JP2005263277A - Easily openable sealant film, packaging material and container using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily openable sealant film which retains excellent heat bonding capability and moderate peeling strength without causing stringiness on a peeling surface, exhibits excellent openability, and furthermore is excellent in economy, with respect to a container whose surface to be bonded is formed of polypropylene, and a packaging material and a container using the same. <P>SOLUTION: The easily openable sealant film 100 is formed of a resin layer (A)1 that is a surface to be heat-sealed to a material to be bonded, and a resin layer (B)4 laminated adjacent thereto, while, for the resin layer (A)1, a mixed resin is used which mixes a mixed resin 2 which is a mixture of of PP and PB-1 in a proportion of 100 part by weight of the mixed resin 2 with respect to 20 to 90 part by weight of a high pressure process LDPE or an ethylene system copolymer 3, and for the resin layer (B)4, an ethylene α olefin copolymer or HDPE or PP polymerized by the use of a single site catalyst is used, both the resin layers formed by a coextrusion inflation molding method to form the film. Furthermore, a base material 5 is stuck to the resin layer (B)4 side of the sealant film 100 to manufacture the packaging material 200. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an easily-openable sealant film and a packaging material and container using the same, and more particularly to an easily-openable sealant film that can be suitably used when the adherend is polypropylene and a packaging material and container using the same.

Conventionally, various cohesive failure type easy peel sealants have been proposed in order to combine the heat-sealed portion with good thermal adhesiveness, sealing property and easy-opening property.
These use a polyolefin resin such as polyethylene, polypropylene, or a copolymer thereof as a thermal adhesive component, and as a dissimilar material that lowers the cohesive force, for example, waxes, hard resins, polystyrene, or modified products thereof Polybutene-1, or polyethylene, polypropylene, etc. having different melting points and densities, etc. are added as appropriate to give easy opening.
For such an easy peel sealant, the thermal adhesive component is selected according to the material of the adherend. For example, in a lid used for a paper cup container in which low density polyethylene is laminated on the innermost layer, the innermost layer There is one in which a low-density polyethylene is used as a heat bonding component of the sealant layer, and the above-described different material that reduces cohesive force is appropriately added to form a sealant layer (see, for example, Patent Document 1).

In the same way, when the adherend is polypropylene, for example, a lid used for a polypropylene molded container or a paper cup container in which polypropylene is laminated as the innermost layer, polypropylene is used as an easy peel sealant of the cohesive failure type. Used for heat-adhesive components, and mixed with ethylene / α-olefin copolymer, low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polystyrene, or modified products thereof to give easy opening (See, for example, Patent Document 2).
Japanese Patent Laid-Open No. 2002-128128 (pages 2 to 4, FIG. 1) JP 2001-301831 (pages 2 and 3, FIG. 1)

  However, when polypropylene is used as the easy-peeling sealant, the heat-sealing component increases the heat-sealing temperature and lacks the low-temperature sealing property. Property) and easy-openability, and it is easy to generate a so-called stringing phenomenon in which the resin of the sealant layer remains in a fibrous state on the peeled surface after peeling after heat sealing. was there. Furthermore, polypropylene itself has a problem that it is inferior in physical properties and resistance at low temperatures such as refrigeration, and an easy peel sealant that can satisfy the overall performance has not been obtained yet.

  In order to solve such a problem, the present inventor previously described an easy peel sealant that can be suitably used in the case of using polypropylene as an adherend in Japanese Patent Application No. 2002-206121, that is, an easy-open sealant. As a film, “a sealant film used for an easily openable heat seal layer, the resin layer (A) formed on the surface of the sealant film heat-sealed to the adherend, and the resin layer (A)” The resin layer (A) is laminated adjacent to the resin layer (A), and the resin layer (A) is 20 to 90 parts by weight of high-pressure low-density polyethylene or ethylene-based copolymer with respect to 100 parts by weight of polybutene-1. The resin layer (B) is formed of an ethylene / α-olefin copolymer polymerized using a single site catalyst. Easy-to-open sealant film and features. "Was proposed the easy-open sealant film of the structure which is based.

The proposed easy-open sealant film improves low-temperature sealability, stabilizes thermal adhesion (sealability) and easy-openability, prevents occurrence of string pulling due to uniform cohesive failure, and physical properties and resistance at low temperatures As a result, many of the conventional problems could be solved.
However, even in such an easy-open sealant film, polybutene-1 is used as a thermal adhesive component for the polypropylene of the adherend, so that butene-1 which is a monomer of polybutene-1 is used in terms of the manufacturing process. Compared with ethylene and propylene, the supply amount is limited, the price is also expensive, and the use of a large amount of polybutene-1 has disadvantages in terms of economy as well as inconvenience in obtaining materials. .

  The present invention has been made in order to solve such problems, and the object of the present invention is to apply polypropylene in particular in the field of containers that peel and open the heat seal portion of a sealed container. As an easy-peeling sealant of cohesive failure type, it has both good thermal adhesiveness (sealing property) and easy-openability, and can be heat-sealed at a relatively low temperature. In addition to reducing the inconvenience of obtaining materials and reducing the inconvenience of obtaining materials, the cost can also be reduced. To provide a sealant film and a packaging material and container using the same.

The above problems can be solved by the following present invention.
That is, the invention described in claim 1 is a sealant film used for an easily openable heat seal layer, wherein the sealant film is formed on a surface to be heat sealed to an adherend, and a resin layer (A) The resin layer (B) is laminated adjacent to the resin layer (A), and the resin layer (A) is a high pressure method low density with respect to 100 parts by mass of a mixed resin of polypropylene and polybutene-1. An ethylene / α-olefin copolymer formed of a mixed resin in which polyethylene or an ethylene-based copolymer is mixed at a ratio of 20 to 90 parts by mass, and the resin layer (B) is polymerized using a single site catalyst or It consists of an easy-open sealant film characterized by being formed of high-density polyethylene or polypropylene.

In the present invention, as polybutene-1 used for the resin layer (A), in addition to 1-butene homopolymer, a copolymer obtained by copolymerizing ethylene or other α-olefin as a comonomer with 1-butene is used. be able to.
Among the high-pressure low-density polyethylene or ethylene-based copolymer used for the resin layer (A), the ethylene-based copolymer includes an ethylene / vinyl acetate copolymer, an ethylene / acrylic acid copolymer, ethylene A methacrylic acid copolymer, an ethylene / acrylic acid ester copolymer, an ethylene / methacrylic acid ester copolymer, or the like can be used.
When an ethylene / α-olefin copolymer polymerized using a single site catalyst is used for the resin layer (B), the ethylene / α-olefin copolymer polymerized using the single site catalyst is a metallocene catalyst or phenoxy. It is a copolymer of ethylene and α-olefin polymerized using a catalyst having a single active site such as an imine catalyst, and among them, one using 1-hexene or 1-octene as the α-olefin of the comonomer is particularly preferable. .
When using a high density polyethylene for the said resin layer (B), the copolymer with a propylene and butene-1 other than the homopolymer of ethylene can be used for a high density polyethylene. Moreover, also when using a polypropylene for the said resin layer (B), a polypropylene can use the copolymer with ethylene, butene-1, and another alpha olefin other than the homopolymer of propylene.

In addition, the resin layer (B) has a good lamination strength with the resin layer (A) in addition to acting as a support layer for the resin layer (A) when forming an easily openable sealant film. When the adhesive sealant film is bonded to a base material to form a packaging material such as a lid, it acts as a cushion layer during the heat sealing, and has a function of stabilizing the heat sealing strength by the resin layer (A).
Therefore, as will be described later, the thickness of the resin layer (B) is preferably larger than the thickness of the resin layer (A).
In particular, when the ethylene / α-olefin copolymer polymerized using the single site catalyst is used for the resin layer (B), the ethylene / α-olefin copolymer polymerized using the single site catalyst is the resin layer. Excellent in lamination strength with (A) and preferable in terms of having good cushioning properties, but because of high toughness, for example, when the thickness is increased to 25 μm or more, when used as a cover material, punching failure It becomes easy to generate.
In order to solve such a problem, the resin layer (B) has, for example, a two-layer structure, and a layer on the side in contact with the resin layer (A) is an ethylene / α-olefin polymerized using the single site catalyst. For the layer on the other side (side to be bonded to the base material), a high-pressure low-density polyethylene that has low toughness and is easy to cut can be used.

The mixing ratio of the mixed resin of polypropylene and polybutene-1 in the resin layer (A) and the high-pressure method low-density polyethylene or ethylene copolymer is 100 parts by mass of the mixed resin of polypropylene and polybutene-1. The high-pressure low-density polyethylene or ethylene-based copolymer is preferably 20 to 90 parts by mass.
When the mixing ratio of the high-pressure method low-density polyethylene or ethylene copolymer is less than 20 parts by mass, when the resin is thermally bonded to polypropylene as an adherend, the adhesive strength becomes too strong and good easy peel properties can be obtained. In addition, when the mixing ratio of the high-pressure method low-density polyethylene or the ethylene copolymer exceeds 90 parts by mass, the cohesive force becomes too weak, the adhesive strength is lowered, and the sealing property is inferior.

  The invention described in claim 2 is such that the mixing ratio of polypropylene and polybutene-1 in the mixed resin of polypropylene and polybutene-1 in the resin layer (A) is such that polybutene-1 is 30 to 100 parts by mass of polypropylene. It is 150 mass parts, It is an easily openable sealant film of Claim 1.

The mixing ratio of polypropylene and polybutene-1 in the mixed resin of polypropylene and polybutene-1 in the resin layer (A) is preferably 30 to 150 parts by mass of polybutene-1 with respect to 100 parts by mass of polypropylene.
When the amount of the polybutene-1 is less than 30 parts by mass, the low-temperature heat-sealing property is deteriorated, and it is not preferable because it is likely to cause stringing when peeled after being thermally bonded to the polypropylene of the adherend. . In addition, when the amount of polybutene-1 exceeds 150 parts by mass, there is no problem in terms of performance. However, during film formation, polybutene-1 has a slow crystallization rate and poor cooling efficiency. As a result, the production of polybutene-1 is lower than that of polypropylene. Polybutene-1 is currently limited in supply and expensive, and its use ratio cannot be reduced. This is not preferable.

According to a third aspect of the present invention, in the mixed resin of the resin layer (A), polypropylene has an MFR in the range of 5 to 40, and polybutene-1 has a melting point of 110 to 130 ° C and an MFR of 2 to 2. The easy-opening according to claim 1 or 2, wherein the high-pressure low-density polyethylene or ethylene-based copolymer has an MFR smaller than that of polypropylene and MFR of polybutene-1 in the range of 30. It consists of an adhesive sealant film.
In the present invention, MFR (melt flow rate) is based on a thermoplastic plastic flow test method of JIS K7210. The MFR of the high-pressure method low-density polyethylene or ethylene-based copolymer is a value according to Condition 4 (190 ° C., 21.18 N). All units are [g / 10 min].

In the resin layer (A), polypropylene and polybutene-1 are compatible with each other and form a sea portion of a sea / island structure, and the high-pressure low-density polyethylene or ethylene-based copolymer is the polypropylene and polybutene-1 And is not compatible with each other and forms an island portion.
In order to easily form the resin layer (A) having such a structure together with the resin layer (B) by, for example, a co-extrusion inflation molding method, the MFR of polypropylene is preferably in the range of 5 to 40, In addition, it is preferable that polybutene-1 has a melting point of 110 to 130 ° C. and the MFR is 2 to 30. If the melting point and MFR of polypropylene MFR and polybutene-1 deviate from this range, it is not preferable because the film formation process becomes difficult.

Further, the MFR of the high pressure method low density polyethylene or ethylene copolymer of the resin layer (A) is related to stringing when heat-sealed to the adherend polypropylene and then opened, and the high pressure method low density polyethylene or When the MFR of the ethylene copolymer is larger than the MFR of polypropylene and polybutene-1, it is not preferable because stringing tends to occur at the time of opening.
In order to suppress the occurrence of this stringing, the MFR of the high pressure method low density polyethylene or ethylene copolymer is preferably smaller than the MFR of polypropylene and polybutene-1, and the high pressure method low density polyethylene or ethylene system More preferably, the MFR ratio of the copolymer to polypropylene and polybutene-1 is in the range of 1/2 to 1/20.

In the invention described in claim 4, the ethylene / α-olefin copolymer polymerized using the single-site catalyst of the resin layer (B) has a density in the range of 0.910 to 0.930 g / cm ^3. It consists of an easily openable sealant film according to any one of claims 1 to 3.

The ethylene / α-olefin copolymer polymerized using the single-site catalyst of the resin layer (B) preferably has a density in the range of 0.910 to 0.930 g / cm ³ and a density of 0.910 g. When the sealant film is less than / cm ^3, the packaging material using the sealant film is heat-sealed to the polypropylene of the adherend, and then, when opened, stringing occurs, and the density is 0.930 g / cm ³ . When exceeding, the lamination strength with the resin layer (A) becomes weak, and the heat seal strength necessary for the sealant film cannot be obtained, which is not preferable.

  The invention described in claim 5 is characterized in that the thickness of the resin layer (A) is in the range of 2 to 15 μm, and the thickness of the resin layer (B) is larger than the thickness of the resin layer (A). It consists of the easy-open sealant film in any one of Claim 1 thru | or 4.

The thickness of the resin layer (A) is preferably in the range of 2 to 15 μm, and the thickness of the resin layer (B) is preferably larger than the thickness of the resin layer (A).
When the thickness of the resin layer (A) is less than 2 μm, when this sealant film is heat-sealed to the adherend, the sealing strength is weak and the sealing property cannot be maintained, and the thickness of the resin layer (A) When the thickness exceeds 15 μm, the peel strength becomes unstable, and good easy peel properties are not exhibited.
Moreover, when the thickness of the resin layer (B) is thinner than the thickness of the resin layer (A), it is not preferable because it becomes difficult to form a sealant film.

  In the invention described in claim 6, the easy-open sealant film according to any one of claims 1 to 5 is laminated on the base material on the resin layer (B) side as a heat seal layer, and the resin layer (A) Is made of a packaging material configured to be the innermost layer.

The said base material is not specifically limited, Paper, a plastic film, metal foil, etc. can be used individually or suitably laminated | stacked.
Such a base material and an easy-open sealant film can be easily laminated by a dry lamination method or an extrusion lamination method (so-called sandwich lamination method). When laminating, the laminated surface of the base material and easy-open sealant film is subjected to flame treatment, corona discharge treatment, ozone treatment as well as easy adhesion treatment such as anchor coat treatment and primer coat treatment as necessary. Can be applied.

  In the invention described in claim 7, the packaging material described in claim 6 is heat-sealed to the opening of the container in which the adhesive surface of the container opening is formed of polypropylene as a lid, and the resin of the lid is opened when opened. It consists of a packaging container characterized in that the layer (A) is cohesively broken and opened.

Examples of the container in which the adhesive surface of the container opening is formed of polypropylene include, for example, a single injection molding or sheet molding container of polypropylene alone, a multilayer injection molding container or a multilayer sheet molding container using polypropylene as the innermost layer, or A cup-shaped or tray-shaped paper container in which polypropylene is laminated on the innermost layer, and a cup-shaped composite produced by inserting a blank plate into an injection mold and injection-molding polypropylene into the flange and other required parts A container etc. can be used.
When the container is a multilayer sheet molding container and requires gas barrier properties, for example, a multilayer sheet for molding is provided, and a gas barrier resin layer such as saponified ethylene / vinyl acetate copolymer is provided in the intermediate layer, A gas barrier container can be manufactured by laminating and forming a polypropylene layer on both sides of the polypropylene layer and molding the layer into a container by a compressed air or vacuum forming method.

According to the first aspect of the present invention, the easy-open sealant film is laminated adjacent to the resin layer (A) formed on the surface to be heat sealed to the adherend and the resin layer (A). The resin layer (A) is a mixture of polypropylene (hereinafter sometimes referred to as PP) and polybutene-1 (hereinafter sometimes referred to as PB-1). High-pressure method low-density polyethylene (hereinafter sometimes referred to as high-pressure method LDPE) or ethylene-based copolymer mixed at a ratio of 20 to 90 parts by mass with respect to 100 parts by mass of the resin, and The resin layer (B) is formed of an ethylene / α-olefin copolymer polymerized using a single site catalyst, high density polyethylene (hereinafter sometimes referred to as HDPE) or polypropylene. Runode, provide the following operational effects.
That is, the easy-open sealant film is formed by, for example, a co-extrusion inflation molding method, so that PP and PB-1 are compatible with each other in the resin layer (A). Since LDPE or ethylene-based copolymer is not compatible with either PP or PB-1, PP and PB-1 are used as matrix components (sea components), and high-pressure LDPE is contained therein. Alternatively, the film can be formed into a sea / island structure in which an ethylene copolymer is dispersed in an island shape.

  And since PP and PB-1 which make a sea part have heat adhesiveness with respect to PP of a to-be-adhered material, they act as a heat-adhesive component with respect to PP to-be-adhered material. On the other hand, the high-pressure LDPE or ethylene copolymer forming the island portion reduces the cohesive strength of PP and PB-1, and at the same time has no thermal adhesiveness to the adherend polypropylene. When a packaging material using an openable sealant film as a sealant layer is heat-sealed, for example, in a container made of polypropylene, the resin layer (A) will cause cohesive failure at the time of opening, and an easy peel property will be exhibited. Is done.

  By using a mixed resin of PP and PB-1 as the matrix component of the resin layer (A), both of the disadvantages of the resin layer are complemented with each other. In addition, threading at the time of peeling after thermal bonding is prevented, and cost can be reduced by PP.

For the resin layer (B), it is preferable to use an ethylene / α-olefin copolymer or HDPE or PP polymerized using a single site catalyst. The use of polymerized linear low density polyethylene is not preferable because the lamination strength with the resin layer (A) becomes weak, and as a result, the necessary heat seal strength with the resin layer (A) cannot be obtained.
The resin layer (B) has a cohesive force stronger than that of the resin layer (A), and causes cohesive failure to occur only in the resin layer (A) at the time of peeling to stabilize the peel strength. It has the effect of absorbing the uneven contact of the head and stabilizing the seal strength.
Further, when the resin layer (A) is formed thin by providing the resin layer (B), the resin layer (A) and the resin layer (B) are formed by coextrusion and film formation by the inflation method. The thickness of the layer (A) is stabilized, and the easy-open sealant film can be easily formed.
Therefore, there is an effect that it is possible to provide an easily-openable sealant film having stable heat-sealability and sealing property and stable easy-opening property due to cohesive failure, and excellent in economic efficiency with high productivity.

  According to the invention described in claim 2, in the structure of the easy-open sealant film of the invention described in claim 1, polypropylene and polybutene-1 in a mixed resin of polypropylene and polybutene-1 in the resin layer (A). Is mixed with 30 to 150 parts by mass of polybutene-1 with respect to 100 parts by mass of polypropylene. In addition to the effects of the invention described in claim 1, the polypropylene and polybutene-1 The mixing ratio can be adjusted to a more suitable range, with a good balance between the effect of improving the low-temperature sealability, the effect of preventing stringing when peeled after being thermally bonded to the adherend polypropylene, and the cost reduction effect. It can be obtained more reliably.

According to the invention described in claim 3, in the structure of the easy-open sealant film of the invention described in claim 1 or 2, the mixed resin polypropylene of the resin layer (A) has a MFR in the range of 5-40. Polybutene-1 has a melting point in the range of 110 to 130 ° C. and an MFR in the range of 2 to 30, and the high-pressure low-density polyethylene or ethylene copolymer has an MFR of the polypropylene MFR and polybutene. -1 is smaller than the MFR, and therefore, when the easy-open sealant film is formed, the polypropylene and polybutene-1 in the resin layer (A) and the high-pressure low-density polyethylene or ethylene-based copolymer are used. It becomes easier to form a sea-island structure. Further, it is possible to prevent the occurrence of stringing when the easy-open sealant film is heat-sealed to the adherend polypropylene and then opened.
Therefore, in addition to the effects of the invention described in claim 1 or 2, the cohesive failure by the resin layer (A) at the time of opening after the heat-sealing of the easy-open sealant film is more reliably performed, An easy-open sealant film having excellent sealing properties and having a more stable easy-open property without stringing on the release surface can be produced with high productivity.

According to the invention described in claim 4, in the structure of the easy-open sealant film of the invention described in any one of claims 1 to 3, the ethylene layer polymerized using the single-site catalyst of the resin layer (B). Since the density of the α-olefin copolymer is in the range of 0.910 to 0.930 g / cm ³ , the lamination strength of the resin layer (B) with respect to the resin layer (A) can be strongly stabilized, It is possible to prevent stringing when the easy-open sealant film is heat-sealed to the adherend polypropylene and then opened.
Therefore, in addition to the operational effects of the invention described in any one of claims 1 to 3, there is no occurrence of stringing at the time of opening the easily-openable sealant film, and there is an appropriate heat-sealing strength, and an easily-openable property. At the same time, it is possible to reliably produce an easy-open sealant film that is further excellent in thermal adhesiveness and sealing performance.

  According to the invention described in claim 5, in the configuration of the easy-open sealant film of the invention described in any one of claims 1 to 4, the thickness of the resin layer (A) is in the range of 2 to 15 μm, and Since the thickness of the resin layer (B) is larger than the thickness of the resin layer (A), in addition to the operational effects of the invention according to any one of claims 1 to 4, the easy-open sealant film The film can be formed more easily, and an easy-open sealant film having stable heat-sealing strength, sealing properties, and easy peel properties can be manufactured more easily.

  According to the invention described in claim 6, the packaging material using the easy-open sealant film is used as the heat-seal layer of the easy-open sealant film described in any one of claims 1 to 5, and the resin layer (B Since the resin layer (A) is the innermost layer, the performance of the easy-open sealant film according to any one of claims 1 to 5 is maintained as it is. It can be applied to the heat seal layer of the packaging material. Therefore, as a packaging material for containers such as lids and bags made of polypropylene, the adhesive surface of the lid material has both good thermal adhesiveness and easy opening, as well as low-temperature sealing properties and physical properties at low temperatures such as freezing. In addition, it is possible to provide a packaging material that is excellent in resistance and the like, and further excellent in economic efficiency.

  According to the seventh aspect of the present invention, the adhesive surface of the container opening is formed of polypropylene using the packaging container using the easy-open sealant film and the packaging material according to the sixth aspect as a lid. The container is heat sealed at the opening of the container, and the lid resin layer (A) is agglomerated and broken when opened. Therefore, the lid has good thermal adhesiveness and excellent sealing performance. Since the resin layer (A) of the lid material is coagulated and broken, it is opened cleanly without causing stringing on the peeled surface, and it has an easy peel property and is also economical. Can be provided.

FIG. 1 is a schematic cross-sectional view showing the configuration of an example of an easy-open sealant film of the present invention.
FIG. 2 is a schematic cross-sectional view showing a configuration of an embodiment of a packaging material manufactured using the easy-open sealant film of the present invention.
FIG. 3 is a schematic cross-sectional view showing the configuration of an embodiment of a packaging container manufactured using a packaging material using the easy-open sealant film of the present invention as a lid.

When used as a packaging material, the easy-open sealant film 100 shown in FIG. 1 is usually laminated on a substrate as shown in FIG. 2 and used as a heat seal layer. The resin layer (A) 1 formed on the surface to be heat-sealed to the side adherend and the resin layer (B) 4 laminated adjacent to the resin layer (A) 1, the resin layer (B) 4 is a single layer It is formed of ethylene / α-olefin copolymer or HDPE or PP polymerized using a site catalyst, and the resin layer (A) 1 is a mixed resin 2 of PP and PB-1 with respect to 100 parts by mass. The high pressure method LDPE or the ethylene-based copolymer 3 is mixed resin mixed at a ratio of 20 to 90 parts by mass. Furthermore, as for the mixing ratio of both in the mixed resin 2 of PP and PB-1, it is preferable that PB-1 is 30-150 mass parts with respect to 100 mass parts of PP.
In the resin layer (A) 1, PP and PB-1 are compatible with each other so that a homogeneous phase is formed. However, the high pressure LDPE or the ethylene copolymer 3 is compatible with both PP and PB-1. Therefore, in the resin layer (A) 1 formed into a film, a mixed resin 2 of PP and PB-1 is used as a matrix component (sea component), and a high pressure method LDPE or an ethylene copolymer 3 is an island component therein. It is formed and configured to take a distributed sea / island structure.

The mixed resin 2 of PP and PB-1 that is a matrix component of the resin layer (A) 1 has good thermal adhesiveness to the polypropylene of the adherend, and by PB-1 of the mixed resin 2, As described above, heat sealing at low temperatures is possible, and physical properties and resistance at low temperatures such as freezing can be improved. In addition, the PP of the mixed resin 2 can reduce the cost while maintaining the performance as compared with the case where PB-1 is used alone.
Then, a resin layer (A) 1 is formed into a sea / island structure by using a mixed resin 2 of PP and PB-1 and a high pressure LDPE or ethylene copolymer 3 used by mixing with the resin, and agglomerates the resin layer (A) 1. When peeling after sealing by reducing the force, good easy peel property is developed by cohesive failure.

As the PB-1, as described above, in addition to a homopolymer of 1-butene, a copolymer obtained by copolymerizing ethylene or another α-olefin as a comonomer with 1-butene may be used. The melting point is preferably in the range of 110 to 130 ° C., and the MFR is preferably in the range of 2 to 30.
As the PP, a homopolymer of propylene may be used, but a random copolymer obtained by copolymerizing propylene with ethylene, butene-1, or other α-olefin as a comonomer can be preferably used. Further, the MFR of PP is preferably in the range of 5 to 40, and more preferably in the range of 10 to 30. The melting point of PP is preferably as low as 150 ° C. or less from the viewpoint of preventing stringing at the time of opening, and PP is preferably a random copolymer.
As described above, the high pressure process LDPE or ethylene copolymer 3 used in the resin layer (A) 1 together with the PP and PB-1 may be combined with the ethylene / vinyl acetate copolymer in addition to the high pressure process LDPE. An ethylene copolymer such as a polymer, an ethylene / acrylic acid copolymer, an ethylene / methacrylic acid copolymer, an ethylene / acrylic acid ester copolymer, and an ethylene / methacrylic acid ester copolymer can be used.
Such a high-pressure LDPE or ethylene copolymer 3 has an MFR that is higher than that of PP and PB-1 from the viewpoint of the formation of a sea-island structure with the mixed resin 2 of PP and PB-1. Is preferably small.

In addition, the resin layer (B) 4 laminated adjacent to the resin layer (A) 1 forms a good easy-open sealant film 100 in cooperation with the resin layer (A) 1. Those having good adhesion to the resin layer (A) 1 and cushioning properties and capable of stabilizing the heat sealability of the resin layer (A) 1 are preferred.
As such a resin layer (B) 4, ethylene / α-olefin copolymer polymerized using a single site catalyst, HDPE, PP is suitable, and in particular, ethylene / α polymerized using a single site catalyst. An ethylene / α-olefin copolymer using 1-hexene or 1-octene as an α-olefin as a comonomer in an olefin copolymer is particularly suitable. The ethylene / α-olefin copolymer polymerized using such a single site catalyst preferably has a density in the range of 0.910 to 0.930 g / cm ³ .

The resin layer (A) 1 formed of the mixed resin 2 of PP and PB-1 as described above and the mixed resin of the high pressure method LDPE or the ethylene-based copolymer 3 has an appropriate heat seal strength and peeling after sealing. It is preferable that the resin layer (A) 1 is relatively thin and has a thickness in the range of 2 to 15 μm. Is preferred.
In addition, the thickness of the resin layer (B) 4 laminated adjacent to the resin layer (A) 1 is preferably relatively thick so that the cushioning property is effectively applied, and at least the resin layer (A) 1 It is preferable that the thickness is larger than the thickness.

  In the manufacturing method of the easy-open sealant film 100 formed by the laminate of the resin layer (A) 1 and the resin layer (B) 4 as described above, the thickness of the resin layer (A) 1 is, for example, 5 μm or less. In the case of forming a thin film, it is difficult to form the film alone with a stable thickness, and a method of forming the resin layer (A) 1 and the resin layer (B) 4 at the same time by co-extrusion is formed. Sex is also effective.

  Next, FIG. 2 is a schematic cross-sectional view showing a configuration of an embodiment of a packaging material manufactured using the easy-open sealant film of the present invention, and the packaging material 200 shown in FIG. The easy-open sealant film 100 shown in FIG. 5 is arranged so that the resin layer (B) 4 faces the base material 5, and both are bonded together via the adhesive layer 6.

  As the substrate 5, paper, plastic film, metal foil alone, or a laminate in which two or more of these are laminated can be used. The plastic film may be a vapor deposition film provided with a thin film layer of an inorganic oxide such as silica or alumina or a thin film layer of a metal such as aluminum in order to further improve the gas barrier property.

Such a packaging material 200 is obtained by applying the base material 5 and the easy-open sealant film 100 as the adhesive layer 6 by a dry laminating method using, for example, a dry laminating adhesive such as a two-component curable polyurethane adhesive. In addition to being able to be manufactured together, the adhesive layer 6 is manufactured by sticking together by an extrusion laminating method (sandwich laminating method) using a thermal adhesive resin such as low density polyethylene, ethylene copolymer, or polyethylene blend resin. You can also.
In addition, such a packaging material 200 can be suitably used as an easy-opening lid material for various packaging containers in which the lid adhesive surface of the opening is made of polypropylene, and can be made into various shapes and easily opened. It can also be used as a sex bag.

FIG. 3 is a schematic cross-sectional view showing the configuration of an embodiment of a packaging container manufactured using the packaging material using the easy-open sealant film of the present invention as a lid, and the packaging container shown in FIG. 300 is a container body 10 having an opening at the top and a flange portion 11 provided at the periphery of the top of the opening, a shape that covers the opening, and a knob portion 21 at one end. It is comprised with the cover material 20 used by heat-sealing.
For example, a material obtained by punching the easy-open packaging material 200 having the configuration shown in FIG. 2 is used as the lid member 20, and an adhesive surface of the lid member, in this case, a flange, is used for the container body 10. A container in which at least the upper surface of the portion 11 is made of polypropylene can be used.

As such a container body 10, in addition to a container by injection molding or sheet molding of polypropylene alone, a container by multilayer injection molding or multilayer sheet molding using polypropylene as the innermost layer, or a cup shape in which polypropylene is laminated on the innermost layer Or, use a tray-shaped paper container, or a cup-type composite container that is manufactured by inserting a blank plate into an injection mold and injection-molding polypropylene into a flange or other necessary parts into a framework. be able to.
By adopting such a configuration, heat sealing of the packaging container 300 is performed by heat sealing between the polypropylene surface of the flange portion 11 of the container and the resin layer (A) surface of the lid member 20, so that an appropriate sealing strength is obtained. In addition to being able to heat-seal with good sealing performance, when opening the packaging container 300, the resin layer (A) is agglomerated and broken by pinching the lid member 20 by grasping the knob portion 21, and stringing is performed on the peeling surface. Can be opened with good easy peel property.

  Hereinafter, examples of the easy-open sealant film of the present invention and a packaging material using the same will be described in more detail. However, this invention is not limited to these unless it exceeds the gist.

The packaging material having the structure shown in FIG. 2 was prepared. The easy-open sealant film 100 was formed on the resin layer (A) 1 with PP (random copolymer using ethylene as a comonomer, melting point 134 ° C., MFR = 20) and PB-1 (melting point 125 ° C., MFR = 20) mixed at a mass ratio of 5: 2 with respect to 100 parts by mass, high-pressure LDPE (MFR = 4) is 43 parts by mass. In the resin layer (B) 4, an ethylene / α-olefin copolymer polymerized using a metallocene catalyst (hereinafter referred to as M-ethylene / α-olefin copolymer) is used. (In this case, 1-hexene is used for the α-olefin) (density 0.920 g / cm ³ ), the thickness of the resin layer (A) is 5 μm, and the thickness of the resin layer (B) is 25 μm. Co-extrusion so that A film was formed by a blow molding method (extrusion temperature 230 ° C.).

Next, a biaxially stretched polyethylene terephthalate film (hereinafter sometimes referred to as a PET film) (thickness: 12 μm) / high pressure method LDPE layer (thickness: 20 μm) / aluminum foil (thickness: 7 μm) / adhesion is applied to the substrate 5 from the outside. Using the laminated film (total thickness 54 μm) laminated in the order of the agent layer (thickness 3 μm) / PET film (thickness 12 μm), an anchor coat is applied to the inner PET film surface (with corona discharge treatment), and then the anchor The coated surface and the resin layer (B) 4 surface of the easy-open sealant film 100 are opposed to each other, and an extrusion laminating method (sandwich laminating method) using a high-pressure LDPE (thickness 20 μm) as the adhesive layer 6 therebetween. The easy-open packaging material of Example 1 was produced by bonding.
In addition, regarding the lamination of the laminated film of the base material 5, the outer PET film and the aluminum foil of the intermediate layer are stuck by an extrusion laminating method using a high pressure method LDPE (thickness 20 μm) as an adhesive layer between them. In addition, the aluminum foil of the intermediate layer and the inner PET film are bonded together by a dry laminating method using a two-component curable polyurethane adhesive (thickness 3 μm) as an adhesive. .

  From the outside, the packaging material of Example 1 is composed of PET film (thickness 12 μm) / high pressure method LDPE layer (thickness 20 μm) / aluminum foil (thickness 7 μm) / adhesive layer (thickness 3 μm) / PET film (thickness 12 μm). ) / High-pressure method LDPE layer (thickness 20 μm) / M-ethylene / α-olefin copolymer (α-olefin is 1-hexene) layer (thickness 25 μm) / mixed resin of PP and PB-1 (100 parts by mass) : High pressure LDPE (43 parts by mass) mixed resin layer (5 μm thick).

The packaging material having the configuration shown in FIG. 2 was produced as follows to obtain the packaging material of Example 2.
The easy-open sealant film 100 has a resin layer (A) 1 with PP (random copolymer using ethylene as a comonomer, melting point 134 ° C., MFR = 20) and PB-1 (melting point 125 ° C., MFR = 20). ) With a mass ratio of 4.5: 2 with respect to 100 parts by mass of the mixed resin obtained by mixing the high pressure method LDPE at a ratio of 54 parts by mass. As a two-layer structure, the same M-ethylene / α-olefin copolymer as that used for the resin layer (B) of Example 1 is used for the layer on the side in contact with the resin layer (A), and the substrate 5 is pasted. A high-pressure method LDPE (density 0.925 g / cm ³ , MFR = 2.2) was used for the layer to be combined, the resin layer (A) had a thickness of 5 μm, and the resin layer (B) The thickness of the high pressure LDPE layer on the bonding side is 13 μm, and the resin layer (A The film is formed by coextrusion inflation molding (extrusion temperature 230 ° C.) so that the thickness of the M-ethylene / α-olefin copolymer layer on the side in contact with the resin layer is 12 μm (the total thickness of the resin layer (B) is 25 μm). And produced.

Next, on the base material 5, a PET film (thickness 12 μm) and a PET film (thickness 12 μm) provided with a silica vapor deposition layer on one side are directed so that the silica vapor deposition layer becomes a bonding surface, Using a laminated film bonded by a dry lamination method using a two-component curing type polyurethane adhesive, the PET film surface on the silica-deposited PET film side and the resin layer (B) 4 surfaces of the easy-open sealant film 100 The two were bonded together by a dry laminating method using a two-component curable polyurethane adhesive as an adhesive layer 6 to prepare an easy-open packaging material.
In the case of the above dry lamination, the PET film surface to be the bonding surface and the high pressure LDPE layer surface of the resin layer (B) 4 of the easy-open sealant film 100 are both subjected to corona discharge treatment and bonded. It is.

  The structure of the packaging material of Example 2 is as follows: PET film (thickness 12 μm) / adhesive layer (thickness 3 μm) / silica vapor deposition layer / PET film (thickness 12 μm) / adhesive layer (thickness 3 μm) / high pressure method LDPE layer (thickness 13 μm) / M-ethylene / α-olefin copolymer (α-olefin is 1-hexene) layer (thickness 12 μm) / mixed resin of PP and PB-1 (100 parts by mass): high pressure method LDPE It is a mixed resin layer (thickness 5 μm) of (54 parts by mass).

(Comparative Example 1)
In the configuration of the packaging material of Example 1, PB-1 was removed from the mixed resin of the resin layer (A) used for forming the easy-open sealant film 100, and PP (random copolymer using ethylene as a comonomer) , Melting point 134 ° C., MFR = 20) 100 parts by mass, all except that the resin layer (A) was formed using a mixed resin obtained by mixing 43 parts by mass of high-pressure LDPE (MFR = 4) The packaging material of Comparative Example 1 was produced by processing in the same manner as in Example 1.

  The structure of the packaging material of Comparative Example 1 is as follows: PET film (thickness 12 μm) / high pressure method LDPE layer (thickness 20 μm) / aluminum foil (thickness 7 μm) / adhesive layer (thickness 3 μm) / PET film (thickness 12 μm). ) / High pressure method LDPE layer (thickness 20 μm) / M-ethylene / α-olefin copolymer (α-olefin is 1-hexene) layer (thickness 25 μm) / PP (100 parts by mass): high pressure method LDPE (43 mass) Part) mixed resin layer (thickness: 5 μm).

(Comparative Example 2)
In the configuration of the packaging material of Example 1, the M-ethylene / α-olefin copolymer (α-olefin is 1-hexene) (density) of the resin layer (B) used for forming the easy-open sealant film 100 A packaging material of Comparative Example 2 was produced in the same manner as in Example 1 except that only 0.920 g / cm ³ and MFR = 2) were changed to the high pressure method LDPE to form a film.

The structure of the packaging material of Comparative Example 2 is as follows: PET film (thickness 12 μm) / high pressure method LDPE layer (thickness 20 μm) / aluminum foil (thickness 7 μm) / adhesive layer (thickness 3 μm) / PET film (thickness 12 μm). ) / High pressure method LDPE layer (thickness 20 μm) / high pressure method LDPE (density 0.925 g / cm ³ , MFR = 2.2) layer (thickness 25 μm) / mixed resin of PP and PB-1 (100 parts by mass): It is a mixed resin layer (thickness 5 μm) of high pressure method LDPE (43 parts by mass).

[Tests and results]
Using the packaging materials of Examples 1 and 2 and Comparative Examples 1 and 2 produced as described above as samples, each was sealed on a polypropylene sheet having a thickness of 500 μm, a seal temperature of 190 ° C. to 200 ° C., a pressure of 98 kPa, and a time of 1 second. After heat-sealing under the conditions, each packaging material was peeled from the polypropylene sheet, and the peel strength, the state of the peeled surface, that is, whether uniform cohesive failure was performed, and the presence of stringing were examined. .

  The packaging materials of Example 1 and Example 2 both show appropriate peel strength (range of 6 to 15 N / 15 mm width), and the resin layer (A) aggregates without causing stringing on the peeled surface. It was destroyed and could be peeled off uniformly, and had good thermal adhesiveness and easy peelability (easy opening).

In contrast, in the packaging material of Comparative Example 1, PB-1 was not mixed with the resin of the matrix component of the resin layer (A) of the easy-open sealant film, and PP (random copolymer using ethylene as a comonomer). Since only the union) was used, stringing occurred on the peeled surface, and the cohesive failure was not uniform.
Moreover, since the packaging material of Comparative Example 2 was formed with the resin layer (B) of the easy-open sealant film by the high pressure method LDPE, the lamination strength with the resin layer (A) was weakened, and the resin layer Peeling occurred between (B) and the resin layer (A), and it was not preferable because good heat seal strength and sealability could not be obtained.

The easy-open sealant film of the present invention can be used as a heat seal layer for a lid or bag of a molded container, and is particularly stable with respect to a molded container or bag having an adherend surface formed of polypropylene. The heat sealability, sealing property, and easy-opening property by easy peel can be suitably used, and at the same time, the manufacturing cost can be reduced.
The contents filled in these molded containers and bags can be used for a wide range of contents such as various foods and medicines and are not particularly limited.

It is a schematic cross section which shows the structure of one Example of the easily openable sealant film of this invention. It is a schematic cross section which shows the structure of one Example of the packaging material manufactured using the easily openable sealant film of this invention. It is a schematic cross section which shows the structure of one Example of the packaging container manufactured using the packaging material using the easily openable sealant film of this invention for a cover material.

Explanation of symbols

1 Resin layer (A)
2 Mixed resin of PP and PB-1 3 High pressure method LDPE or ethylene copolymer 4 Resin layer (B)
DESCRIPTION OF SYMBOLS 5 Base material 6 Adhesion layer 10 Container main body 11 Flange part 20 Cover material 21 Knob part 100 Easy-open sealant film 200 Packaging material 300 Packaging container

Claims (7)

A sealant film used for an easily openable heat seal layer, wherein the sealant film is adjacent to the resin layer (A) formed on the surface to be heat sealed to the adherend, and the resin layer (A). The resin layer (A) comprises a laminated resin layer (B), and the resin layer (A) comprises 20 to 90 of high-pressure low-density polyethylene or ethylene copolymer with respect to 100 parts by mass of a mixed resin of polypropylene and polybutene-1. The resin layer (B) is formed of an ethylene / α-olefin copolymer or high density polyethylene or polypropylene polymerized using a single site catalyst. Easy-to-open sealant film characterized by The mixing ratio of polypropylene and polybutene-1 in the mixed resin of polypropylene and polybutene-1 in the resin layer (A) is such that polybutene-1 is 30 to 150 parts by mass with respect to 100 parts by mass of polypropylene. The easily openable sealant film according to claim 1. In the mixed resin of the resin layer (A), polypropylene has an MFR in the range of 5 to 40, polybutene-1 has a melting point of 110 to 130 ° C., an MFR in the range of 2 to 30, and high pressure. 3. The easy-open sealant film according to claim 1 or 2, wherein the low density polyethylene or ethylene copolymer has an MFR smaller than that of polypropylene and MFR of polybutene-1. The ethylene / α-olefin copolymer polymerized using the single-site catalyst of the resin layer (B) has a density in the range of 0.910 to 0.930 g / cm ^3. The easily openable sealant film according to any one of 3 above. The thickness of the resin layer (A) is in the range of 2 to 15 µm, and the thickness of the resin layer (B) is larger than the thickness of the resin layer (A). The easy-open sealant film described in 1. The easy-open sealant film according to any one of claims 1 to 5 is laminated on a base material on the resin layer (B) side as a heat seal layer, and the resin layer (A) is an innermost layer. Packaging material. The packaging material according to claim 6 is heat-sealed to the opening of the container in which the adhesive surface of the container opening is formed of polypropylene as a lid, and the resin layer (A) of the lid is agglomerated and broken at the time of opening. A packaging container characterized by being opened.

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