _TD = 0. .23.

[Example 3]
As the synthetic resin 5 forming the second resin layer, LLDPE polymerized with a Ziegler-Natta catalyst (Novatec ^TM UF320, manufactured by Nippon Polyethylene Co., Ltd., density = 0.922 g / cm ³ , MI = 0.9 g / 10 min) 70 A mixed resin of 30% by mass of cyclic olefin copolymer (TOPAS ^(R) 8007F-500 manufactured by Polyplastics Co., Ltd.) is prepared, and the first resin layer (15 μm) / second resin layer (5 μm) ) / The sealant film of the present invention was produced in the same manner as in Example 2 except that the thickness of the third resin layer (20 μm) was changed.
The breaking elongation E _{MD in the} MD direction was 170%, the breaking elongation E _{TD in} the TD direction was 830%, and E _MD / E _TD was 0.20.

[Example 4]
A sealant film of the present invention was produced in the same manner as in Example 2 except that the synthetic resin 5 described above was used as the synthetic resin for forming the second resin layer.
The breaking elongation E _{MD in the} MD direction was 260%, the breaking elongation E _{TD in} the TD direction was 760%, and E _MD / E _TD was 0.34.

[Comparative Example 1]
As the synthetic resin 6 forming the second resin layer, LLDPE (Novatech ^TM UF320 manufactured by Nippon Polyethylene Co., Ltd., density = 0.922 g / cm ³ , MI = 0.9 g / 10 min) polymerized with a Ziegler-Natta catalyst A sealant film was produced in the same manner as in Example 2 except that the thickness was prepared and the first resin layer (15 μm) / second resin layer (5 μm) / third resin layer (20 μm) were used. .
The breaking elongation E _{MD in the} MD direction was 680%, the breaking elongation E _{TD in} the TD direction was 810%, and E _MD / E _TD was 0.84.

[Comparative Example 2]
As the synthetic resin 7 forming the second resin layer, LLDPE polymerized with a Ziegler-Natta catalyst (Novatech ^TM UF320, manufactured by Nippon Polyethylene Co., Ltd., density = 0.922 g / cm ³ , MI = 0.9 g / 10 min) 95 A mixed resin of 5% by mass and 5% by mass of cyclic olefin copolymer (TOPAS ^(R) 8007F-500 manufactured by Polyplastics Co., Ltd.) was prepared, and the first resin layer (15 μm) / second resin layer (5 μm ) / A sealant film was produced in the same manner as in Example 2 except that the thickness of the third resin layer (20 μm) was changed.
The breaking elongation E _{MD in the} MD direction was 430%, the breaking elongation E _{TD in} the TD direction was 830%, and E _MD / E _TD was 0.52.

[Comparative Example 3]
A sealant film was produced in the same manner as in Example 2 except that the above synthetic resin 7 was used as the synthetic resin for forming the second resin layer.
The breaking elongation E _{MD in the} MD direction was 340%, the breaking elongation E _{TD in} the TD direction was 820%, and E _MD / E _TD was 0.41.

[Comparative Example 4]
The synthetic resin 7 was formed by extrusion using an inflation method with a film thickness of 40 μm to produce a single-layer sealant film.
The breaking elongation E _{MD in the} MD direction was 380%, the breaking elongation E _{TD in} the TD direction was 820%, and E _MD / E _TD was 0.46.

[Comparative Example 5]
As the synthetic resin 8 forming the second resin layer, LLDPE polymerized with a Ziegler-Natta catalyst (Novatec ^™ UF320, manufactured by Nippon Polyethylene Co., Ltd., density = 0.922 g / cm ³ , MI = 0.9 g / 10 min) 90 A mixed resin of 10% by mass of cyclic olefin copolymer (TOPAS ^(R) 8007F-500 manufactured by Polyplastics Co., Ltd.) is prepared, and a first resin layer (15 μm) / second resin layer (5 μm) is prepared. ) / A sealant film was produced in the same manner as in Example 2 except that the thickness of the third resin layer (20 μm) was changed.
The breaking elongation E _{MD in the} MD direction was 360%, the breaking elongation E _{TD in} the TD direction was 800%, and E _MD / E _TD was 0.45.

[Comparative Example 6]
A sealant film was produced in the same manner as in Example 2 except that the above synthetic resin 8 was used as the synthetic resin for forming the second resin layer.
The breaking elongation E _{MD in the} MD direction was 420%, the breaking elongation E _{TD in} the TD direction was 790%, and E _MD / E _TD = 0.53.

[Comparative Example 7]
The synthetic resin 8 was formed by extrusion using an inflation method with a film thickness of 40 μm to produce a single-layer sealant film.
The breaking elongation E _{MD in the} MD direction was 330%, the breaking elongation E _{TD in} the TD direction was 800%, and E _MD / E _TD was 0.41.

[Comparative Example 8]
The synthetic resin 4 is used as the synthetic resin for forming the second resin layer, and the film thickness of the first resin layer (15 μm) / second resin layer (5 μm) / third resin layer (20 μm) is used. A sealant film was produced in the same manner as in Example 2 except that.
The breaking elongation E _{MD in the} MD direction was 480%, the breaking elongation E _{TD in} the TD direction was 820%, and E _MD / E _TD was 0.59.

[Comparative Example 9]
The synthetic resin 4 was formed into a film having a thickness of 40 μm by an extrusion method to produce a single-layer sealant film.
The breaking elongation E _{MD in the} MD direction was 300%, the breaking elongation E _{TD in} the TD direction was 790%, and E _MD / E _TD was 0.38.

[Comparative Example 10]
The synthetic resin 5 was formed by extrusion using an inflation method with a film thickness of 40 μm to produce a single-layer sealant film.
The breaking elongation E _{MD in the} MD direction was 260%, the breaking elongation E _{TD in} the TD direction was 720%, and E _MD / E _TD was 0.36.

  Table 1 shows a summary of the synthetic resin constituting each layer of Examples 1 to 4 and Comparative Examples 1 to 10, the content of cyclic polyolefin in the second resin layer, and the thickness of each layer. In Table 1, the numbers in each cell indicate the numbers of the synthetic resins used in Examples 1 to 4 and Comparative Examples 1 to 10, and the numbers in parentheses indicate the thickness. is there. The unit of thickness is μm.

  For the sealant films produced in the above Examples and Comparative Examples, the thickness ratio of the second resin layer to the thickness of the entire sealant film, the content of cyclic polyolefin relative to the entire sealant film, and the evaluation results of the straight cut performance are summarized. Is shown in Table 2. The straight cut property test was performed as follows.

(Straight cut test)
A test piece of 10 cm × 10 cm was cut out from each of the sealant films produced in the above Examples and Comparative Examples, and the straight cut property was evaluated by tearing by hand in the MD direction and the TD direction without a notch. Each test was performed three times. In addition, the evaluation result of the straight cut performance is 1 in the case of tearing in a straight line in the TD direction and meandering in the MD direction, 2 in the case of tearing in the TD direction and the MD direction, and 2 in the TD direction In the MD direction, 3 was defined as the case of tearing in a straight line.

The ratio of the MD direction breaking elongation E _MD , the TD direction breaking elongation E _TD , the TD direction breaking elongation E _TD to the MD direction breaking elongation E _MD of the sealant films produced in the above examples and comparative examples. Table 3 summarizes the measurement results of a certain E _MD / E _TD . Incidentally, the elongation at break E _TD elongation at break E _MD and TD directions of the MD direction conforms to tensile test JIS Z1702, is measured using Ltd. Orientec "RTC-1210A". Moreover, the value shown in Table 3 is an average value obtained by measuring three times.

(Elmendorf tear test)
About the sealant film manufactured by the said Example and the comparative example, based on JIS-K-7128, using the Elmendorf tear tester (Tester Sangyo Co., Ltd. "IM-701"), MD direction and TD which put a notch The tear strength in the direction was measured. Except for Example 1, each test was performed twice, and the average value was calculated.
The results are shown in Table 4 and FIG. The tear strength of TD in Example 1 was below the measurement limit of the testing machine.

(Sealability test)
Two sealant films were prepared for the sealant films produced in the above examples and comparative examples. Thereafter, the third resin layer of one sealant film and the third resin layer of the other sealant film are opposed to each other, and the seal temperature is measured using a heat seal device (Tester Sangyo Co., Ltd. “TP-701-B”). After heat sealing at 120 ° C., a sealing pressure of 1 kgf / cm ² and a sealing time of 1 second, a strip-shaped test piece having a width of 15 mm was cut out. And based on JIS-Z-1707, peeling strength was evaluated using the tensile testing machine (Orientec "RTC-1210A"). Each test was performed 5 times, and the average value was calculated.
The results are shown in Table 5. In addition, the peel strength in Table 5 is a value of peel strength at a width of 15 mm, and the unit is N. Moreover, the case where peeling strength is 5 N / 15mm or more was made into (circle) and the case where less than 5 N / 15mm was made into x.

In the sealant films of Examples 1 to 4, the thickness ratio of the second resin layer to the thickness of the entire sealant film is 1/8 to 1/4, and the content of cyclic polyolefin with respect to the entire sealant film is 3.75 to 7 Since it was .50% by mass, it showed excellent straight cut performance only in the TD direction and good low-temperature sealability.
On the other hand, the sealant films of Comparative Examples 1 to 8 did not have a straight cut property excellent only in one direction. Moreover, the sealant films of Comparative Examples 4, 7, 9, and 10 were inferior in low-temperature sealability.

1. 1st resin layer 2. Second resin layer Third resin layer 4. Intermediate layer 5. Intermediate layer 10. Pillow packaging bag 11. Bottom seal 12. Top seal part 13. Gassho seal part

Claims (6)

At least a sealant film in which a first resin layer, a second resin layer, and a third resin layer are laminated in order,
The first resin layer and the third resin layer are outermost layers of a sealant film and are layers made of a polyethylene resin,
The second resin layer is a layer made of a mixed resin of a polyethylene resin and a cyclic polyolefin,
The thickness of the second resin layer is 1/10 to 1/3 of the thickness of the entire sealant film,
The above sealant film, wherein the cyclic polyolefin is contained in an amount of 3.0 to 25% by mass based on the mass of the entire sealant film.   The polyethylene resin constituting the first resin layer and the third resin layer is an ethylene / α-olefin copolymer polymerized using a single site catalyst, and constitutes the second resin layer. The sealant film according to claim 1, wherein the polyethylene-based resin in the mixed resin is an ethylene / α-olefin copolymer polymerized using a multisite catalyst.   2. An intermediate layer made of a thermoplastic resin is included between the first resin layer and the second resin layer and / or between the second resin layer and the third resin layer. 2. The sealant film according to 2.   The sealant film according to claim 1, which is coextruded.   The package which consists of a packaging material which has the sealant film of any one of Claims 1-4 as a heat seal layer. At least a sealant film in which a first resin layer, a second resin layer, and a third resin layer are sequentially laminated, a method for producing a sealant film, which is co-extruded by an inflation method,
The first resin layer and the third resin layer are outermost layers of the sealant film and are layers made of a polyethylene resin,
The second resin layer is a layer made of a mixed resin of a polyethylene resin and a cyclic polyolefin,
The thickness of the second resin layer is 1/10 to 1/3 of the thickness of the entire sealant film,
A method for producing a sealant film, comprising 3.0 to 25% by mass of the cyclic polyolefin based on the mass of the entire sealant film.

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