JP6464661B2 - Easy-open packaging material - Google Patents

Description

  The present invention relates to an easy-open packaging material excellent in oil resistance without using a polypropylene film for the innermost layer of the packaging material.

  Packaging materials such as foods, beverages, and pharmaceuticals are generally polyolefin resin films that become a sealant layer via an anchor coating agent on one surface of a barrier film such as polyester or nylon that is excellent in film strength, especially polypropylene, Laminates obtained by laminating high-pressure low-density polyethylene, ethylene homopolymer, ethylene-vinyl acetate and the like are widely used.

  Such a packaging material is mainly manufactured by an extrusion laminating method, a solvent-type dry laminating method, a solventless dry laminating method, or the like.

  Among them, the extrusion lamination method exhibits excellent productivity, and is therefore used as a manufacturing method for various packaging materials. High pressure method low density polyethylene (hereinafter referred to as LDPE) that is excellent in extrusion lamination processability is widely used.

  However, in the field of oily food packaging such as snacks and instant noodles, it has not been used so far because LDPE has low oil resistance. Therefore, at present, in the field of oil-based food packaging, a packaging material made of a polypropylene film having excellent oil resistance is used.

  In recent years, in the food packaging field, easy-openability may be required. However, a laminate obtained by extrusion-laminating a single LDPE could not exhibit excellent easy-openability. Because of this background, polypropylene films have been used for many years in the field of oil-based food packaging.

  As mentioned above, polypropylene film is excellent as an internal material for oil-based food packaging, but the polypropylene film alone has poor adhesion to the barrier film, and the barrier film and unstretched polypropylene film are sandwich laminated using LDPE. The method of doing was common. For this reason, it has been difficult to reduce the thickness of the packaging material.

  This invention is made | formed in view of the above situations, Comprising: It aims at providing the easy-open packaging material excellent in oil resistance, without using a polypropylene film.

A laminate film in which polyethylene (B) is extrusion-laminated through an anchor coating agent on at least a barrier film (A), and the polyethylene (B) satisfies the following requirements (a) and (b), and the polyethylene (B) The easy-open packaging material in which the layer satisfies the following requirements (c) and (d).
(A) The density measured based on JIS K6922-1 is 927 to 947 kg / m ^3.
(B) Melt mass flow rate measured in accordance with JIS K6922-1 (hereinafter sometimes referred to as MFR) is 2 to 30 g / 10 minutes (c) Film thickness is 5 to 25 μm
(D) At a sealing temperature of 125 to 130 ° C., the heat seal strength at 180 ° peeling (sample width 15 mm, tensile speed of 300 mm / min) is 3 to 20 N / 15 mm width. The present invention will be described in detail below.

  Examples of the polyethylene (B) constituting the laminate of the present invention include an ethylene homopolymer, an ethylene / α-olefin copolymer, a high-pressure method low-density polyethylene, and a composition thereof.

  The production method of the ethylene homopolymer or ethylene / α-olefin copolymer is not particularly limited, and examples thereof include a high / medium / low pressure ion polymerization method using a Ziegler-Natta catalyst, a Philips catalyst, or a metallocene catalyst. Such a resin can be conveniently selected from commercially available products. For example, they are commercially available from Tosoh Corporation under the trade names Nipolon Hard, Nipolon-L and Nipolon-Z.

  Examples of the α-olefin constituting the ethylene / α-olefin copolymer include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene and 1-decene. can do.

  The method for producing the high-pressure low-density polyethylene can be exemplified by high-pressure radical polymerization, and such a resin can be conveniently selected from commercially available products, for example, commercially available under the trade name of Petrocene from Tosoh Corporation. ing.

  The polyethylene (B) may be a composition, the linear ethylene homopolymer (C) or the ethylene / α-olefin copolymer (D) is 10 to 90% by weight, the high-pressure low-density polyethylene (E ) 10 to 90% by weight, preferably 20 to 80% by weight of linear ethylene homopolymer (C) or ethylene / α-olefin copolymer (D), 20 to 80% by weight of high-pressure low-density polyethylene (E) %, More preferably 20 to 50% by weight of linear ethylene homopolymer (C) or ethylene / α-olefin copolymer (D), 50 to 80% by weight (E) ((C) ), (D) and (E) are preferably a composition containing 100% by weight), because of having excellent easy-openability.

The polyethylene (B) of the present invention has a density measured by JIS K6922-1 (1997) of 927 to 947 kg / m ³ , preferably 930 to 942 kg / m ³ . When the density is less than 927 kg / m ³ , the oil resistance is poor, which is not preferable. On the other hand, when the density exceeds 947 kg / m ³ , although the oil resistance is high, the appearance when opened is not preferable.

  Further, such polyethylene (B) has an MFR measured by JIS K6922-1 (1997) of 2 to 30 g / 10 minutes, preferably 2 to 25 g / 10 minutes, and more preferably 3 to 20 g / 10 minutes. It is. When MFR is less than 2 g / 10 minutes or more than 30 g / 10 minutes, a laminate film cannot be stably produced, which is not preferable. Further, from the viewpoint of the appearance of the opening portion, the most preferable range of MFR is 10 to 20 g / 10 minutes.

In addition, the polyethylene (B) of the present invention includes additives such as antioxidants, lubricants, neutralizers, anti-blocking agents, surfactants, slip agents, etc., which are usually used for polyolefins, and other polyolefins, if necessary. It is also possible to add a thermoplastic resin.
Polyethylene (B) can be produced by a commonly used resin mixing device. For example, a single-screw extruder, a twin-screw extruder, a Banbury mixer, a pressure kneader, a melt kneader such as a rotating roll, a Henschel mixer, a V blender, a ribbon blender, a tumbler, and the like can be given. When using a melt kneader, the melting temperature is preferably about the melting point of polyethylene (B) to about 350 ° C.

  When the weight change rate after being immersed in edible oil (salad oil) at 60 ° C. for 24 hours by pressing a molded product (about 20 g) of polyethylene (B) with a size of 150 mm × 150 mm × 1 mm is 1.2% or less, This is preferable because delamination due to edible oil contained in the package is less likely to occur.

  Examples of the barrier film (A) include polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66, saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol, polypropylene resin, and acrylic resin. , Polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polycarbonate, films made of polymer polymers such as cellulosic resin, polyester, polyamide, polypropylene, ethylene-vinyl acetate copolymer saponified product, polyvinyl alcohol Preferably, the film is at least one film selected from the following group.

  Further, these barrier films (A) may be further subjected to aluminum vapor deposition, alumina vapor deposition, silicon dioxide vapor deposition, or acrylic treatment, and have a vapor deposition thin film made of a metal or metal oxide such as aluminum, alumina, or silica. It is preferable that

  Among these, a barrier film (A) which is a biaxially stretched polyester film or a polyamide film having one selected from the group consisting of an aluminum vapor deposition layer, an alumina vapor deposition layer, a silicon dioxide vapor deposition layer, and an acrylic treatment layer, Since adhesiveness with polyethylene (B) is favorable, it is preferable.

  Furthermore, in order for the barrier film (A) to have improved adhesion to the anchor coating agent, the surface of the barrier film (A) that contacts the anchor coating agent is subjected to corona treatment, flame treatment, plasma treatment, etc. It is preferable to perform known surface treatment.

  The anchor coating agent constituting the present invention is not particularly limited, and examples thereof include polyurethane adhesives, isocyanate adhesives, polyethyleneimine adhesives, polybutadiene adhesives, and the like. Of these, a polyurethane-based adhesive or an isocyanate-based adhesive is preferable because it is easy to open, and particularly the appearance when opened. Such a polyurethane-based adhesive or an isocyanate-based adhesive includes at least one polyol component having at least two hydroxyl groups in the molecule and at least one species having at least two isocyanate groups in the molecule. An adhesive composed of a polyisocyanate component, diisocyanate, an adduct of diisocyanate, a burette, an isocyanurate, and the like is preferable. The polyol component can be appropriately selected from polyester polyol, polyether polyol, acrylic polyol, polyolefin polyol, and the like. Diisocyanates include 4,4′-, 2,4′- and 2,2′-diisocyanate diphenylmethane, 1,5-diisocyanate naphthalene, 4,4′-diisocyanate dicyclohexylmethane, 1,4-diisocyanate benzene, and / or Aromatic diisocyanates such as 2,4- or 2,6-diisocyanate toluene, 1,6-diisocyanate hexane, 1,10-diisocyanate decane, 1,3-diisocyanate cyclopentane, 1,4-diisocyanate cyclohexane, 1-isocyanate- Illustrative are aliphatic and cycloaliphatic diisocyanates such as 3,3,5-trimethyl-3 or -5-isocyanatomethanecyclohexane. The polyisocyanate component can be produced from these diisocyanate monomers.

  Further, the polyurethane adhesive or the isocyanate adhesive is preferably -40 to 10 ° C. because the glass transition temperature measured according to JIS K7121 is easy to open, particularly the appearance at the time of opening is preferably -20 to 20 ° C. The range of 6 ° C is more suitable, and more preferably -15 to 0 ° C. The glass transition temperature can be adjusted by the polyol structure and the ratio of the polyol component and the isocyanate component.

  Such a polyurethane-based adhesive can be appropriately selected from commercially available products, and the product name NIPPOLAN 3228 and the like are commercially available from Nippon Polyurethane Industry Co., Ltd.

  The thickness of the polyurethane-based adhesive is not particularly limited, and a range of 0.01 to 3 μm is excellent in adhesiveness and easy opening, and a range of 0.1 to 1 μm is more preferable, and more preferably 0. .1 to 0.7 μm.

  Such an adhesive is applied to the barrier film (A) with a coater attached to a known extrusion laminator.

  The solvent used for diluting the adhesive is not particularly limited, but esters such as ethyl acetate, butyl acetate and cellosolve acetate, ketones such as acetone, methyl ethyl ketone, isobutyl ketone and cyclohexanone, tetrahydrofuran, dioxane and the like Exemplified ethers, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, alcohols such as dimethyl sulfoxide, dimethyl sulfoamide, methanol, ethanol and isopropanol, water, etc. be able to.

  The polyethylene (B) of the present invention can be extrusion laminated to each barrier film (A) via an anchor coating agent.

When subjected to extrusion lamination, in order to obtain good adhesion, at least the surface in contact with the anchor coating agent of the molten film made of polyethylene (B) extruded from the die is preferably oxidized by air or ozone gas. When the oxidation reaction with air proceeds, the temperature of the polyethylene (B) extruded from the die is preferably 290 ° C. or higher. When the oxidation reaction with ozone gas proceeds, the polyethylene (B) extruded from the die The temperature is preferably 200 ° C. or higher. Further, the treatment amount of ozone gas is preferably 0.5 mg or more per 1 m ^{2 of the} film made of polyethylene (B) extruded from the die. The film thickness of the layer made of polyethylene (B) is 5 to 25 μm, preferably 15-25 μm. When the film thickness of the layer made of polyethylene (B) is less than 5 μm, the substrate adhesion to the barrier film (A) and the oil resistance are inferior, and when it exceeds 25 μm, not only the economy is deteriorated but also the peeled appearance Gets worse.

It measured by 180 degree | times peeling (sample width: 15 mm, tensile speed: 300 mm / min) at the time of heat-sealing the layers which consist of polyethylene (B) of the laminated film which comprises this invention at 125 to 130 degreeC with a heat sealer. The heat seal strength is 3 to 20 N / 15 mm width, preferably 5 to 15 N / 15 mm width. When the heat seal strength is less than 3 N / 15 mm width, the contents are not sufficiently protected as a packaging material, and when the heat seal strength exceeds 20 N / 15 mm width, the heat seal strength is strong and the easy-openability is poor.
The easy-open packaging material of the present invention has excellent oil resistance and high base material adhesion to the barrier film (A), so that it can be easily opened in a wide variety of oil-based food packaging such as snacks and instant noodles. It is preferably used as a packaging material.

  Since the easy-open packaging material of the present invention has excellent oil resistance and base material adhesion to a barrier film, the easy-open packaging material has a wide variety of easy-open packaging, such as food packaging that requires oil resistance such as snacks and instant noodles. It can be used as a material.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.
(1) Melt mass flow rate (MFR)
It measured based on JISK6922-1 (1997).
(2) Density The density was measured in accordance with JIS K6922-1 (1997).
(3) Oil resistance About 20 g of the pellets obtained in the examples were press-molded using a 50-ton automatic press machine manufactured by Shinto Kogyo Co., Ltd. The size of the molded product was 150 mm × 150 mm × 1 mm. The obtained molded product was immersed in a 60 ° C. salad oil (trade name: Nissin Salad Oil) for 24 hours, and the weight change rate before and after immersion was investigated.
(4) Heat seal strength The laminate film obtained in the examples was heat-sealed by heating up and down at a seal temperature of 130 ° C., a seal pressure of 0.2 MPa, and a seal time of 1 second using a hot tack tester manufactured by Tester Sangyo Co., Ltd. Then, using a tensile tester (TENSILON RTE-1210 manufactured by ORIENTEC), the heat seal strength at 180 ° peeling was measured at a sample width of 15 mm and a tensile speed of 300 mm / min. Further, as a peel appearance, the occurrence of delamination on the peel surface was observed.
(5) Formability During extrusion lamination, it was confirmed whether molding defects such as film breakage and large width fluctuation did not occur and a stable laminate film could be obtained.

Example 1
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

As polyethylene (B), an ethylene / α-olefin copolymer having a melt mass flow rate of 20 g / 10 min and a density of 964 kg / m ³ (trade name Nipolon Hard 1000 manufactured by Tosoh Corporation) and a melt mass flow rate of 3 g / 10 min, density A single-screw extruder having a 924 kg / m ³ high-pressure low-density polyethylene (trade name Petrocene 205, manufactured by Tosoh Corporation, trade name: 25/75 by weight) and having a 50 mmφ screw and a strand die ((stock) Extruded into a strand shape at a set temperature of 180 ° C. and a discharge rate of 25 kg / hour, and pellets were formed using a strand cutter (manufactured by Seiwa Ironworks Co., Ltd.). This mixture was evaluated for MFR, density, and oil resistance. The results are shown in Table 1. Further, this mixture was supplied to an extrusion laminator having a 90 mmφ screw (manufactured by Musashinokikai Co., Ltd.), and the substrate take-up speed was set to 100 m / min. (A) Corona-treated surface of biaxially stretched polyester film (trade name Toyobo Ester Film E-5100, thickness 25 μm, hereinafter referred to as PET) manufactured by Toyobo Co., Ltd. Then, a polyurethane adhesive blended in the following ratio as an anchor coating agent layer was applied, the solvent was dried, and a laminate film obtained by extrusion lamination so that the polyethylene (B) had a thickness of 20 μm was obtained. This laminate film was used to evaluate heat seal strength and peel appearance. The results are shown in Table 2.

Polyurethane-based adhesive Polyester-based polyurethane resin (Nippon Polyurethane Co., Ltd., trade name NIPPOLAN 3228) and polyisocyanate (Nippon Polyurethane Co., Ltd., trade name Coronate L) are mixed at a weight ratio of 10/1, and ethyl acetate is added. Used to dilute to a solid content concentration of 7%. (Hereafter, it may be described as PU.)
Anchor coating layer thickness: 0.6 μm
Glass transition temperature: -10 ° C
Example 2
A laminate film was prepared in the same manner as in Example 1 except that the thickness of polyethylene (B) was 15 μm, and the physical properties of the obtained laminate film were evaluated. The results are shown in Tables 1 and 2.

Example 3
As polyethylene (B), an ethylene / α-olefin copolymer having a melt mass flow rate of 20 g / 10 min and a density of 964 kg / m ³ (trade name Nipolon Hard 1000 manufactured by Tosoh Corporation) and a melt mass flow rate of 3 g / 10 min, density A laminate film was prepared in the same manner as in Example 1, except that 924 kg / m ³ of high-pressure method low-density polyethylene (trade name Petrocene 205, manufactured by Tosoh Corporation) was used at a weight ratio of 40/60. Then, the physical properties of the obtained laminate film were evaluated. The results are shown in Tables 1 and 2.

Example 4
The same method as in Example 1 except that only the high pressure method low density polyethylene (trade name Petrocene 221 manufactured by Tosoh Corporation) having a melt mass flow rate of 6 g / 10 min and a density of 934 kg / m ³ was used as polyethylene (B). A laminate film was prepared and the physical properties of the obtained laminate film were evaluated. The results are shown in Tables 1 and 2.

Example 5
As polyethylene (B), an ethylene / α-olefin copolymer having a melt mass flow rate of 20 g / 10 min and a density of 964 kg / m ³ (trade name Nipolon Hard 1000 manufactured by Tosoh Corporation) and a melt mass flow rate of 8 g / 10 min, density 925 kg / m ³ ethylene / α-olefin copolymer (trade name Nipolon L M60, manufactured by Tosoh Corporation), melt mass flow rate 3 g / 10 min, high pressure method low density polyethylene (Tosoh Corporation) with a density of 924 kg / m ³ ), A laminate film was prepared in the same manner as in Example 1 except that the product name Petrocene 205) was used at a weight ratio of 20/5/75, and the physical properties of the obtained laminate film were evaluated. . The results are shown in Tables 1 and 2.

Example 6
As polyethylene (B), an ethylene / α-olefin copolymer having a melt mass flow rate of 20 g / 10 min and a density of 964 kg / m ³ (trade name Nipolon Hard 1000 manufactured by Tosoh Corporation) and a melt mass flow rate of 3 g / 10 min, density 936kg / ^{m 3} of ethylene · alpha-olefin copolymer (manufactured by Tosoh Corporation, trade name Niporon -L M50) and melt mass flow rate 24 g / 10 min, high-pressure low-density polyethylene having a density of 918 kg / ^{m 3} (Tosoh ( A laminate film was prepared in the same manner as in Example 1 except that a product having a weight ratio of 28/10/62 was used (trade name Petrocene 202), and the physical properties of the resulting laminate film were evaluated. did. The results are shown in Tables 1 and 2.

Example 7
A laminate film was produced in the same manner as in Example 1 except that the solid content concentration of the anchor coating agent was 3%. The results are shown in Tables 1 and 2.

Example 8
A laminate film was prepared in the same manner as in Example 1 except that a polyurethane-based adhesive blended at the ratio shown below was used as the anchor coating agent layer, and the physical properties of the obtained laminate film were evaluated. The results are shown in Tables 1 and 2.

Polyurethane adhesive Polyester polyurethane resin (Mitsui Chemicals, trade name Takelac A-3210) and polyisocyanate (Mitsui Chemicals, trade name Takenate A-3072) are mixed at a weight ratio of 3/1. The solution was diluted with ethyl acetate to a solid content concentration of 7%. (Hereafter, it may be written as PU2)
Anchor coating layer thickness: 0.6 μm
Glass transition temperature: 5 ° C
Example 9
A laminate film was prepared in the same manner as in Example 1 except that a polyethyleneimine-based adhesive blended at the ratio shown below was used as the anchor coating agent layer, and the physical properties of the obtained laminate film were evaluated. The results are shown in Tables 1 and 2.

A polyethyleneimine-based adhesive polyethyleneimine (trade name Toyobain 210K, manufactured by Tosoh Corporation) was diluted in a water / methanol mixed solvent (weight ratio 50/50) to a solid content concentration of 0.5%. (Hereafter referred to as PEI)
Anchor coating layer thickness: 0.1 μm
Example 10
Other than using an aluminum vapor-deposited polyester film (trade name: Diastar ST, thickness: 12 μm, hereinafter referred to as VPET, manufactured by Reiko) as the barrier film (A) layer from the first paper feeding unit Prepared a laminate film in the same manner as in Example 1, and evaluated the physical properties of the obtained laminate film. The results are shown in Tables 1 and 2.

Comparative Example 1
The same method as in Example 1 except that only the high pressure method low density polyethylene (trade name Petrocene 203 manufactured by Tosoh Corporation) having a melt mass flow rate of 8 g / 10 min and a density of 919 kg / m ³ was used as polyethylene (B). A laminate film was prepared and the physical properties of the obtained laminate film were evaluated. The results are shown in Table 1 and Table 2. The heat seal strength was strong and the easy-openability was poor, and the oil resistance was also poor.

Comparative Example 2
As polyethylene (B), the same method as in Example 1 was used except that high-pressure low-density polyethylene (trade name Petrocene 205, manufactured by Tosoh Corporation) having a melt mass flow rate of 3 g / 10 min and a density of 924 kg / m ³ was used. A laminate film was prepared and the physical properties of the obtained laminate film were evaluated. Although a result is shown in Table 1 and Table 2, the heat seal intensity | strength was strong and it was inferior to easy openability.

Comparative Example 3
As polyethylene (B), Example 1 was used except that only an ethylene / α-olefin copolymer having a melt mass flow rate of 21 g / 10 min and a density of 952 kg / m ³ (trade name Nipolon Hard 1200, manufactured by Tosoh Corporation) was used. An attempt was made to produce a laminate film in the same manner, but a stable laminate film could not be produced.

Comparative Example 4
A laminate film was prepared in the same manner as in Example 1 except that the thickness of polyethylene (B) was 30 μm, and the physical properties of the obtained laminate film were evaluated. Although a result is shown in Table 1 and Table 2, peeling (delamination) has arisen between the barrier film and polyethylene (B), and it was not preferred.

Claims (7)

A laminate film in which polyethylene (B) is extrusion laminated to at least a barrier film (A) through an anchor coating agent, and the polyethylene (B) is a linear ethylene homopolymer (C) or ethylene / α-olefin copolymer. 10 to 90% by weight of polymer (D), and 10 to 90% by weight of high-pressure process low density polyethylene (E) (total of (C), (D) and (E) is 100% by weight). An easy-open packaging material that satisfies the following requirements (a) and (b), and the layer made of polyethylene (B) satisfies the following requirements (c) and (d).
(A) The density measured based on JIS K6922-1 is 927 to 947 kg / m ^3.
(B) The melt mass flow rate measured based on JIS K6922-1 is 2 to 30 g / 10 min.
(C) Film thickness is 5 to 25 μm
(D) At a sealing temperature of 125 to 130 ° C., the heat seal strength at 180 ° peeling (sample width 15 mm, tensile speed of 300 mm / min) is 3 to 20 N / 15 mm width. The easy-open packaging material according to claim 1, wherein the anchor coating agent layer has a thickness of 0.1 to 1.0 µm. The easy-open packaging material according to claim 1 or 2 , wherein the anchor coating agent is a polyurethane adhesive or an isocyanate adhesive. The barrier film (A) is at least one film selected from the group consisting of polyester, polyamide, polypropylene, saponified ethylene-vinyl acetate copolymer and polyvinyl alcohol, and / or aluminum, alumina, silica. The easy-open packaging according to any one of claims 1 to 3 , which is at least one kind of vapor-deposited film selected from the group consisting of the barrier films having a vapor-deposited thin film made of metal or metal oxide. material. The easy-open packaging material according to any one of claims 1 to 4 , wherein the barrier film (A) is a biaxially stretched polyester film or a polyamide film having an aluminum vapor deposition layer. Polyethylene (B) of the press-molded product (150mm × 150mm × 1mm) to 60 ° C. The weight change rate when immersed for 24 hours in the edible oil is 1 to claim, characterized in that 1.2% or less 5 The easy-open packaging material according to any one of the above. The easily openable packaging material according to any one of claims 1 to 6 , wherein the packaging material is a package for fat and oil component-containing contents.