JP4352888B2 - Laminated polyolefin film and laminated packaging material with excellent transparency - Google Patents

Description

  The present invention relates to a laminated polyolefin film and a laminated packaging material excellent in transparency, and in particular, for packaging that is excellent in tearing property, pinhole resistance, transparency and strength in practical use, and requires consumer convenience. The present invention relates to a suitable laminated polyolefin film and a laminated packaging material excellent in heat sealability obtained by laminating a laminated polyolefin film on a base material layer.

  Conventionally, as a film used for packaging, a polyolefin film having heat sealability is generally laminated to form a package with a base film having excellent strength such as polyamide and polyester. However, a laminated packaging material using a conventional polyolefin film as a heat seal layer cannot satisfy the above required characteristics. For example, laminated packaging materials using polypropylene film as the heat seal layer are insufficient in hot tack strength at low temperatures, so in high-speed packaging applications, they are released from the automatic packaging machine until the heat seal portion is fixed, and the heat seal portion Peels off, resulting in poor heat seal. In addition, a laminated packaging material using a linear low density polyethylene film as a heat seal layer is suitable for high-speed packaging, and has excellent pinhole resistance but poor tearability. On the other hand, a laminated packaging material using a film made of cyclic polyolefin for the heat seal layer is excellent in tearing property but inferior in pinhole resistance. Furthermore, a film (see Patent Document 1) in which a linear low-density polyethylene film is laminated on a film made of cyclic polyolefin is known, but the transparency is insufficient. Furthermore, even if linear low density polyethylene films are arranged on the outer layer and the inner layer to provide transparency, there is a problem that sufficient transparency cannot be obtained yet.

JP-A-10-237234

  The present invention solves the problems of the above-described conventional packaging film, is excellent in tearing property, pinhole resistance, transparency and strength in practical use, and is suitable for packaging that requires consumer convenience. An object is to provide a laminated polyolefin film and a laminated packaging material excellent in transparency.

In order to achieve the above object, the laminated polyolefin film excellent in transparency of the present invention is an outer layer (A) comprising a linear low density polyethylene having a density of 0.925 g / cm ³ or more and 0.9 35 g / cm ³ or less. An intermediate layer (B) comprising a mixture of 80 to 90 wt% of linear low density polyethylene copolymerized with 0.2 to 20 mol% of butene-1 and 10 to 20 wt% of cyclic polyolefin The inner layer (C) constituting the heat seal layer made of linear low density polyethylene of 0.925 g / cm ³ or less is laminated in order.

  In this case, the haze value of the entire laminated polyolefin film at a thickness of 40 μm can be 6.0% or less.

  In this case, the laminated polyolefin film can be laminated on the base material layer (D) to obtain a laminated packaging material.

  The polyolefin resin film and laminated packaging material of the present invention are excellent in tearability, pinhole resistance, transparency and practical strength, and are suitable for packaging that requires consumer convenience.

  Hereinafter, embodiments of the laminated polyolefin film and laminated packaging material excellent in transparency of the present invention will be described.

Laminated polyolefin film of the present invention, density of 0.925 g / cm ³ or more, outer layer of linear low density polyethylene of less than 0.940g / cm ³ (A), linear low density polyethylene 60～90Wt% and cyclic polyolefin 10 An intermediate layer (B) made of a mixture of ˜40 wt% and an inner layer (C) constituting a heat seal layer made of linear low density polyethylene having a density of 0.925 g / cm ³ or less are laminated in order. .

The outer layer (A) of the laminated polyolefin film of the present invention has a density 0.925 g / cm ³ or more, is formed from a linear low density polyethylene is less than 0.940 g / cm ^3, to form such a layer (A) The linear low density polyethylene used in the above is linear polyethylene, and is ethylene and is preferably 0.2 to 20 mol%, more preferably 0.5 to 10 mol% of an α-olefin having 3 to 10 carbon atoms. Those obtained by copolymerizing at least one of the above with a liquid phase method or a gas phase method can be used. Specific examples of the α-olefin include propylene, butene-1, pentene-1, hexene-1, octene-1, nonene-1, decene-1, 4-methylpentene-1, 4-methylhexene-1, Examples include 4,4-dimethylpentene-1. Especially, when α-olefin having 6 or more carbon atoms is used as a copolymerization component, the film strength tends to increase, and it is preferably used for increasing the strength of the packaging material, and is polymerized using a single-site catalyst such as a metallocene system. A linear low density polyethylene film is particularly preferred because of its high packaging strength. Moreover, it is normal that melting | fusing point is about 85-135 degreeC.
The melt flow rate (hereinafter abbreviated as MFR (value at 190 ° C. according to JIS K7210)) is usually 1 to 15 g / 10 minutes, preferably about 4.0 to 8.0 g / 10 minutes. And the surface state of a film can be made smooth by using what has the said density as a linear low density polyethylene used for forming the outer layer (A) of the laminated polyolefin film of this invention. This also makes the laminated polyolefin film excellent in transparency.

Further, the intermediate layer (B) of the laminated polyolefin film of the present invention is formed from a mixture of 60 to 90 wt% linear low density polyethylene and 10 to 40 wt% cyclic polyolefin, and this intermediate layer (B) is formed. Cyclic polyolefin used for is a linear monomer such as α-olefin such as ethylene, propylene, butene-1, pentene-1, hexene-1, heptene-1 and octene-1, and cyclic such as tetracyclododecene and norbornene. Examples thereof include cyclic polyolefins obtained from monomers. Among them, it is preferable to use a cyclic polyolefin of a combination of ethylene and norbornene. More specifically, the above-mentioned linear monomer, monocycloalkene having 3 to 20 carbon atoms, bicyclo [2.2.1] -2-heptene (norbornene) and derivatives thereof, tricyclo [4.3.0.1]. ^2,5 ] -3-decene and its derivatives, tetracyclo [4.4.0.1. ^2,5 . 1 ^7,10 ] -3-dodecene and its derivatives, pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13] -4-pentadecene and derivatives thereof, pentacyclo [7.4.0.1 ^2,5. 1 ^9,12 . 0 ^8,13] -3-pentadecene and derivatives thereof, pentacyclo [8.4.0.1 ^2,5. 1 ^9,12 . 0 ^8,13] -3-hexadecene and derivatives thereof, pentacyclo [6.6.1.1 ^{3, 6.} 0 ^2,7 . 0 ^9,14] -4-hexadecene and derivatives thereof, hexacyclo [6.6.1.1 ^{3, 6.} 1 ^10,13 . 0 ^2,7 . 0 ^9,14] -4-heptadecene and derivatives thereof, heptacyclo [8.7.0.1 ^2,9. 1 ^4,7 . 1 ^{11, 17} . 0 ^3,8 . 0 ^12,16 ] -5-eicosene and the like and derivatives thereof, heptacyclo [8.7.0.1 ^3,6 . 1 ^{10, 17} . 1 ^{12, 15} . 0 ^2,7 . 0 ^11,16 ] -4-eicosene and its derivatives, heptacyclo [8.8.0.1 ^2,9 . 1 ^4,7 . 1 ^{11, 18} . 0 ^3,8 . 0 ^12,17 ] -5- ^heneicosene and its derivatives, octacyclo [8.8.0.1 ^2,9 . 1 ^4,7 . 1 ^{11, 18} . 1 ^13,16 . 0 ^3,8 . 0 ^12,17] -5-docosene and derivatives thereof, Nonashikuro [10.9.1.1 ^{4, 7.} 1 ^13,20 . 1 ^{15, 18} . 0 ^2,10 . 0 ^3,8 . 0 ^{12, 21} . 0 ^{14,19] -5-pentacosene} and cyclic polyolefins composed of a copolymer of a cyclic olefin of the derivatives, such as amorphous polymers include having a bulky alicyclic structure in its main skeleton.

  In the production of the cyclic polyolefin used in the present invention, the copolymerization ratio of the linear monomer such as α-olefin and the cyclic olefin is from 2 to 80 in terms of tearing performance when a laminated polyolefin film is used. It is preferable that the cyclic olefin is 20 to 98 mol%, preferably 20 to 60 mol%, based on mol%, preferably 40 to 80 mol%. Further, in the case of a laminated product having a layer in which a cyclic polyolefin is mixed as the heat seal surface side, heat seal interface peeling tends to occur and the heat seal strength tends to be weakened. Therefore, it is practically desirable not to use the layer in which the cyclic polyolefin is mixed on the heat seal surface.

Furthermore, the linear low density polyethylene used to form the intermediate layer (B) is a linear polyethylene similar to the linear low density polyethylene used to form the outer layer (A), and ethylene, Preferably 0.2 to 20 mol%, more preferably 0.5 to 10 mol% of an α-olefin having 3 to 10 carbon atoms copolymerized by a liquid phase method or a gas phase method Can be used. Specific examples of the α-olefin include propylene, butene-1, pentene-1, hexene-1, octene-1, nonene-1, decene-1, 4-methylpentene-1, 4-methylhexene-1, Examples include 4,4-dimethylpentene-1. Especially, when α-olefin having 6 or more carbon atoms is used as a copolymerization component, the film strength tends to increase, and it is preferably used for increasing the strength of the packaging material, and is polymerized using a single-site catalyst such as a metallocene system. The linear low density polyethylene film has particularly high packaging strength.
Moreover, it is normal that melting | fusing point is about 85-135 degreeC. The density is not particularly limited, but a density in the range of usually 0.910 to 0.960 g / cm ³ , preferably 0.910 to 0.930 g / cm ³ is used. Moreover, MFR is 1-15 g / 10min normally, Preferably it is about 4.0-8.0 g / 10min.
When the α-olefin of the linear low density polyethylene used to form the intermediate layer (B) of the laminated polyolefin film of the present invention is butene-1, the amount of cyclic polyolefin is less than that of hexene-1. The desired cut property can be obtained.

  Moreover, the mixing ratio of the linear low density polyethylene and cyclic polyolefin used for forming this intermediate | middle layer (B) is 10-40 wt% of cyclic polyolefin with respect to 60-90 wt% of linear low density polyethylene. If the amount of cyclic polyolefin is less than 10 wt%, the pinhole resistance is excellent, but the tearability is poor. If the amount of cyclic polyolefin is more than 40 wt%, the tearability is good but the pinhole resistance is poor.

  The thickness ratio of the intermediate layer (B) in the laminated polyolefin film of the present invention is preferably 10 to 80%, particularly 30 to 70% of the total thickness of the laminated polyolefin film, and easy tearability is easily obtained. Furthermore, the thickness ratio of the intermediate layer (B) in the laminated polyolefin film of the present invention is preferably 20 to 500%, particularly 100 to 350% of the thickness of the inner layer (C). As a laminated polyolefin film, easy tearing by hand is easily obtained, and the object of the present invention can be achieved while maintaining the original excellent performance of linear low density polyethylene.

Furthermore, the inner layer (C) of the laminated polyolefin film of the present invention is formed from a linear low density polyethylene having a density of 0.925 g / cm ³ or less, and the linear low density polyethylene used to form the inner layer (C). Is a linear polyethylene similar to the linear low density polyethylene used to form the outer layer (A), and is preferably 0.2 to 20 mol%, more preferably 0.5 to 10 mol, with ethylene. % Of C 3-10 α-olefins copolymerized by a liquid phase method or a gas phase method can be used. Specific examples of the α-olefin include propylene, butene-1, pentene-1, hexene-1, octene-1, nonene-1, decene-1, 4-methylpentene-1, 4-methylhexene-1, Examples include 4,4-dimethylpentene-1. Especially, when α-olefin having 6 or more carbon atoms is used as a copolymerization component, the film strength tends to increase, and it is preferably used for increasing the strength of the packaging material, and is polymerized using a single-site catalyst such as a metallocene system. A linear low density polyethylene film is particularly preferred because of its high packaging strength. Moreover, it is normal that melting | fusing point is about 85-135 degreeC. Further, a density of 0.925 g / cm ³ or less, preferably 0.910~0.925g / cm ^3, and more preferably about using the range of 0.915~0.925g / cm ^3. Moreover, MFR is 1-15 g / 10min normally, Preferably it is about 4.0-8.0 g / 10min. And by using what has the said density as a linear low density polyethylene used for forming the inner layer (C) of the laminated polyolefin film of the present invention, the inner layer (C) has excellent heat sealability as a heat seal layer. Can show. The reason why the density of the linear low density polyethylene forming the inner layer (C) is specified to be 0.925 g / cm ³ or less is that the smaller the density, the better the impact resistance and the pinhole resistance, and the continuous This is because the suitability for filling by an automatic packaging machine is improved, and a tough packaging material can be produced. However, when only this inner layer (C) is used alone, it tends to be difficult to tear both vertically and horizontally, and the characteristics can be exhibited only by having the laminated structure of the present invention.

  In addition, the laminated polyolefin film of the present invention has various additives that are usually used in polyolefin, for example, plasticizers, heat stabilizers, ultraviolet absorbers, antioxidants, colorants, fillers, electrification, as appropriate layers. An appropriate amount of an inhibitor, an antibacterial agent, a lubricant, an antiblocking agent, etc. may be added as long as the effects of the present invention are not impaired. As the antiblocking agent, it is preferable to use spherical fine particles. The spherical fine particles have an effect of balancing the transparency, slipperiness and blocking resistance of the film.

  In order to produce the laminated polyolefin film of the present invention, for example, a T-die molding using a T-die or an inflation molding method using a circular die can be employed. Moreover, a coextrusion molding method can be used if necessary. When performing T-die molding, it is preferable to extrude onto a cooling drum with a draft rate of 1 to 10% and a resin temperature of 150 to 300 ° C. The thickness of the laminated polyolefin film is usually in the range of 5 to 150 μm, more generally 15 to 80 μm. When the thickness of the laminated polyolefin film exceeds 150 μm, the flexibility is insufficient, and when it is less than 5 μm, there arises a problem that the package is broken.

  The laminated polyolefin film of the present invention can be used alone, or as a sealant layer composed of a laminated film and laminated with a base material layer as a laminated packaging material. It is also preferable that it has excellent properties, slipperiness, blocking resistance, laminating properties, gas barrier properties, impact resistance, surface protection, mechanical properties and the like. Therefore, the laminated polyolefin film of the present invention may have a single structure, but it is also preferable that the above properties are shared by different layers to form a laminated structure as a laminated packaging material.

  The layer structure in the case of laminating the base material layer in order to produce a laminated packaging material from the laminated polyolefin film of the present invention is not particularly limited, but the laminated polyolefin film of the present invention is suitable as a sealant film. It is preferably used as a laminated packaging material in which the following base material layer (D) is laminated on the outer layer (A) side.

  As a base material layer (D) in this invention, the film which consists of a thermoplastic resin, a metal vapor deposition film, metal foil, or these laminated bodies can be mentioned. Examples of thermoplastic resins include polyolefin resins such as polypropylene and polyethylene, polyethylene terephthalate, polyethylene-2,6-naphthalate, polyester resins typified by polybutylene terephthalate and copolymers thereof, and polyoxymethylene. Represented by polyether resins, nylon 6, nylon 66, polyamide resins represented by polymetaxylene adipamide, polystyrene, poly (meth) acrylic acid ester, polyacrylonitrile, polyvinyl acetate and their copolymers Cellulosic resins represented by vinyl resins, polycarbonate resins, cellophane, acetate, etc., as well as polyimide, polyetherimide, fluorine-containing polymers and many other resins alone, copolymers, mixtures, Include coalescence, and the like oriented film stretched in biaxial directions unstretched or uniaxially or straight as a film. Among them, those having easy tearability can be preferably used.

  Although the thickness of a base material layer (D) is not specifically limited, Usually, it is 1-250 micrometers, and it is preferable that it is 3-50 micrometers. This base material layer (D) may be a single body or a composite multilayer film, and the composite method and the number of layers in the multilayer film are arbitrary.

  The laminated polyolefin film of the present invention is laminated as it is or laminated with the base material layer (D), taking advantage of the properties of tearing, pinhole resistance and transparency, heat sealability and practical strength. As a packaging material, if necessary, it has a configuration that includes an adhesive layer and a printing layer between the base layer (D) and the outer layer (A). It can be widely used as a laminated packaging material. For example, miso, pickles, side dishes, baby food, boiled konnyaku, chikuwa, seafood, processed fishery products, meatballs, hamburger, genghis khan, ham, sausage, other processed meat products, tea, coffee, tea, For packaging of oil confectionery such as bonito, taro kelp, potato chips, butter peanuts, rice crackers, biscuits, cookies, cakes, buns, castella, cheese, butter, cut rice, soup, sauce, ramen, wasabi, or toothpaste It is widely used, and can also be used widely for medical food, electronic, chemical, mechanical and other industrial material packaging such as pet food, agricultural chemicals, fertilizers, infusion packs, semiconductor and precision material packaging. Moreover, there is no restriction | limiting in particular also in the usage form of laminated packaging material, and it can be widely utilized as a bag, a cover material, a cup, a tube, a standing pouch etc.

  Hereinafter, the contents and effects of the present invention will be specifically described with reference to examples. In addition, this invention is not limited to a following example, unless it deviates from the summary. In addition, various performance tests employed in the following examples in this specification were performed by the following methods.

(1) Cut property The force required for tearing the laminated polyolefin film obtained by T-die molding was measured according to JIS-K-7128-2. The average value of the force required to tear the film in the machine and transverse directions was taken as the cut property.

(2) Adhesive strength After printing and laminating the printed surface of a biaxially stretched polyamide film (Toyobo Co., Ltd .: N1102, thickness 15 μm) with red printing on a polyester adhesive, the resulting laminated film has a width of 15 mm. The adhesive strength was measured by cutting and peeling speed of 200 mm / min. A stable region during peeling was read, the n number was 5, and the average value was taken as the adhesive strength.

(3) Pinhole resistance After dry lamination with a biaxially stretched polyamide film (manufactured by Toyobo Co., Ltd .: N1102, thickness 15 μm) and a polyester-based adhesive, the obtained laminate film is mounted on a gelbo flex tester 400 times. The number of pinholes generated was counted by bending fatigue 3000 times at a speed of / min. The measurement was performed at 23 ° C.

(4) Haze The transparency of the film was measured according to JIS-K-6714.

(5) Density In accordance with JIS-K-7112 (according to D method (density gradient tube method) among the density measuring methods described in JIS-K-7112), the test temperature was 23 ± 0.1 ° C. The sample was annealed by the following method and then measured. The annealing conditions were in accordance with the method described in JIS-K-6922-2 4.2 Specific gravity and density.

(Example 1)
In order to form a three-layer laminated polyolefin film, as the outer layer (A), a linear low density polyethylene (density 0.935 g / cm ³ , MFR 4.0 g / 10 min, melting point 122 ° C., manufactured by Sumitomo Mitsui Polyolefin Co., Ltd., trade name SP3530) ) As the intermediate layer (B), linear low density polyethylene (density 0.923 g / cm ³ , MFR 4.0 g / 10 min, melting point 120 ° C .: Ube Industries, Ltd., trade name 725FT) and cyclic polyolefin (ethylene-norbornene) A mixture of 80:20 (wt ratio) with a copolymer, manufactured by Ticona (trade name Topas 8007) was used as an inner layer (C) as a linear low density polyethylene (density 0.923 g / cm ³ , MFR 4.0 g / 10 minutes, melting point 120 ° C .: made by Sumitomo Mitsui Polyolefin Co., Ltd., trade name SP2540) Extruded from a T-die at and type film-forming machine onto a chill roll to obtain a laminated polyolefin film of total thickness 40μm as thickness ratio 1/3/1.

(Example 2)
A laminated polyolefin film (total thickness 40 μm) was obtained in the same manner as in Example 1 except that the following points were changed. The linear low-density polyethylene used in the inner layer (C) was changed to a linear low-density polyethylene having a density of 0.915 g / cm ³ and a melting point of 112 ° C .: trade name SP1540 manufactured by Sumitomo Mitsui Polyolefin.

(Comparative Example 1)
A laminated polyolefin film (total 40 μm) was obtained in the same manner as in Example 1 except that the following points were changed. The linear low density polyethylene used in the outer layer (A) was changed to (density 0.940 g / cm ³ , MFR 4.0 g / 10 min, melting point 126 ° C .: trade name 4040F manufactured by Ube Industries, Ltd.).

(Comparative Example 2)
A laminated polyolefin film (total thickness 40 μm) was obtained in the same manner as in Example 1 except that the following points were changed. The linear low density polyethylene used in the intermediate layer (B) was changed to (density 0.923 g / cm ³ , MFR 4.0 g / 10 min, melting point 120 ° C .: trade name SP2540, manufactured by Sumitomo Mitsui Polyolefin Co., Ltd.).

  Cut properties, adhesive strength, pinhole resistance, and transparency of the laminated polyolefin films obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were measured. The evaluation results are shown in Table 1.

  As described above, the polyolefin resin film and the laminated packaging material of the present invention have been described based on a plurality of examples. However, the present invention is not limited to the configuration described in the above examples, and is described in each example. The configuration can be changed as appropriate within a range not departing from the gist, such as appropriately combining the configurations.

  The polyolefin-based resin film and the laminated packaging material of the present invention have characteristics of excellent tearability, pinhole resistance, transparency and strength in practical use, so that convenience for consumers is required. It can be suitably used for packaging applications.

In the figure, (a) is an example of the laminated structure of the laminated polyolefin film of the present invention, (b) is an example of the laminated structure of the laminated packaging material of the present invention, and (c) is a packaging application of the laminated packaging material of the present invention. Examples of use for the laminates are respectively shown.

Explanation of symbols

A outer layer B intermediate layer C inner layer D base material layer E adhesive layer F printing layer

Claims (3)

An outer layer (A) made of linear low density polyethylene having a density of 0.925 g / cm ³ or more and 0.9 35 g / cm ³ or less, and ethylene and 0.2 to 20 mol% of butene-1 were copolymerized. An intermediate layer (B) made of a mixture of linear low density polyethylene 80 to 90 wt% and cyclic polyolefin 10 to 20 wt% and a heat seal layer made of linear low density polyethylene having a density of 0.925 g / cm ³ or less A laminated polyolefin film excellent in transparency, wherein the inner layer (C) is laminated in order.   The laminated polyolefin film excellent in transparency according to claim 1, wherein a haze value of the whole laminated polyolefin film at a thickness of 40 μm is 6.0% or less.   A laminated packaging material obtained by laminating the laminated polyolefin film according to claim 1 or 2 on a base material layer (D).

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