JP2019209541A - Laminate film and packaging material - Google Patents

Abstract

To provide a laminate film having impact resistance and abrasion resistance which is hardly torn while having good seal strength.SOLUTION: A laminate film has a surface layer (A), an intermediate layer (B1), an intermediate layer (B2) and a heat seal layer (C), in which the surface layer (A) is a layer containing a propylene-based resin as a main resin component, the intermediate layer (B1) is a layer containing 60 mass% or more of a propylene homopolymer, the intermediate layer (B2) is a layer containing 50 mass% or more of a propylene-based resin and 10 mass% or more of straight chain low density polyethylene, the heat seal layer (C) is a layer containing 10-30 mass% of a butene-based resin, and each of the layers are laminated in order of (A)/(B1)/(B2)/(C) or (A)/(B2)/(B1)/(C).SELECTED DRAWING: None

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 packaging film using an olefin resin has been used as a film for packaging various foods, and in particular, a laminated film using a propylene resin as a main resin component has been used as a bread packaging film. (For example, see Patent Documents 1 and 2).

JP 2008-162162 A JP 2009-061705 A

  Films using these propylene-based resins are easy to obtain suitable rigidity and sealing strength, and are therefore used in various applications including food packaging such as bread. However, since a thin film is used for such a laminated film in consideration of the environment and cost, bag breakage may occur due to external impact during distribution, contact with protrusions, or the like. In particular, when food is packaged, transported, or stored, it is often exposed to a low temperature, and improvement in bag-breaking resistance at a low temperature has been demanded. In addition, such a thin packaging film may be torn or torn due to contact or rubbing when enclosing the contents depending on the contents to be packaged.

  The problem to be solved by the present invention is to realize a laminated film having a favorable impact strength and a suitable rub resistance that hardly causes tearing while having good sealing strength.

  In this inventor, it is a laminated film which has a surface layer (A), a 1st intermediate | middle layer (B1), a 2nd intermediate | middle layer (B2), and a heat seal layer (C), Comprising: Said surface layer (A) Is a layer containing a propylene-based resin as a main resin component, and the first intermediate layer (B1) contains a propylene homopolymer in an amount of 60% by mass or more in the resin component contained in the intermediate layer (B1). The second intermediate layer (B2) is a layer containing a propylene-based resin in an amount of 50% by mass or more in the resin component contained in the intermediate layer (B2) and 10% by mass or more in a linear low density polyethylene. Yes, the heat seal layer (C) is a layer containing 10-30% by mass of a resin component contained in the heat seal layer (C) butene-based resin, and each layer is a surface layer (A) / Intermediate layer (B1) / Intermediate layer (B2) / Heat sea The above-mentioned problems are solved by a laminated film laminated in the order of layer (C), or in the order of surface layer (A) / intermediate layer (B2) / intermediate layer (B1) / heat seal layer (C). .

  In a laminated film containing a propylene resin as a main resin component, the intermediate layer has a two-layer structure, the first intermediate layer is a layer containing 60% by mass or more of a propylene homopolymer, and the second intermediate layer is a propylene type By using a layer containing a resin and linear low-density polyethylene, suitable impact resistance and scratch resistance can be realized while maintaining good sealing strength. Among them, particularly excellent effects can be easily achieved in a mat-like laminated film using a propylene-based block copolymer resin as a propylene-based resin for a surface layer or an intermediate layer. Thus, since the laminated film of the present invention is excellent in friction resistance, it is difficult to cause tearing or tearing due to contact or rubbing when enclosing contents even when used for packaging applications. It can be suitably applied to. In particular, since it has excellent impact resistance at low temperatures, it can be suitably applied in food packaging applications that are often packaged and distributed at low temperatures.

  In addition, when the bread becomes the contents, the freshly baked bread, particularly the ears of the bread may be sharp, and the laminated film is made into a gusset-shaped packaging bag, When the bread is enclosed, the packaging bag may be torn. As described above, since packaging bags used for food packaging and the like are discarded when the contents are used or consumed, there is a high demand for volume reduction in consideration of the environment and cost. In response to these demands, packaging films have been made thinner and packaging bags have been reduced in volume, and the amount and size of internal products (bread) have not changed, but the size of the bags has been reduced, and bread and film The bag is shifting to a tightly packed form. Therefore, the problem of tearing of the package due to the contents is more likely to occur. Since the packaging film of this invention can suppress suitably the tear and tear at the time of content enclosure as above-mentioned, it can be applied suitably for the bread packaging use which such a tear tends to produce. In particular, in bread packaging applications, a mat-like laminated film using a highly rigid propylene block copolymer may be used, but the laminated film of the present invention is a propylene block copolymer as a propylene resin. It is also possible to suppress the tearing suitably when using.

  The laminated film of the present invention has a surface layer (A), a first intermediate layer (B1), a second intermediate layer (B2), and a heat seal layer (C), and the surface layer (A) is a propylene resin. The first intermediate layer (B1) is a layer containing 60% by mass or more of the propylene homopolymer in the resin component contained in the intermediate layer (B1), and the second intermediate layer (B1). The intermediate layer (B2) is a layer containing 50% by mass or more of the propylene-based resin in the resin component contained in the intermediate layer (B2) and 10% by mass or more of the linear low density polyethylene, and the heat seal layer (C ) Is a layer containing 10 to 30% by mass of a butene resin in the resin component contained in the heat seal layer (C), and each layer is a surface layer (A) / intermediate layer (B1) / intermediate layer ( B2) / Heat seal layer (C), or Surface layer (A) / Medium Layer (B2) is a laminate film laminated in this order / intermediate layer (B1) / heat seal layer (C).

[Surface layer (A)]
The surface layer (A) of the laminated film of the present invention is a layer containing a propylene-based resin as a main resin component. By using the surface layer (A), the laminated film of the present invention can realize an appearance suitable for various packaging, good impact resistance, and the like. Examples of the propylene resin include propylene homopolymer, propylene random copolymer (propylene-α-olefin random copolymer) which is a random copolymer of propylene and α-olefin, and propylene and α-olefin. Examples thereof include a propylene block copolymer (propylene-α-olefin block copolymer) which is a block copolymer. Examples of the α-olefin used in the copolymer include ethylene, 1-butene, 1-hexene, 4-methyl / 1-pentene, 1-octene and the like.

  Among these, it is preferable to use a propylene-based block copolymer because it is easy to obtain impact resistance at a low temperature and a suitable matte feeling. As the α-olefin used in the propylene-based block copolymer, those exemplified above can be used as appropriate. Among them, ethylene is preferable because it is excellent in matte feeling, cold resistance and rigidity balance. The α-olefin content in the propylene-based block copolymer is preferably 2 to 10% by mass and more preferably 4 to 8% by mass because it is easy to obtain impact resistance and rigidity.

  In the case of using a propylene-based block copolymer, the melt flow rate (MFR) of the propylene-based block copolymer is easy to mold, and suitable impact resistance and mat feeling are easily obtained. It is preferably 5 g / 10 min or more, and more preferably 1 g / 10 min or more. Moreover, it is preferable that it is 20 g / 10min or less, and it is more preferable that it is 10 g / 10min or less.

  In the case of using a propylene-based block copolymer, the melting point of the propylene-based block copolymer is preferably 155 ° C. or more, and preferably 165 ° C. or less because it is easy to obtain suitable bag-making properties. preferable.

  The surface layer (A) is mainly composed of the propylene-based resin, and may be used in combination with other resins that can be coextruded as long as the effects of the present invention are not impaired. Specifically, 70% by mass or more of the resin component used for the surface layer (A) is preferably a propylene-based resin, more preferably 80% by mass or more is a propylene-based resin, and 90% by mass. The above is more preferably a propylene-based resin. It is also preferred that all of the resin components in the surface layer (A) are propylene resins.

  When using a propylene-based block copolymer, the content of the propylene-based block copolymer is determined by the balance of mat feeling, fusing strength and bag-making suitability, but the resin used for the surface layer (A) It is preferable to contain 70% by mass or more of the components. By setting it as the said range, it becomes easy to obtain the uniform mat feeling excellent in the designability. Especially, when making impact resistance high, it is preferable to set it as 80-100 mass%, and when improving a mat feeling, it is preferable to set it as 70-90 mass%.

  The propylene block copolymer used for the surface layer (A) may be a single copolymer or a plurality of copolymers. When using two or more, it is preferable to make the total content of the propylene-type block copolymer used into the said range.

  BC8, BC7 (manufactured by Nippon Polypro Co., Ltd.), E150GK, F704V (Prime) are used in the surface layer (A) and have a good balance with mat feeling, fusing strength and bag making suitability. Polymer)), PC480A, PC684S, PC380A, VB370A (manufactured by Sun Allomer), and the like.

  In the case of using a resin other than the propylene resin in the surface layer (A), various olefin resins used for the packaging film can be used. For example, very low density polyethylene (VLDPE), linear -Like low density polyethylene (LLDPE), polyethylene resin such as low density polyethylene (LDPE), 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 Ethylene copolymer such as polymer (EMAA); and ethylene-acrylic acid copolymer Body ionomers, ethylene - the ionomers of methacrylic acid copolymer can be used.

  The content of the resin other than the propylene-based resin is preferably 30% by mass or less in the resin component contained in the surface layer (A), and more preferably 20% by mass or less. Although not particularly limited, when the other polyolefin-based resin is used, the content is preferably 10% by mass or more.

  Various additives may be blended in the surface layer (A) as long as the effects of the present invention are not impaired. Examples of the additive include an antioxidant, a weather resistance stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a lubricant, a nucleating agent, and a pigment. When using these additives, it is preferably 5 parts by mass or less, more preferably 2 parts by mass or less, and still more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the resin component used in the heat seal layer. Use at a degree.

  The surface roughness (Ra) of the surface layer (A) based on JIS B-0601 is preferably 0.5 to 2.0, and more preferably 0.7 to 1.7. By making the surface roughness within this range, the amount of other components (additives such as slip agents and antiblocking agents) can be reduced, or even if not used in combination, a film with excellent surface slipperiness can be obtained. As a result, the speed of bag making is improved, the associating after bag making and the improvement and efficiency of packing work are improved, and the workability at the time of packing by the automatic packing machine after filling the contents is improved.

  The surface friction coefficient (ASTM D-1894) in the surface layer (A) is preferably 0.05 to 0.8, more preferably 0.07 to 0.7, and more preferably 0.1 to 0.6. . By setting it as the said range, it becomes easy to improve the film feeding property at the time of packaging, the alignment property after bag making, packing workability | operativity, etc., and it becomes easy to suppress suitably the film 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.

[First intermediate layer (B1)]
The 1st intermediate | middle layer (B1) in the laminated | multilayer film of this invention is a layer which contains a propylene homopolymer 60 mass% or more in the resin component contained in an intermediate | middle layer (B1). By using the intermediate layer, it is possible to obtain a laminated film having excellent bag breaking resistance, in particular, excellent friction resistance at low temperatures. The content of the propylene homopolymer in the resin component contained in the first intermediate layer (B1) is preferably 70% by mass or more because it is easier to obtain friction resistance at low temperatures, and is 80% by mass. % Or more is more preferable, and it is further more preferable that it is 90 mass% or more. Moreover, it is also preferable that the resin component used for an intermediate | middle layer (B1) is only a propylene homopolymer.

  The propylene homopolymer MFR (230 ° C., 21.18 N) contained in the first intermediate layer (B1) is easy to mold and can easily obtain suitable friction resistance, so that it is 10 g / 10 min or less. It is preferable that it is 1-6 g / 10min, and it is further more preferable that it is 2-4g / 10min.

  The melting point of the propylene homopolymer used for the first intermediate layer (B1) is preferably 160 ° C. or higher and preferably 175 ° C. or lower because it is easy to obtain suitable moldability and bag-making property. .

  The propylene homopolymer used for the first intermediate layer (B1) may be a single propylene homopolymer or a plurality of propylene homopolymers. When using two or more, it is preferable to make the total content of the propylene homopolymer used into the said range.

  Moreover, when using resin other than a propylene homopolymer for a 1st intermediate | middle layer (B1), the various olefin resin etc. which are used for a packaging film can be used. Examples of the resin other than the propylene homopolymer include propylene resins other than the propylene homopolymer such as a propylene random copolymer and a propylene block copolymer. In the surface layer (A), polyethylene resins such as very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), and low density polyethylene (LDPE) exemplified as resins other than the propylene resin, , Ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate -Ethylene copolymers such as maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA); and ethylene-acrylic acid Copolymer ionomer, ethylene-methacrylic acid copolymer ionomer, etc. It can be used. When a resin other than the propylene homopolymer is used, it is preferable to use a polyethylene resin because it is easy to improve impact resistance, and it is more preferable to use a linear low density polyethylene.

  When using a resin other than the propylene homopolymer, the content of the resin other than the propylene homopolymer is 40% by mass or less in the resin component contained in the first intermediate layer (B1). Is preferable, it is more preferable to set it as 30 mass% or less, and it is further more preferable to set it as 20 mass% or less.

  In addition, you may use suitably the additive which was illustrated by the said surface layer (A) also in the 1st intermediate | middle layer (B1). The preferred amount used is also the same as that of the surface layer (A).

[Second intermediate layer (B2)]
The second intermediate layer (B2) of the laminated film of the present invention is a layer containing a propylene resin and a linear low density polyethylene, and the propylene resin in the resin component contained in the intermediate layer (B2). Is 50% by mass or more, and the content of linear low density polyethylene is 10% by mass or more. By using the said intermediate | middle layer (B2), the suitable impact resistance, especially the laminated film excellent in the impact resistance under low temperature can be obtained.

  The content of the propylene-based resin in the intermediate layer (B2) is preferably 60 to 90% by mass, more preferably 70 to 80% by mass. The content of the linear low density polyethylene is preferably 10 to 40% by mass, more preferably 20 to 30% by mass. By making content of the propylene-type resin and linear low density polyethylene in an intermediate | middle layer (B2) into the said range, it becomes easy to obtain especially suitable rigidity, bag-making aptitude, and bag-breaking resistance.

  As the propylene resin in the resin component contained in the second intermediate layer (B2), the propylene resin exemplified in the surface layer (A) can be used. Of these, the use of a propylene-based block copolymer is preferred because it is easy to obtain impact resistance and bag-breaking resistance at low temperatures and a suitable matte feeling.

  When using a propylene-based block copolymer, the content of the propylene-based block copolymer in the resin component contained in the intermediate layer (B2) is suitable for impact resistance, mat feeling, and bag making properties. Is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more. Moreover, it is preferable to set it as 90 mass% or less, and it is more preferable to set it as 80 mass% or less.

  As a propylene type block copolymer, the thing similar to the propylene type block copolymer used for the said surface layer (A) can be used preferably. The propylene-based block copolymer may be a single copolymer or a plurality of copolymers. When using two or more, it is preferable to make the total content of the propylene-type block copolymer used into the said range.

  When using a propylene-based block copolymer, it is also preferable to use only a propylene-based block copolymer as the propylene-based resin, and it is preferable to use the propylene-based block copolymer directly in the second intermediate layer (B2). The content ratio with the chain low-density polyethylene is preferably 90/10 to 60/40, more preferably 80/20 to 70/30, in terms of mass ratio. By setting the ratio, it is possible to obtain a laminated film having excellent bag resistance and particularly excellent bag resistance at low temperatures while having a suitable matte tone.

The linear low density polyethylene used for the second intermediate layer (B2), 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 906 g / cm ³ or less. By setting the density of the linear low-density polyethylene to be used within the above range, it is easy to combine suitable fusing strength, high impact resistance, and bag breaking resistance.

  The MFR (190 ° C., 21.18N) of the linear low density polyethylene is preferably 10 g / 10 minutes or less, and more preferably 1 to 5 g / 10 minutes. By making MFR into the said range, it becomes easy to improve the film-forming property of a film, dispersibility is good, and it becomes easy to obtain a uniform film.

  A plurality of linear low-density polyethylenes may be used in combination. When a plurality of linear low-density polyethylenes are used, it is preferable that the total content of the linear low-density polyethylene used is within the above range.

  In addition, you may use suitably the additive which was illustrated by the said surface layer (A) also in the 2nd intermediate | middle layer (B2). The preferred amount used is also the same as that of the surface layer (A).

[Heat seal layer (C)]
The heat seal layer (C) used in the present invention is a layer used for adhesion between the seal layers of the laminated film and adhesion between the laminated film and other containers or films. What is necessary is just to select suitably the resin seed | species from which the suitable seal | sticker intensity | strength is obtained for the said heat seal layer according to a use aspect or to-be-sealed object. As a resin used for the heat seal layer (C), an olefin resin used for a heat seal film can be preferably used. For example, a propylene-ethylene random copolymer or propylene is used from the viewpoint of obtaining an appropriate seal strength. Propylene-α-olefin copolymers such as -1-butene copolymer, α-olefin-propylene copolymers such as 1-butene-propylene copolymer, and the like can be suitably used. Among these, propylene-1-butene is easy to adjust heat seal temperature and strength at easy opening seal at low temperature, wide heat seal temperature range, and easy to obtain appropriate heat seal strength as easy opening seal. A butene-containing copolymer such as a polymer or 1-butene-propylene copolymer is preferred.

  When a butene-containing copolymer, particularly a 1-butene-propylene copolymer, is used, it is easy to obtain suitable sealing properties and blocking resistance, so that the 1-butene content in the copolymer is 60 to 95. It is preferably 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 2 to 10 mol%, more preferably 3 to 9 mol%, and further preferably 4 to 8 mol%. preferable.

  When the butene-containing copolymer is used, the content of the butene-containing copolymer is preferably 50% by mass or less, more preferably 40% by mass or less in the resin component contained in the seal layer. More preferably, the content is 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 butene-containing copolymer is within this range, it is easy to obtain suitable low-temperature sealing properties, fusing strength and tear resistance of bag-made products, and it is advantageous for cost reduction.

  As the resin used in combination with the butene-containing copolymer, polyolefin resins other than the butene-containing copolymer can be used as appropriate, and propylene-based resins and ethylene-based resins can be preferably used. Among these, since it is easy to suitably adjust the seal strength, a propylene random copolymer that is a random copolymer of propylene and α-olefin, and an ethylene random copolymer that is a random copolymer of ethylene and α-olefin. A polymer can be preferably used, and a propylene random copolymer can be particularly preferably used.

  The content of the α-olefin in the propylene random 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. Among these, a propylene-ethylene random copolymer 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.

  Since the content of the olefin resin other than the butene-containing copolymer used in the heat seal layer (C) is easy to obtain a suitable low temperature seal property, the resin component contained in the heat seal layer (C) It is preferable to set it as 90 mass% or less, and it is more preferable to set it as 85 mass% or less. 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.

  You may mix | blend various additives in a heat seal layer (C) in the range which does not impair the effect of this invention. Examples of the additive include an antioxidant, a weather resistance stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a lubricant, a nucleating agent, and a pigment. The preferred amount used is the same as that of the surface layer (A).

  As a friction coefficient (ASTM D1894) of the heat seal layer surface, 0.01-0.4 are preferable, 0.02-0.35 are still more preferable, 0.05-0.30 are more preferable. By setting it as the said range, it becomes easy to improve the packaging work by the film feedability at the time of packaging, the wrinkle after bag making, and suppression of swell. In addition, it is easy to suppress scratches caused by rubbing between the contents when filling the contents such as bread and the film inner surface, and to improve wear resistance and tear resistance, and to easily suppress film tearing. In addition, the said friction coefficient can be adjusted by adding additives, such as a lubricant and an antiblocking agent, suitably according to the resin component used for a heat seal layer.

[Laminated film]
The laminated film of the present invention is a laminated film having at least the surface layer (A), the first intermediate layer (B1), the second intermediate layer (B2), and the heat seal layer (C), and each layer is Surface layer (A) / intermediate layer (B1) / intermediate layer (B2) / heat seal layer (C), or surface layer (A) / intermediate layer (B2) / intermediate layer (B1) / heat seal layer It is a laminated film characterized by being laminated in the order of (C). 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.

  Moreover, the thickness and thickness ratio of each layer are not particularly limited, but for example, the thickness of the surface layer is preferably 2 to 20 μm, and more preferably 3 to 15 μm. The thickness of the first intermediate layer is preferably 1 to 10 μm, and more preferably 2 to 8 μm. The thickness of the second intermediate layer is preferably 2 to 20 μm, and more preferably 3 to 15 μm. The thickness of the heat seal layer is preferably 1 to 10 μm, and more preferably 2 to 8 μm.

  In addition, the thickness ratio of the surface layer (A) is preferably 20 to 40% of the total thickness of the laminated film, because it is easy to obtain a suitable matte feeling, fusing strength, and bag making suitability, and 25 to 35%. More preferably. The thickness ratio of the first intermediate layer (B1) is preferably 5 to 25%, more preferably 10 to 20% of the total thickness of the laminated film because it is easy to obtain suitable friction resistance. Since it is easy to obtain suitable impact resistance, fusing strength, and bag-making resistance, the second intermediate layer (B2) is preferably 25 to 55% or more, more preferably 35 to 45%. The thickness ratio of the heat seal layer (C) is preferably 5 to 25%, more preferably 10 to 20% 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 preferably has an impact strength measured by a film impact method of 0.2 (J) or more, and more preferably 0.3 (J) or more. The impact strength is measured by using a spherical metallic impact head having a diameter of 1.5 inches after holding a laminated film manufactured at a thickness of 30 μm for 6 hours in a temperature-controlled room adjusted to 0 ° C. It is.

  When the laminated film of the present invention is used as a mat-like packaging material, the haze is preferably 50 to 80%, more preferably 60 to 70%. The said haze is haze (unit:%) measured using the haze meter based on JIS K7105 for the laminated film manufactured by 30 micrometers thickness.

  The laminated film of the present invention preferably has a fusing strength of a gusset portion and a side portion of 15 N / 15 mm or more when a bottom gusset bag is produced using a laminated film produced with a thickness of 30 μm. The fusing strength is determined by measuring the length of the test piece having a length of 70 mm and a width of 15 mm from the center of the gusset portion on both sides of the five bottom gusset bags and the center of the side portion other than the gusset, respectively. It is a numerical value obtained by cutting out 10 sheets each so as to be the central part of the film, measuring the maximum load as the fusing strength when pulled with a Tensilon tensile tester at 23 ° C. and a tensile speed of 300 mm / min, and calculating the average value thereof. is there.

  The laminated film of the present invention preferably has a heat seal strength of less than 5 N / 15 mm when the sealing surfaces of the laminated film produced with a thickness of 30 μm are heat-sealed and peeled off. The heat seal strength is a heat sealer (manufactured by Tester Sangyo Co., Ltd .: pressure 0.2 MPa, time 1 second, seal temperature: upper seal bar 95 ° C., lower seal bar 50 ° C., seal bar shape: plane of 300 m × 10 mm) The maximum load when ten pieces of 70 mm long and 15 mm wide test pieces that were heat-sealed with a Tensilon tensile tester at 23 ° C. and a tensile speed of 300 mm / min were measured as the heat seal strength, and the average value was obtained. Is a numerical value obtained by calculating. In addition, it is preferable that the film is not torn when it is peeled off.

  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 surface layer (A) is preferably subjected to a surface treatment in order to improve adhesiveness with the 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.

  The packaging bag is a package in which the heat-sealing layer of the laminated film of the present invention is heat-sealed by overlapping the sealing layers, or heat-sealing by overlapping the printing layer and the sealing layer, so that the sealing layer is formed inside. A 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, it is preferable to adjust the fusing seal temperature and the bag making speed so that the fusing seal strength of the side portion of the bottom gusset bag and the bottom gusset portion (folded portion of the bottom portion) is 15 N / 15 mm or more.

  The obtained bottom gusset bag is supplied to a bread bread automatic filling machine, and after filling bread, heat-sealing is performed under the condition that it is easy to open and the heat seal strength is preferably less than 5 N / 15 mm, more preferably less than 4 N / 15 mm. Then, an easily openable bread packaging bag is formed, and if necessary, an easily openable seal portion is formed on the upper part of the bag, preferably the upper part of the bread, and the upper part of the bag is bound with a binder such as a plastic plate, tape, string, etc. You may seal by bundling using. Although a minimum in particular is not restrict | limited, Preferably it is 0.1 N / 15mm, More preferably, it is 0.2 N / 15mm or more.

  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. . Next, heat-sealing is performed under conditions that allow easy opening and heat seal strength is preferably 0.1 or more and less than 5 N / 15 mm, more preferably 0.2 or more and less than 4 N / 15 mm, thereby forming an easy-open seal part. Alternatively, the vicinity thereof 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 heat-sealable layer and another heat-sealable film. In this case, as another film to be used, a film such as LDPE, EVA, or polypropylene having relatively low mechanical strength can be used. Also, a laminate film in which a film of LDPE, EVA, polypropylene, etc., and a stretched film having relatively good tearability, for example, a biaxially stretched polyethylene terephthalate film (OPET), a biaxially stretched polypropylene film (OPP), etc. are bonded together. Can be used.

  As described above, since the laminated film of the present invention can realize suitable bag breaking resistance and friction resistance, it can be suitably applied to various packaging applications. In particular, since excellent impact resistance and friction resistance can be realized even at low temperatures, it is suitable for food packaging applications that are often packaged and distributed at low temperatures.

  In particular, the laminated film of the present invention can be suitably applied to bread packaging applications because it is less likely to tear or tear when the contents are enclosed when applied to bread packaging such as bread and confectionery bread. In particular, since it is possible to suitably suppress tearing and tearing due to ear cuts by bread, it can be particularly suitably applied to bread bread packaging applications.

  Next, the present invention will be described in more detail with reference to examples and comparative examples. Hereinafter, unless otherwise specified, “part” and “%” are based on mass.

(Example 1)
As the resin component forming each layer of the surface layer (A), the first intermediate layer (B1), the second intermediate layer (B2) and the heat seal layer (C), the following resins are used respectively, The resin mixture to be formed was adjusted. Each of these mixtures is supplied to four extruders, and a laminated film formed of surface layer (A) / first intermediate layer (B1) / second intermediate layer (B2) / heat seal layer (C) Each layer was coextruded so that the average thickness of each layer was 9/5/12/4 μm to form a laminated film having a thickness of 30 μm. 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.
Surface layer (A): propylene block copolymer (propylene-derived component content: 90%, density: 0.90 g / cm ³ , MFR (measuring temperature 230 ° C.): 6 g / 10 min) (hereinafter referred to as propylene block copolymer) 100% by mass (referred to as polymer (1))
First intermediate layer (B1): propylene homopolymer (density 0.90 g / cm ³ , MFR (measurement temperature 230 ° C.): 7 g / 10 min) (hereinafter referred to as propylene homopolymer (1)) 100 mass %
Second intermediate layer (B2): Propylene block copolymer (1) 75% by mass, linear low density polyethylene (density: 0.905 g / cm ³ , MFR (measurement temperature 190 ° C.): 4 g / 10 minutes ) (Hereinafter referred to as LLDPE (1)) 25% by mass
Heat seal layer (C): 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 referred to as COPP ( 1)) 70% by mass, 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 coalesced (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 first intermediate layer (B1) was as follows.
First intermediate layer (B1): 90% by mass of propylene homopolymer (1), 10% by mass of LLDPE (1)

(Example 3)
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 first intermediate layer (B1) was as follows.
First intermediate layer (B1): propylene homopolymer (density 0.90 g / cm ³ , MFR (measuring temperature 230 ° C.): 2.3 g / 10 min) (hereinafter referred to as propylene homopolymer (2)) 100%

(Example 4)
A laminated film is obtained in the same manner as in Example 1 except that the order of lamination is the surface layer (A) / second intermediate layer (B2) / first intermediate layer (B1) / heat seal layer (C). It was.
(Example 5)
A laminated film is obtained in the same manner as in Example 3 except that the order of laminating is: surface layer (A) / second intermediate layer (B2) / first intermediate layer (B1) / heat seal layer (C). It was.

(Comparative Example 1)
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 first intermediate layer (B1) and the second intermediate layer (B2) were as follows.
First intermediate layer (B1), second intermediate layer (B2): Propylene-based block copolymer (1) 85% by mass, LLDPE (1) 15% by mass

(Comparative Example 2)
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 first intermediate layer (B1) and the second intermediate layer (B2) were as follows.
1st intermediate | middle layer (B1), 2nd intermediate | middle layer (B2): Propylene homopolymer (1) 100 mass%

(Comparative 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 first intermediate layer (B1) and the second intermediate layer (B2) were as follows.
1st intermediate | middle layer (B1), 2nd intermediate | middle layer (B2): Propylene homopolymer (1) 75 mass%, LLDPE (1) 25 mass%

(Comparative 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 first intermediate layer (B1) and the second intermediate layer (B2) were as follows.
First intermediate layer (B1), second intermediate layer (B2): propylene block copolymer (1) 50% by mass, propylene homopolymer (1) 30% by mass, LLDPE (1) 20% by mass

(Comparative 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 first intermediate layer (B1) and the second intermediate layer (B2) were as follows.
Intermediate layer (B1), intermediate layer (B2): propylene-based block copolymer (1) 60% by mass, propylene homopolymer (1) 20% by mass, LLDPE (1) 20% by 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.

[Measurement of friction coefficient]
The films obtained in Examples and Comparative Examples were aged at 38 ° C. for 24 hours, and then the surface friction coefficient was measured according to ASTM (D-1894).

[Measurement of haze]
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.

[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 0.3 (J) or more ○: Impact strength is 0.2 (J) or more and less than 0.3 △: Impact strength is 0.1 (J) or more and less than 0.2 ×: Impact strength is 0 Less than 1 (J)

[Abrasion resistance]
From the films obtained in Examples and Comparative Examples, a test piece was cut out so that the test piece was 6 cm in the MD direction and 10 cm in the CD direction, and the rubbing tester (Imoto Seisakusho Co., Ltd.) was used so that the seal layer was on the upper surface. The tape was affixed to the reciprocating plate. 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.
◎: Number of times until pinholes and tears occur 40 times or more ○: Number of times until pinholes and tears occur 30 times or more and less than 40 times △: Number of times until pinholes or tears occur 20 times Less than 30 times x: Pinholes and tears occur 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 the bag even at a bag-making speed of 120 shots, and there is no problem with the alignment. Δ: The film follows the bag-making speed at 120 shots, but the alignment property becomes a problem. There are things that can not follow the bag speed, poor alignment

[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 would be the central part in the width direction. 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

  As is clear from the above table, the laminated films of the present invention of Examples 1 to 5 had suitable seal strength, impact resistance and friction resistance, and were excellent in bag breaking resistance. On the other hand, the laminated films of Comparative Examples 1 to 5 cannot have suitable impact resistance and friction resistance.

Claims (10)

A laminated film having a surface layer (A), a first intermediate layer (B1), a second intermediate layer (B2) and a heat seal layer (C),
The surface layer (A) is a layer containing a propylene-based resin as a main resin component,
Said 1st intermediate | middle layer (B1) is a layer containing 60 mass% or more in the resin component contained in an intermediate | middle layer (B1) a propylene homopolymer,
Said 2nd intermediate | middle layer (B2) is a layer containing 50 mass% or more in a resin component contained in an intermediate | middle layer (B2) propylene-type resin, and 10 mass% or more of linear low density polyethylene,
The heat seal layer (C) is a layer containing 10 to 30% by mass of a resin component contained in the heat seal layer (C) butene-based resin,
Each layer is in the order of surface layer (A) / intermediate layer (B1) / intermediate layer (B2) / heat seal layer (C), or surface layer (A) / intermediate layer (B2) / intermediate layer (B1). / Laminated film characterized by being laminated in the order of heat seal layer (C).   The thickness ratio of said 1st intermediate | middle layer (B1) with respect to the total thickness of a laminated | multilayer film is 15 to 35%, The thickness ratio of said 2nd intermediate | middle layer (B2) is 25 to 50%. Laminated film.   The surface layer (A) contains a propylene block copolymer resin as a main resin component, and the second intermediate layer (B2) contains a propylene block copolymer resin in the intermediate layer (B2). The laminated film according to claim 1 or 2, which is contained in an amount of 50% by mass or more.   The laminated film according to any one of claims 1 to 3, wherein the content of the propylene homopolymer in the resin component contained in the intermediate layer (B1) is 90% by mass or more.   The laminated film according to any one of claims 1 to 4, wherein the intermediate layer (B1) contains 5% by mass or more of linear low-density polyethylene in the resin component contained in the intermediate layer (B1).   The laminated film according to any one of claims 1 to 5, wherein the heat seal layer (C) contains 50% by mass or more of a propylene-based resin.   The laminated film according to any one of claims 1 to 6, wherein the butene-based resin in the heat seal layer (C) is a 1-butene-propylene copolymer.   The laminated film according to claim 1, having a total thickness of 20 to 60 μm.   A packaging material comprising the laminated film according to claim 1.   The packaging material according to claim 9, which is a packaging bag for food.