JP2016215412A - Belt-state film and package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt-state film excellent in adhesion.SOLUTION: A belt-state film is configured so that film layers comprising at least a first resin layer and a second resin layer are laminated so that the first resin layer becomes an outermost layer on one side, and the second resin layer becomes an outermost layer on the other side, from one side toward the other side. The first resin layer and second resin layer contain a polyolefin resin, and at least one layer out of the film layers contains a glycerine fatty acid ester, and a gel fraction of the first resin layer is 0.5-5.0 mass%, and a gel fraction of the second resin layer is 5.0-15.0 mass%. A package formed by coating a contact part between a container and a lid with the belt-state film, is also provided.SELECTED DRAWING: None

Description

  The present invention relates to a band-shaped film used for binding, covering, labeling, etc. in the field of container packaging, in particular, a band-shaped film with improved adhesion tearing and liquid leakage prevention properties, and a package using the band-shaped film About.

  The method of packaging fruits and vegetables, fresh fish, meat, prepared dishes, etc. in a container, covering the container with a lid or film from the top, and selling the packaged containers together is to maintain the freshness of food, prevent dust, prevent leakage, and transfer odors. It is often used in supermarkets and convenience stores from the viewpoint of prevention.

  Conventionally, when a container containing food or the like is sealed, a resin or paper container and a resin film or lid are generally used from the viewpoint of cost and cosmetics.

  For example, Patent Document 1 describes a heat-shrinkable polyester resin film used for bundling, covering, labeling, and the like, and Patent Document 2 describes a heat-shrinkable polystyrene system as a container label or cap seal. A resin laminated film roll is described. Patent Document 3 describes a method for sealing a packaging container in which the overlapping portion of the container and the lid is covered with an elastic band film.

JP 2013-39787 A International Publication No. 2008/129598 JP 2005-22688 A

  However, the polyester resin film described in Patent Document 1 and the polystyrene-based resin laminated film roll described in Patent Document 2 are excellent in transparency, heat shrinkability, and heat sealability, but the slipperiness of the film itself is good. Therefore, when it is used for packaging a lunch box, a gap is formed between the film and the packed lunch box body, and the contents are liable to leak. In addition, the prior art document 3 only describes a sealing method, and does not describe a specific strip film.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a belt-like film having excellent adhesion.

  In order to solve the above problems, the present inventor uses a film layer containing a polyolefin-based resin, and the glycerin is formed in at least one layer of the film layer while keeping the gel fraction of both layers of the film layer within a predetermined range. It has been found that by kneading the fatty acid ester, the adhesion to the contact portion between the container and the lid can be improved, and the present invention has been made.

That is, the present invention is as follows.
[1] A film layer including at least a first resin layer and a second resin layer is directed from one side to the other side, the first resin layer becomes the outermost layer on the one side, and the second resin layer is It is a band-shaped film that is laminated so as to be the outermost layer on the other side,
The first resin layer and the second resin layer include a polyolefin resin, and at least one of the film layers includes a glycerin fatty acid ester,
The gel fraction of the first resin layer is 0.5 to 5.0 mass%, and the gel fraction of the second resin layer is 5.0 to 15.0 mass%,
A belt-like film characterized by that.

[2] The strip-shaped film according to [1], wherein the content of the glycerin fatty acid ester is 0.1 to 10% by mass with respect to 100% by mass of the film layer.

[3] The strip-shaped film according to [1] or [2], which is stretched at least in the flow direction (MD direction) and has a heat shrinkage ratio SM in the flow direction (MD direction) at 110 ° C. of 5% or more.

[4] The surface roughness RaA of the outer surface A of the first resin layer is 4.0 to 10.0,
The surface roughness RaB of the outer surface B of the second resin layer is 3.0 to 5.0,
Here, the RaA and the RaB satisfy the following formula (1).
1.1 ≦ RaA / RaB ≦ 3.0 (1)
[1] to [3] The belt-like film according to any one of [3].

[5] The strip-shaped film according to any one of [1] to [4], wherein the gel fraction of the first resin layer and the second resin layer is 10 to 35% by mass.

[6] A package formed by covering the contact portion between the container and the lid with the belt-like film according to any one of [1] to [5].

  According to the present invention, it is possible to provide a belt-like film having excellent adhesion.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented with appropriate modifications within the scope of the gist.

(Strip film)
The belt-like film of the present embodiment is obtained by laminating a film layer including at least a first resin layer and a second resin layer from one side to the other side. Here, in the strip | belt-shaped film of this embodiment, it laminate | stacks so that a 1st resin layer may become an outermost layer of one side, and a 2nd resin layer may become an outermost layer of the other side.

  In addition, the film layer of the strip | belt-shaped film of this embodiment may contain the intermediate | middle layer (after-mentioned) at least 1 layer between the 1st resin layer and the 2nd resin layer as needed.

Here, in the strip film of the present embodiment, the first resin layer and the second resin layer contain a polyolefin-based resin.
Moreover, in the strip | belt-shaped film of this embodiment, at least 1 layer among film layers contains glycerol fatty acid ester.
Furthermore, in the strip | belt-shaped film of this embodiment, the gel fraction of the 1st resin layer is 0.5-5.0 mass%, and the gel fraction of the 2nd resin layer is 5.0-15.0 mass. %.

  In addition, the strip | belt-shaped film of this embodiment is used suitably with the form of the band which has the shape of a ring without a twist so that a 1st resin layer may face an inner side and a 2nd resin layer may face an outer side so that it may mention later. It is done.

  According to the strip-shaped film of this embodiment, it is excellent in adhesiveness, especially the adhesiveness with respect to a polypropylene container or a polypropylene container. That is, since the strip | belt-shaped film of this embodiment is excellent in heat-shrinkability, it can suppress generation | occurrence | production of the liquid leakage of a package content.

Moreover, since the strip | belt-shaped film of this embodiment has the hand cutting property at the time of opening a package, it can make it easy to open the package using this strip | belt-shaped film.
Furthermore, since the belt-like film of the present embodiment has high heat resistance, film fusion hardly occurs and secondary shrinkage hardly occurs when heated in a microwave oven. Therefore, according to this embodiment, a strip-shaped film excellent in suitability for microwave ovens that does not cause container deformation can be obtained.

  In addition, according to the strip-shaped film of the present embodiment, for example, when full shrink wrapping is performed to cover the entire lunch box with a film, the amount of film used during packaging is reduced, so that waste can be reduced. . Therefore, it is excellent in environmental suitability and effective for global warming countermeasures.

-1st resin layer, 2nd resin layer-
The 1st resin layer and 2nd resin layer in the strip | belt-shaped film of this embodiment contain polyolefin resin, and may further contain other resin as needed. The first resin layer and the second resin layer are made of a resin or a resin composition, and are preferably formed into a film shape.

--- Polyolefin resin--
The polyolefin resin is a polymer having a simple olefin or alkene as a unit structure.
Examples of polyolefin resins include polyethylene resins, polypropylene resins, polyolefin polymer alloys, polybutene resins, polymethylpentene resins, etc. Among them, the viewpoint of obtaining excellent mechanical strength and heat seal strength are given. From the viewpoint of achieving this, an ethylene-α-olefin copolymer is preferred.

Here, the ethylene-α-olefin copolymer refers to a copolymer of ethylene and at least one monomer selected from the group consisting of α-olefins having 3 to 18 carbon atoms.
Examples of the α-olefin used as the monomer of the ethylene-α-olefin copolymer include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene and 1-decene. From the viewpoint of improving the strength of the film, 4-methyl-1-pentene, 1-hexene, and 1-octene are preferable, and 4-methyl-1-pentene and 1-octene are particularly preferable. .

  The polymerization catalyst used for producing the ethylene-α-olefin copolymer is not particularly limited, and examples thereof include a multisite catalyst and a single site catalyst.

The density of the ethylene-α-olefin copolymer is preferably 0.900 g / cm ³ or more, from the viewpoint of increasing the stiffness of the film and improving the running property in the packaging machine, and 0.907 g / cm ^3. More preferably, it is more preferably 0.910 g / cm ³ or more, and from the viewpoint of improving the stretchability of the film, it is preferably 0.950 g / cm ³ or less, and 0.940 g / more preferably cm ³ or less, particularly preferably at 0.930 g / cm ³ or less, and most preferably 0.920 g / cm ³ or less.
In addition, as an ethylene-alpha-olefin copolymer which forms a 1st resin layer and a 2nd resin layer, you may adjust the density by mix | blending 2 or more types from which a density and a melt index differ.

  From the viewpoint of extrusion moldability, the melt flow rate of the ethylene-α-olefin copolymer is preferably 0.2 or more, more preferably 0.5 or more, and from the viewpoint of film film formability. Therefore, it is preferably 15 or less, and more preferably 10 or less.

  The ethylene-α-olefin copolymer may be used alone or in combination of two or more of different densities and comonomer types, depending on the purpose, as long as it is within the above specified density range. In general, ethylene-α-olefin copolymer has a low melt tension, so from the viewpoint of extrusion stability of a sheet or unstretched tube, it is considered difficult to use alone as a layer constituent material. It has been practiced to adjust the melt tension of the layer constituting material by mixing with a high pressure method low density polyethylene or ethylene-vinyl acetate copolymer having a high melt tension. However, high-pressure low-density polyethylene and ethylene-vinyl acetate copolymer have lower tear strength than ethylene-α-olefin copolymer, so high-pressure low-density polyethylene and ethylene-vinyl acetate copolymer are blended. As the ratio increases, the tear strength of the layer constituent material tends to decrease.

-Other resins-
The 1st resin layer and 2nd resin layer in the strip | belt-shaped film of this embodiment may further contain other resin other than the above-mentioned ethylene-alpha-olefin copolymer, unless the transparency of a film is impaired.
Examples of other resins include polypropylene resins, styrene resins, polybutene resins, and ethylene resins such as high-pressure low-density polyethylene.

-Intermediate layer-
The film layer of the belt-like film of the present embodiment may include at least one intermediate layer between the first resin layer and the second resin layer as necessary. In this case, the film layer has three or more layers. It becomes the multilayer film which consists of layers.

The intermediate layer may contain a polyolefin resin in the first resin layer and the second resin layer, and the polyolefin resin is preferably an ethylene-α-olefin copolymer as described above. Further, the intermediate layer may include other resins in the first resin layer and the second resin layer described above.
The intermediate layer may include a material obtained by adding another resin to the above-described ethylene-α-olefin copolymer. For example, a high-pressure low-density polyethylene having a density of 0.930 g / cm ³ or less is made of ethylene- What added to the alpha olefin copolymer may be included.

Further, recycled materials can be used for the intermediate layer from the viewpoint of resource saving and the like.
The recycled material is obtained by pulverizing / melting and extruding an excess film or the like generated when slitting to a predetermined width.
The recycled material has a higher molecular weight and a higher melt viscosity than the non-recycled material due to a crosslinking treatment or the like. Therefore, when the recycled material is used for the outermost layer of the strip film, the film surface may be rough due to the difference in viscosity from the non-recycled material, and the transparency of the film may be lowered. On the other hand, when the recycled material is used for the intermediate layer of the belt-like film, the surface is hardly roughened and the transparency of the film is maintained.

  In the belt-like film of the present embodiment, at least one of the layers constituting the film layer (the first resin layer, the second resin layer, and at least one intermediate layer) needs to contain a glycerin fatty acid ester. And

  Examples of the glycerin fatty acid ester include diglycerin laurate, diglycerin oleate, and glycerin monooleate. Glycerol monooleate is preferable from the viewpoint of improving slipperiness, and diglycerin oleate and glycerin from the viewpoint of adhesion. A mixture of monooleates is particularly preferred.

  In the belt-like film of the present embodiment, at least one of the layers constituting the above-described film layer may contain a lubricant as long as the original characteristics and transparency of the film are not impaired. Examples of such lubricants include natural silica, synthetic silica, saturated fatty acid amide, unsaturated fatty acid amide, and talc.

  In the belt-like film of this embodiment, at least one layer among the layers constituting the film layer described above may contain a plasticizer. Examples of such plasticizers include tackifying resins and petroleum-based resins, such as Alcon (trademark), Clearon (registered trademark), and Imabe (registered trademark).

  Here, in the strip | belt-shaped film of this embodiment, the gel fraction of a 1st resin layer is 0.5-5.0 mass%, and the gel fraction of a 2nd resin layer is 5.0-15.0. % By mass.

In addition, a gel fraction points out the value measured by the following method, and is used as a scale of the crosslinking degree of the polymer contained in each layer which comprises a film layer.
When a 100 mg sample of the layer to be measured is enclosed in a 150 mesh stainless steel wire folded in a bag shape and extracted for 12 hours in boiling p-xylene, it is insoluble after extraction. The value obtained by dividing the mass of the remaining fraction by the initial mass before extraction is determined as the gel fraction (mass%).
Gel fraction (mass%) = (sample weight after extraction / sample weight before extraction) × 100

When a band is prepared so that the first resin layer having a gel fraction of 0.5 to 5.0% by mass is on the inner side, and the joint between the container and the lid is covered using this band, The adhesion between the film, the container and the lid can be enhanced.
In addition, the 1st resin layer side is good also as a low bridge | crosslinking side in the below-mentioned crosslinking process, and it is good also considering the outer surface of a 1st resin layer as a heat seal surface.
In the belt-like film of the present embodiment, from the viewpoint of improving the adhesion as described above, the gel fraction of the first resin layer is 0.5% by mass or more, preferably 1% by mass or more, It is more preferably at least mass%, more preferably at most 5.0 mass%, preferably at most 4 mass%, more preferably at most 3.9 mass%.

When a band is prepared so that the second resin layer having the gel fraction of 5.0 to 15.0% by mass is on the outer side, and the contact part between the container and the lid is covered with this band, the band shape The wear and heat resistance of the film can be improved, and the deterioration of the fusing cutability during packaging can be suppressed.
In addition, a 2nd resin layer is good also as a highly crosslinked side in the below-mentioned crosslinking process.
In the belt-like film of the present embodiment, the gel fraction of the second resin layer is 5.0% by mass or more and 6.0% by mass or more from the viewpoint of improving the wear and heat resistance as described above. Is preferably 7.0% by mass or more, and is 15.0% by mass or less and 14.0% by mass or less from the viewpoint of suppressing deterioration of fusing cutability as described above. Is preferable, and it is more preferable that it is 13.0 mass% or less.

  Moreover, in the strip | belt-shaped film in this embodiment, it is preferable that the gel fraction of a 1st resin layer and a 2nd resin layer is 10 mass% or more from a viewpoint of the stretchability or heat resistance of a film, and 15 mass% or more. More preferably, it is preferably 35% by mass or less, and more preferably 30% by mass or less.

Further, in the belt-like film of the present embodiment, the surface roughness RaA of the outer surface A of the first resin layer is preferably 4.0 to 10.0, and the surface of the outer surface B of the second resin layer The roughness RaB is preferably 3.0 to 5.0.
And it is preferable that RaA and RaB satisfy | fill following formula (1).
2.1 ≦ RaA / RaB ≦ 3.0 (1)

The surface roughness refers to a value measured using an atomic force microscope.
In the atomic force microscope, the surface of the sample is scanned with a probe attached to the tip of the cantilever, and the displacement of the cantilever is measured in the vertical direction to evaluate the uneven shape of the sample surface. And the information of a height direction is represented as a surface roughness parameter (Ra).

When the surface of the cross-linked and stretched film is observed using an atomic force microscope, a network-like network-like network is observed. However, the higher the degree of cross-linking, the more dense the molecular orientation-like network is. The lower the degree of crosslinking, the rougher the network is.
When the film is highly cross-linked, the dense network is leveled by stretching so that the film surface becomes flat, so the Ra value becomes small. Moreover, since it is hard to receive the influence of extending | stretching in the case of low bridge | crosslinking, a film surface is hard to be leveled and Ra value becomes large.

When a band is produced so that the first resin layer having a surface roughness RaA of 4.0 to 10.0 on the outer surface is inside, and the contact portion between the container and the lid is covered using this band Moreover, the adhesiveness and sealing property of a strip | belt-shaped film, a container, and a lid | cover can be improved, and the transparency of a strip | belt-shaped film can be improved.
In the belt-like film of the present embodiment, the surface roughness RaA of the outer surface A of the first resin layer is 4.0 or more and 4.5 or more from the viewpoint of improving adhesion and sealing properties as described above. From the viewpoint of enhancing the transparency of the strip film, it is 10.0 or less, preferably 9.5 or less, and 9.0 or less. Is more preferable and 8.5 or less is most preferable.

When using a band prepared so that the second resin layer having a surface roughness RaB of 3.0 to 5.0 on the outer surface is on the outside, the stretchability of the belt-like film can be improved, The rubbing and tearing of the belt-like film can be suppressed.
In the belt-like film of the present embodiment, the surface roughness RaB of the outer surface B of the second resin layer is 3.0 or more and preferably 3.3 or more from the viewpoint of improving stretchability as described above. , More preferably 3.5 or more, most preferably 3.7 or more, and from the viewpoint of suppressing rubbing and tearing, from the viewpoint of enhancing the transparency of the strip film, is 5.0 or less, It is preferably 4.8 or less, more preferably 4.7 or less, and most preferably 4.6 or less.

  Moreover, when there is too much difference in the degree of cross-linking between the front and back of the film, the orientation balance of the film is deteriorated, so that the film curls away from the weakly oriented side (low cross-linked side). From the viewpoint of preventing curling of the film, RaA / RaB is preferably 3.0 or less, the sealing property of the outer surface A of the first resin layer, and the abrasion resistance of the outer surface B of the second resin layer. In view of the above, RaA / RaB is preferably 1.1 or more. RaA / RaB is more preferably 1.15 or more, further preferably 1.2 or more, particularly preferably 1.25 or more, and preferably 2.9 or less, It is more preferably 2.8 or less, and particularly preferably 2.7 or less.

  Hereinafter, it describes about content of each component.

  The content of the polyolefin-based resin in the film layer in the belt-like film of the present embodiment is such that the strip film has extrudability, extrusion moldability, and stretching stability, and tear strength with respect to 100% by mass of the film layer. From the viewpoint of improving and reducing troubles such as crack propagation during packaging, it is preferably 50% by mass or more, more preferably 60% by mass or more, particularly preferably 70% by mass or more, 95% by mass or less is preferable.

  It is preferable that content of the other resin in the film layer in the strip | belt-shaped film of this embodiment is 0-30 mass% with respect to 100 mass% of film layers.

In the first resin layer and the second resin layer in the belt-like film of this embodiment, the ratio of the other resin to the polyolefin resin is preferably 50 parts by weight or less with respect to 100 parts by weight of the polyolefin resin. The amount is more preferably no more than parts by weight, and particularly preferably no more than 20 parts by weight.
In particular, from the viewpoint of improving hot tack sealability and transparency, an ethylene-α-olefin copolymer is used as the polyolefin resin, and the density is 0.930 g / cm ³ or less as the other resin. Here, the ratio of the high-pressure low-density polyethylene having the above density to the ethylene-α-olefin copolymer is 1 to 25 parts by weight with respect to 100 parts by weight of the ethylene-α-olefin copolymer. It is preferable to use 5 to 20 parts by weight.

The content of the glycerin fatty acid ester in the film layer in the belt-like film of the present embodiment is based on 100% by mass of the film layer.
From the viewpoint of improving the workability, the runnability of the film at the time of packaging, and the viewpoint of improving the adhesion between the lid and the container when the package is sealed, it is preferably 0.1% by mass or more. The content is more preferably at least mass%, more preferably at most 10.0 mass%, even more preferably at most 8 mass%.

  The content of the lubricant in the film layer in the belt-like film of the present embodiment is preferably 0.1 to 0.5% by mass with respect to 100% by mass of the film layer from the viewpoint of not inhibiting the adhesion.

  The content of the plasticizer in the film layer in the belt-like film of the present embodiment is preferably 0.1 to 10% by mass with respect to 100% by mass of the film layer from the viewpoint of improving shrinkage and transparency. .

The belt-like film of the present embodiment can be made into a film suitable for printing applications by performing surface treatment such as corona treatment, ozone treatment, and flame treatment.
When performing a printing process, glycerol fatty acid ester etc. are 0.5-5 with respect to 100 mass% of 1st resin layers or 2nd resin layers in the 1st resin layer or 2nd resin layer which makes a to-be-printed surface. It is preferable that 0.0% by mass is added to form a film, and then the surface to be printed is subjected to corona treatment and then subjected to printing. Here, the content of the glycerin fatty acid ester or the like in the first resin layer or the second resin layer is based on 100% by mass of the first resin layer or the second resin layer from the viewpoint of antistatic properties and prevention of ink peeling. It is more preferable that it is 0.8-3.0 mass%.

Hereinafter, it describes about the manufacturing method of the strip | belt-shaped film of this embodiment.
As a manufacturing method of the strip | belt-shaped film of this embodiment, the process (bridge | crosslinking) of a raw material by irradiating an electron beam with the acceleration voltage and irradiation dose of specific conditions with respect to the raw material before extending | stretching, for example. And a step of performing a stretching process (stretching step) at a temperature equal to or higher than the melting peak temperature of the resin or resin composition constituting the raw fabric with respect to the original fabric after crosslinking.
In addition, about the method of obtaining the raw material before extending | stretching, it is not specifically limited, For example, when the film layer of the obtained strip | belt-shaped film contains a 1st resin layer, an intermediate | middle layer, and a 2nd resin layer (that is, When the film layer is a multilayer film), a method of producing by coextrusion by a melt extrusion method is preferable. In this case, for example, a resin or a resin composition contained in each layer of the film layer is an extruder for each. And can be coextruded using a multilayer T die (tenter method), a multilayer circular die (inflation method), or the like.

Hereinafter, the crosslinking step will be described in detail.
In the manufacturing method of the strip-shaped film of the present embodiment, first, the raw film is subjected to a crosslinking treatment by irradiating the original film before stretching with an electron beam. Thereby, each characteristic (above-mentioned) is provided to the both surfaces of a film layer, ie, the outer surface A of a 1st resin layer, and the outer surface B of a 2nd resin layer in terms of a gel fraction and surface roughness. be able to.

As conditions for the acceleration voltage of electron beam irradiation, the thickness T (unit: μm) of the original fabric, the average density D (unit: g / cm ³ ) of the original fabric, and the acceleration voltage V (unit: kV) are as follows: Conditions that satisfy (2) and the following formula (3) are preferable.
T × D = α (2)
α + 10 ≦ V ≦ α + 70 (3)
(In the formula, T represents the thickness (μm) of the original fabric, D represents the average density (g / cm ³ ) of the original fabric, and V represents the acceleration voltage (kV).)

  When the acceleration voltage V is less than α + 10, the degree of cross-linking of the outer surface A of the first resin layer becomes too low, and the film layer may curl and handleability may deteriorate. In addition, when the acceleration voltage V exceeds α + 70, the degree of cross-linking of the outer surface A of the first resin layer, which may be a heat seal surface, becomes too high, and there is a risk of hindering improvement in heat sealability of the belt-like film. is there.

  In the present embodiment, when the acceleration voltage V is set to 300 to 450 kV, the intended crosslinking treatment tends to be effectively performed.

  In the production of the strip film of the present embodiment, for example, by irradiating the electron beam with the acceleration voltage V from the outer surface A side of the first resin layer toward the outer surface B side of the second resin layer, A gradient of the degree of cross-linking is generated in the thickness direction of the original fabric, and on the outer surface A of the first resin layer, the gel fraction is lowered, the surface roughness (Ra) is increased, and the outer surface of the second resin layer In B, the gel fraction can be made higher and the surface roughness (Ra) can be made lower.

  As a condition for the irradiation dose of electron beam irradiation, from the viewpoint of heat sealability and stretching stability of the belt-like film, it is preferably 40 kGy or more, more preferably 60 kGy or more, and 200 kGy or less. Preferably, it is 150 kGy or less.

Hereinafter, the stretching step will be described in detail.
Next, in the manufacturing method of the strip | belt-shaped film of this embodiment, it extends | stretches with respect to the raw material after bridge | crosslinking.

  As a stretching method, a tenter method is used to uniaxially stretch in the flow direction (MD) of the original fabric, a method of stretching sequentially in the flow direction and then a stretch in the width direction (TD) of the original fabric, or inflation. Simultaneous biaxial stretching, which is a method of simultaneously stretching in the flow direction and the width direction using a method, is preferred.

  The temperature condition is preferably a temperature that is 10 ° C. or more higher than the melting peak temperature of the resin or resin composition constituting the film layer.

The draw ratio in the flow direction is preferably 2 to 10 times. When it is 2 times or more, stretching is stable, and when it is 10 times or less, film breakage during stretching hardly occurs.
Moreover, as a draw ratio of the width direction, it is preferable to set it as 0-2 times. In the case of more than 2 times, when the container and the lid are sealed with the belt-like film, the belt-like film shrinks in the width direction, and the container and the lid may not be successfully sealed.

  Thus, by combining the crosslinking step and the stretching step, Ra (surface roughness) on both surfaces of the belt-like film of the present embodiment is set to a specific value (RaA: 4.0 to 10 in the present embodiment). 0.0, RaB: 3.0 to 5.0).

  The thickness of the belt-like film of the present embodiment is preferably 5 μm or more, more preferably 8 μm or more, most preferably 10 μm or more, and 30 μm or less from the viewpoint of practicality of the film. Preferably, it is 25 μm or less, and most preferably 20 μm or less.

  When the belt-like film of this embodiment is a multilayer film, the ratio of the thickness of the first resin layer and the second resin layer to the thickness of the belt-like film (the thickness of the entire film layer) is the extrudability of the belt-like film, From the viewpoints of sealability and transparency, it is preferably 5% or more, more preferably 8% or more, most preferably 10% or more, and preferably 50% or less. 30% or less is more preferable, and 20% or less is most preferable.

In a preferred embodiment, the belt-like film of this embodiment is preferably stretched at least in the flow direction (MD), and the heat shrinkage ratio SM in the flow direction at 110 ° C. is preferably 5% or more.
The heat shrinkage ratio SM (%) in the flow direction at 110 ° C. of the belt-shaped film was treated for 1 minute with a distance L in the flow direction between two points determined on the belt film at room temperature and a hot air dryer at 110 ° C. It calculates | requires by following formula (4) from the distance L 'of the flow direction between the said 2 points | pieces in a back strip | belt-shaped film.
SM (%) = {(L−L ′) / L} × 100 (4)

In a more preferred embodiment, the belt-like film of this embodiment is stretched in the MD and TD, where the heat shrinkage SB in the flow direction and the width direction at 110 ° C. is preferably 5% or more.
In addition, the heat shrinkage SB (%) in the flow direction and the width direction at 110 ° C. of the strip film is the average M of the distance in the flow direction and the distance in the width direction defined on the strip film at room temperature, and
It is calculated | required by following formula (5) from the average M 'of the distance of the flow direction between the said 2 points | pieces, and the distance of the width direction in the strip | belt-shaped film after processing for 1 minute with a 110 degreeC hot air dryer.
SB (%) = {(M−M ′) / M} × 100 (5)

The strip film of this embodiment can be slit into a predetermined size and used.
The width of the belt-like film of the present embodiment is preferably 30 to 50 mm in order to fit the package from the viewpoint of sealing the container and the lid.

The belt-like film of the present embodiment may be used in any form, and is not particularly limited. For example, the belt-like film may be formed by cutting at a certain length in the longitudinal direction and bonding the both ends in the longitudinal direction by sealing or the like. Examples of the shape of a band having a ring shape without twisting are possible.
When the belt-like film of the present embodiment is in contact with the contact portion between the container and the lid, the above-described effects such as adhesion are exhibited.

The belt-like film of the present embodiment is suitably used in packaging using a packaging machine, and specifically used in the following embodiments.
Rolls of belt-like films are set on the left and right of the packaging machine, respectively, and the two belt-like films heat-sealed in the middle are put on standby. The packaged body (for example, lunch box) that has flowed from the conveyor is moved toward the goal tape made of the heat-sealed film. When the packaged body reaches the goal tape, the tape is unwound from the roll with the weight of the packaged body. And when a tape turns to the front-end | tip part of this to-be-packaged body, a chorus seal is performed at the edge part of a tape, and a to-be-packaged body is packaged with the strip | belt-shaped film which became band shape. Let the tape left at this time be the head part of the tape used for packaging the next package body. The heat seal bar used for heat sealing varies depending on the packaging machine, but it is set to 110 to 120 ° C., and is a seal that is not problematic in practice as long as it does not cause melt holes or seal breakage in the heat sealed portion of the film. You may set to the temperature from which intensity | strength is acquired.

(Packaging body)
The package of this embodiment is formed by covering the contact portion between the container and the lid with the belt-like film of this embodiment.
Here, as a container and a lid, as long as the lid can close the opening of the container by contacting the container with the lid, it may be a general one, and is not particularly limited. Examples include chemical bottles. Further, the contact portion between the container and the lid may be a joint portion, a fitting portion, a joining portion, a overlapping portion, or the like, and the covering of the contact portion may be direct or indirect.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to these Examples.

  The analytical methods used in the examples and comparative examples are as follows.

[1] Measurement of surface roughness About the obtained strip | belt-shaped film, the surface roughness was measured in the following procedures using atomic force microscope (The product made by Asylum Research, brand name: Cypher).
The film was cut into a size of about 5 × 5 mm square at an arbitrary place, and one surface and the other surface (the surface opposite to the one surface) were fixed to a sample fixing disk. For these samples, surface morphology observation is performed by AC mode imaging (cantilever: Olympus, trade name: AC200TS, observation field of view: 2 × 2 μm ² , resolution: 512 × 512 pixels) using an atomic force microscope. Thus, an observed image of the film was obtained. The surface morphology of each surface of each sample was observed in any three fields.
Next, the difference in structure was confirmed by comparing with the form of the phase image obtained simultaneously with the form of the obtained observation image. Also, Ra (average of the absolute value of the difference from the average value), which is generally used for evaluating the surface roughness, is calculated, and the surface roughness (Ra) of each surface of each sample is evaluated. It was. The surface roughness of the first resin layer was determined as RaA, and the surface roughness of the second resin layer was determined as RaB.
When moisture is attached to the film surface, measurement is likely to be affected. Therefore, the film is sandwiched between neutral papers having a thickness of 85 μm and stored in a desiccator with a relative humidity of 30% or less for 24 hours. Conditioning was performed.

[2] Measurement of gel fraction In a 150 mesh stainless steel wire net folded in a bag shape, 100 mg of the sample of the first resin layer or the second resin layer peeled off from the obtained belt-shaped film is sealed and boiled. When the sample was extracted for 12 hours in p-xylene, the value obtained by dividing the mass of the insoluble matter after extraction by the initial mass before extraction was determined as the gel fraction (% by mass).
Gel fraction (mass%) = (sample weight after extraction / sample weight before extraction) × 100
Moreover, the same measurement as the above was performed also about the 1st resin layer and the 2nd resin layer.

  The evaluation methods used in Examples and Comparative Examples are as follows.

[3] Evaluation of Adhesiveness (Liquid Leakage) HS Aiko 24-20-6 manufactured by FP Corporation was used for the container, and T-HS SAKURA 24-20 manufactured by FP Corporation was used for the lid. After putting 30 mL of water in the container, the obtained band-like film having a width of 5 cm was wound around the fitting portion between the container and the lid to produce a package.
By heating the package (particularly, the belt-shaped film part) at 120 ° C. for 3 seconds using a shrink tunnel (trade name: MS-8441 BS, manufactured by Keiyu System Co., Ltd.) Thus, the adhesiveness (liquid leakage) of the belt-like film was evaluated according to the following evaluation criteria by visually confirming whether or not liquid leakage of water in the container occurred.
[Evaluation criteria] ("Evaluation results: Evaluation content")
○: Liquid leakage does not occur even if the top and bottom of the package is turned over. ×: When the top and bottom of the package is turned over, the spillage of the contents leaks out.

[4] Evaluation of hand cutting property The container and lid used in [3] above were used. The obtained belt-like film was wound around the fitting portion between the container and the lid to produce a package. Thereafter, the belt-like film was heat-shrinked by the same method as used in [1] above, and the tearability of the belt-like film when the belt-like film was opened was evaluated according to the following evaluation criteria.
[Evaluation criteria] ("Evaluation results: Evaluation content")
○: Can be cut by hand in the tear direction △: Can be cut by hand, but can not be cut in the tear direction, but can be cut diagonally ×: Can not be cut by hand

[5] Evaluation of suitability for microwave oven The container and lid used in [3] above were used. After putting 100 g of cooked rice in the container, the obtained band-shaped film having a width of 5 cm was wound around the fitting portion between the container and the lid to prepare a package.
Thereafter, the belt-shaped film was heat-shrinked by the same method as used in [1] above, and the package was heated as it was in a 500 W microwave oven for 5 minutes.
[Evaluation criteria] ("Evaluation results: Evaluation content")
○: When using a microwave oven, there is no film fusion and no container deformation ×: When using a microwave oven, there is film fusion or container deformation occurs

  In the examples and comparative examples, the materials used and the method for producing the strip-shaped film are as follows.

The following materials were used as materials for the first resin layer, the second resin layer, and the intermediate layer.
LL1: ethylene-α-olefin random copolymer (manufactured by Dow Chemical Japan Co., Ltd., trade name: dowlex 2032, polymerized with a multi-site catalyst, α-olefin: 1-octene, melt flow rate (230 ° C., 2.16 kg, the same applies hereinafter) = 2.0 g / 10 min, density: 0.926 g / cm ³ )
LL2: ethylene-α-olefin random copolymer (manufactured by Ube Maruzen Polyethylene Co., Ltd., trade name: Umerit 1520F, α-olefin: 4-methyl-1-pentene, melt flow rate = 2.0 g / 10 min, density = 0 .915 g / cm ³ )
LL3: ethylene-α-olefin random copolymer (manufactured by Prime Polymer Co., Ltd., trade name: MORETECH 0278G, α-olefin: 1-octene, melt flow rate = 2.1 g / 10 min, density = 0.939 g / cm ³ )
LL4: ethylene-α-olefin random copolymer (manufactured by Ube Maruzen Polyethylene Co., Ltd., trade name: Umerit 2525F, α-olefin: 4-methyl-1-pentene, melt flow rate = 2.5 g / 10 min, density = 0 .925 g / cm ³ )
LL5: ethylene-α-olefin random copolymer (manufactured by Prime Polymer Co., Ltd., trade name: Evolue SP1028, α-olefin: 1-hexene, melt flow rate = 2.2 g / 10 min, density = 0.910 g / cm ³ )
LD1: High pressure method low density polyethylene (manufactured by Asahi Kasei Chemicals Corporation, trade name: Suntech LD M2004, melt flow rate = 0.4 g / 10 min, density = 0.922 g / cm ³ )
LD2: high-pressure low-density polyethylene (manufactured by Asahi Kasei Chemicals Corporation, trade name: Suntech LD M2102, melt flow rate = 0.2 g / 10 min, density = 0.922 g / cm ³ )
Additive 1: 1: 1 mixture of diglycerol oleate and glycerol monooleate

[Example 1]
A resin composition having the composition shown in Table 1 with 2.0% by mass (100% by mass of resin composition) of Additive 1 added is extruded using a multi-layer T die, and then cooled and solidified with a cooling roll. Thus, a tubular multilayer (three layers) original fabric having a folding width of 200 mm and a thickness of 320 μm was prepared.
The multilayer raw material is guided to an electron beam irradiation apparatus (EBC-300 in NHV Corporation Kyoto EB Center), set to the acceleration voltage and irradiation dose shown in Table 1, and the outer surface side of the first resin layer A cross-linking treatment was performed by irradiating an electron beam toward the outer surface of the second resin layer.
By guiding the cross-linked multilayer raw material to a stretching machine, setting the heating temperature at the stretching start point to 140 ° C., and stretching each at a stretching ratio of 8 times in the flow direction and 2 times in the width direction, A belt-like film having an average thickness of 20 μm and a thickness ratio (%) of the first resin layer / intermediate layer / second resin layer of 15/70/15 was obtained.

[Examples 2-14, Comparative Examples 1-4]
A belt-like film was obtained in the same manner as in Example 1 except that the conditions shown in Table 1 were used.

  About the strip | belt-shaped film of each Example and each comparative example, the test was done with the above-mentioned analysis method and measuring method (1)-(5). The results are shown in Table 1.

As shown in Table 1, Examples 1 to 14 were excellent in package evaluation (adhesiveness (liquid leakage), hand cutting property of film, suitability for microwave oven).
In Comparative Example 1, since the acceleration voltage in the electron beam irradiation is too high with respect to the thickness of the original fabric, the surface roughness RaA of the outer surface A of the first resin layer on the seal surface side is small, and the first resin layer The gel fraction was also high, and as a whole it was highly crosslinked. Moreover, since there is no difference in the degree of cross-linking between the front and back, the adhesion (liquid leakage) deteriorated when it was made into a package.
In the comparative example 2, the irradiation dose in electron beam irradiation was low, and it became low bridge | crosslinking as a whole, and microwave oven suitability (resistance in use of a microwave oven) deteriorated.
In Comparative Example 3, since glycerin fatty acid ester was not used, when the lid and the container were sealed, they could not be brought into close contact with each other and liquid leakage occurred.
In Comparative Example 4, since the electron beam irradiation was not performed, no crosslinking occurred, and the evaluation of the hand cutting property and the microwave oven suitability of the film was low.

According to the present invention, it is possible to provide a belt-like film having excellent adhesion.
The strip film of the present invention can be suitably used for packaging lunch boxes such as convenience stores.

Claims (6)

A film layer including at least a first resin layer and a second resin layer is directed from one side to the other side, the first resin layer is the outermost layer on the one side, and the second resin layer is on the other side. It is a band-shaped film that is laminated so as to be the outermost layer,
The first resin layer and the second resin layer include a polyolefin resin, and at least one of the film layers includes a glycerin fatty acid ester,
The gel fraction of the first resin layer is 0.5 to 5.0 mass%, and the gel fraction of the second resin layer is 5.0 to 15.0 mass%,
A belt-like film characterized by that.   The strip | belt-shaped film of Claim 1 whose content of the said glycerol fatty acid ester is 0.1-10 mass% with respect to 100 mass% of said film layers.   The strip-shaped film according to claim 1 or 2, which is stretched at least in the flow direction (MD direction) and has a heat shrinkage ratio SM in the flow direction (MD direction) at 110 ° C of 5% or more. The surface roughness RaA of the outer surface A of the first resin layer is 4.0 to 10.0,
The surface roughness RaB of the outer surface B of the second resin layer is 3.0 to 5.0,
Here, the RaA and the RaB satisfy the following formula (1).
1.1 ≦ RaA / RaB ≦ 3.0 (1)
The strip | belt-shaped film of any one of Claims 1-3.   The strip | belt-shaped film of any one of Claims 1-4 whose gel fraction of a said 1st resin layer and a said 2nd resin layer is 10-35 mass%. A package comprising a contact portion between a container and a lid covered with the belt-like film according to any one of claims 1 to 5.