TWI686296B - Laminated film and packaging materials - Google Patents

Abstract

The invention has a laminated film, which can have better sealing performance, and even when the external impact during distribution or contact with the protrusions, the bag breakage is not easy to occur, and the better bag breakage resistance can be achieved, especially A better bag resistance at low temperature; it is a laminated film with at least a printed layer, an intermediate layer and a sealing layer, and the surface layer on one side contains the printing layer, and the surface layer on the other side contains the sealing layer, wherein the printed layer contains For the propylene-based resin, the intermediate layer contains 5 to 60% by mass of a propylene-ethylene random copolymer.

Description

Laminated film and packaging materials

The present invention relates to a laminated film used for packaging packaging materials for food, groceries, magazines, etc., and packaging materials containing the film.

Conventionally, a laminated film in which plural resins are laminated is used as a packaging film for packaging bread or other foods. As such a packaging film, from the viewpoint of easily obtaining heat sealability, etc., a laminated film using an olefin-based resin is widely used (for example, refer to Patent Documents 1 to 2).

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2005-111857

[Patent Document 2] Japanese Patent Laid-Open No. 2007-45049

As a laminated film for packaging, especially food packaging, for the purpose of improving low-temperature heat sealability, it has been proposed to use olefin resins such as ethylene-α-olefin resins or propylene-α-olefin resins for each layer Laminated film. However, due to environmental or Since a thin film is used, it may be cracked or damaged due to external impacts during delivery, contact with protrusions, or when sealed with a bundle of sealed packaging materials. In addition, when packaging, transporting, and storing food, it is often carried out at a low temperature, and it is required to improve the resistance to bag breakage at a low temperature.

The problem to be solved by the present invention is to provide a laminated film that has better sealing performance, is excellent in bag resistance, and can better suppress cracking, in particular to achieve a laminated film with excellent bag resistance at low temperatures .

The present invention solves the above-mentioned problem by means of a laminated film: it is a laminated film having at least a printing layer, an intermediate layer and a sealing layer, and a surface layer on one side including a printing layer and a surface layer on the other side including a sealing layer, wherein the printing The layer contains a propylene-based resin, and the intermediate layer contains 5 to 60% by mass of a propylene-ethylene random copolymer.

The laminated film of the present invention has the above-mentioned structure, and can have a good sealing property, and even when an external impact at the time of delivery or contact with a protrusion does not easily cause bag breakage, a better bag breakage resistance can be achieved , In particular, better bag resistance at low temperatures. In addition, even when the harness is used for sealing, it is not easily broken, and a better applicability of the harness can be achieved.

In addition, the packaging material using a laminated film may be cracked or damaged due to contact or friction when the contents are packed, especially when the contents are long bread, The end of the baked long bread is sharp, and it is easy to happen Cracked or broken. The laminated film of the present invention is also more resistant to cracking or breakage due to friction such as "contact or abrasion during loading of such contents".

In addition, the laminated film used for packaging has many applications using a highly transparent film whose contents can be visually confirmed. The film with high transparency tends to have low rigidity, but the laminated film of the present invention can achieve excellent bag-break resistance even when forming the structure with high transparency, and thus can achieve better applicability for harnesses .

The laminated film of the present invention is suitable for various packaging applications. Among them, due to the requirements of volume reduction, it is particularly suitable for the development of thinner films and smaller packaging "package bread" Use, especially the use of packaging long bread.

[Forms for carrying out the invention]

The laminated film of the present invention is a laminated film having at least a printing layer, an intermediate layer and a sealing layer, and the surface layer on one side includes a printing layer and the surface layer on the other side includes a sealing layer, wherein the printing layer contains an acrylic resin, the The intermediate layer contains a propylene-ethylene random copolymer according to 5 to 60% by mass of the resin component contained in the intermediate layer.

[Printed layer]

The printed layer used in the laminated film of the present invention constitutes a layered body provided with a printed surface layer of a packaging film. The printed layer contains an acrylic resin. As the acrylic resin, for example, a homopolymer of propylene, Propylene-α-olefin random copolymer, propylene-α-olefin block copolymer, etc. In the present invention, among these components, a propylene-α-olefin random copolymer is preferably used from the viewpoint of easily obtaining adhesion to the intermediate layer.

Examples of the propylene-α-olefin random copolymer include propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, etc. These copolymers can be used alone, Can also be used in combination. Among them, from the viewpoint of easily obtaining better transparency, a propylene-ethylene random copolymer is preferably used.

The propylene-ethylene random copolymer has an ethylene content of preferably 10% by mass or less, more preferably 8% by mass or less, and still more preferably 6% by mass from the viewpoint of easily obtaining better blocking resistance. In addition, from the viewpoint of easily obtaining better impact resistance, the ethylene content is preferably 2% by mass or more, more preferably 3% by mass or more, and still more preferably 4% by mass or more.

The melt flow rate (MFR) of the propylene-ethylene random copolymer is not particularly limited as long as it can form a laminated film, but from the viewpoint of easily obtaining good formability, it is preferably 0.5 g/10 More than 3 minutes, more preferably 3 g/10 minutes or more, and still more preferably 5 g/10 minutes or more. In addition, from the viewpoint of easily obtaining better impact resistance or melt-cutting strength, the MFR is preferably 20 g/10 minutes or less, more preferably 15 g/10 minutes or less, and still more preferably 12 g/10 minutes or less.

From the viewpoint of easily obtaining packaging suitability or suitability of bag-making machinery during bag making, the density of the propylene-ethylene random copolymer is preferably 0.880 g/cm ³ or more, and more preferably 0.89 g/cm ³ or more. In addition, from the viewpoint of easily obtaining impact resistance at a low temperature, it is preferably 0.90 g/cm ³ or less, and 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 from the viewpoint of easily improving bag-making applicability or slidability. In addition, from the viewpoint of easily improving crack resistance or bag-break resistance at low temperatures, it is preferably 150°C or lower, and more preferably 145°C or lower.

In addition, in the present invention, from the viewpoint of easily obtaining a better fusion cut seal strength, it is also preferable to use two types of propylene-ethylene random copolymers having different melting points in combination. 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.

From the viewpoint of easily obtaining better transparency or packaging applicability, the content of the propylene-based resin in the resin component included in the printing layer is preferably 50% by mass or more of the resin component included in the printing layer, more preferably 60 Above mass%, especially good is 75~95 mass%.

It is also preferable to use resins other than the above-mentioned acrylic resins in combination in the printed layer. As the other resin, for example, a polyethylene-based resin is preferably used, and examples of the polyethylene-based resin include linear low-density polyethylene (LLDPE), linear medium-density polyethylene (LMDPE), and linear Polyethylene resins such as chain high-density polyethylene (LHDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), etc.; ethylene-butene-rubber copolymer (EBR) , Ethylene-propylene-rubber copolymer (ethylene-propylene rubber (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; furthermore, the ionomer of ethylene-acrylic acid copolymer, the ion of ethylene-methacrylic acid copolymer The polymer and the like may be used alone or in combination of two or more.

Among them, ethylene-butene-rubber copolymers, ethylene-propylene-rubber copolymers, and other ethylene-based elastomers are preferably used from the viewpoint of easily improving the melt-cutting strength, and ethylene-butene-rubber is particularly preferably used. Copolymer.

When using this ethylene-based elastomer, from the viewpoint of easily obtaining better transparency, it is preferably 5 to 25% by mass, more preferably 5 to 20% by mass of the resin component contained in the printed layer, and even more preferably It is 5~15% by mass.

The friction coefficient (ASTM D-1894) of the surface of the printed layer is preferably 0.05 to 0.7, more preferably 0.07 to 0.6, and even more preferably 0.1 to 0.5. By making it within this range, it is easy to improve the film transportability at the time of packaging, the calibration after bag making, the operability of packing, and the like, and it is easy to preferably suppress the film damage or breakage when the binding is performed by the binding tool. In addition, the friction coefficient can be adjusted by appropriately adding additives such as slip agents and anti-caking agents depending on the resin component applied to the printed layer.

Within the range not detrimental to the purpose of the present invention, anti-fogging agent, antistatic agent, heat stabilizer, nucleating agent, antioxidant, slip agent, anti-caking agent, mold release agent, Components such as ultraviolet absorbers are used as components other than the above-mentioned resin components.

[middle layer]

In the laminated film of the present invention, by using an intermediate layer containing 5 to 60% by mass of a propylene-ethylene random copolymer, the laminated thickness can be suppressed better Rupture of the membrane. The content of the propylene-ethylene random copolymer is preferably 8% by mass or more in the resin component contained in the intermediate layer, and more preferably 10% by mass or more. In addition, it is preferably 50% by mass or less, and more preferably 40% by mass or less. If the content of the propylene-ethylene random copolymer is within this range, it is easy to obtain better crack resistance and good bag resistance.

As the propylene-ethylene random copolymer, a propylene-ethylene random copolymer having the same ethylene content, MFR, density, and melting point as the preferred examples of the above-mentioned printed layer can be preferably used.

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

As the olefin-based resin, for example, propylene-α-olefin random copolymers (propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, Metallocene catalyst polypropylene, etc.), propylene-α-olefin copolymer, propylene homopolymer, ultra low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), etc. Polyethylene resin, ethylene-vinyl acetate copolymer (EVA), etc.

Among these components, it is preferable to contain a linear low-density polyethylene from the viewpoint of easily obtaining better impact resistance or bag breaking resistance, particularly, better bag breaking resistance at low temperatures. When linear low-density polyethylene is used, the content of linear low-density polyethylene is preferably 5% by mass or more, and more preferably 8% by mass or more of the resin component contained in the intermediate layer. Also, it is preferably 20% by mass or less, and more preferably 15% by mass or less under.

From the viewpoint of easily obtaining better bag-breaking resistance, the density of the linear low-density polyethylene is preferably 0.915 g/cm ³ or less, more preferably 0.910 g/cm ³ or less, and still more preferably 0.907 g/cm ³ or less. In addition, from the viewpoint of easily obtaining a better melt-cutting strength, the density is preferably 0.890 g/cm ³ or more, and more preferably 0.895 g/cm ³ or more.

As the linear low-density polyethylene, the MFR is preferably 0.5 to 15 g/10 minutes (190°C), and more preferably 1.0 to 10 g/10 minutes.

As the intermediate layer used in the present invention, an intermediate layer containing the above propylene-ethylene random copolymer and other polyolefin-based resin as a resin component is preferably used. However, in the case of forming a transparent laminated film, it is preferable to form a resin component An intermediate layer containing the above propylene-ethylene random copolymer, linear low-density polyethylene, and propylene homopolymer.

In the case of forming the intermediate layer, the content of the propylene-ethylene random copolymer in the resin component is preferably 5 to 60% by mass, more preferably 15 to 50% by mass. In addition, the content of the linear low-density polyethylene is preferably 5 to 20% by mass, and more preferably 10 to 18% by mass. Furthermore, the content of the propylene homopolymer is preferably 20 to 85% by mass, and more preferably 30 to 80% by mass. With this structure, it is easy to obtain good transparency and good bag-breaking resistance or crack resistance.

As the homopolymer of propylene, its MFR is preferably 3 to 20 g/10 minutes, and more preferably 5 to 15 g/10 minutes. In addition, the density is preferably 0.880 to 0.900 g/cm ³ , and more preferably 0.890 to 0.900 g/cm ³ .

Anti-fogging agent, antistatic agent, heat stabilizer, nucleating agent, antioxidant Ingredients such as a chemical agent, a slip agent, an anti-caking agent, a mold release agent, and an ultraviolet absorber are used as other components than the above resin components.

[Sealing layer]

The sealing layer used in the present invention is a layered body for adhering the sealing layers of the laminated film to each other or the laminated film and other containers or films. As for the sealing layer, it is only necessary to appropriately select the type of resin that can obtain a better sealing strength in accordance with the aspect of use or the object to be sealed. For example, in the case where the sealing layers are sealed to each other to be used as a packaging bag, from the viewpoint of obtaining a moderate seal strength, it is preferable to use a propylene-ethylene random copolymer or a propylene-1-butene copolymer. It is a sealing layer of α-olefin-propylene copolymer such as propylene-α-olefin copolymer and 1-butene-propylene copolymer. Among them, propylene-1-butene copolymer or 1-butene is preferred from the viewpoints of easy adjustment of the heat sealing temperature or strength at the time of easy opening and sealing at low temperature, and easy to obtain moderate heat sealing strength of easy opening and sealing. -Butene-containing copolymers such as propylene copolymers.

When 1-butene-propylene copolymer is used, 1-butene-propylene copolymer contains 1-butadiene from the viewpoint of easily obtaining better low-temperature sealing properties, blocking resistance, and film-forming properties. The content of ene is preferably 60 to 95 mol%, more preferably 65 to 95 mol%, and even more preferably 70 to 90 mol%. In addition, from the viewpoint of easily obtaining better low-temperature sealing properties, the propylene content is preferably 5 to 40 mol%, more preferably 3 to 30 mol%, and still more preferably 4 to 20 mol%.

When using a 1-butene-propylene copolymer, the content of the 1-butene-propylene copolymer is preferably 50% by mass or less of the resin component contained in the sealing layer, more preferably 40% by mass or less, and It is preferably 30% by mass or less. Moreover, it is preferably 10% by mass or more, and more preferably 15% by mass or more. If the content of the 1-butene-propylene copolymer is within this range, it is easy to obtain good low-temperature sealability, melt-cutting strength, and crack resistance, and it is also advantageous for cost reduction.

As the resin used in combination with the above 1-butene-propylene copolymer, other polyolefin-based resins can be suitably used, but from the viewpoint of easy and appropriate adjustment of the seal strength, a propylene-α-olefin copolymer, or For the ethylene-α-olefin copolymer, particularly preferably, a propylene-α-olefin copolymer can be used.

The content of α-olefin in the propylene-α-olefin copolymer is not particularly limited, but it is preferably 1 to 20% by mass, and more preferably 1.5 to 15% by mass. Examples of α-olefins include ethylene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. Among them, the propylene-ethylene random copolymers listed in the above-mentioned intermediate layer can be preferably used. From the viewpoint of easily obtaining good formability, the MFR is preferably 0.5 to 20 g/10 minutes, and more preferably 2 to 10 g/10 minutes.

From the viewpoint of easily obtaining better low-temperature sealing properties, the content of the other olefin-based resin is preferably 90% by mass or less, and more preferably 85% by mass or less in the resin component contained in the sealing layer. Moreover, it is preferably 50% by mass or more, and more preferably 60% by mass or more.

In particular, when forming a packaging bag using the laminated film of the present invention, in the case where an easy-to-open portion that heat seals the sealing layers is provided, it is preferable to copolymerize 1-butene-propylene copolymer/propylene-α-olefin The mass ratio represented by the substance is 20/80 to 50/50, and the 1-butene-propylene copolymer and the propylene-α-olefin copolymer are used in combination.

The friction coefficient (ASTM D1894) of the surface of the sealing layer is preferably 0.05 to 0.6, more preferably 0.06 to 0.5, and even more preferably 0.06 to 0.45. By making it within this range, it is easy to better improve the Film transportability, filling suitability of contents, friction resistance and crack resistance of contents and film inner surface. In addition, the friction coefficient can be adjusted by appropriately adding additives such as slip materials and anti-caking agents depending on the resin component applied to the sealing layer.

Anti-fogging agent, antistatic agent, heat stabilizer, nucleating agent, antioxidant, slip agent, anti-caking agent, release agent, Components such as ultraviolet absorbers are used as components other than the above-mentioned resin components.

[Laminated Film]

The laminated film of the present invention is a laminated film having at least the above-mentioned printed layer, intermediate layer, and sealing layer. The surface layer on one side of the laminated film includes a printed layer, and the surface layer on the other side includes a sealing layer. The laminated film of this structure has a good fusion-cut sealing strength, and from the viewpoint of excellent impact resistance or bag-breaking resistance, it is suitable for use as a film for various packaging.

The thickness of the laminated film of the present invention may be appropriately adjusted according to the application or form to be used, but from the viewpoint of easily combining volume reduction in packaging applications and bag resistance at the time of distribution, the total thickness It is preferably 20 to 60 μm, and more preferably 25 to 50 μm.

In addition, the thickness or thickness ratio of each layer is not particularly limited. For example, the thickness of the printed 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. The thickness of the sealing layer is preferably 1-10 μm, more preferably 2-8 μm.

In addition, from the viewpoint of easy to obtain better transparency or high gloss, easy to obtain better fusion cut strength or bag-making applicability, printing The thickness ratio of the layer is preferably 20% or more of the total thickness of the laminated film, and more preferably 25% or more. Moreover, it is preferably 40% or less, and more preferably 35% or less. From the viewpoint of easily obtaining better matting feeling, fusion cutting strength, and bag-making applicability, the thickness ratio of the intermediate layer is preferably 30% or more of the total thickness of the laminated film, and more preferably 40% or more. Moreover, it is preferably 70% or less, and more preferably 65% or less. From the viewpoint of easy availability of better unsealing ability, fusion cutting strength, and bag-making applicability, the thickness ratio of the sealing layer is preferably 5% to 30% of the total thickness of the laminated film, and more preferably 10 to 25%.

The laminated film of the present invention may be laminated with any other resin layer other than the above-mentioned printed layer, intermediate layer, and sealing layer, but the thickness of the other resin layer is preferably 20% or less of the total thickness, particularly preferably including the above-mentioned printed layer, intermediate The composition of the layer and the sealing layer. In addition, in this configuration, it may be an intermediate layer in which a plurality of intermediate layers are laminated.

From the viewpoint of easily visually confirming the contents of the package, the haze of the laminated film of the present invention is preferably 10% or less, and more preferably 2 to 8%. The laminated film of the present invention has better packaging applicability even in the case of such high transparency, and is less likely to cause breakage or other broken bags due to friction or friction between the contents and the film. When increasing the transparency of the laminated film of the present invention, in each layer, a resin component that increases the haze of the block copolymer or the like is not used, or it is preferable to make the content 10% or less when using it , More preferably 5% or less, which can improve transparency.

The manufacturing method of the laminated film of the present invention is not particularly limited, and examples thereof include the following co-extrusion method: each resin or resin mixture used for each layer is heated and melted by each extruder, and then multiple layers are produced by co-extrusion After the lamination in the molten state by methods such as the die method or the feeder method, it is formed into a film shape by the air blowing method or the T-shaped die, the cooling roll method, or the like. This co-extrusion method can adjust the thickness ratio of each layer relatively freely, and can obtain a multilayer film with excellent hygiene and excellent cost performance, which is preferable. The laminated film obtained by this manufacturing method can substantially obtain a non-stretched multi-layer film, and therefore secondary forming such as deep drawing forming can also be performed by vacuum forming.

In order to improve adhesion to printing ink, etc., it is also preferable to perform surface treatment on the printing layer. As such surface treatment, for example: corona treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, ozone. Surface oxidation treatment such as ultraviolet treatment or surface roughness treatment such as sandblasting is preferred, but corona treatment is preferred.

Examples of the packaging material including the laminated film of the present invention include packaging bags, containers, and covering materials for containers used in applications such as food, medicine, industrial parts, groceries, and magazines. In particular, from the viewpoint that the transparency and gloss are superior to those in the past, it can provide packaging materials that make the contents look exquisite, and is suitable for food applications that add a sense of quality.

The packaging bag is preferably a packaging bag formed by using the sealing layer of the laminated film of the present invention as a heat sealing layer, overlapping the sealing layers with each other to perform heat sealing, or overlapping the printed layer and the sealing layer Heat sealing is performed, whereby the sealing layer is used as the inner side. For example, after cutting two pieces of the laminated film into a desired bag size, overlapping them, and heat-sealing the three sides to form a bag shape, filling the contents from the unheated one side, and then heat-sealing , Which can be used as a packaging bag. Furthermore, you can also use The dynamic packaging machine seals the end of the drum-shaped film into a cylindrical shape, and then forms a packaging bag by sealing the top and bottom.

In addition, in the case of forming a bag for long bread, by folding and sealing the printing surface inward, a bag with a folded portion can be formed. Specifically, the sealing layer of the laminated film of the present invention is made into the inner side of the packaging bag, and is processed into a bottom hemming bag by a bag making machine, for example, HK-40 manufactured by Totani Technology Co., Ltd. At this time, it is preferable to adjust the fusion-cut sealing temperature or the bag-making speed so that the fusion-sealing strength of the side edge portion of the bottom hemming bag and the bottom hemming portion (inner folded portion of the bottom) is 7.5N~30N/15mm, It is preferably 10 to 30 N/15 mm.

The obtained bottom folded bag is supplied to an automatic baguette filling machine, and after filling the baguette, it is easy to open and has a heat sealing strength of 0.1~5N/15mm, preferably 0.2~4N/15mm Heat-sealing under the conditions to form an easy-openable long bread packaging bag. Furthermore, according to demand, an easy-opening sealable part can be formed on the upper part of the packaging bag, preferably the long bread, or a plastic plate, A binding tool such as tape or rope binds the upper part of the bag to seal it.

Also, in the case of assembling packaging of various breads such as cream meal packs, the sealing layer is placed inside the packaging bag, and it is supplied to a horizontal automatic packaging machine, such as FUJI MACHINERY Co., Ltd., in the form of a drum Co., Ltd. made FW-3400αV type. In the horizontal automatic packaging machine, the hot cover of the film is overlapped and heat-sealed to form a packaging bag, and the bread is loaded inward. At this time, it is preferable to adjust the heat sealing temperature or the packaging speed, so that the bottom of the pillow package bag (pillow package bag) and the back part of the packaging machine are sealed by the packaging machine The strength is 7.5N~30N/15mm, preferably 8~20N/15mm. Then, it can be heat-sealed under the condition that it has easy-opening property and the heat-sealing strength is 0.1~5N/15mm, preferably 0.2~4N/15mm, to form an easy-opening sealing part, or a plastic plate, Bundling tools such as tapes and ropes are used to bundle the vicinity.

In addition, the outer cover of the packaging bag, container, and container may be formed by overlapping the sealing layer with other heat-sealable films or sheets and heat-sealing. At this time, as other films used, films such as polypropylene or linear low-density polyethylene can be used. In addition, in order to exhibit better rigidity, it can also be used as a stretch film with polyester-based adhesives, such as biaxially stretched polyethylene terephthalate film (OPET), biaxially stretched polypropylene film ( OPP) and other laminated films.

As described above, the laminated film of the present invention has good packaging applicability, is less likely to break when the contents are loaded, and can achieve better crack resistance. Therefore, even when a content with a sharp portion is loaded, especially when a large amount of content is continuously and quickly loaded by a packaging machine or the like, a packaging bag that is less likely to be broken can be realized.

In addition, the structure in which the linear low-density polyethylene is contained in the intermediate layer is particularly suitable for various packaging applications from the viewpoint of achieving excellent impact resistance and bag-break resistance. In particular, from the viewpoint of achieving excellent impact resistance at low temperatures, it is suitable for most food packaging applications where packaging and distribution are performed at low temperatures.

Among them, even when the laminated film of the present invention is made into a folded bag, and bread is packed in the bag, cracking can be suppressed better, and from this point of view, it is particularly suitable for use in thin Molding or the small volume of packaging bags require high bread packaging applications.

[Example]

Next, the present invention will be described in more detail with examples and comparative examples. In addition, "parts" and "%" in the blending of resin composition and the like are quality standards.

(Example 1)

Each resin described below was used as the resin component of each layer forming the printing layer, the intermediate layer, and the sealing layer, and the resin mixture forming each layer was adjusted. These mixtures were fed to three extruders, respectively, and co-extruded so that the thickness of each layer of the laminated film formed by the printed layer/intermediate layer/sealing layer was 7/18/5μm, and formed into a thickness 30μm laminated film. Next, the printed layer of the obtained laminated film was subjected to corona discharge treatment so that the surface energy was 35 mN/m to obtain a laminated film.

Printed layer: propylene-ethylene copolymer (component content derived from ethylene: 5.0% by mass, density: 0.90 g/cm ³ , MFR (measurement temperature 230°C): 7 g/10 minutes) (hereinafter referred to as COPP(1)) 90% by mass, ethylene-butene-rubber copolymer (density: 0.890g/cm ³ , melting point 66°C, MFR (measurement temperature: 190°C): 3g/10 minutes) (hereinafter referred to as EBR(1)) 10% %

Intermediate layer: 15% by mass of COPP(1), propylene homopolymer (density: 0.90g/cm ³ , MFR (measurement temperature: 230°C): 8g/10 minutes) (hereinafter referred to as HOPP(1)) 75% by mass , Linear low-density polyethylene (density: 0.905g/cm ³ , MFR (measurement temperature 190°C): 4g/10 minutes) (hereinafter referred to as LLDPE (1)) 10% by mass

Sealing layer: 70% by mass of COPP(1), 1-butene-propylene copolymer (density: 0.90g/cm ³ , MFR (measurement temperature 230°C): 4g/10 minutes) (hereinafter referred to as 1-butene system Copolymer (1)) 30% by mass

(Example 2)

A laminated film was obtained in the same manner as in Example 1, except that the resin composition of the resin mixture used for the intermediate layer was changed to the following composition.

Middle 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 composition of the resin mixture used for the printing layer was changed to the following composition.

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 composition of the resin mixture used for the printing layer was changed to the following composition.

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 composition of the resin mixture used for the printing layer was changed to the following composition.

COPP(1) 65% by mass, propylene-ethylene copolymer (component content derived from ethylene: 5.5% by mass, density: 0.89g/cm ³ , MFR (measurement temperature 230°C): 7g/10 minutes) (hereinafter referred to as 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 composition of the resin mixture used for the printing layer was changed to the following composition.

COPP (1) 55% by mass, COPP (2) 35% by mass, EBR (1) 10% the amount%

(Example 7)

A laminated film was obtained in the same manner as in Example 1 except that the resin composition of the resin mixture used for the printing layer was changed to the following composition.

COPP(1) 50% by mass, COPP(2) 40% by mass, EBR(1) 10% by mass

(Example 8)

A laminated film was obtained in the same manner as in Example 1 except that the resin composition of the resin mixture used for the printing layer was changed to the following composition.

COPP (1) 45% by mass, COPP (2) 35% by mass, high-density polyethylene (density: 0.955g/cm ³ , MFR (measurement temperature 190°C): 0.35g/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 composition of the resin mixture used for the intermediate layer was changed to the following composition.

Middle 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 average thickness of each layer of the laminated film formed by the printed layer/intermediate layer/sealing 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 composition of the resin mixture used for the sealing layer was changed to the following composition.

Sealing layer: 60% by mass of COPP (1), 1-butene-based copolymer (1) 40 quality%

(Example 12)

A laminated film was obtained in the same manner as in Example 1, except that the resin composition of the resin mixture used for the intermediate layer was changed to the following composition.

Middle 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 composition of the resin mixture used for the intermediate layer was changed to the following composition.

Intermediate layer: 15% by mass of COPP(1), 70% by mass of HOPP(1), linear low-density polyethylene (density: 0.91g/cm ³ , MFR (measurement temperature 190°C): 4g/10 minutes) (below Called LLDPE(2)) 10% by mass

(Comparative example 1)

A laminated film was obtained in the same manner as in Example 1, except that the resin composition of the resin mixture used for the intermediate layer was changed to the following composition.

Middle 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 composition of the resin mixture used for the intermediate layer was changed to the following composition.

Middle layer: 65% by mass of COPP(1), 25% by mass of HOPP(1), 10% by mass of LLDPE(1)

Using the laminated films obtained in the above examples and comparative examples, the following tests and evaluations were performed. The results obtained are shown in the table below. In addition, the numerical value of the resin composition in the table is the content (mass %) of each component in the resin components in each layer.

[Measurement of Friction Coefficient]

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

[Measurement of haze, evaluation of transparency]

In accordance with JIS K7105, the haze (unit: %) of the films obtained in Examples and Comparative Examples was measured using a haze meter (manufactured by Nippon Denshi Co., Ltd.). The transparency was evaluated according to the following criteria.

◎: Haze is below 5%

○: Haze over 5% and below 10%

×: Haze exceeds 10%

[Measurement of rigidity]

According to ASTM D-882, the 1% tangent modulus (unit: MPa) at 23° C. of the films obtained in Examples and Comparative Examples was measured using a TENSILON tensile tester [manufactured by A&D Co., Ltd.]. Measurements were carried out in the extrusion direction (hereinafter referred to as "MD") and film width direction (hereinafter referred to as "CD") during film production.

[Measurement of impact strength]

After holding the films obtained in Examples and Comparative Examples for 6 hours in a thermostatic chamber adjusted to 0°C, the impact strength was measured by a film impact method using a spherical metal impact head with a diameter of 1.5 inches .

◎: Impact strength is above 0.15J

○: Impact strength is 0.1J or more and less than 0.15J

△: Impact strength is more than 0.05J and less than 0.1J

×: Impact strength is less than 0.05J

[Friction resistance]

From the films obtained in the examples and comparative examples, test pieces of 6 cm in the MD direction and 10 cm in the CD direction were cut out, and the sealing layer was made to be the top surface, and the tape was attached to a friction tester with a tape (Jinyuan Manufacturing Co., Ltd. (Company system) on the tablet operating back and forth. Next, double-sided tape was used to attach sandpaper #150 (manufactured by Sankyo Ligaku Co., Ltd.) to the front end portion in contact with the test piece of the friction tester, under a low-temperature 0°C environment with a load of 600 g. Next, the back-and-forth speed was 133 m/min, 70 times as the upper limit, and the friction resistance was evaluated. The number of times until the occurrence of pinholes or cracks was counted, and this was used as an evaluation index of friction resistance.

○: The number of times until the occurrence of pinholes or cracks is 20 or more

×: Pinholes or cracks occur less than 20 times

[Evaluation of suitability for bag making]

Using the sealing layer of the film obtained in the Examples and Comparative Examples as the inner side, the film was half-folded, and the bottom was folded at the bottom, and the film was sealed by fusion sealing at a sealing temperature (bag making temperature) of 300°C (bag making machine: Totani) HK-40, manufactured by Giken Industries Co., Ltd., bag-making speed: 120 pieces/minute), making bottom hemming bag (length: 345mm (side: 245mm, hemming: 60mm), width 235mm), evaluation of bag making applicability. In addition, 300 pieces were used as a group, and they were arranged into bundles to evaluate the calibration.

○: The film can keep up with the bag-making speed of 120 pieces (shot), no problem with calibration

△: Although the film can keep up with the speed of 120 bags, some calibration problems

×: Can't keep up with the 120 bags making speed, poor calibration

[Fusion Seal Strength]

Using the films obtained in Examples and Comparative Examples, a bottom hemming bag was produced in the same manner as the above-mentioned evaluation of the suitability for bag making. Each of the five bottom seal bags was cut into 10 pieces from the center of the hem portion on both sides of the bottom hem bag and the center of the side portions other than the hem so that the fusion cut seal portion became the center portion in the longitudinal direction. A test piece with a length of 70 mm and a width of 15 mm was measured under the conditions of 23° C. and a tensile speed of 300 mm/min. under the conditions of a TENSILON tensile testing machine (manufactured by A&D Co., Ltd.), and the maximum load was measured. Cut strength.

○: The fusing strength of the hemming part and the side part is 15N/15mm or more

×: The fusing strength of at least one side of the hemming part and the side part is less than 15N/15mm

[Heat sealing strength]

Using the films obtained in Examples and Comparative Examples, a bottom hemming bag was produced in the same manner as the above-mentioned evaluation of the applicability of bag making. Using a heat sealing machine (made by TESTER SANGYO Co., Ltd.: pressure 0.2 MPa, time 1 second, sealing temperature: upper sealing rod 95°C, lower sealing rod 50°C, sealing rod shape: 300m×10mm flat surface), from the obtained The portion of the bottom of the opening of the bottom hemming bag that is 50 mm below the upper end is heat-sealed parallel to the opening. From the five heat-sealed parts of the bottom hemming bag obtained by cutting the heat-sealed part as the center part in the width direction, 10 test pieces each having a length of 70 mm and a width of 15 mm were cut out in 2 pieces and 2 pieces. Under the conditions of ℃ and a tensile speed of 300mm/min, the maximum load when peeling with a TENSILON tensile tester (manufactured by A&D Co., Ltd.) was measured, and this was regarded as the heat seal strength degree.

○: The heat seal strength is less than 5N/15mm, and there is no film damage during peeling

×: The heat seal strength is 5N/15mm or more, or the film is damaged when peeled off

[Applicability of harness]

Using the films obtained in Examples and Comparative Examples, a bottom hemming bag was produced in the same manner as the above-mentioned evaluation of the suitability for bag making. Insert 1 kg of long bread into the bottom hemming bag, and use an automatic bundling machine (model: 1084F) made by Kwik Lok Japan under an environment of about 10°C to install plastic bundling at a speed of 50 bags/min. After the tool (made by Kwik Lok Japan), the binding tool is stretched to remove the binding tool. This bundle tool was attached and detached to five packaging bags, and it was evaluated whether the attachment and detachment caused cracking or damage.

○: No cracking or breakage

×: One or more packaging bags are cracked or damaged

As is clear from the above table, the laminated films of the present invention of Examples 1 to 13 have good transparency and sealing properties, and they have better resistance to bag breakage even at low temperatures. In addition, even in the friction test or sealing with a harness, it is not likely to crack and has better crack resistance. On the other hand, the laminated film of Comparative Example 1 had poor sealing performance and cracked when it was sealed with a harness. Also, the laminated film of Comparative Example 2, It is easy to crack or break when rubbed, and its crack resistance is poor.

Claims (8)

A laminated film having at least a printing layer, an intermediate layer and a sealing layer, and a surface layer including a printing layer on one side and a sealing layer on the other side, characterized in that the printing layer contains an acrylic resin, The intermediate layer contains a propylene-ethylene random copolymer, a linear low-density polyethylene and a propylene homopolymer, and the content of the propylene-ethylene random copolymer in the resin component contained in the intermediate layer is 5 to 60% by mass The content of linear low-density polyethylene is 5-20% by mass, and the content of propylene homopolymer is 20-80% by mass. 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 density of the linear low-density polyethylene contained in the intermediate layer is 0.915 g/cm ³ or less. The laminated film according to claim 1 or 2, wherein the friction coefficient of the sealing layer is 0.05 to 0.6. The laminated film according to claim 1 or 2, wherein the sealing layer contains a copolymer having a structural unit containing 1-butene. The laminated film of claim 1 or 2 is used for packaging materials. A packaging material characterized by comprising the laminated film according to any one of claims 1 to 6. If the packaging material of claim 7 is a food packaging bag.