TWI686301B - Laminated film and packaging materials - Google Patents

Abstract

The invention can achieve better sealing strength and excellent bag-breaking resistance by means of a laminated film, which has at least a printing layer, an intermediate layer and a sealing layer, and the surface layer on one side includes the printing layer and the surface layer on the other side A laminated film including a sealing layer, wherein the printed layer contains a propylene-based block copolymer, and the intermediate layer contains a propylene-based block copolymer and linear low-density polyethylene.

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, packaging films using olefin resins have been used as films for packaging bread or other foods. In packaging films, due to the diversified design requirements of packaging materials in recent years, the demand for matting films is increasing. As a matte laminated film used for such packaging materials, a laminated film using a propylene-based block copolymer has been disclosed (for example, refer to Patent Documents 1 and 2).

Prior technical literature Patent Literature

Patent Literature 1 Japanese Patent Laid-Open No. 2008-162162

Patent Literature 2 Japanese Patent Laid-Open No. 2009-61705

The matte laminated film using the propylene-based block copolymer has higher rigidity than the transparent laminated film, so it can be used for various applications including bread and other food packaging. However, this laminated film uses a thin film in consideration of the environment or cost, so the bag may be broken due to external impact during delivery or contact with protrusions. Especially when packaging, transporting, and storing food, it is often carried out at low temperatures, and it is required to improve the bag resistance at low temperatures.

In addition, such a thin packaging film may be cracked or broken due to contact or friction when the contents are packed, depending on the contents of the package. In the case where the content is bread, the freshly baked bread, especially the long bread, has a sharp end, so the laminated film is made into a folded bag and the bread is put into the bag In the case of, the packaging bag is easy to break. Next, as described above, the packaging bags used for food packaging and the like are discarded when the contents are used or after consumption, so in consideration of environment and cost, the requirements for volume reduction are high. In response to such requirements, the thinning of packaging films and the reduction in volume of packaging bags are being developed. Although the amount and size of the contents (bread) remain unchanged, the size of the packaging bag becomes smaller, and gradually transforms into tightly packed bread With the shape of the film bag. Therefore, the problem of breakage of the package due to the contents is more likely to occur.

The problem to be solved by the present invention is to realize a matting film, which has a sealing strength that does not fall out during packaging or distribution, is strong and does not open, and has better bag resistance; especially in achieving A matte film with excellent bag resistance at low temperatures.

Furthermore, in addition to the above-mentioned problems, an object of the present invention is to realize a matting film excellent in friction resistance, which is less likely to be cracked or broken due to contact or friction when the contents are loaded.

The inventor of the present invention solved the above-mentioned problem by a laminated film, which 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 The printed layer contains a propylene-based block copolymer, and the intermediate layer contains a propylene-based block copolymer and linear low-density polyethylene.

The laminated film of the present invention can achieve matting and high rigidity because the printed layer contains a propylene-based block copolymer. Next, it has this printing layer and also has an intermediate layer containing a propylene-based block copolymer and a linear low-density polyethylene, whereby excellent bag-breaking resistance can be achieved, especially at low temperatures. Sex. In addition, the laminated film of the present invention is excellent in friction resistance, so even when used in packaging applications, it is less likely to crack or break due to contact or friction when the contents are loaded. Therefore, the laminated film of the present invention is suitable for various packaging applications, especially food packaging applications where packaging or distribution is mostly performed at low temperatures.

Forms for carrying out the invention

The laminated film of the present invention has 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 a propylene block copolymer The intermediate layer contains propylene-based block copolymer and linear low-density polyethylene.

[Printed layer]

The printed layer of the laminated film of the present invention is a layered body containing a propylene block copolymer. Since the printed layer contains a propylene-based block copolymer, a matte build-up film having high rigidity, excellent design, and better impact resistance and friction resistance can be formed.

As the propylene-based block copolymer, a copolymer of propylene and other α-olefin can be used. Examples of α-olefins include ethylene, 1-butene, 1-hexene, and 4-methyl. 1-pentene, 1-octene, etc. Among them, the extinction and cold resistance of ethylene. The balance of rigidity is excellent, so it is preferable. From the viewpoint of easily obtaining impact resistance or rigidity, the content of α-olefin in the propylene-based block copolymer is preferably 2 to 10% by mass, and more preferably 4 to 8% by mass.

From the viewpoint of ease of forming, and easy to obtain better impact resistance or matte feeling, the melt flow rate (MFR) of the propylene-based block copolymer is preferably 0.5 g/10 min or more, more preferably 1 g/10 min the above. In addition, it is preferably 20 g/10 minutes or less, and more preferably 10 g/10 minutes or less.

The melting point of the propylene-based block copolymer is preferably 155°C or higher, and preferably 165°C or lower from the viewpoint of easily obtaining better bag-making properties.

The content of the propylene-based block copolymer in the printed layer is determined by the balance of matting feeling, melt-cutting strength, and suitability for bag making, but the content is preferably 70% by mass or more of the resin component used in the printed layer. By setting the content within this range, it is easy to obtain a uniform matting feeling excellent in design. Among them, when the impact resistance is improved, it is preferably 80 to 100% by mass, and when the matt feeling is improved, it is preferably 70 to 90% by mass.

For the propylene-based block copolymer used in the printing layer, a single copolymer or plural copolymers may be used. When a plurality of copolymers are used, it is preferable to set the total content of the propylene-based block copolymer used within the above range.

Examples of the propylene-based block copolymer resin excellent in the balance of matting feeling, melt-cutting strength, and bag-making applicability used in the printed layer include BC8, BC7 (manufactured by Japan Polypropylene Corporation), E150GK, and F704V (Prime Polymer Company), PC480A, PC684S, PC380A, VB370A (made by SUNAROMA), etc.

In addition, when resins other than propylene-based block copolymers are used in the printed layer, various olefin-based resins for packaging films can be used, for example, propylene homopolymers and propylene-α-olefin random copolymers can be used (Acrylic- (Ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, metallocene catalyst polypropylene, etc.), ultra-low density polyethylene (VLDPE), linear low density polyethylene (LLDPE ), low-density polyethylene (LDPE) and other polyethylene resins; 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), etc. Ethylene-based copolymer; furthermore, ionic polymer of ethylene-acrylic acid copolymer, ionic polymer of ethylene-methacrylic acid copolymer, etc.

Among them, in the case of improving the matting feeling, it is preferable to use a vinyl resin in combination, and it is more preferable to use a high-density polyethylene.

When this other polyolefin-based resin is used, its content is preferably 10 to 30% by mass in the resin component contained in the printed layer.

As long as the effect of the present invention is not impaired, various additives may be blended in the printed layer. Examples of the additives include antioxidants, weather-resistant stabilizers, antistatic agents, anti-fogging agents, anti-caking agents, slip agents, nucleating agents, and pigments.

The surface roughness (Ra) of the printed layer measured according to 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, even if other components (slip agent or anti-caking agent, etc.) are reduced Additives), or do not use them in combination due to circumstances, can also obtain a film with excellent surface slidability, which is related to the increase in the speed of bag making, and can improve the calibration and bagging operations after bag making. It improves efficiency and improves the operability when packaging with an automatic packaging machine after filling the contents.

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 the bag, and the like, and it is easy to better suppress the cause when the binding is performed by the closure (closure) Broken film. In addition, the friction coefficient can be adjusted by appropriately adding additives such as a slip material and an anti-caking agent according to the resin component used in the printed layer.

[middle layer]

The intermediate layer of the laminated film of the present invention contains a layered body of propylene-based block copolymer and linear low-density polyethylene. By using this intermediate layer, it is possible to obtain a laminated film having a good matt feeling and excellent bag resistance, particularly excellent bag resistance or friction resistance at low temperatures.

The content of the propylene-based block copolymer in the resin component contained in the intermediate layer is preferably 15% by mass or more, more preferably 25% by mass or more from the viewpoint of easily obtaining better impact resistance or matting feeling It is more than 35% by mass. Moreover, from the viewpoint of easily obtaining a better fusion-cut sealing strength or bag-making property, it is preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 70% by mass or less, and particularly preferably 60% by mass. the following.

From the viewpoint of easily obtaining better bag-making applicability or fusion-cut sealing strength and bag-breaking resistance, the content of the linear low-density polyethylene in the resin component contained in the intermediate layer is preferably 5% by mass or more, more It is preferably 8% by mass or more, and more preferably 10% by mass or more. In addition, it is preferably 30% by mass or less, more preferably 20% by mass or less, and still more preferably 15% by mass or less.

In addition, the content ratio of the propylene-based block copolymer and the linear low-density polyethylene in the intermediate layer is preferably 95/5 to 60/40 in terms of mass ratio, and more preferably 90/10 to 70/30. By setting it to this ratio, it is possible to obtain a good matt feeling and excellent bag resistance, especially excellent bag resistance at low temperatures. Laminated film with abrasion resistance.

For the propylene-based block copolymer used in the intermediate layer, it is preferable to use the same components as the propylene-based block copolymer used in the printing layer. As the propylene-based block copolymer, a single copolymer or plural copolymers may be used. When a plurality of copolymers are used, it is preferable that the total content of the propylene-based block copolymer used is within the above range.

The linear low-density polyethylene used for the intermediate layer preferably has a density of 0.915 g/cm ³ or less, more preferably 0.910 g/cm ³ or less, and even more preferably 0.906 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 have both good melt-cutting strength, high impact resistance, and bag 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 setting the MFR within this range, it is easy to improve the film-forming property of the film, and it is easy to obtain a uniform film with good dispersibility.

Straight-chain low-density polyethylene may be used in combination of plural kinds. When plural kinds are used, it is preferable to set the total content of the straight-chain low-density polyethylene used in the above range.

In addition, resins other than the above-mentioned propylene-based block copolymers, such as the above-mentioned olefin-based resins, may be used in combination in the intermediate layer. Among them, propylene-α-olefin random copolymers are preferably used, and propylene-ethylene is particularly preferable. Random copolymer. The content of α-olefins such as ethylene, butene-1,4-methylpentene-1, and octene-1 in the propylene-α-olefin random copolymer is preferably 0.3 to 10% by mass, more preferably 0.5 to 6% by mass. By setting the content of α-olefin within this range, it is easy to obtain better rigidity or resistance to caking, and it is easy to achieve better bag-making suitability and packaging suitability. The content of α-olefins such as ethylene can be determined by infrared absorption spectroscopy.

The MFR of the propylene-α-olefin random copolymer is preferably from 1 to 20 g/10 minutes, particularly preferably from 3 to 7 g/10 minutes. By setting it to 1 g/10 minutes or more, it is easy to obtain better matting property or film-forming property, and by setting it to 20 g/10 minutes or less, it is easy to obtain better formability.

The method for producing the propylene-α-olefin random copolymer used in the present invention is not particularly limited, and it can be produced by a conventional method. For example, a manufacturing method using a Ziegler-Natta catalyst or a metallocene catalyst can be mentioned.

Specific examples include the following method: In a catalyst system that uses a titanium-containing compound itself or a titanium-containing compound carried on a carrier such as a magnesium compound as a main catalyst and uses an organoaluminum compound as an auxiliary catalyst, only propylene or A method of adding a desired α-olefin such as ethylene and polymerizing it. The polymerization may be any process such as slurry polymerization, solution polymerization, and gas phase polymerization.

In addition, a homogeneous catalyst can be used, for example: a catalyst containing a vanadium compound and an organoaluminum compound that has been used conventionally; or containing "substituted cyclopentadiene with 1 or 2 cyclopentadienyl groups". Transition metal compounds such as zirconium, titanium, hafnium, etc. whose ligands are base, indenyl, substituted indenyl, etc., transition metal compounds that geometrically control the ligand" and "aluminoxane or ionic compounds and other auxiliary catalysts" Homogeneous catalysts such as metallocene catalysts. The metallocene catalyst can use an organoaluminum compound according to needs. In addition to homogeneous polymerization in the presence of a solvent, it can also be any process such as slurry polymerization or gas phase polymerization.

In addition, in the intermediate layer, additives listed at the above-mentioned printed layer can be appropriately used.

[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, a propylene-1-butene copolymer is preferred from the viewpoints of easy adjustment of the heat sealing temperature or strength at the time of easy opening and sealing at a low temperature, a wide heat sealing temperature range, and easy to obtain a moderate heat sealing strength for easy opening and sealing. Or 1-butene-propylene copolymer and other copolymers containing butene.

In the case of using a 1-butene-propylene copolymer, the content of 1-butene in the 1-butene-propylene copolymer is preferably 60 from the viewpoint of easily obtaining better sealability or blocking resistance. ~95 mole%, more preferably 65~95%, and even more preferably 70~90 mole%. In addition, from the viewpoint of easily obtaining better low-temperature sealing properties, the propylene content is preferably 2 to 10 mol%, more preferably 3 to 9 mol%, and still more preferably 4 to 8 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, fused strength and crack resistance of the bag-making product, 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 adjustment of the seal strength, propylene-α-olefin copolymer, and 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 for heat-sealing 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.

As long as the effect of the present invention is not impaired, various additives may be blended in the sealing layer. Examples of the additives include antioxidants, weather-resistant stabilizers, antistatic agents, anti-fogging agents, anti-caking agents, slip agents, nucleating agents, and pigments.

The friction coefficient (ASTM D1894) of the surface of the sealing layer is preferably 0.01 to 0.4, more preferably 0.02 to 0.35, and even more preferably 0.05 to 0.30. By making it within this range, it is easy to improve the film transportability during packaging or to suppress wrinkles or bumps after bag making to improve the packing operation. In addition, it is easy to suppress damage caused by friction between the content and the inner surface of the film when filling the content such as bread, improve wear resistance and crack resistance, and it is easy to better suppress film damage. 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.

[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 having such a structure has good fusion cut sealing strength, and from the viewpoint of excellent impact resistance or bag resistance, it is suitable for use as various packaging films.

The thickness of the laminated film of the present invention may be appropriately adjusted according to the application or form to be used, but it is easy to have a volume reduction in packaging applications. From the viewpoint of the resistance to bag breakage during chemical distribution and distribution, the total thickness 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 easily obtaining a better matting feeling, fusion cutting strength, and bag-making applicability, the thickness ratio of the printed 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.

As an example of a specific layer structure, preferably, a three-layer structure of a printing layer/intermediate layer/sealing layer in which an intermediate layer is provided between the printing layer and the sealing layer, or printing composed of a plurality of intermediate layers The four-layer structure of the layer/intermediate layer 1/intermediate layer 2/sealing layer, etc. Among them, from the viewpoint of easily adjusting the characteristics of the film and making the film easy, it is preferable to use a three-layer structure including a printing layer/intermediate layer/sealing layer.

The manufacturing method of the laminated film of the present invention is not particularly limited, and for example, the following co-extrusion method: each resin or resin mixture used for each layer is heated and melted by each extruder, and then the multi-layer die method by co-extrusion or After the feeding equipment method and other methods are laminated in the molten state, by the blowing method or T-shaped mold. It is formed into a film shape by a 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 matting feeling is superior to the past, it can provide packaging materials similar to Japanese paper, etc., 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, the end of the drum-shaped film can be sealed into a cylindrical shape by an automatic packaging machine, and the packaging bag can be formed 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.

In addition, when assembling packaging of various breads such as butter rolls, the sealing layer is placed inside the packaging bag, and it is supplied to a horizontal automatic packaging machine in the form of a roller. For example, FW-3400αV type manufactured by FUJI MACHINERY Co., Ltd. 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 sealing strength of the bottom and back of the pillow package bag carried out by the packaging machine is 7.5N~30N/15mm, preferably It is 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, the container, and the container may also be formed by overlapping the sealing layer with other heat-sealable films and heat-sealing. at this time, As other films used, films with low mechanical strength such as LDPE, EVA, and polypropylene can be used. In addition, LDPE, EVA, polypropylene and other films and stretch films with good tearability, such as biaxially stretched polyethylene terephthalate film (OPET) and biaxially stretched polypropylene film (OPP), can also be used The laminated film to be laminated.

As described above, the laminated film of the present invention is suitable for various packaging applications from the viewpoint of achieving better impact resistance or bag resistance. In particular, from the viewpoint of achieving excellent impact resistance at low temperatures, it is suitable for most food packaging applications where packaging or distribution is performed at low temperatures.

Among them, when the laminated film of the present invention is applied to bread packaging such as long bread or confectionary bread using a bundling tool (bundle) with a sharp front end or hook portion, bag breakage is unlikely to occur during bundling, and During transportation, even in the case of contact with the binding tool or the transportation container, pinholes or cracks are unlikely to occur. In addition, it is not easy to cause pinholes or cracks due to friction between the food of the contents and the inner surface (sealing surface) of the film or the friction and puncturing of the mixed plastic disc. Furthermore, the laminated film of the present invention is particularly suitable for use in bread packaging from the viewpoint of ensuring a better fusion seal strength even when the hemmed portion is formed.

[Example]

Next, the present invention will be described in more detail with examples and comparative examples. Unless otherwise specified, "parts" and "%" 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 block copolymer resin (component content derived from propylene: 90% by mass, density: 0.90 g/cm ³ , MFR (measurement temperature 230° C.): 5 g/10 minutes) (hereinafter referred to as propylene-based Block copolymer (1)) 100% by mass

Intermediate layer: 85% by mass of propylene-based block copolymer (1), linear low-density polyethylene (density: 0.905g/cm ³ , MFR (measurement temperature 190°C): 4g/10 minutes) (hereinafter referred to as LLDPE (1)) 15% by mass

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

(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.

Intermediate layer: 95% by mass of propylene block copolymer (1), 5% by mass of LLDPE (1)

(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 intermediate layer was changed to the following composition.

Intermediate layer: 95% by mass of propylene-based block copolymer (1), 10% by mass of LLDPE (1)

(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 intermediate layer was changed to the following composition.

Intermediate layer: 95% by mass of propylene-based block copolymer (1), 25% by mass of LLDPE (1)

(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 intermediate layer was changed to the following composition.

Intermediate layer: 45% by mass of propylene-based block copolymer (1), 40% by mass of COPP (1), 15% by mass of LLDPE (1)

(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 intermediate layer was changed to the following composition.

Intermediate layer: propylene-based block copolymer (1) 35% by mass, COPP (1) 50% by mass, LLDPE (1) 15% by mass

(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 intermediate layer was changed to the following composition.

Intermediate layer: propylene-based block copolymer (1) 55% by mass, COPP (1) 30% by mass, LLDPE (1) 15% 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.

Printed layer: 85% by mass of propylene-based block copolymer (1), high-density polyethylene (density: 0.955g/cm ³ , MFR (measurement temperature 190°C): 0.35g/10 minutes) (hereinafter referred to as HDPE (1 )) 15 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 printing layer was changed to the following composition.

Printing layer: 75% by mass of propylene block copolymer (1), 25% by mass of HDPE (1)

(Example 10)

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 printing layer was changed to the following composition.

Printing layer: 85% by mass of propylene block copolymer (1), 15% by mass of HDPE (1)

(Example 11)

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 12)

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), 40% by mass of 1-butene copolymer (1)

(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: 85% by mass of propylene-based block copolymer (1), linear low-density polyethylene (density: 0.91g/cm ³ , MFR (measurement temperature 190°C): 4g/10 minutes) (hereinafter referred to as LLDPE (2)) 15% by mass

(Example 14)

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.

Printed layer: propylene-ethylene block copolymer resin (propylene-derived component content: 85% by mass, density: 0.90 g/cm ³ , MFR (measurement temperature 230° C.): 8 g/10 minutes) (hereinafter referred to as propylene-based block Copolymer (2)) 100% by mass

(Example 15)

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: 85% by mass of propylene block copolymer (2), 15% by mass of LLDPE (1)

(Example 16)

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: 45% by mass of propylene-based block copolymer (1), 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)) 40% by mass, LLDPE(1) 15% by mass

(Example 17)

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: Propylene block copolymer (1) 55% by mass, COPP (1) 40% by mass, LLDPE (1) 5% by mass

(Example 18)

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: Propylene block copolymer (1) 50% by mass, COPP (1) 40% by mass, LLDPE (1) 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.

Intermediate layer: 85% by mass of propylene-based block copolymer (1), low-density polyethylene (density: 0.925g/cm ³ , MFR (measurement temperature 230°C): 5g/10 minutes) (hereinafter referred to as LDPE (1) )15 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.

Intermediate layer: propylene homopolymer (density: 0.90 g/cm ³ , MFR: 8 g/10 minutes) (hereinafter referred to as HOPP(1)) 85% by mass, LLDPE(1) 15% by mass

(Comparative 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.

Printed layer: 85% by mass of COPP (1), 15% by mass of HDPE (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.

[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 extinction]

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 matting property was evaluated according to the following criteria.

◎: Haze exceeds 65%

○: Haze over 55% and below 65%

△: Haze over 35% and below 55%

×: Haze is below 35%

[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.]. The measurement was carried out in the extrusion direction (hereinafter referred to as "MD") and the width direction of the film (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 more than 0.3 (J)

○: 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 less than 0.1 (J)

[Friction resistance]

From the films obtained in 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-made) 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 more than 20 times

○: The number of times until the occurrence of pinholes or cracks is 10 or more and less than 20

×: Pinholes or cracks occur less than 10 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 then folded at the bottom, and then fused and sealed at a sealing temperature (bag making temperature) of 300°C for bag making (bag making machine: Totani HK-40 manufactured by Jiyan Workshop Co., Ltd., bag-making speed: 120 pieces/minute), making bottom hemming bag (length: 345mm (side: 245mm, hemming: 60mm), width 235mm), evaluating 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 portions of the bottom hemming bag obtained, 2 pieces were cut out in two pieces so that the heat-sealed portion was the center portion in the width direction, and 10 test pieces each having a length of 70 mm and a width of 15 mm were cut out. The maximum load at the time of peeling with a TENSILON tensile tester (manufactured by A&D Co., Ltd.) was measured under the conditions of 23° C. and a tensile speed of 300 mm/min, and this was regarded as the heat seal strength.

○: 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 film breakage occurs during peeling

As is clear from the above table, the laminated films of the present invention of Examples 1 to 18 have a good matt appearance, good seal strength, impact resistance, and friction resistance, and have excellent resistance to breakage. On the other hand, the laminated films of Comparative Examples 1 to 3 cannot have both good impact resistance and sealing strength.

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 block Copolymer resin, the intermediate layer contains a propylene-based block copolymer resin and linear low-density polyethylene, the content ratio of the propylene-based block copolymer and the linear low-density polyethylene contained in the intermediate layer, in terms of mass The ratio is 95/5~60/40. The laminated film according to claim 1, 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, wherein the content of the propylene-based block copolymer in the resin component contained in the intermediate layer is 30% by mass or more, and the content of the linear low-density polyethylene is 5 to 30% by mass. The laminated film according to any one of claims 1 to 3, wherein the content of the propylene-based block copolymer in the printed layer is 70% by mass or more of the resin component contained in the printed layer. The laminated film according to any one of claims 1 to 3, wherein the sealing layer contains a 1-butene-propylene copolymer. The laminated film according to claim 4, wherein the sealing layer contains a 1-butene-propylene copolymer. 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.