JP5161686B2 - Food packaging film - Google Patents

Description

The present invention relates to a food packaging film, and more particularly to a food packaging film suitably used as a household film. More specifically, the present invention relates to a food packaging film having excellent heat resistance, cutability and adhesiveness.

Conventionally, stretch films used as so-called wrap films for household use include polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC) formed by blending an appropriate amount of plasticizer into a film, and polyethylene having an appropriate density. A film obtained by forming a film of (PE) with good transparency is known. However, the wrap film made of such a material becomes too soft at a high temperature and cannot maintain the shape as a film. In addition, when a highly oily food is directly wrapped and heated in a microwave oven or the like for a relatively long time, there is a problem that the film melts or tears.

On the other hand, wrap films using plastics having good heat resistance such as polyethylene terephthalate (PET) and polyamide (PA) are also known, but these films have a problem that it is difficult to impart adhesiveness.

Further, a wrap film of a composition in which a 4-methyl-1-pentene polymer having excellent heat resistance is used and liquid polybutene (a polymer having isobutylene as a main component) is added thereto as a tackifier is proposed. However, for example, Patent Document 1 has such a drawback that a film of such a composition develops a blocking phenomenon with time and is extremely difficult to remove from the box.

A single-layer packaging film composed of a resin composition obtained by mixing a methyl-1-pentene polymer as a main component and an ethylene / α-olefin copolymer mixed therewith has been proposed (for example, patents). References 2 and 3). However, a single layer is inferior in cutting properties as compared with a multilayer structure, and a compound containing a large amount of methyl-1-pentene polymer has the disadvantages that the transparency of the film is impaired and the adhesiveness is lowered. On the other hand, a single-layer film composed only of a methyl-1-pentene polymer has good cutability, transparency, and heat resistance, but is made of a plastic having good heat resistance such as polyethylene terephthalate (PET) or polyamide (PA). Similar to the used wrap film, there is a problem that it is difficult to impart adhesiveness. A single-layer film composed only of an ethylene / α-olefin copolymer has good transparency and adhesiveness but is inferior in terms of cutability and heat resistance. Stretching techniques are known to improve the cutting performance, but the temperature range that can be stretched is narrow, and if the temperature is low, the film cannot be stretched and tears. For molding, advanced techniques such as mixing other resins to widen the stretching temperature range are required.

Further, a packaging film in which a surface layer made of a propylene-based resin or an ethylene / α-olefin-based resin is laminated on one side or both sides of a layer mainly composed of a methyl-1-pentene polymer, or a methyl-1-pentene-based polymer A packaging film in which an intermediate layer is provided between a layer composed mainly of coalescence and a surface layer has also been proposed (for example, Patent Documents 4 to 7). However, since the resin film layer made of propylene resin or ethylene / α-olefin resin as the surface layer is inferior in heat resistance, the food film layer wrapped with such a packaging film is exposed to high temperatures. There is a problem that the low-temperature eluate contained in the food is transferred to food.
JP 05-239291 A JP-A-11-29670 JP-A-11-29671 Japanese Patent Laid-Open No. 06-23927 Japanese Patent Laid-Open No. 2003-200539 Japanese Patent Laid-Open No. 02-107438 JP 2006-231622 A

The present invention is a packaging film having excellent heat resistance, and there is no problem that even if the food packaged with the above film is exposed to high temperature, there is no problem that the eluate from the film migrates to the food. It aims at providing the film for food packaging which has this.

The present inventors have found that a film having excellent heat resistance, cutability and adhesiveness can be obtained by laminating a layer made of a methyl-1-pentene polymer on both sides of a layer made of an olefin resin. The invention has been reached.

That is, in the present invention, the layer (B) consisting only of the methyl-1-pentene polymer (b) is laminated on both surfaces of the layer (A) consisting of the olefin resin (a). a) is a food packaging film having a flexural modulus (JIS K7171: 2008) of 100 to 950 MPa.

The food packaging film of the present invention is excellent in heat resistance, cutability and adhesiveness, and there is no problem that even if the food packaged with the above film is exposed to high temperature, the effluent from the film does not migrate to the food. It is particularly suitable as a food packaging film for the range.

Examples of the polyolefin resin (a) used as the layer (A) in the present invention include low density polyethylene, ethylene / α-olefin copolymer, propylene polymer, and butene-1 polymer. These can be used individually by 1 type or in combination of 2 or more types.

Low density polyethylene includes linear low density polyethylene (LL), branched low density polyethylene (LD) alone or a blend thereof. Examples of the linear low density polyethylene include a copolymer of ethylene and an α-olefin having 4 to 10 carbon atoms, preferably a copolymer of an α-olefin having 6 to 8 carbon atoms.

The ethylene / α-olefin copolymer is a copolymer of ethylene and an α-olefin having 4 to 8 carbon atoms. The α-olefin content is 5 wt% or more, preferably 8 to 25 wt%, more preferably 10 to 20 wt%. Examples of the α-olefin include butene, hexene, octene, 4-methylpentene-1, and the like. Among them, an α-olefin having 6 to 8 carbon atoms, particularly hexene, octene, and 4-methylpentene-1 are preferable.

The ethylene / α-olefin copolymer preferably has a melt flow rate (according to ASTM D1238; measurement temperature: 190 ° C .; load: 2.16 kg) of 0.1 to 20 g / 10 min, more preferably 1 -10 g / 10 min. The ethylene / α-olefin copolymer preferably has a density (ASTM D1505) of less than 0.93 g / cm ³ from the viewpoints of flexibility, strength, transparency and heat resistance of the obtained film.

The propylene-based polymer is a propylene homopolymer, a propylene-based random copolymer, or a propylene-based block copolymer, and can be used alone or in combination of two or more.

Examples of the propylene random copolymer include a propylene-ethylene random copolymer obtained by copolymerizing propylene and ethylene, and a copolymer obtained by copolymerizing propylene and at least one α-olefin having 4 to 20 carbon atoms. Examples thereof include a propylene / α-olefin random copolymer or a propylene / ethylene / α-olefin random copolymer obtained by copolymerizing propylene, ethylene and at least one α-olefin having 4 to 20 carbon atoms. .

Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 2-methyl-1-propene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, and 1-hexene. 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1 -Butene, 1-heptene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1-pentene, trimethyl-1-butene, methylethyl-1-butene, 1-octene, methyl-1-pentene, ethyl- 1-hexene, dimethyl-1-hexene, propyl-1-heptene, methylethyl-1-heptene, trimethyl-1-pentene, propyl-1-pentene, diethyl-1-butene, - nonene, 1-decene, 1-undecene, 1-dodecene, and the like. 1-butene, 1-pentene, 1-hexene and 1-octene are preferable, and 1-butene and 1-hexene are more preferable.

Specific examples of the propylene random copolymer include a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, a propylene-1-hexene random copolymer, and a propylene-1-octene random copolymer. Polymer, propylene-ethylene-1-butene random copolymer, propylene-ethylene-1-hexene random copolymer, propylene-ethylene-1-octene random copolymer, and the like, preferably propylene-ethylene random copolymer. A polymer, a propylene-1-butene random copolymer, a propylene-1-hexene random copolymer, a propylene-ethylene-1-butene random copolymer, and a propylene-ethylene-1-hexene random copolymer.

The propylene-based block copolymer is a block copolymer composed of a crystalline propylene-based polymer portion and an amorphous propylene / α-olefin copolymer portion. Examples of the crystalline propylene polymer part include a homopolymer of propylene or a random copolymer of propylene and a small amount of other α-olefin. On the other hand, examples of the amorphous propylene / α-olefin copolymer include non-crystalline random copolymers of propylene and other α-olefins.

The other α-olefins are preferably those having 2 or 4 to 12 carbon atoms, and specific examples include ethylene, 1-butene, 3-methyl-1-butene, 3-methyl-1-pentene, 4 -Methyl-1-pentene, 4,4-dimethyl-1-pentene, vinylcyclopentane, vinylcyclohexane and the like. These α-olefins may be used alone or in combination of two or more.

In addition to the above-mentioned other α-olefins, the propylene block copolymer may be 1,4-hexadiene, 5-methyl-1,5-hexadiene, 1,4-octadiene, cyclohexadiene, cyclooctadiene, diene. A ternary or quaternary or more quaternary copolymerized with a non-conjugated diene such as cyclopentadiene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, 5-isopropenyl-2-norbornene These copolymers can also be used.

The butene-1 polymer includes a homopolymer obtained by catalytic polymerization of a liquid butene-1 monomer and a copolymer with an α-olefin having 2 to 3 carbon atoms. The melt flow rate (according to ASTM D1238; measurement temperature: 190 ° C .; load: 2.16 kg) is preferably in the range of 0.1 to 5 g / 10 min. The density (ASTM D1505) is preferably 0.890 to 0.920 g / cm ³ .

The polyolefin resin (a) constituting the layer (A) preferably has a flexural modulus (JIS K7171: 2008) of 100 to 950 MPa, more preferably 150 MPa to 900 MPa, and further preferably 200 MPa to 800 MPa. . If the flexural modulus is less than 100 MPa, the resulting film may be inferior in cutability, and if it exceeds 950 MPa, the resulting film may be inferior in adhesiveness. In addition, when a layer (A) is comprised with the mixture of two or more polyolefin resin, the said bending elastic modulus is a value in the said mixture.

In addition to the polyolefin resin (a), the layer (A) may contain various additives such as an antioxidant, a neutralizing agent, and a nucleating agent as necessary within the range not impairing the object of the present invention. May be included.

The layer (B) laminated on both surfaces of the layer (A) is composed of a methyl-1-pentene polymer (b). The methyl-1-pentene polymer (b) includes 4-methyl-1-pentene and / or 3-methyl in addition to 4-methyl-1-pentene or 3-methyl-1-pentene homopolymer. Including copolymers of -1-pentene and other α-olefins. The α-olefins may be used alone or in combination of two or more. The content of α-olefin in the copolymer is 10% by weight or less when C2 to C5 α-olefin is used, 8% by weight or less when C6 to C10 α-olefin is used, and C11. When ˜C14 α-olefin is used, it is preferably 5% by weight or less. When these are used in combination, the total α-olefin is preferably 5% by weight or less. These (co) polymers can be used singly or in combination of two or more. Moreover, what modified | denatured the said (co) polymer with maleic anhydride can also be used as a methyl-1-pentene polymer (b), In that case, content of maleic anhydride is 10 weight% or less. preferable. As the methyl-1-pentene polymer (b), a (co) polymer of 4-methyl-1-pentene is preferable.

The methyl-1-pentene polymer (b) preferably has a melt flow rate (according to ASTM D1238; measurement temperature: 260 ° C .; load: 5.00 kg) of 15 to 50 g / 10 minutes, more preferably 20 ~ 30 g / 10 min.

The layer (B) is composed of the methyl-1-pentene polymer (b), but the additives described below are within a range that does not impair the effect of the methyl-1-pentene polymer (b). For example, it may be included in an amount of 1 to 20 parts by weight with respect to 100 parts by weight of the methyl-1-pentene polymer (b). The amount is preferably 1 to 10 parts by weight, more preferably 1 to 5 parts by weight.

The said additive includes liquid polybutene, a liquid paraffin, and a butene-1 type | system | group polymer, These can be used individually by 1 type or in combination of 2 or more types. When the layer (B) contains these additives, the transparency becomes better.

The liquid polybutene is liquid at room temperature and has a kinematic viscosity at 100 ° C. of 2 to 5000 cSt. The kinematic viscosity is preferably 50 to 1000 cSt in that a heat-resistant wrap film excellent in moldability and quality is obtained.

Examples of the liquid paraffin include paraffinic compounds having 4 to 155 carbon atoms, preferably paraffinic compounds having 4 to 50 carbon atoms, and specifically include butane, pentane, hexane, heptane, octane, nonane, decane, and undecane. , Dodecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosan, heneicosan, docosan, tricosan, tetracosan, pentacosan, hexacosan, heptacosan, octacosan, nonacosan, triacontane, entriacontan, dotriacontane, pentatriacontane, N-paraffins (linear saturated hydrocarbons) such as hexacontan and heptacontane; isobutane, isopentane, neopentane, isohexane, isopentane, neohexane, 2, 3 Dimethylbutane, 2-methylhexane, 3-methylhexane, 3-ethylpentane, 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 2,2, 3-trimethylbutane, 3-methylheptane, 2,2-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 3,4-dimethylhexane, 2,2,3 -Trimethylpentane, isooctane, 2,3,4-trimethylpentane, 2,3,3-trimethylpentane, 2,3,4-trimethylpentane, isononane, 2-methylnonane, isodecane, isoundecane, isododecane, isotridecane, isotetradecane , Isopentadecane, isooctadecane, isonanodecane, iso Icosane, 4-ethyl-5-isoparaffins methyl octane (branched saturated hydrocarbons) and can include derivatives of these saturated hydrocarbons. These paraffins are used in a mixture and are preferably liquid at room temperature.

In addition, a small amount of unsaturated hydrocarbons and derivatives thereof may coexist in the paraffin oil. Unsaturated hydrocarbons include ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 2-pentene, 3-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2 -Ethylene hydrocarbons such as butene, 1-hexene, 2,3-dimethyl-2-butene, 1-heptene, 1-octene, 1-nonene, 1-decene; acetylene, methylacetylene, 1-butyne, 2- Examples thereof include acetylene hydrocarbons such as butyne, 1-pentyne, 1-hexyne, 1-octyne, 1-nonine and 1-decyne.

The butene-1 polymer is obtained by polymerizing a butene-1 monomer as a main component, for example, butene-1 homopolymer, butene-1 and one kind of α-olefin component having 2 to 8 carbon atoms. Copolymers with the above are included. The butene-1 polymer is solid at normal temperature, and its mass average molecular weight is preferably 1 million to 3 million.

Moreover, in order to improve the self-adhesiveness, anti-fogging property, antistatic property, slipperiness, and workability of the resulting film, the layer (B) is formed from the following oil and fat with a methyl-1-pentene polymer (b ) You may contain in less than 20 weight part with respect to 100 weight part.

Specific examples of fats and oils include glycerin fatty acid ester and polyglycerin fatty acid ester compounds such as (di) glycerin mono (or di or tri) oleate, (di) glycerin mono (or di or tri) stearate, (di) glycerin mono ( Or di) palmitate, (di) glycerol mono (or di) laurate, (di) glycerol mono (or di or tri) oleate laurate; sorbitan fatty acid ester compounds such as sorbitan laurate, sorbitan palmitate, sorbitan (tri) stear Rate, sorbitan (tri) oleate; ethylene oxide adducts such as polyoxyethylene alkyl (phenyl) ether, polyoxyethylene sorbitan monooleate, polyoxyethylene glycerin monosteale It encompasses and propylene glycol fatty acid esters, such as propylene glycol monolaurate, propylene glycol monopalmitate, propylene glycol monostearate, propylene glycol monooleate, propylene glycol monobehenate; DOO, polyoxyethylene glycerin monooleate. These can be blended in an amount of preferably 0.5 to 5 parts by weight, more preferably 1 to 4 parts by weight with respect to 100 parts by weight of the methyl-1-pentene polymer (b).

Other specific examples of fats and oils include oleic acid amide, stearic acid amide, erucic acid amide, lauric acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide. These are blended in an amount of preferably 0.01 to 0.5 parts by weight, more preferably 0.05 to 0.2 parts by weight with respect to 100 parts by weight of the methyl-1-pentene polymer (b). it can.

The film for food packaging of the present invention is a multilayer film in which the above-described layer (B) is laminated on both surfaces of the above-described layer (A). Each thickness of the layer (A) and the layer (B) is not particularly limited, but the thickness ratio (B / A / B) is (0.25 / 1 / 0.25) to (2.5 / 1/2. 5) is preferable, and (0.5 / 1 / 0.5) to (1/1/1) is more preferable. When the thickness of the layer (B) relative to the thickness of the layer (A) is less than the above range, the heat resistance of the resulting film may be inferior, and when it exceeds the above range, the resulting film is inferior in adhesiveness. There is.

The total thickness of the resulting multilayer film is preferably 5 μm or more and less than 30 μm, particularly preferably 5 to 15 μm. If the film is too thick, the transparency may be insufficient.

The method for producing the food packaging film of the present invention is not particularly limited. For example, the resins for layers (A) and (B) are melt-kneaded using two or more extruders and one multilayer die, respectively. After that, it can be formed into a film using a known film forming method such as T-die or inflation. In order to increase the heat resistance and strength of the film, the film may be stretched by a tenter method, a tubular method, or the like.

The following examples further illustrate the present invention. These do not limit the present invention.

The film tests performed in the examples and comparative examples are as follows.
(1) Heat resistance The heat resistance temperature was measured in accordance with the quality labeling method for Tokyo household goods.
(2) The sticking property to the adhesive glass container was evaluated by a questionnaire by 10 panelists. The evaluation criteria are as follows.
◎: Nine or more people judged that the tackiness was good ○: Seven to eight people judged that the tackiness was good Δ: Four to six people judged that the tackiness was good ×: Seven or more people The adhesiveness was judged to be poor.
(3) The cut film was made into a small volume and put in a decorative box having a metal saw blade, and the cut performance of the film was evaluated by a questionnaire by 10 panelists. The evaluation criteria are as follows.
◎: Nine or more people judged that the cutting property was good ○: Seven to eight people judged that the cutting property was good Δ: Four to six people judged that the cutting property was good ×: Seven or more people It was judged that the cutting property was bad.
(4) Transparency Haze value was measured according to JIS K7105.
(5) High temperature elution test A circular test piece (diameter 11.3 cm) having a surface area of 100 cm ² was cut out, and the entire surface was brought into contact with 200 ml of olive oil having a temperature of 175 ° C. for 2 hours, and then extracted from the test piece extracted into olive oil The amount of eluate was determined. The amount of extraction was determined by (mass of test piece before extraction with olive oil) − (mass of test piece after extraction with olive oil) + (mass of olive oil soaked in the test piece). The value obtained by converting the extracted amount into the concentration per 1 ml of olive oil was taken as the elution amount. The unit is μg / ml. The mass of olive oil soaked in the test piece was determined by extracting olive oil from the extracted test piece with n-heptane.
(6) Flexural modulus Measured with a test speed of 2 mm / min and an indenter R3 in accordance with JIS K7171: 2008. The size of the test piece is 80 mm in length, 10 mm in width, and 4 mm in thickness. In addition, the test piece was shape | molded by injection molding or compression molding based on JISK6921-2, JISK6922-2, and JISK6925-2.

Example 1
NAC4 (propylene block copolymer; MFR (measurement temperature: 230 ° C., load: 2.16 kg)) manufactured by Nippon Polypro Co., Ltd. as the olefin resin (a) constituting the layer (A): 6.0 g / 10 Min: Density: 0.9 g / cm ³ ; Flexural modulus: 760 MPa), and as a methyl-1-pentene polymer (b) constituting the layer (B) laminated on both sides, Mitsui Chemicals ( Co., Ltd. MX-004 (poly (4-methyl-1-pentene); MFR (measurement temperature: 260 ° C., load: 5.00 kg): 23 g / 10 min; density: 0.833 g / cm ³ ) , And supplied to an extruder (Ikekai Tekko Co., Ltd., screw diameter: 40 mm, L / D: 28). Each layer of the three-layer film (B / A / B) is laminated with a co-extrusion multilayer T-die so that the thickness (μm) is 2/8/2 (thickness ratio: 0.25 / 1 / 0.25). Thus, a film having a total thickness of 12 μm was prepared. The test results of this film are shown in Table 1.

Example 2
A three-layer film (B / A) having a total thickness of 12 μm, as in Example 1, except that the thickness (μm) of each layer was 3/6/3 (thickness ratio: 0.5 / 1 / 0.5). / B). The test results of this film are shown in Table 1.

Example 3
A three-layer film (B / A / B) having a total thickness of 12 μm was prepared in the same manner as in Example 1 except that the thickness (μm) of each layer was 4/4/4 (thickness ratio: 1/1/1). Created. The test results of this film are shown in Table 1.

Example 4
A three-layer film (B / A) having a total thickness of 12 μm, as in Example 1, except that the thickness (μm) of each layer was 5/2/5 (thickness ratio: 2.5 / 1 / 2.5). / B). The test results of this film are shown in Table 1.

Example 5
As the olefin resin (a) constituting the layer (A), 1471 (syndiotactic ethylene propylene; MFR (measurement temperature: 190 ° C., load: 2.16 kg)) manufactured by TOTAL PETROCHEMICAL: 4.0 g / 10 Min: density: 0.88 g / cm ³ ; flexural modulus: 340 MPa) In the same manner as in Example 2, the total thickness was 12 μm, and the thickness (μm) of each layer was 3/6/3 ( A three-layer film (B / A / B) having a thickness ratio of 0.5 / 1 / 0.5) was produced. The test results of this film are shown in Table 1.

Example 6
As the olefin resin (a) constituting the layer (A), WFX4T (metallocene catalyst propylene copolymer manufactured by Nippon Polypro Co., Ltd .; MFR (measurement temperature: 190 ° C., load: 2.16 kg): 7.0 g / 10 min; density: 0.90 g / cm ³ ; flexural modulus: 700 MPa), the total thickness is 12 μm and the thickness (μm) of each layer is 3/6 / in the same manner as in Example 2. A three-layer film (B / A / B) of 3 (thickness ratio: 0.5 / 1 / 0.5) was prepared. The test results of this film are shown in Table 1.

Example 7
As the olefin resin (a) constituting the layer (A), FW4BT (propylene random copolymer; MFR (measurement temperature: 190 ° C., load: 2.16 kg)) manufactured by Nippon Polypro Co., Ltd .: 6.5 g / 10 minutes; density: 0.90 g / cm ³ ; flexural modulus: 850 MPa), the total thickness was 12 μm and the thickness (μm) of each layer was 3/6/3, as in Example 2. A three-layer film (B / A / B) having a thickness ratio of 0.5 / 1 / 0.5 was prepared. The test results of this film are shown in Table 1.

Example 8
As the olefin resin (a) constituting the layer (A), BL3110 (ethylene-pentene-1 copolymer; MFR (measurement temperature: 190 ° C., load: 2.16 kg)) manufactured by Mitsui Chemicals, Inc .: 0 g / 10 min; density: 0.91 g / cm ³ ; flexural modulus: 250 MPa), in the same manner as in Example 2, the total thickness was 12 μm, and the thickness (μm) of each layer was 3/6. A three-layer film (B / A / B) having a thickness of / 3 (thickness ratio: 0.5 / 1 / 0.5) was prepared. The test results of this film are shown in Table 1.

Comparative Example 1
Methyl-1-pentene polymer (Mitsui Chemical Co., Ltd., MX-004) was used as the layer (A), and KF260 (ethylene) manufactured by Nippon Polyethylene Co., Ltd., which is an olefin resin, was used as the layer (B). Except for using hexene-1 copolymer; MFR (measurement temperature 190 ° C., load: 2.16 kg): 2.0 g / 10 min; density: 0.903 g / cm ³ ; flexural modulus: 82 MPa) In the same manner as in Example 3, a three-layer film (B / A / B) having a total thickness of 12 μm and a thickness (μm) of each layer of 4/4/4 (thickness ratio: 1/1/1) was prepared. did. The test results of this film are shown in Table 1.

Comparative Example 2
Using only the methyl-1-pentene polymer (Mitsui Chemical Co., Ltd., MX-004) used as the layer (B) in Example 1, a single-layer film having a thickness of 12 μm was prepared using a single-layer extruder. did. The test results of this film are shown in Table 1.

Comparative Example 3
Using only the olefin-based resin (manufactured by Nippon Polyethylene Co., Ltd., KF260) used as the layer (B) in Comparative Example 1, a single-layer film having a thickness of 12 μm was prepared using a single-layer extruder. The test results of this film are shown in Table 1.

Comparative Example 4
Methyl-1-pentene polymer (Mitsui Chemical Co., Ltd., MX-004) used as layer (B) in Example 1 and olefin resin (Japan Polypro Co., Ltd.) used as layer (A), NAC4) was mixed at a weight ratio of 70:30, and a single layer film having a thickness of 12 μm was prepared using a single layer extruder using the obtained resin composition. The test results of this film are shown in Table 1.

Reference example 1
The total thickness is 12 μm and the thickness (μm) of each layer is the same as in Example 2 except that KF260 manufactured by Nippon Polyethylene Co., Ltd. is used as the olefin resin (a) constituting the layer (A). A three-layer film (B / A / B) having a thickness of 3/6/3 (thickness ratio: 0.5 / 1 / 0.5) was prepared. The test results of this film are shown in Table 1.

Reference example 2
232J (High Density Polyethylene; MFR (Measurement Temperature 190 ° C., Load: 2.16 kg): 5.0 g / 10 min) manufactured by Prime Polymer Co., Ltd. as the olefin resin (a) constituting the layer (A): Density: 0.958 g / cm ³ ; flexural modulus: 1100 MPa) was used in the same manner as in Example 2, the total thickness was 12 μm, and the thickness (μm) of each layer was 3/6/3 (thickness ratio: 0). A three-layer film (B / A / B) that is .5 / 1 / 0.5) was produced. The test results of this film are shown in Table 1.

As is apparent from Table 1, the film of the present invention is excellent in heat resistance, adhesiveness and cutability, and has a small amount of elution at high temperatures. In addition, the film of Example 3 was subjected to a heating test in which 0.5 g of mayonnaise was placed on the surface and heated in a microwave oven with an output of 700 W for 60 seconds, and changes in the film surface before and after the heating test were examined. . FIG. 1 is an electron micrograph (magnification: 500 times) of the film surface before the heating test, and FIG. 2 is an electron micrograph (magnification: 500 times) of the film surface after the heating test. 1 and 2 that the film of the present invention does not melt even when exposed to high temperatures. Therefore, the film of the present invention has no concern that the effluent from the film will be transferred to the packaged food or that the film on the surface will melt and mix with the food.

On the other hand, as shown in Table 1, the film of Comparative Example 1 using the methyl-1-pentene polymer (b) as the layer (A) and the olefin resin (a) as the layer (B) is The amount of elution at high temperature was large. Also, this film was subjected to the same heating test as in Example 3. FIG. 3 is an electron micrograph (magnification: 500 times) of the film surface before the heating test, and FIG. 4 is an electron micrograph (magnification: 500 times) of the film surface after the heating test. 3 and 4 that the film after the heating test is melted.

Further, as apparent from Table 1, the film of Comparative Example 2 using only the methyl-1-pentene polymer is inferior in adhesiveness, and the film of Comparative Example 3 using only the olefin resin is heat resistant and cut. In addition to inferiority, the amount of elution at a high temperature was large. The film of Comparative Example 4 was a single layer film made of a mixture of a methyl-1-pentene polymer and an olefin resin, and was inferior in adhesiveness and had a large amount of elution at a high temperature. The film of Reference Example 1 using an olefinic resin having a flexural modulus of less than 100 MPa as the layer (A) has poor cutting properties, and the film of Reference Example 2 using an olefinic resin having a flexural modulus of greater than 950 MPa is adhesive. Inferior to sex.

Example 9
Instead of the methyl-1-pentene polymer (Mitsui Chemical Co., Ltd., MX-004) used as the layer (B) in Example 2, the methyl-1-pentene polymer (Mitsui Chemical Co., Ltd.) was used. Manufactured by MX-004) and liquid paraffin (manufactured by Matsumura Oil Research Co., Ltd., P-350P; kinematic viscosity (measurement temperature: 37.8 ° C.): 75.9 cSt; density: 0.868 g / cm ³ ) 97 : The total thickness was 12 μm and the thickness (μm) of each layer was 3/6/3 (thickness ratio) in the same manner as in Example 2 except that the resin composition obtained by mixing at 3 (weight ratio) was used. : 0.5 / 1 / 0.5), a three-layer film (B / A / B) was prepared. The transparency of the obtained film was 0.9% in terms of haze value, which was superior to the film of Example 2 (haze value: 6.2%).

It is an electron micrograph (magnification: 500 times) of the surface of the film of Example 3 before performing a heating test. It is an electron micrograph (magnification: 500 times) of the surface after performing the heating test of the film of Example 3. It is an electron micrograph (magnification: 500 times) of the surface of the film of Comparative Example 1 before performing a heating test. It is an electron micrograph (magnification: 500 times) of the surface after performing the heating test of the film of comparative example 1.

Claims (4)

The layer (B) consisting only of the methyl-1-pentene polymer (b) is laminated on both sides of the layer (A) consisting of the olefin resin (a), and the olefin resin (a) is 100 to 100%. A food packaging film characterized by having a flexural modulus (JIS K7171: 2008) of 950 MPa. The olefin resin (a) is at least one selected from the group consisting of low density polyethylene, ethylene / α-olefin copolymer, propylene polymer and butene-1 polymer, and the film has a thickness of 5 μm or more. The thickness ratio of each layer of the film (layer (B) / layer (A) / layer (B)) has a thickness of less than 30 μm (0.25 / 1 / 0.25) to (2.5. The food packaging film according to claim 1, which is /1/2.5). The film was cut into a circular shape (diameter 1 1.3 cm) having a surface area of 10 cm ² and used as a test piece, and the entire surface was brought into contact with olive oil 20 ° ml at a temperature of 175 ° C. for 2 hours. Then, measure the amount of eluate from the test piece extracted into olive oil, (mass of test piece before extraction with olive oil)-(mass of test piece after extraction with olive oil) + (soaked in test piece) 3. The high-temperature elution amount is 2 to 9 μg / ml, when the extraction amount determined by the mass of olive oil is converted into the concentration per 1 ml of olive oil as the high-temperature elution amount. Food packaging film as described in 1. The film for food packaging according to any one of claims 1 to 3 , wherein the heat-resistant temperature measured according to the quality indication method for Tokyo household goods is 160 ° C to 200 ° C.