JPWO2017018281A1 - Laminated film and packaging material - Google Patents

Abstract

The present invention relates to a laminated film used for a packaging material for packaging food, miscellaneous goods, magazines, etc., and has at least a printing layer, an intermediate layer and a sealing layer, one surface layer being a printing layer and the other surface layer being a sealing layer. A laminated film, in which the printed layer contains a propylene-based resin, and the intermediate layer contains a propylene-ethylene random copolymer in an amount of 5 to 60% by mass while having a suitable sealing property It is possible to realize suitable bag-breaking resistance that is unlikely to cause bag breakage even at the time of external impact or contact with protrusions, particularly at low temperatures.

Description

  The present invention relates to a laminated film used for a packaging material for packaging food, miscellaneous goods, magazines and the like, and a packaging material comprising the film.

  Conventionally, a laminated film obtained by laminating a plurality of resins has been used as a packaging film used for packaging bread and other foods. As such a packaging film, a laminated film using an olefin resin is widely used because it is easy to obtain heat sealability and the like. (For example, refer to Patent Documents 1 and 2).

JP 2005-111857 A JP 2007-45049 A

  As a laminated film for packaging, particularly food packaging, an olefin resin such as ethylene-α-olefin resin or propylene-α-olefin resin was used for each layer for the purpose of improving low-temperature heat sealability and the like. Laminated films have been proposed. However, since a thin film is used for such a laminated film in consideration of the environment and cost, it tears when sealed by an external impact during distribution, contact with protrusions, or a closure that seals the packaging material. Or tearing. In addition, food is often exposed to low temperatures during packaging, transportation, and storage, and improvement in bag-breaking resistance at low temperatures has been demanded.

  The problem to be solved by the present invention is to provide a laminated film that has a suitable sealing property and is excellent in bag-breaking resistance and can suitably suppress tearing, and is particularly resistant to bag-breaking at low temperatures. It is to realize a laminated film excellent in.

  In the present invention, it has at least a printing layer, an intermediate layer and a sealing layer, one surface layer is a printed film, and the other surface layer is a laminated film comprising a sealing layer, and the printing layer contains a propylene-based resin, The said intermediate | middle layer solves the said subject with the laminated | multilayer film which contains 5-60 mass% of propylene-ethylene random copolymers.

  The laminated film of the present invention has the above-described configuration, and has a suitable sealing property, and also has a suitable bag-breaking resistance, particularly at low temperatures, which is unlikely to cause bag breakage upon contact with an external impact or protrusion during distribution. It is possible to realize a suitable resistance to rupture of bags below. In addition, it is possible to realize suitable closure suitability even when sealing with a closure is difficult to tear.

  In addition, depending on the contents to be wrapped, the packaging material using a laminated film may be torn or torn due to contact or rubbing when enclosing the contents, especially when bread is the contents. The ears of bread are sharp and tend to tear and tear. The laminated film of the present invention is also suitable for resistance to tearing and tearing due to friction such as contact and rubbing when enclosing such contents.

  Moreover, the laminated film used for packaging has many uses where a highly transparent film is used so that the contents can be visually recognized. Although a highly transparent film tends to have low rigidity, the laminated film of the present invention can realize excellent bag resistance even when the highly transparent structure is adopted, and can realize suitable closure suitability.

  Such a laminated film of the present invention can be suitably applied to various packaging applications, and in particular, bread packaging applications, particularly bread bread packaging, where the thickness of the film and the volume of packaging bags are decreasing due to the demand for volume reduction. It can be particularly suitably used for applications.

  The laminated film of the present invention has at least a printing layer, an intermediate layer, and a sealing layer, one surface layer is a printing layer, and the other surface layer is a sealing film, and the printing layer contains a propylene-based resin. And the said intermediate | middle layer is a laminated | multilayer film which contains 5-60 mass% in the resin component contained in an intermediate | middle layer for a propylene-ethylene random copolymer.

[Print layer]
The printing layer used for the laminated film of the present invention is a layer constituting a surface layer on which printing of a packaging film is provided. The printing layer contains a propylene-based resin, and as the propylene-based resin, for example, a propylene homopolymer, a propylene-α-olefin random copolymer, a propylene-α-olefin block copolymer, or the like can be used. In the present invention, among these, a propylene-α-olefin random copolymer can be preferably used because adhesion to the intermediate layer is easily obtained.

  Examples of the propylene-α-olefin random copolymer include a propylene-ethylene copolymer, a propylene-butene-1 copolymer, and a propylene-ethylene-butene-1 copolymer, which are used alone. Or may be used in combination. Especially, since suitable transparency is easy to be obtained, a propylene-ethylene random copolymer can be used preferably.

  As a propylene-ethylene random copolymer, since it is easy to obtain suitable blocking resistance, the ethylene content is preferably 10% by mass or less, more preferably 8% by mass or less, and 6% by mass. More preferably. Moreover, since it is easy to obtain suitable impact resistance, the ethylene content is preferably 2% by mass or more, more preferably 3% by mass or more, and further preferably 4% by mass or more.

  The melt flow rate (MFR) of the propylene-ethylene random copolymer is not particularly limited as long as a laminated film can be formed, but it is 0.5 g / 10 min or more because good moldability is easily obtained. Is preferably 3 g / 10 min or more, more preferably 5 g / 10 min or more. Moreover, since it is easy to obtain suitable impact resistance and fusing strength, the MFR is preferably 20 g / 10 min or less, more preferably 15 g / 10 min or less, and 12 g / 10 min or less. More preferred.

Propylene - density of the ethylene random copolymer, since it is easy to obtain a bag making machine suitability when wrapping suitability and bag-making, is preferably 0.880 g / cm ³ or more, is 0.89 g / cm ³ or more It is more preferable. Further, since the easily obtained impact resistance at low temperatures, it is preferably 0.90 g / cm ³ or less, more preferably 0.895 g / cm ³ or less.

  The melting point of the propylene-ethylene random copolymer is preferably 110 ° C. or higher, and more preferably 115 ° C. or higher, because bag suitability and slipperiness are easily improved. Moreover, it is preferable that it is 150 degrees C or less, and it is more preferable that it is 145 degrees C or less from being easy to improve the tearability at the time of low temperature and bag-breaking resistance.

  In the present invention, it is also preferable to use two types of propylene-ethylene random copolymers having different melting points in combination because it is easy to obtain a suitable fusing seal strength. The melting point of the high melting point propylene-ethylene random copolymer is preferably 130 ° C. or higher, and more preferably 135 to 158 ° C. The melting point of the low melting point propylene-ethylene random copolymer is preferably less than 130 ° C, more preferably 110 to 128 ° C.

  The content of the propylene-based resin in the resin component contained in the printing layer is preferably 50% by mass or more in the resin component contained in the printing layer because it is easy to obtain suitable transparency and packaging suitability. It is more preferable to set it as mass% or more, and it is especially preferable to set it as 75-95 mass%.

  It is also preferable to use a resin other than the propylene-based resin in the print layer. As the other resin, for example, a polyethylene resin can be preferably used, and as the polyethylene resin, a linear low density polyethylene (LLDPE), a linear medium density polyethylene (LMDPE), a linear high density polyethylene, for example. (LHDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), polyethylene resin such as high density polyethylene (HDPE), ethylene-butene-rubber copolymer (EBR), ethylene-propylene-rubber copolymer (EPR), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene -Ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), and other ethylene-based copolymers; and ethylene-acrylic acid copolymer ionomers, Examples thereof include ionomers of ethylene-methacrylic acid copolymer, and two or more kinds may be used alone or in combination.

  Among them, ethylene elastomers such as ethylene-butene-rubber copolymers and ethylene-propylene-rubber copolymers can be preferably used because the fusing strength is easily improved, and ethylene-butene-rubber copolymers are particularly preferred. Can be used.

  When using the said ethylene-type elastomer, since it is easy to obtain suitable transparency, it is preferable to set it as 5-25 mass% in the resin component contained in a printing layer, and setting it as 5-20 mass%. More preferably, it is more preferable to set it as 5-15 mass%.

  As a friction coefficient (ASTM D-1894) of the printing layer surface, 0.05-0.7 are preferable, 0.07-0.6 are still more preferable, 0.1-0.5 are more preferable. By setting it as the said range, it is easy to improve the film feedability at the time of packaging, the alignment property after bag making, packing workability | operativity, etc., and it is easy to suppress suitably the film damage and tear at the time of binding by a closure. The friction coefficient can be adjusted by appropriately adding additives such as a lubricant and an anti-blocking agent according to the resin component used in the printing layer.

  In the printing layer, as components other than the above resin components, antifogging agents, antistatic agents, heat stabilizers, nucleating agents, antioxidants, lubricants, antiblocking agents, mold release agents, ultraviolet absorbers, etc. These components may be added as long as the object of the present invention is not impaired.

[Middle layer]
In the laminated film of the present invention, tearing of the laminated film can be suitably suppressed by using an intermediate layer containing 5 to 60% by mass of a propylene-ethylene random copolymer. The content of the propylene-ethylene random copolymer is preferably 8% by mass or more, and more preferably 10% by mass or more in the resin component contained in the intermediate layer. Moreover, it is preferable to set it as 50 mass% or less, and it is more preferable to set it as 40 mass% or less. When the content of the propylene-ethylene random copolymer is in this range, it becomes easy to obtain good tear resistance as well as suitable tear resistance.

  As the propylene-ethylene random copolymer, a propylene-ethylene random copolymer similar to the ethylene content, MFR, density and melting point exemplified as preferred in the printing layer can be preferably used.

  The intermediate layer contains the propylene-ethylene random copolymer and other resin components. As said other resin component, olefin resin other than the said propylene-ethylene random copolymer can be used preferably. The olefin-based resin is preferably contained in an amount of 40 to 95% by mass in the intermediate layer.

  Examples of the olefin resin include propylene-α-olefin random copolymers other than the propylene-ethylene random copolymer (propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, metallocene). Catalyst-based polypropylene, etc.), propylene-α-olefin copolymer, propylene homopolymer, very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE) and other polyethylene resins, ethylene -Vinyl acetate copolymer (EVA) etc. can be used.

  Among these, since it is easy to obtain suitable impact resistance and bag breaking resistance, particularly suitable bag breaking resistance at low temperatures, it is preferable to contain linear low density polyethylene. When linear low density polyethylene is used, the content of linear low density polyethylene is preferably 5% by mass or more in the resin component contained in the intermediate layer, and preferably 8% by mass or more. Further preferred. Moreover, it is preferable that it is 20 mass% or less, and it is more preferable that it is 15 mass% or less.

Linear low density polyethylene, since it is easy to obtain a suitable rupture bag resistance, it is preferable that density of 0.915 g / cm ³ or less, more preferably 0.910 g / cm ³ or less, 0 More preferably, it is 907 g / cm ³ or less. Moreover, since it is easy to obtain suitable fusing strength, the density is preferably 0.890 g / cm ³ or more, and more preferably 0.895 g / cm ³ or more.

  The linear low density polyethylene preferably has an MFR of 0.5 to 15 g / 10 minutes (190 ° C.), more preferably 1.0 to 10 g / 10 minutes.

  As the intermediate layer used in the present invention, an intermediate layer comprising the propylene-ethylene random copolymer and another polyolefin resin as a resin component can be preferably used. Is preferably an intermediate layer composed of the propylene-ethylene random copolymer, linear low density polyethylene and propylene homopolymer.

  When setting it as the said intermediate | middle layer, it is preferable that content of the propylene-ethylene random copolymer in a resin component is 5-60 mass%, and it is more preferable that it is 15-50 mass%. Moreover, it is preferable that content of a linear low density polyethylene is 5-20 mass%, and it is preferable that it is 10-18 mass%. Furthermore, it is preferable that content of a propylene homopolymer is 20-85 mass%, and it is more preferable that it is 30-80 mass%. By setting it as the said structure, it becomes easy to obtain favorable bag breaking resistance and tear resistance with favorable transparency.

The propylene homopolymer preferably has an MFR of 3 to 20 g / 10 minutes, more preferably 5 to 15 g / 10 minutes. Further, it is preferable that the density of 0.880~0.900g / cm ^3, more preferably 0.890~0.900g / cm ^3.

  In the intermediate layer, as components other than the above resin components, antifogging agents, antistatic agents, heat stabilizers, nucleating agents, antioxidants, lubricants, antiblocking agents, mold release agents, UV absorbers, etc. These components may be added as long as the object of the present invention is not impaired.

[Seal layer]
The sealing layer used for this invention is a layer used for adhesion | attachment of the sealing layers of laminated | multilayer film, and adhesion | attachment of laminated | multilayer film, another container, a film, etc. What is necessary is just to select suitably the resin seed | species from which the suitable sealing strength is obtained for the said sealing layer according to a use aspect or to-be-sealed object. For example, when the sealing layers are sealed and used as a packaging bag, propylene-α- such as propylene-ethylene random copolymer, propylene-1-butene copolymer, etc., from the point that an appropriate sealing strength is obtained. A seal layer containing an α-olefin-propylene copolymer such as an olefin copolymer or 1-butene-propylene copolymer can be suitably used. Among them, since it is easy to adjust the heat seal temperature and strength at the time of easy-opening sealing at low temperature and it is easy to obtain an appropriate heat-sealing strength as an easy-opening seal, propylene-1-butene copolymer or 1-butene- A butene-containing copolymer such as a propylene copolymer is preferred.

  When 1-butene-propylene copolymer is used, the 1-butene content in the 1-butene-propylene copolymer is easily obtained because it is easy to obtain suitable low-temperature sealing properties, blocking resistance, film forming properties, and the like. It is preferably 60 to 95 mol%, more preferably 65 to 95%, and even more preferably 70 to 90 mol%. Moreover, since it is easy to obtain suitable low temperature sealing properties, the propylene content is preferably 5 to 40 mol%, more preferably 3 to 30 mol%, and further preferably 4 to 20 mol%. preferable.

  When 1-butene-propylene copolymer is used, the content of 1-butene-propylene copolymer is preferably 50% by mass or less, and 40% by mass or less in the resin component contained in the seal layer. More preferably, it is more preferably 30% by mass or less. Moreover, it is preferable to set it as 10 mass% or more, and it is more preferable to set it as 15 mass% or more. When the content of the 1-butene-propylene copolymer is within this range, it is easy to obtain suitable low-temperature sealing properties, fusing strength, and tear resistance, and it is advantageous for cost reduction.

  As the resin used in combination with the 1-butene-propylene copolymer, other polyolefin-based resins can be used as appropriate, but since the seal strength is easily adjusted, a propylene-α-olefin copolymer, ethylene- An α-olefin copolymer can be preferably used, and a propylene-α-olefin copolymer can be particularly preferably used.

  The content of the α-olefin in the propylene-α-olefin copolymer is not particularly limited, but is preferably 1 to 20% by mass, and more preferably 1.5 to 15% by mass. Examples of the α-olefin include ethylene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. Of these, propylene-ethylene random copolymers as exemplified in the intermediate layer can be preferably used. MFR is preferably from 0.5 to 20 g / 10 minutes, more preferably from 2 to 10 g / 10 minutes, since good moldability is easily obtained.

  The content of the other olefinic resin is preferably 90% by mass or less, more preferably 85% by mass or less in the resin component contained in the seal layer, because it is easy to obtain suitable low-temperature sealing properties. . Moreover, it is preferable to set it as 50 mass% or more, and it is more preferable to set it as 60 mass% or more.

  In particular, when forming a packaging bag using the laminated film of the present invention, a 1-butene-propylene copolymer and a propylene-α-olefin copolymer are used when providing an easy-opening portion in which the sealing layers are heat-sealed. It is preferable to use the polymer in combination at a mass ratio represented by 1-butene-propylene copolymer / propylene-α-olefin copolymer of 20/80 to 50/50.

  The friction coefficient (ASTM D1894) of the seal layer surface is preferably 0.05 to 0.6, more preferably 0.06 to 0.5, and more preferably 0.06 to 0.45. By setting it as the said range, it becomes easy to improve suitably the film feedability at the time of bag making or packaging, the filling ability of the contents, the friction resistance between the contents and the film inner surface, the tear resistance, and the like. The friction coefficient can be adjusted by appropriately adding additives such as a lubricant and an anti-blocking agent according to the resin component used for the seal layer.

  In the seal layer, other components than the above resin components include antifogging agents, antistatic agents, heat stabilizers, nucleating agents, antioxidants, lubricants, antiblocking agents, mold release agents, ultraviolet absorbers, etc. These components may be added as long as the object of the present invention is not impaired.

[Laminated film]
The laminated film of the present invention is a laminated film having at least the above-mentioned print layer, intermediate layer and seal layer, and one surface layer of the laminate film is a print layer and the other surface layer is a laminate film comprising a seal layer. The laminated film having such a configuration can be suitably used as a film for various packaging because it has a suitable fusing seal strength and is excellent in impact resistance and bag breaking resistance.

  The thickness of the laminated film of the present invention may be appropriately adjusted according to the use and mode to be used. However, the total thickness is 20 because it is easy to achieve both volume reduction in packaging applications and resistance to bag breakage during distribution. It is preferably ˜60 μm, and more preferably 25 to 50 μm.

  In addition, the thickness and thickness ratio of each layer are not particularly limited, but for example, the thickness of the printing layer is preferably 2 to 20 μm, and more preferably 3 to 15 μm. The thickness of the intermediate layer is preferably 3 to 30 μm, and more preferably 5 to 20 μm. It is preferable that the thickness of a sealing layer is 1-10 micrometers, and it is more preferable that it is 2-8 micrometers.

  In addition, the thickness ratio of the printed layer is preferably 20% or more of the total thickness of the laminated film because it is easy to obtain suitable transparency and high gloss, and it is easy to obtain suitable fusing strength and bag-making suitability. 25% or more is more preferable. Moreover, it is preferable to set it as 40% or less, and it is more preferable to set it as 35% or less. The thickness ratio of the intermediate layer is preferably 30% or more, more preferably 40% or more of the total thickness of the laminated film because it is easy to obtain suitable matte feeling, fusing strength, and bag-making suitability. Moreover, it is preferable to set it as 70% or less, and it is more preferable to set it as 65% or less. The thickness ratio of the sealing layer is preferably 5% to 30%, more preferably 10 to 25% of the total thickness of the laminated film because it is easy to obtain suitable easy-openability, fusing strength, and bag-making suitability.

  The laminated film of the present invention may be laminated with any other resin layer other than the printed layer, intermediate layer and seal layer, but the thickness of the other resin layer is 20% or less of the total thickness. It is particularly preferable that the printing layer, the intermediate layer, and the sealing layer be used. In this configuration, an intermediate layer in which a plurality of intermediate layers are stacked may be used.

  The haze of the laminated film of the present invention is preferably 10% or less, more preferably 2 to 8%, since the contents to be packaged are easily visible. Even when the laminated film of the present invention has such high transparency, it is difficult to cause bag breakage such as tearing due to friction or rubbing between the contents and the film while having suitable packaging properties. When increasing the transparency of the laminated film of the present invention, the resin component that increases the haze such as a block copolymer is not used in each layer, or the content is preferably 10% even when used. Hereinafter, the transparency can be improved by more preferably 5% or less.

  Although it does not specifically limit as a manufacturing method of the laminated | multilayer film of this invention, For example, the resin or resin mixture used for each layer is heat-melted with a respectively separate extruder, By methods, such as a coextrusion multilayer die method and a feed block method, etc. Examples thereof include a coextrusion method in which a film is laminated in a molten state and then formed into a film by inflation, a T-die / chill roll method, or the like. This coextrusion method is preferable because the thickness ratio of each layer can be adjusted relatively freely, and a multilayer film excellent in hygiene and cost performance can be obtained. Since the laminated film obtained by the production method is obtained as a substantially unstretched multilayer film, secondary molding such as deep drawing by vacuum molding is also possible.

  The printing layer is preferably subjected to a surface treatment in order to improve adhesion with printing ink. Examples of such surface treatment include corona treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, surface oxidation treatment such as ozone / ultraviolet treatment, and surface unevenness treatment such as sandblasting. Corona treatment is preferable.

  Examples of the packaging material comprising the laminated film of the present invention include packaging bags, containers, container lids and the like used for foods, medicines, industrial parts, miscellaneous goods, magazines and the like. In particular, since the transparency and gloss are unprecedented, it is possible to provide a packaging material excellent in the appearance of internal products, and it can be suitably used for foods used to bring out a high-class feeling.

  In the packaging bag, the sealing layer of the laminated film of the present invention is used as a heat sealing layer, heat sealing is performed by stacking the sealing layers, or heat sealing is performed by stacking the printing layer and the sealing layer. A formed packaging bag is preferred. For example, after cutting the two laminated films into the desired size of the packaging bag, overlapping them and heat-sealing the three sides to form a bag, filling the contents from one side that is not heat-sealed It can be used as a packaging bag by heat sealing. Furthermore, it is also possible to form a packaging bag by sealing the upper and lower sides after sealing the end of a roll-shaped film into a cylindrical shape by an automatic packaging machine.

Moreover, when it is set as the packaging bag for bread, it can be set as the packaging bag which has a gusset part by folding and sealing a printing surface. Specifically, it is processed into a bottom gusset bag by a bag making machine such as HK-40 manufactured by Totani Giken Kogyo Co., Ltd. so that the sealing layer of the laminated film of the present invention is inside the bag. At this time, the fusing seal temperature and the bag making speed are set so that the fusing seal strength of the side part of the bottom gusset bag and the bottom gusset part (folding part of the bottom part) is 7.5 N to 30 N / 15 mm, preferably 10 to 30 N / 15 mm. It is preferable to adjust.
The obtained bottom gusset bag is supplied to a bread bread automatic filling machine, and after filling bread, is easily opened and has a heat seal strength of 0.1 to 5 N / 15 mm, preferably 0.2 to 4 N / 15 mm. Heat-sealed to make an easily openable bread wrapping bag, and if necessary, form an easily openable seal part at the top of the bag, preferably the top of the bread, and the top of the bag with a plastic plate, tape, string, etc. You may seal by bundling using this binding tool.

  Also, when collecting various types of bread, such as butter rolls, in a horizontal pillow type automatic packaging machine, such as FW-3400αV type manufactured by Fujikikai Co., Ltd., the seal layer should be inside the bag. Supplied in roll form. In the horizontal pillow type automatic packaging machine, the heat seal surfaces of the film are overlapped and heat sealed to form a bag and to enclose the bread. At this time, it is preferable to adjust the heat seal temperature and the packaging speed so that the sealing strength of the bottom and back-attached part of the pillow packaging bag by the packaging machine is 7.5 N to 30 N / 15 mm, preferably 8 to 20 N / 15 mm. . Subsequently, an easily openable seal portion may be formed by heat sealing under conditions that allow easy opening and a heat seal strength of 0.1 to 5 N / 15 mm, preferably 0.2 to 4 N / 15 mm. May be bound using a binding tool such as a plastic plate, tape, or string.

  Moreover, it is also possible to form a packaging bag, a container, and a lid of a container by stacking and heat-sealing another film or sheet that can be heat-sealed with the sealing layer. In that case, as another film to be used, films such as polypropylene and linear low density polyethylene can be used. Moreover, in order to express suitable rigidity, it can also be used as a laminate film in which a stretched film, for example, a biaxially stretched polyethylene terephthalate film (OPET), a biaxially stretched polypropylene film (OPP), or the like is bonded with a polyester adhesive or the like. Can do.

  As above-mentioned, this invention laminated film can implement | achieve the suitable tear resistance which a tear does not produce easily when enclosing a content, having favorable packaging aptitude. For this reason, when enclosing contents having sharp portions, especially when enclosing a large number of contents continuously and at high speed by a packaging machine or the like, it is possible to realize a packaging bag which does not easily tear.

  Moreover, since the structure which contains a linear low density polyethylene in an intermediate | middle layer can implement | achieve especially outstanding impact resistance and bag breaking resistance, it can apply suitably for various packaging uses. In particular, since excellent impact resistance can be realized even at low temperatures, it is suitable for food packaging applications that are often packaged and distributed at low temperatures.

  Among them, the laminated film of the present invention can be suitably formed even when a bag is made in a gusset-shaped packaging bag and a bread is enclosed in the packaging bag, so that the thickness is reduced and the packaging bag is reduced in volume. Can be particularly suitably applied to bread packaging applications where there is a high demand.

  Next, the present invention will be described in more detail with reference to examples and comparative examples. In addition, “part” and “%” in the blending of the resin composition and the like are based on mass.

Example 1
The resin mixture which forms each layer was prepared using the following resin as a resin component which forms each layer of a printing layer, an intermediate | middle layer, and a sealing layer, respectively. Each of these mixtures was supplied to three extruders and coextruded so that the average thickness of each layer of the laminated film formed by the printing layer / intermediate layer / sealing layer was 7/18/5 μm. A 30 μm laminated film was formed. Next, the printed layer of the obtained laminated film was subjected to a corona discharge treatment so that the surface energy was 35 mN / m to obtain a laminated film.
Printing layer: propylene-ethylene copolymer (ethylene-derived component content: 5.0 mass%, density: 0.90 g / cm ³ , MFR (measuring temperature 230 ° C.): 7 g / 10 minutes) (hereinafter, COPP (1) 90% by mass, ethylene-butene-rubber copolymer (density: 0.890 g / cm ³ , melting point 66 ° C., MFR (measurement temperature: 190 ° C.): 3 g / 10 minutes) (hereinafter referred to as EBR (1) 10% by mass)
Intermediate layer: 15% by mass of COPP (1), propylene homopolymer (density: 0.90 g / cm ³ , MFR (measurement temperature: 230 ° C.): 8 g / 10 min) (hereinafter referred to as HOPP (1)) 75 10% by mass, linear low density polyethylene (density: 0.905 g / cm ³ , MFR (measurement temperature 190 ° C.): 4 g / 10 min) (hereinafter referred to as LLDPE (1))
Seal layer: 70% by mass of COPP (1), 1-butene-propylene copolymer (density: 0.90 g / cm ³ , MFR (measuring temperature 230 ° C.): 4 g / 10 minutes) (hereinafter referred to as 1-butene copolymer) 30% by mass (referred to as polymer (1))

(Example 2)
A laminated film was obtained in the same manner as in Example 1 except that the resin component of the resin mixture used for the intermediate layer was as follows.
Intermediate layer: COPP (1) 30% by mass, HOPP (1) 60% by mass, LLDPE (1) 10% by mass

(Example 3)
A laminated film was obtained in the same manner as in Example 1 except that the resin components of the resin mixture used for the printed layer were as follows.
COPP (1) 95% by mass, EBR (1) 5% by mass

Example 4
A laminated film was obtained in the same manner as in Example 1 except that the resin components of the resin mixture used for the printed layer were as follows.
COPP (1) 85% by mass, EBR (1) 15% by mass

(Example 5)
A laminated film was obtained in the same manner as in Example 1 except that the resin components of the resin mixture used for the printed layer were as follows.
COPP (1) 65% by mass, propylene-ethylene copolymer (ethylene-derived component content: 5.5% by mass, density: 0.89 g / cm ³ , MFR (measuring temperature 230 ° C.): 7 g / 10 minutes) (below COPP (2))) 25% by mass, EBR (1) 10% by mass

(Example 6)
A laminated film was obtained in the same manner as in Example 1 except that the resin components of the resin mixture used for the printed layer were as follows.
COPP (1) 55 mass%, COPP (2) 35 mass%, EBR (1) 10 mass%

(Example 7)
A laminated film was obtained in the same manner as in Example 1 except that the resin components of the resin mixture used for the printed layer were as follows.
COPP (1) 50 mass%, COPP (2) 40 mass%, EBR (1) 10 mass%

(Example 8)
A laminated film was obtained in the same manner as in Example 1 except that the resin components of the resin mixture used for the printed layer were as follows.
COPP (1) 45 mass%, COPP (2) 35 mass%, high density polyethylene (density: 0.955 g / cm ³ , MFR (measuring temperature 190 ° C.): 0.35 g / 10 minutes) (hereinafter referred to as HDPE (1 ))) 10% by mass, EBR (1) 10% by mass

Example 9
A laminated film was obtained in the same manner as in Example 1 except that the resin component of the resin mixture used for the intermediate layer was as follows.
Intermediate layer: 15% by mass of COPP (2), 75% by mass of HOPP (1), 10% by mass of LLDPE (1)

(Example 10)
A laminated film was obtained in the same manner as in Example 1 except that the laminated film formed by the printing layer / intermediate layer / sealing layer was coextruded so that the average thickness of each layer was 9/14/7 μm.

(Example 11)
A laminated film was obtained in the same manner as in Example 5 except that the resin component of the resin mixture used for the seal layer was as follows.
Seal layer: COPP (1) 60% by mass, 1-butene copolymer (1) 40% by mass

(Example 12)
A laminated film was obtained in the same manner as in Example 1 except that the resin component of the resin mixture used for the intermediate layer was as follows.
Intermediate layer: COPP (1) 15% by mass, HOPP (1) 70% by mass, LLDPE (1) 10% by mass

(Example 13)
A laminated film was obtained in the same manner as in Example 1 except that the resin component of the resin mixture used for the intermediate layer was as follows.
Intermediate layer: COPP (1) 15% by mass, HOPP (1) 70% by mass, linear low density polyethylene (density: 0.91 g / cm ³ , MFR (measurement temperature 190 ° C.): 4 g / 10 min) (below , Referred to as LLDPE (2)) 10% by weight

(Comparative Example 1)
A laminated film was obtained in the same manner as in Example 1 except that the resin component of the resin mixture used for the intermediate layer was as follows.
Intermediate layer: HOPP (1) 90% by mass, LLDPE (1) 10% by mass

(Comparative Example 2)
A laminated film was obtained in the same manner as in Example 1 except that the resin component of the resin mixture used for the intermediate layer was as follows.
Intermediate layer: COPP (1) 65 mass%, HOPP (1) 25 mass%, LLDPE (1) 10 mass%

  The following tests and evaluations were performed using the laminated films obtained in the above Examples and Comparative Examples. The results obtained are as shown in the table below. In addition, the numerical value of the resin composition in a table | surface is content (mass%) of each component in the resin component used in each layer.

[Measurement of friction coefficient]
The films obtained in Examples and Comparative Examples were aged at 38 ° C. for 48 hours, and then the surface friction coefficient was measured according to ASTM (D-1894).

[Measurement of haze, transparency evaluation]
The haze of the films obtained in Examples and Comparative Examples was measured (unit:%) using a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd.) based on JIS K7105. Transparency was evaluated according to the following criteria.
◎: Haze is 5% or less ○: Haze exceeds 5% and 10% or less ×: Haze exceeds 10%

[Measurement of rigidity]
Using a Tensilon tensile tester (manufactured by A & D Co., Ltd.), based on ASTM D-882, the 1% tangential modulus (unit: MPa) at 23 ° C. of the films obtained in Examples and Comparative Examples is used. It was measured. The measurement was performed in the extrusion direction (hereinafter referred to as “MD”) and the film width direction (hereinafter referred to as “CD”) during film production.

[Measurement of impact strength]
The films obtained in Examples and Comparative Examples were held in a thermostatic chamber adjusted to 0 ° C. for 6 hours, and then impact strength by a film impact method using a spherical metallic impact head having a diameter of 1.5 inches. Was measured.
◎: Impact strength is 0.15J or more ○: Impact strength is 0.1J or more and less than 0.15J △: Impact strength is 0.05J or more and less than 0.1J ×: Impact strength is less than 0.05J

[Abrasion resistance]
From the films obtained in the examples and comparative examples, a test piece is cut out 6 cm in the MD direction and 10 cm in the CD direction, and a rubbing tester (manufactured by Imoto Seisakusho Co., Ltd.) reciprocates so that the seal layer is on the upper surface. Affixed to the plate with tape. Next, sandpaper # 150 (manufactured by Sankyo Rikagaku Co., Ltd.) is affixed to the tip of the rubbing tester test piece with double-sided tape, and under a low temperature of 0 ° C. under a weight of 600 g. Thus, the friction resistance was evaluated with a reciprocating speed of 133 m / min and 70 times as the upper limit. The number of times until pinholes and tears occurred was counted and used as an evaluation index for friction resistance.
○: Pinholes and tears occur 20 times or more ×: Pinholes and tears occur when less than 20 times

[Evaluation of bag aptitude]
The film obtained in the Examples and Comparative Examples was folded in half with the sealing layer inside, and then gusseted in the bottom, and fused and sealed at a sealing temperature (bag-making temperature) of 300 ° C. Machine: Totani Giken Factory Co., Ltd. HK-40, bag making speed: 120 sheets / min) to produce a bottom gusset bag (length: 345 mm (side portion: 245 mm, gusset portion: 60 mm), width 235 mm), The suitability for bag making was evaluated. In addition, 300 sheets were grouped together as a set and bundled into a bundle to evaluate the alignment characteristics.
◯: The film follows even at a bag-making speed of 120 shots, and there is no problem with alignment.
Δ: The film follows even at a bag-making speed of 120 shots, but there is a problem with partly alignability.
X: Some things cannot follow the bag-making speed of 120 shots, and the alignment is poor.

[Fusing seal strength]
Using the films obtained in Examples and Comparative Examples, bottom gusset bags were produced in the same manner as in the bag-making suitability evaluation. From the center of the gusset portion on both sides of the obtained five bottom gusset bags and the center of the side portion other than the gusset, respectively, a test piece having a length of 70 mm and a width of 15 mm is set so that the fusing seal portion is the center portion in the length direction. 10 sheets were cut out each, and the maximum load at the time of pulling with a Tensilon tensile tester (manufactured by A & D Co., Ltd.) at 23 ° C. and a tensile speed of 300 mm / min was measured as the fusing strength.
○: The fusing strength of the gusset portion and the side portion is 15 N / 15 mm or more. X: The fusing strength of at least one of the gusset portion and the side portion is less than 15 N / 15 mm.

[Heat seal strength]
Using the films obtained in Examples and Comparative Examples, bottom gusset bags were produced in the same manner as in the bag-making suitability evaluation. A heat sealer (Tester Sangyo Co., Ltd .: pressure 0.2 MPa, time 1 second, seal temperature: upper seal bar 95 ° C., parallel to the 50 mm portion and the opening downward from the upper end of the opening of the obtained bottom gusset bag. Heat sealing was performed at a lower seal bar of 50 ° C. and a seal bar shape: a plane of 300 m × 10 mm. From the obtained heat-seal part of the five bottom gusset bags, 10 pieces of test pieces each having a length of 70 mm and a width of 15 mm were cut out by two pieces each so that the heat-seal part was the central part in the width direction, and 23 ° C. The maximum load when peeling with a Tensilon tensile tester (manufactured by A & D Co., Ltd.) at a tensile speed of 300 mm / min was measured as the heat seal strength.
○: Heat seal strength is less than 5N / 15mm, no film tear when peeled off ×: Heat seal strength is 5N / 15mm or more, or film tear when peeled off

[Closure suitability]
Using the films obtained in Examples and Comparative Examples, bottom gusset bags were produced in the same manner as in the bag-making suitability evaluation. Insert 1 loaf of bread into the bottom gusset bag and use a quick lock Japan automatic binding machine (model: 1084F) in an atmosphere of about 10 ° C. After attaching Quick Lock Japan), the binding tool was pulled to remove the binding tool. Detachment of the binding tool was carried out with 5 bags, and the presence or absence of tearing or tearing due to desorption was evaluated.
○: No tearing or tearing ×: Torn to more than one bag, with tearing

  As is clear from the above table, the laminated films of the present invention of Examples 1 to 13 had good bag breaking resistance even at low temperatures while having good transparency and sealing properties. In addition, tearing hardly occurs during the friction test or the sealing by the closure, and it has suitable tear resistance. On the other hand, the laminated film of Comparative Example 1 was inferior in sealing properties and was torn upon sealing with a closure. In addition, the laminated film of Comparative Example 2 was liable to be torn or torn during friction and was inferior in tear resistance.

Claims (8)

A laminated film having at least a printing layer, an intermediate layer and a sealing layer, wherein one surface layer is a printing layer and the other surface layer is a sealing layer;
The printing layer contains a propylene-based resin;
The said intermediate | middle layer contains 5-60 mass% of propylene-ethylene random copolymers, The laminated film characterized by the above-mentioned.   The laminated film according to claim 1, wherein the printed layer contains 50% by mass or more of a propylene-ethylene random copolymer as a propylene-based resin.   The laminated film according to claim 1 or 2, wherein the intermediate layer contains 5 to 20% by mass of linear low-density polyethylene.   The laminated film according to any one of claims 1 to 3, wherein the intermediate layer contains 20 to 80% by mass of a propylene homopolymer.   The laminated film according to any one of claims 1 to 4, wherein the seal layer contains a copolymer having a structural unit composed of 1-butene.   The laminated film according to any one of claims 1 to 5, which is used for a packaging material.   A packaging material comprising the laminated film according to claim 1.   The packaging material according to claim 7, which is a packaging bag for food.