TW201800226A - Multi-layer resin film and shaping container with excellent thermoforming property, oxygen-blocking property, water vapor blocking property, and oil resistance to suppress warpage of the film - Google Patents

Abstract

The present invention provides a multi-layer resin film, which comprises a polyolefin-type resin layer that serves as a skin layer, jointing layers, an oxygen-blocking layer, and a polystyrene-type resin layer that serves as a bottom skin layer. An overall thickness of the film is 200~1300 [mu]m. A ratio of polyolefin-type resin layer thickness to the overall thickness of the film is 1~30%. The polyolefin-type resin layer is preferably formed of block polypropylene. The oxygen-blocking resin layer has a thickness that is preferably 10~50 [mu]m and has oxygen permeability thereof that is preferably below 10cc/m2*day and water vapor permeability thereof that is preferably below 10g/m2*day. The multi-layer resin film formed in this way has excellent thermoforming property, oxygen-blocking property, water vapor blocking property, and oil resistance, which can suppress warpage of the film.

Description

Multi-layer resin film and molded container

The invention relates to a multilayer resin film with high barrier properties and a molding container obtained by using the film.

Containers for traditional refreshing beverages, fruit drinks, and foods are made of polystyrene resins with excellent thermoformability and rigidity. In recent years, multilayer resin films and multilayer containers made from them have been promoted. This type of product uses a polystyrene resin layer as the outermost layer, with a bonding layer such as a modified olefin resin interposed therebetween, and then provides ethylene- The vinyl alcohol copolymer resin layer has a function of blocking oxygen, thereby preventing the content from being degraded due to oxidation (see Patent Document 1).

In addition, Patent Document 2 discloses a gas barrier film, which is characterized by using a gas barrier material containing a silicon-containing polymer and a thermoplastic resin, so that the glass transition temperature of the thermoplastic resin reaches 100 ° C or higher, and a plasma is applied to the gas barrier material. In the injection treatment, the silicon-containing polymer is a polysilazane compound, and the thermoplastic resin is at least one selected from the group consisting of a polycarbonate resin, a cycloolefin resin, and a polyfluorene resin.

In addition, an optical resin film having barrier properties against solvents such as oxygen, water vapor, and moisture, and solvent resistance has also been disclosed (see Patent Document 3).

Specifically, it is characterized in that a coating film containing a polysilazane inorganic polymer as a main component is formed on at least one side surface of an optically transparent resin film, and then it is cured by heating It is processed so as to have a gas barrier layer having a thickness of about 0.02 to 5 μm.

Patent Document 4 discloses a composite film which is formed by stacking a scent-resistant resin layer, an impact-resistant layer, a water vapor barrier resin layer, a gas barrier resin layer, and a thermoplastic support resin layer in this order. The fragrant resin layer is composed of a mixture of terephthalic acid, ethylene glycol, 1,4-cyclohexanedimethanol and other three-component copolymer resin and polybutylene terephthalate resin. The impact-resistant layer is composed of It consists of polyamide resin.

Patent Document 5 discloses a film which is excellent in mechanical properties such as barrier properties (especially oxygen barrier properties), formability, and rigidity. A polypropylene-based resin layer is laminated on one side of a barrier resin. The total thickness of the polypropylene resin layer accounts for 10 to 40% of the total film thickness.

In general, when foods and other items stored in containers contain polyphenols, tannins, catechins, etc., they will undergo oxidative deterioration due to their dissolved oxygen or oxygen invading from the outside of the container. In addition, in addition to the above, for example, the bifidobacteria in yogurt, etc. will also reduce the number of bacteria due to its dissolved oxygen or oxygen invading from the outside of the container.

For containers containing liquids such as milk drinks that contain a lot of water in the ingredients, if there is no layer with a water vapor barrier in the structure, the water in the ingredients will also escape to the outside of the container in the form of water vapor. The liquid becomes thick and is not easy to pour out, or the phenomenon of discoloration occurs.

In addition, when transporting a container holding food, in order to avoid damage to the container due to vibration during transportation and external temperature environment, and to prevent the quality of the food in the container from being degraded, multiple containers are stacked in the package for protection, or It is carried out by a temperature-controlled transportation method. However, many of the foods stored in containers contain oil and fat components. When there is a polar group in the molecular skeleton of the oil and fat component, it will enter the polar group of the resin constituting the container. The reaction reduces the strength of the container. If care is not taken during handling and storage, the contents of the container will flow out due to damage to the container.

The film disclosed in Patent Document 5 is formed of a polypropylene resin having oil resistance on the outermost surface of the film, and a resin composed of a styrene resin, a styrene-diene copolymer, and an olefin resin is combined. Layer as its supporting layer. However, laminating a crystalline polypropylene resin and a non-crystalline styrene resin together can easily warp the molded container, thereby changing the seal between the lid and the container of the container. Poor or the appearance of the container becomes bad.

Therefore, the above-mentioned Patent Documents 1 to 5 mainly focus on how to block components that adversely affect the contents of the container, such as oxygen and water vapor, but affect the oil resistance or the appearance and functionality of the container. There are no countermeasures for additional performances such as music.

Patent Document 1 Japanese Patent Laid-Open No. 11-58619

Patent Document 2 PCT International Patent Publication No. WO2013175911A1

Patent Document 3 Japanese Patent Laid-Open No. 8-169078

Patent Document 4 Japanese Patent Laid-Open No. 2000-108288

Patent Document 5 Japanese Patent No. 3967899

The present invention is a product developed after considering the above problems, and provides a multilayer resin film with high barrier properties and a molded container manufactured by using the film. The multilayer resin film has excellent thermoformability, oxygen barrier properties, and water vapor barrier properties. And oil resistance, and can suppress the film and its warpage after molding.

That is, a multilayer resin film of the present invention is formed by laminating a plurality of resin layers, and includes a polyolefin-based resin layer as a skin layer, a bonding layer, an oxygen barrier layer, and a polystyrene-based resin layer as a lower skin layer. The overall thickness of the film The thickness of the polyolefin-based resin layer is 200 to 1300 μm, and the layer composition ratio thereof is 1 to 30% compared to the thickness of the entire film.

In addition, as a preferred embodiment of the present invention, the polyolefin-based resin layer is formed of a block polypropylene, and the block polypropylene herein refers to a homogeneous propylene block as a continuous phase and formed of ethylene propylene rubber (EPR) and dispersed. Layer of stuff.

In addition, as a preferred embodiment of the present invention, the thickness of the polyolefin-based resin layer is less than or equal to 5% and less than 10% of the total layer thickness of the film.

In addition, as a preferred embodiment of the present invention, the thickness of the oxygen-barrier resin layer is 10 to 50 μm, and its oxygen transmission rate is 10 cc / m ² ˙day or less.

The water vapor transmission rate of the multilayer resin film having the above-mentioned structure is 10 g / m ² mday or less.

Furthermore, the present invention also provides a molded container formed by thermoforming a multilayer resin film having the above-mentioned structure. The polyolefin-based resin layer in the multilayer resin film is located on the inner surface of the container.

The multilayer resin film configured as described above and a molded container manufactured by using the film have excellent thermoformability, oxygen barrier property, water vapor barrier property, and oil resistance, and can suppress warping of the film and after molding.

10‧‧‧Polyolefin resin layer

11a, 11b‧‧‧ bonding layer

12‧‧‧ oxygen barrier resin layer

13‧‧‧polystyrene resin layer

FIG. 1 is a schematic longitudinal sectional view of a multilayer structure of a multilayer resin film according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a method for evaluating warpage of a multilayer resin film of the present invention.

FIG. 3 is a schematic diagram of a method for evaluating warpage of a molded container according to the present invention.

FIG. 4 is a schematic diagram of a method for evaluating oil resistance of the present invention.

As shown in FIG. 1, a multilayer resin film according to an embodiment of the present invention has a structure in which a polyolefin-based resin layer 10 as a skin layer is laminated on the outermost surface of the oxygen-barrier resin layer 12 via a bonding layer 11 a, and On the opposite side, a polystyrene resin layer is laminated via the same bonding layer 11b. The overall thickness of the film is 200 to 1300 μm, and the thickness of the polyolefin-based resin layer is 1 to 30% of the layer composition ratio compared to the overall thickness of the film. As a preferred embodiment, the thickness of the polyolefin-based resin layer is 2% or more and less than 10% of the layer composition ratio compared with the overall thickness of the film. As a further preferred solution, the thickness of the polyolefin-based resin layer is less than or equal to 5% and less than 10% of the total thickness of the film.

The above-mentioned multilayer resin film and a molded container manufactured by using the film will be described in detail below.

The layer structure of the multilayer resin film according to one embodiment of the present invention is: polyolefin resin layer / bonding layer / oxygen-barrier resin layer / bonding layer / styrene-based resin layer, which is simply a skin layer / bonding layer / oxygen barrier Layer / bonding layer / skin layer. The lower skin layer may be formed by adding a layer composed of the multilayered resin film of the present invention or a waste resin generated in a manufacturing process of a molded container or a layer composed of a waste product recovered after thermal fusion treatment.

In addition, on the lower skin layer side, for example, direct printing or laminated printing can be used. A thin film method is used to form the printed surface, but it is not limited to this.

The overall thickness of the film of the present invention is 200-1300 μm. If the overall thickness of the film is less than 200 μm, a thinner portion will be formed on the container after thermoforming, which will cause a decrease in the strength of a container called bending strength, which means resistance to compression or pressure. In this way, for example, when the contents are stored on the inner surface of the container, the container may be deformed or damaged due to vibration or compression generated during transportation and storage. On the other hand, if the overall thickness of the film exceeds 1300 μm, the thermal conduction in the thickness direction of the film is not good during thermoforming, which may cause forming defects.

)的測定拉伸或壓縮所承受的荷重的裝置來測定容器變形時的荷重。但不限於此。只要能較好對其進行評價的方法均可。 As the above-mentioned method for evaluating the bending strength, for example, the flange portion of the molded container can be stabilized downward on a flat surface, and then a hammer with a certain load can be placed on the bottom surface of the upper container, or its deformation can be confirmed, or Is called a push-pull gauge (

) A device for measuring the load subjected to tension or compression to measure the load when the container is deformed. But it is not limited to this. Any method can be used to evaluate it well.

The method for forming the multilayer resin film of the present invention is not particularly limited, and a conventional method can be used. For example, a method of using four or more uniaxial extruders to melt extrude each raw resin and obtain a multilayer resin film through a feed-block and a T-die, or through a multi-runner die Method for obtaining a multilayer resin film and the like.

The polyolefin-based resin layer 10 has a layer composition ratio of 1 to 30% compared to the entire thickness of the film. As a preferred embodiment, the thickness of the polyolefin-based resin layer is 2% or more and less than 10% of the layer composition ratio compared with the overall thickness of the film. As a further preferred solution, the thickness of the polyolefin-based resin layer is less than or equal to 5% and less than 10% of the total thickness of the film. The layer constitution ratio expressed here refers to a numerical ratio in which a value obtained by dividing the thickness of the polyolefin-based resin layer by the entire thickness of the film is expressed as a percentage. If the layer composition ratio of the polyolefin-based resin layer 10 is less than At 1%, especially when the overall thickness of the film is thin, the polyolefin-based resin layer does not have a sufficient thickness and may not exhibit its water vapor barrier function. In contrast, if the layer composition ratio of the polyolefin-based resin layer 10 exceeds 30%, the crystalline polyolefin-based resin layer constituting the skin layer tends to have a larger heat shrinkage during thermoforming. The non-crystalline styrenic resin layer of the skin layer tends to have a smaller heat shrinkage during thermoforming. Because the heat shrinkage of the skin layer and the lower skin layer are different, the film or the thermoformed container Warping may occur.

The skin layer 10 composed of the polyolefin-based resin layer of the present invention is basically located on the inner surface (the surface in contact with the contents) of a container formed by thermoforming a film. It is formed by making it have water vapor barrier property and oil resistance. In addition, for containers that need to store hot water, a resin that can withstand high temperatures above 90 ° C can also be selected to make it heat resistant.

The multilayer resin film having the above-mentioned structure has a water vapor transmission rate of 10 g / m2. less than day. As a preferred solution, its water vapor transmission rate is 5 g / m2. less than day. If its water vapor transmission rate exceeds 10g / m2. Day, the inner part of the thermoformed container will be deteriorated or discolored due to the transmission of moisture, making its water vapor barrier function impossible.

The polyolefin-based resin in the constitution of the present invention includes, but is not limited to, a single polymer having a carbon number of about 2 to 8 such as ethylene, propylene, and n-butene.

Examples of the polyolefin resin include high-density polyolefin (HDPE), linear low-density polyolefin (LLDPE), and low-density polyolefin (LDPE). In addition, as the polypropylene resin, any of a homopolymer, a random copolymer, and a block copolymer is applicable, but the present invention is preferably a block copolymer. As a block copolymer, a viscosity (Pa‧s) of 50000-1000000 at a measurement temperature of 190 ° C and a shear rate of 100-300 (1 / sec) is used. A resin having a viscosity change at 190 ° C to 230 ° C of 0.5 to 15 Pa · s / ° C is preferred. The polyolefin-based resin used can be appropriately mixed and used under the premise that the appearance of the film or the thermoformed container is not damaged.

As the oxygen-barrier resin constituting the oxygen-barrier resin layer 12, representative materials include, but are not limited to, ethylene-vinyl alcohol copolymer resin, polyamide resin, polyvinyl alcohol, polyvinyl chloride, and the like. Among these, an ethylene-vinyl alcohol copolymer resin is preferable from the viewpoint of processability and moldability.

The ethylene-vinyl alcohol copolymer resin is usually obtained by saponifying an ethylene-vinyl acetate copolymer. In order to have oxygen barrier properties, processability, and moldability, the ethylene content should be 10 to 65 mol% (preferably 20 to 50 mol). %), And the degree of saponification should be above 90% (preferably above 95%).

Examples of the polyamidoresin resin include: caprolactam, azatridecane-2-one, and the like; and 6-aminohexanoic acid, 11-aminoundecanoic acid, Amino acid ester polymers such as 12-aminododecanoic acid; 1,6-hexanediamine, 1,10-diaminodecane, dodecane diamine, 2,2,4- or 2,4,4 -Fatty diamines such as trimethylhexadiamine, alicyclic amines such as 1,3- or 1,4-bis (aminomethyl) cyclohexane, 4,4'-diaminodicyclohexylmethane, etc. Diamine units such as aromatic diamines such as xylylenediamine and p-xylylenediamine, and alicyclic carboxylic acids such as aliphatic carboxylic acids such as adipic acid, suberic acid, and sebacic acid, and cyclohexanedicarboxylic acid. Polycondensates formed from carboxylic acid units such as aromatic carboxylic acids such as acids, terephthalic acid, and isophthalic acid; and copolymers of the foregoing.

Examples of the polyamide resin include nylon 6, nylon 9, nylon 11, nylon 12, nylon 66, nylon 610, nylon 611, nylon 612, nylon 6T, nylon 6I, nylon MXD6, nylon 6/66, and nylon 6/610. , Nylon 6 / 6T, nylon 6I / 6T, etc. Among them, nylon 6, nylon MXD6 is the best.

The thickness of the oxygen-barrier resin layer 12 is set to 10 to 50 μm (preferably (20 to 40 μm). If the thickness is less than 10 μm, it may not be possible to achieve oxygen barrier properties that prevent the contents of the molded container from being degraded due to oxidation. In addition, if the thickness exceeds 50 μm, resin dents may occur during the stamping of the thermoformed container to affect the container Exterior.

The oxygen permeability of the oxygen-barrier resin layer 12 is 10 cc / m2. Day or less (preferably 5cc / m2.day or less). If its oxygen transmission rate exceeds 10cc / m2. At day, the inner part of the thermoformed container will be oxidized and deteriorated, so the oxygen barrier function cannot be fully exerted.

The resin constituting the bonding layers 11a and 11b in the present embodiment is preferably a modified polyolefin polymer. Representative examples of the modified olefin polymer constituting the bonding layer include the following: namely, individual polymers of polyolefins having a carbon number of about 2 to 8 such as ethylene, propylene, and n-butene; and these polyolefins and ethylene , Polypropylene, n-butene, isopentene, n-pentene, 4-methylpentene-1, 1-hexene, 1-octene, n-decene and other polyolefins with a carbon number of about 2 to 20 Or polyolefin resins such as copolymers of vinyl compounds such as vinyl acetate, vinyl chloride, acrylic acid, 2-methacrylic acid, acrylate, methyl methacrylate, and polystyrene; or ethylene-propylene copolymers, ethylene- Polyolefin rubbers such as propylene-diene terpolymers, ethylene-1-butene copolymers, and propylene-1-butene copolymers are compatible with acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, maleic acid, and Unsaturated carboxylic acids such as maleic acid, itaconic acid, citraconic acid, and tetrahydrophthalic acid, or derivatives of carboxylic acid halides, ammonium amines, ammonium imines, anhydrous substances, esters (specifically, malonyl chloride , Maleimide, anhydrous maleic acid, anhydrous citraconic acid, monomethyl maleate, maleic acid di ) Modifying substance under graft reaction conditions to give an ester, maleic acid glycidyl ester and the like.

As the modified polyolefin polymer, an ethylene-based resin, a propylene-based resin, ethylene-propylene, or n-butene modified with an unsaturated carboxylic acid or an anhydrous substance, particularly maleic acid or an anhydrous substance, is used. Copolymer rubber is preferred.

The thickness of the bonding layer is set to 5 to 50 μm (preferably 10 to 30 μm) regardless of the layer. If the thickness is less than 5 μm, sufficient interlayer bonding strength may not be obtained, and if the thickness exceeds 50 μm. Resin dents may occur during stamping of the thermoformed container and affect the appearance of the container.

Examples of the polystyrene-based resin constituting the polystyrene-based resin layer 13 in the present embodiment include polystyrene, 2-phenyl-1-propene, 4-methylstyrene, and dimethyl. Homopolymers or copolymers of polystyrene monomers, such as styrene, p-tert-butylstyrene, and chlorostyrene; such as polystyrene-acrylonitrile copolymers (AS resins) Copolymers of other monomers, or the aforementioned polystyrene monomers and other polymers, for example, in the presence of polybutadiene, polystyrene butadiene copolymer, polyisoprene, polychloroprene, etc. In the case of an olefinic rubber polymer, a graft polymer that undergoes graft polymerization, such as high impact polystyrene (HIPS resin), polystyrene-acrylonitrile graft polymer (ABS resin), and the like.

From the viewpoint of rigidity and moldability, polystyrene (GPPS resin) and high-impact polystyrene (HIPS resin) are preferred among the polystyrene resins. They can be used either singly or as a mixture.

As the polystyrene resin, the content percentage of the butadiene rubber component is preferably 4 to 8%. The content of the butadiene rubber component can be adjusted by a simple method of mixing GPPS and HIPS, but it can also be adjusted at the stage of manufacturing HIPS. If the above-mentioned quality percentage is less than 4%, sufficient container strength may not be achieved. If the above-mentioned quality percentage is more than 8%, inconveniences such as hot-plate adhesion may occur especially when using hot-plate for thermoforming.

The polystyrene-based resin layer 13 may be added with a colorant such as a pigment or a dye, a silicone oil or an alkyl ester-based release agent, or a fiber such as glass fiber, as needed, within a range that does not hinder the effects of the present invention. Vitamin-shaped strengthening agents, granular lubricants such as talc, kaolin, cristobalite, salt compounds such as sulfonic acids and alkali metals, or antistatic agents such as polyglycols, ultraviolet absorbers and antibacterial agents. At the same time, the multilayer resin film of the present invention and the waste resin generated in the manufacturing process of the molded container may be mixed and used.

The thickness of the polystyrene-based resin layer 13 in the present embodiment is set to 200 to 900 μm (preferably 300 to 700 μm). If the thickness is less than 200 μm, it may not be possible to achieve uniform thickness of each part of the container after molding, and excellent thermoformability may not be achieved. At the same time, if the thickness exceeds 900 μm, it is difficult to conduct heat sufficiently in the thickness direction of the film during thermoforming. Molding defects may occur.

As shown in FIG. 3, a molded container according to an embodiment of the present invention is formed by thermoforming a multilayer resin film of the present invention. Examples of the thermoforming method include a common vacuum forming method, a pressure forming method, a plunger assisting method in which a plunger is brought into contact with one side of a film, or a pair of male and female dies are brought into contact with both sides of a film to be formed. Counter-molding molding methods. But the method is not limited to this. Meanwhile, as a method of heating and softening the film before molding, non-contact heating using radiant heating by an infrared heater, or hot plate heating in which the film is brought into contact with the heated hot plate to soften it, can be used. heating method.

In addition, the molding temperature during thermoforming is reasonably set in consideration of the melting point of the resin, etc. However, if the film heating temperature is too low, the shape of the container after heating molding is insufficient, and if the film heating temperature is too high, it will cause adhesion. In the case of a hot plate or the like, it is necessary to set an appropriate temperature.

Examples and comparative examples will be listed below to further specifically describe the present invention, but the present invention is not limited to the scope of the examples and the like.

The resin raw materials used in the examples are shown below.

(1) Polyolefin resin layer

PP resin: "3080" (produced by Formosa Plastics Corporation, MI: 8.5g / 10min. (190 ° C, 2.16kgf), Block-PP)

(2) Oxygen-barrier resin layer

Ethylene-vinyl alcohol copolymer (EVOH) "EVAL J171B" (Produced by Kuraray, MI: 1.7g / 10min (190 ° C, 2.16kgf), ethylene content 32mol%)

(3) Joint layer

Modified polyolefin polymer (modified PO) "MODIC F502C" (Mitsubishi Chemical Corporation, MI: 1.3g / 10min (190 ° C, 2.16kgf))

(4) Polystyrene resin layer

HIPS resin: "4241" (manufactured by Total Petrochemicals, MI: 4.0g / 10min. (200 ° C, 5.0kgf))

Moreover, the multilayer resin film was heat-molded under the following conditions, and the container shown in FIG. 3 was obtained.

Equipment: Vacuum pressure molding machine manufactured by Asano Research Institute

Heater: Non-contact far infrared heater

Film surface temperature: Adjusted to a suitable film surface temperature according to the composition of the film

Various evaluations of the multilayer resin film and the container were performed by the following methods. The results are shown in Table 1.

(1) Evaluation of the warpage of the film

As shown in FIG. 2, at an angle of 45 ° with respect to the flow direction (MD) and width direction (TD) of the film, a 120 mm incision was cut, and the maximum warpage height of the film was measured with a ruler.

(2) Evaluation of warpage of the container

As shown in FIG. 3, 20 containers are formed in a multi-row type, and the size of each container is 44 mm in the horizontal direction, 55 mm in the vertical direction, and a draw ratio of 0.5. After stabilizing the flange portions of the plurality of rows of molded parts downward on a flat surface, use a ruler to measure the maximum height from the flat surface to the raised portion of the container / flange portion.

(3) Evaluation of oil resistance

The film was evaluated for oil resistance using the method shown in FIG. 4.

A film test piece having a width of 15 mm and a length of 200 mm was fixed in a circular arc shape between the fixtures under a stress condition, and a gauze soaked with soybean oil was placed on the uppermost part. At this time, the width of the fixture was 130 mm. Also, be careful not to let soybean oil get into the sides of the film. In order to prevent the soybean oil in the gauze from drying, soybean oil was dripped on the gauze every certain day, and the evaluation was performed for 30 consecutive days. Whether the film was cracked or broken was judged according to the following criteria.

A: There are no cracks or breaks at all

B: There is a little crack on the film surface

C: The film is completely broken

(4) Determination of oxygen transmission rate

The oxygen transmission rate of the film was measured by the following method.

[Measurement method] According to GB / T 1038 standard

Equipment: VAC-V1 detection device produced by Labthink

Measurement conditions: 23 ℃ × 65% R.H.

Sample setting: In view of the practicality of the container after molding, when setting the sample, make sure to face it so that oxygen can pass through the lower skin layer side of the thin film sample.

(5) Measurement of water vapor transmission rate

The water vapor transmission rate of the film was measured by the following method.

[Measurement method] According to GB / T 1037 standard

Equipment: W3 / 031 detection device produced by Labthink

Measurement conditions: 40 ℃ × 90% R.H.

(6) Moldability

Using the mold for molding the container shown in FIG. 3, the moldability at the time of thermoforming was evaluated by the following criteria.

A: Good moldability

B: Some parts of the container are thin after molding

C: No formability such as a molding die was obtained. Or found the appearance defect.

<Example 1>

Using three 45mm uniaxial extruders, one 65mm uniaxial extruder, and one 105mm uniaxial extruder, PP resin was used in the polyolefin resin through the feed-block method to obtain It has a layer structure of a polyolefin resin layer 10 of 40 μm / a bonding layer 11a of 15 μm / an oxygen barrier resin layer 12 of 40 μm / a bonding layer 11b of 15 μm / a polystyrene resin layer 13 of a layer structure of 340 μm. A multilayer resin film having a layer composition ratio of 9% and a total thickness of 450 μm.

The water vapor transmission rate of the multilayer resin film obtained above was measured. As shown in Table 1, the water vapor transmission rate was 0.8 g / m2. day. In addition, it is oxygen permeable The results of the over-rate measurement are shown in Table 1. The oxygen transmission rate was 0.5 cc / m2. day. In addition, as a result of evaluating the oil resistance of the multilayer resin film, the oil resistance was A, and as a result of evaluating the warpage of the multilayer resin film, the warp of the multilayer resin film was 13 mm. Furthermore, the moldability of a container formed by using the multilayer resin film was also evaluated. The moldability was evaluated as A. As a result of evaluating the warpage of the molded container, the warpage of the molded container was 0.

<Example 2>

In the same manner as in Example 1, 150 μm of the polyolefin-based resin layer 10/15 μm of the bonding layer 11 a / 15 μm of the oxygen barrier resin layer 12/15 μm of the bonding layer 11 b / 15 μm of the polystyrene-based resin layer 13 were obtained Layer structure, a multilayer resin film having a layer composition ratio of 17% and a total thickness of 900 μm.

The water vapor transmission rate of the multilayer resin film obtained above was measured. As shown in Table 1, the water vapor transmission rate was 0.7 g / m2. day. In addition, as a result of measuring the oxygen transmission rate thereof, as shown in Table 1, the oxygen transmission rate was 0.4 cc / m2. day. In addition, as a result of the oil resistance evaluation of the multilayer resin film, the oil resistance was A, and as a result of the warpage evaluation of the multilayer resin film, the warpage of the multilayer resin film was 15 mm. Furthermore, the moldability of a container formed by using the multilayer resin film was also evaluated. The moldability was evaluated as A. As a result of evaluating the warpage of the molded container, the warpage of the molded container was 0.

<Example 3>

In the same manner as in Example 1, a resin having a polyolefin resin layer 10 of 80 μm / a bonding layer 11a of 15 μm / an oxygen barrier resin layer 12 of 40 μm / a bonding layer 11b of 15 μm / a polystyrene resin layer 13 of 950 μm was obtained. Layer structure. The polyolefin resin layer has a layer composition ratio of 7% and a multilayer resin film with a total thickness of 1100 μm.

The water vapor transmission rate of the multilayer resin film obtained above was measured. As shown in Table 1, the water vapor transmission rate was 0.7 g / m2. day. In addition, as a result of measuring the oxygen transmission rate thereof, as shown in Table 1, the oxygen transmission rate was 0.6 cc / m2. day. In addition, as a result of the oil resistance evaluation of the multilayer resin film, the oil resistance was A, and as a result of the warpage evaluation of the multilayer resin film, the warp of the multilayer resin film was 9 mm. Furthermore, the moldability of a container formed by using the multilayer resin film was also evaluated. The moldability was evaluated as A. As a result of evaluating the warpage of the molded container, the warpage of the molded container was 0.

<Example 4>

In the same manner as in Example 1, a resin having a polyolefin-based resin layer 10 of 50 μm / a bonding layer 11a of 10 μm / oxygen-barrier resin layer 12 of 30 μm / a bonding layer 11b of 10 μm / polystyrene-based resin layer 13 of 900 μm was obtained. Layer structure. A multilayer resin film having a layer composition ratio of 5% and a total thickness of 1000 μm.

The water vapor transmission rate of the multilayer resin film obtained above was measured. As shown in Table 1, the water vapor transmission rate was 0.7 g / m2. day. In addition, as a result of measuring the oxygen transmission rate thereof, as shown in Table 1, the oxygen transmission rate was 0.7 cc / m2. day. In addition, as a result of the oil resistance evaluation of the multilayer resin film, the oil resistance was A, and as a result of the warpage evaluation of the multilayer resin film, the warp of the multilayer resin film was 7 mm. Furthermore, the moldability of a container formed by using the multilayer resin film was also evaluated. The moldability was evaluated as A. As a result of evaluating the warpage of the molded container, the warpage of the molded container was 0.

<Example 5>

In the same manner as in Example 1, 30 μm of polyolefin resin layer 10 was obtained / 20 μm of bonding layer 11a / 40 μm of oxygen barrier resin layer 12/20 μm of bonding layer 11b / The polystyrene-based resin layer 13 has a layer structure of 1090 μm, a multilayer resin film having a layer constitution ratio of 3% and a total thickness of 1200 μm.

The water vapor transmission rate of the multilayer resin film obtained above was measured. As shown in Table 1, the water vapor transmission rate was 0.7 g / m2. day. In addition, as a result of measuring the oxygen transmission rate thereof, as shown in Table 1, the oxygen transmission rate was 0.6 cc / m2. day. In addition, as a result of evaluating the oil resistance of the multilayer resin film, the oil resistance was A, and as a result of evaluating the warpage of the multilayer resin film, the warp of the multilayer resin film was 5 mm. Furthermore, the moldability of a container formed by using the multilayer resin film was also evaluated. The moldability was evaluated as A. As a result of evaluating the warpage of the molded container, the warpage of the molded container was 0.

In the above-mentioned Examples 1 to 5, the polyolefin-based resin is a PP resin, and the polyolefin-based resin may also be a single polyolefin polymer having a carbon number of about 2 to 8, such as ethylene, propylene, and n-butene. Any of them. In this case, the same effects as those of the first to fifth embodiments can be obtained.

On the other hand, compared with Example 1, the total thickness of the polyolefin-based resin layer or the thickness of the polystyrene-based resin layer serving as the skin layer is reduced, or a polystyrene-based resin layer is used to form a water vapor barrier layer. As a comparative example, the following modified examples were evaluated for their performance.

<Comparative example 1>

A single 65 mm uniaxial extruder was used to obtain a film having a 450 μm single layer structure of a polystyrene resin layer. Compared with Example 1, this comparative example is characterized in that the resin film has a single-layer structure composed of only a polystyrene-based resin layer.

As a result of measuring the water vapor transmission rate of the single-layer resin film obtained in this comparative example, as shown in Table 2, the water vapor transmission rate was 7.0 g / m2. day. In addition, it is oxygenated The results of the gas transmission rate measurement are shown in Table 2. The oxygen transmission rate was 350cc / m2. day. As a result of evaluating the oil resistance of the single-layer resin film, the oil resistance was C, and as a result of evaluating the warpage of the single-layer resin film, the warp of the single-layer resin film was 12 mm. Furthermore, the moldability of the container molded using this single-layer resin film was also evaluated. The moldability was evaluated as A. As a result of evaluating the warpage of the molded container, the warpage of the molded container was 0.

Compared with the results of each evaluation standard, the oxygen transmission rate is far more than 10cc / m2. At the same time, in the evaluation of its oil resistance, the film completely cracked, and its oil resistance was unqualified.

<Comparative example 2>

A multilayer resin film was obtained in the same manner as in Example 1 except that the skin layer was composed of a polystyrene resin.

As a result of measuring the water vapor transmission rate of the multilayer resin film obtained in this comparative example, as shown in Table 2, the water vapor transmission rate was 4.2 g / m2. day. In addition, as a result of measuring the oxygen transmission rate thereof, as shown in Table 2, the oxygen transmission rate was 1.2 cc / m2. day. As a result of the oil resistance evaluation of the multilayer resin film, the oil resistance was C, and as a result of the warpage evaluation of the multilayer resin film, the warpage of the multilayer resin film was 15 mm. Furthermore, the moldability of a container formed by using the multilayer resin film was also evaluated. The moldability was evaluated as A. As a result of evaluating the warpage of the molded container, the warpage of the molded container was 0.

As a result of comparison with each evaluation standard, in the evaluation of oil resistance, the film was completely broken, and its oil resistance was also unsatisfactory.

<Comparative example 3>

In the same manner as in Example 1, 200 μm of the polyolefin-based resin layer 10/15 μm of the bonding layer 11 a / 40 μm of the oxygen barrier resin layer 12/15 μ of the bonding layer 11 b were obtained. The m / polystyrene resin layer 13 has a layer structure of 330 μm, a multilayer resin film having a layer constitution ratio of 33% and a total thickness of 600 μm.

As a result of measuring the water vapor transmission rate of the multilayer resin film obtained above, as shown in Table 2, the water vapor transmission rate was 0.7 g / m2. day. In addition, as a result of measuring the oxygen transmission rate thereof, as shown in Table 2, the oxygen transmission rate was 0.8 cc / m2. day. As a result of the oil resistance evaluation of the multilayer resin film, the oil resistance was A, and as a result of the warpage evaluation of the multilayer resin film, the warpage of the multilayer resin film was 43 mm. Furthermore, the moldability of a container formed by using the multilayer resin film was also evaluated. The moldability was evaluated as C. As a result of evaluating the warpage of the molded container, the warpage of the molded container was 12 mm.

As a result of comparison with each evaluation standard, the warpage of the multilayer resin film was 43 mm, and the warpage of a container formed using the multilayer resin film was 12 mm, which did not solve the problems existing in the prior art. In addition, as a result of the evaluation of the moldability, no forming property such as a molding die was obtained, and thus the molded container was unacceptable.

<Comparative Example 4>

In the same manner as in Example 1, a resin having a polyolefin resin layer 10 of 25 μm / a bonding layer 11a of 10 μm / an oxygen barrier resin layer 12 of 30 μm / a bonding layer 11b of 10 μm / a polystyrene resin layer 13 of 120 μm was obtained. Layer structure, a multilayer resin film having a layer composition ratio of 13% and a total thickness of 195 μm.

The water vapor transmission rate of the multilayer resin film obtained above was measured. As shown in Table 2, the water vapor transmission rate was 0.9 g / m2. day. In addition, as a result of measuring the oxygen transmission rate thereof, as shown in Table 2, the oxygen transmission rate was 1.0 cc / m2. day. In addition, as a result of evaluation of the oil resistance of the multilayer resin film, the oil resistance was A, and the As a result of the warpage evaluation, the warpage of the multilayer resin film was 11 mm. Furthermore, the moldability of a container formed by using the multilayer resin film was also evaluated. The moldability was evaluated as B. As a result of evaluating the warpage of the molded container, the warpage of the molded container was 0.

As a result of comparison with each evaluation standard, the moldability was evaluated as B. In the process of use, when a thin portion of the container after the rupture occurred, water vapor or oxygen would invade and the barrier property would decrease.

<Comparative example 5>

In the same manner as in Example 1, 40 μm of the polyolefin-based resin layer 10/15 μm of the bonding layer 11 a / 15 μm of the oxygen barrier resin layer 12/15 μm of the bonding layer 11 b / polyolefin resin layer (the lower skin layer and the outer skin) The layer uses the same resin) as a layer structure of 340 μm, a multilayer resin film having a layer constitution ratio of 84% of a polyolefin-based resin layer and a total thickness of 450 μm.

As a result of measuring the water vapor transmission rate of the multilayer resin film obtained above, as shown in Table 2, the water vapor transmission rate was 0.7 g / m2. day. In addition, as a result of measuring the oxygen transmission rate thereof, as shown in Table 2, the oxygen transmission rate was 0.8 cc / m2. day. In addition, as a result of the oil resistance evaluation of the multilayer resin film, the oil resistance was A, and as a result of the warpage evaluation of the multilayer resin film, the warp of the multilayer resin film was 9 mm. Furthermore, the moldability of a container formed by using the multilayer resin film was also evaluated. The moldability was evaluated as B. As a result of evaluating the warpage of the molded container, the warpage of the molded container was 0.

As a result of comparison with each evaluation standard, the moldability was evaluated as B. In the process of use, when a thin portion of the container after the rupture occurred, water vapor or oxygen would invade and the barrier property would decrease.

Table 1

Based on the results of Examples 1-3 and Comparative Examples 1-5, the multilayer resin film of the present invention is formed by laminating multiple resin layers, and includes a polyolefin-based resin layer as a skin layer, a bonding layer, an oxygen barrier layer, and The thickness of the polystyrene resin layer in the lower skin layer is 200 to 1300 μm, and the thickness of the polyolefin resin layer is 1 to 30% compared to the thickness of the film. It has excellent thermoformability and oil resistance, and can suppress warping of the film.

The thickness of the oxygen-barrier resin layer is 10 to 50 μm, and the oxygen transmission rate thereof is 10 cc / m ² mday or less. The water vapor transmission rate of the multilayer resin film having the above-mentioned structure is 10 g / m ² ˙day or less.

Therefore, the multilayer resin film configured as described above has excellent thermoformability, oxygen barrier property, water vapor barrier property, and oil resistance, and can suppress warping of the film.

In addition, the molded container manufactured by using the multilayer resin film configured as described above has excellent thermoformability, oxygen barrier property, water vapor barrier property, and oil resistance, and can suppress warpage after molding.

10‧‧‧Polyolefin resin layer

11a, 11b‧‧‧ bonding layer

12‧‧‧ oxygen barrier resin layer

13‧‧‧polystyrene resin layer

Claims (6)

A multilayer resin film, which is formed by laminating multiple resin layers, characterized in that the multilayer resin film has a polyolefin-based resin layer as a skin layer, a bonding layer, an oxygen barrier layer, and a polystyrene-based resin layer as a lower skin layer, The overall thickness of the film is 200 to 1300 μm, and the thickness of the polyolefin-based resin layer is 1 to 30% of the layer composition ratio compared to the overall thickness of the film. The multilayer resin film according to item 1 of the patent application scope, wherein the polyolefin-based resin layer is formed of block polypropylene. The multilayer resin film according to item 1 or 2 of the scope of application for a patent, wherein the thickness of the polyolefin-based resin layer is less than or equal to 5% and less than 10% of the total thickness of the film. The multilayer resin film according to item 3 of the scope of patent application, wherein the thickness of the oxygen-barrier resin layer is 10 to 50 μm, and the oxygen transmission rate thereof is 10 cc / m ² ˙day or less. The multilayer resin film according to item 4 of the scope of application for a patent, wherein a water vapor transmission rate of the multilayer resin film is 10 g / m ² ˙day or less. A molded container formed by thermoforming a multilayer resin film according to any one of claims 1 to 5, and the polyolefin-based resin layer in the multilayer resin film is located on the inner surface of the container.