JP2011255931A - Cold-forming press-through pack packaging material including biaxially stretched nylon film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure stable moldability without occurrence of a pinhole, breaking or the like of aluminum foil being a barrier layer even during cold molding of a forming depth or every mold shape, in a cold-forming packaging material used for a press-through pack wherein high dampproofness, barrier properties, light shielding properties, pinking resistance, and pinhole resistance are required.SOLUTION: This cold-forming press-through pack packaging material uses, as a main base material, a biaxially stretched nylon film adjusted such that both the static friction coefficient and the kinetic friction coefficient are 0.30 or below, that breaking strength of all of four directions in a uniaxial tension test is 270 MPa or above, and that the 50% modulus value is 140 MPa or above.

Description

The present invention relates to a press-through pack packaging material for cold forming including a biaxially stretched nylon film having good surface slipperiness and excellent mechanical strength characteristics.

A press-through pack is a food or pharmaceutical product such as a tablet formed in a recess formed on a plastic sheet such as vinyl chloride or polypropylene with a recess formed by hot vacuum forming, hot air pressure forming, hot vacuum air forming, etc. And then sealed with a lid material such as an aluminum foil, a thin rigid plastic sheet, or a flexible film. Since the contents can be easily removed by pushing the finger from the direction of the convex part filled with the contents and tearing the sealing material such as aluminum foil, it has been used for packaging of tablets, capsules of foods, supplements and pharmaceuticals. Yes.

Depending on the contents, there are those that extremely dislike moisture and ultraviolet rays from the outside, and those that contain volatile components, in which case an aluminum foil may be used for the bottom material. However, since the aluminum foil itself has poor moldability and is easily broken, a laminate film obtained by laminating a base material such as a biaxially stretched polyester film or a biaxially stretched nylon film (hereinafter referred to as ONy film) is usually used. The laminate film containing the aluminum foil is formed into a cold (room temperature) shape using a press machine, filled with the contents, and then covered with a lid containing the aluminum foil and heat sealed. can get.

In particular, an aluminum foil laminated with an ONy film as a base material can be used suitably when a large tablet or capsule is used as a filler because very good cold formability is obtained. However, even in this case, there is a problem that pinholes and cracks in the aluminum foil are likely to occur depending on the shape of the filler and the molding conditions, and there is room for improvement in terms of molding stability, in which a sharp shape is formed deeply and stably. was there.

As mentioned above, regarding the main quality issues of the cold-forming packaging material consisting of the base material layer, the barrier layer, and the sealant layer used in the press-through pack with the aluminum foil as the bottom material, that is, ensuring excellent cold formability, Various proposals have been made so far. For example, Patent Document 1 discloses a method for improving moldability by using an ONy film in which a ratio of hot water shrinkage in MD and TD (MD / TD ratio) is limited to a certain range as a base material layer. A method of coating the surface of a material with a fatty acid amide-based slipperiness-imparting component to improve the moldability by improving slipping into the mold during molding, and Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document No. 6 pays attention to the strength properties of the base material layer such as nylon film, and a method of reinforcing the aluminum foil using a base material having little anisotropy and properties such as high strength or high elongation has been proposed. Yes.

Japanese Patent No. 3983131 JP 2002-216714 A Japanese Patent No. 3567230 JP 2006-236938 A JP 2008-44209 A JP 2005-22336 A

However, the method of limiting the ratio of the hot water shrinkage ratios in MD and TD of the ONy film to a certain range does not lead to an improvement in essential moldability although a certain degree of effect is seen in the cold moldability. In addition, the method of coating the surface of the base material layer with the slipperiness imparting component has to provide a coating step, which has a problem that productivity is lowered. In addition, the slipperiness imparting component evaporates during the heat sealing process, and the evaporated component adheres to the processing equipment, so that a cleaning operation for removing them is necessary, which further reduces productivity. . In addition, the method of reinforcing the aluminum foil using a substrate having a high tensile strength or a high elongation has no particular description regarding the slipperiness of the substrate surface, and depending on the state of the substrate surface, the tensile strength or the elongation In some cases, the effect of improvement is reduced, and improvement of moldability is insufficient.

As a result of diligent research, the inventors of the present invention have used the ONy film having a tensile break strength and a friction coefficient limited to a certain range as a base layer for a cold-through press-through pack packaging material. As a result, the present inventors have found that it is possible to achieve excellent cold formability, which has been a major problem, and have completed the present invention. That is, the present invention provides the following means.

[1] In a cold forming press-through pack packaging material composed of a base material layer, a barrier layer, and a sealant layer, a uniaxial tensile test (sample width 15 mm, distance between chucks 100 mm, tensile speed 200 mm / min.) Is used as the base material layer. In all four directions (0 ° (MD), 45 °, 90 ° (TD), 135 °), the breaking strength is 270 MPa or more, the coefficient of static friction, and the coefficient of dynamic friction (23 ° C. × 50% RH, film to film) A press-through pack packaging material for cold forming, characterized by using a biaxially stretched nylon film in which all are 0.30 or less.

[2] The biaxially stretched nylon film has four directions (0 ° (MD), 45 °, 90 ° (TD)) in a uniaxial tensile test (sample width 15 mm, distance between chucks 100 mm, tensile speed 200 mm / min.), 135) The press-through pack packaging material for cold forming according to item 1 above, wherein all 50% modulus values are 140 MPa or more.

[3] A container using the cold-forming press-through pack packaging material according to any one of the preceding items 1 and 2 to form a concave portion by overhang molding or deep drawing so that the sealant layer is on the inner surface. .

[4] A press-through pack characterized in that the contents are stored in the concave portion of the container according to item 3 and sealed.

In the present invention, a biaxially stretched nylon film having both a static friction coefficient and a dynamic friction coefficient of 0.30 or less, low anisotropy and high tensile strength is used as a cold forming packaging material, particularly a press-through pack packaging material. By using it as a base material, it is possible to ensure stable formability without the occurrence of breakage of aluminum foil, pinholes, etc. even during cold forming with any mold shape and molding depth.

The best mode for carrying out the present invention will be described below.
(Raw Material of Biaxially Stretched Nylon Film) The raw material of the biaxially stretched nylon film of the present invention (hereinafter “ONy film”) is not particularly limited as long as it is a polyamide resin. For example, nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6, 66, 12 copolymer, other polyamide copolymers, nylon MXD6, aramid, polyamideimide (PAI), aromatic Polyimide, polyetherimide (PEI), polymaleimidoamine (PMIA), polyaminobismaleimide (PABM), etc. are mentioned. Nylon 6 is used from the viewpoint of film physical properties such as productivity, cold formability and strength properties. Most preferred. In the nylon 6 raw material, the number average molecular weight is preferably 10,000 to 30,000, particularly preferably 22,000 to 24,000. When the number average molecular weight is less than 10,000, the impact strength and tensile strength of the obtained ONy film are insufficient. When the number average molecular weight is larger than 30000, the molecular chain is entangled excessively and excessive strain is generated by the stretching process. Therefore, breakage and puncture frequently occur during the stretching process, and stable production cannot be achieved.

(Manufacturing method of ONy film) The ONy film of the present invention has a draw ratio of 2.8 to 4.0 times for MD and TD, respectively, with respect to an unstretched raw film composed of any of the polyamide-based raw materials It is obtained by heat-treating at a temperature of 150 ° C. or higher and 200 ° C. or lower after performing a biaxial stretching process under the following conditions. The draw ratio is preferably in the range of 2.8 to 4.0 times each of MD and TD, particularly preferably in the range of 3.0 to 3.4 times. When the draw ratio is less than 2.8 times, the impact strength and tensile strength of the obtained ONy film are insufficient. Further, when the ratio is 4.0 times or more, excessive molecular chain distortion occurs due to stretching, and thus breakage and puncture frequently occur during stretching and stable production cannot be achieved. Examples of the biaxial stretching method include simultaneous biaxial stretching by a tubular method or a tenter method, or sequential biaxial stretching, but simultaneous biaxial stretching by a tubular method is preferable from the viewpoint of longitudinal and lateral strength balance. By performing biaxial stretching in this manner, an ONy film having particularly improved strength properties and excellent cold formability can be obtained.

An ONy film of the present invention can be obtained by putting the obtained stretched film into a heat roll system or a tenter system, or a heat treatment facility combining them for an arbitrary time, and performing a heat treatment at 150 ° C. or more and 200 ° C. or less. it can. When the heat treatment temperature is higher than 200 ° C., the bowing phenomenon becomes too large and the anisotropy in the width direction increases, or the crystallinity becomes too high, resulting in a decrease in strength properties. On the other hand, when the heat treatment temperature is lower than 150 ° C., the slipperiness of the ONy film surface is lowered, so that the moldability is deteriorated. In addition, since the thermal dimensional stability of the film is also greatly reduced, the film is easily shrunk during the laminating process, which causes a practical problem.

The thickness of the ONy film is preferably 5 to 50 μm, more preferably 10 to 30 μm. When the thickness is less than 5 μm, the impact resistance of the laminate packaging material becomes low, and the cold formability becomes insufficient. On the other hand, when the thickness exceeds 50 μm, the strength for maintaining the shape is improved, but the effect for preventing breakage and improving the moldability is small, and only the volume energy density is reduced.

The uniaxial tensile strength at break and the 50% modulus value in four directions (0 ° (MD), 45 °, 90 ° (TD), 135 °) of the ONy film are determined by a uniaxial tensile test (sample width: 15 mm, distance between gauge points: 50 mm). , From a stress-strain curve obtained by a tensile speed of 200 mm / min). In this stress-strain curve, the tensile breaking strength in the four directions is preferably 270 MPa or more. As a result, the ONy film and aluminum foil are difficult to break during cold forming even in the case of a mold shape with a large forming depth, which is generally considered difficult to form, ensuring stable and excellent formability. I can do it. If the tensile breaking strength is less than 270 MPa in any one of the four directions, the ONy film easily breaks during cold forming, and the forming depth that requires tensile strength at high elongation is particularly high. When molding a large mold shape, stable moldability cannot be obtained. Further, in the stress-strain curve, the 50% modulus values in the four directions are preferably 140 MPa or more. Thereby, stable moldability can be ensured particularly when a mold shape having a relatively small molding depth is molded. When the 50% modulus value is less than 140 MPa or more in any one of the four directions, the ONy film easily breaks during cold forming, and stable moldability cannot be obtained.

The film-to-film static friction coefficient and dynamic friction coefficient at 20 ° C. × 50% RH of the ONy film are preferably 0.30 or less. If either the static friction coefficient or the dynamic friction coefficient of the ONy film is larger than 0.30, the ONy film slips into the mold at the time of molding, and the aluminum foil tends to break or pinhole due to stress concentration. Therefore, it is not preferable.

In order to control the friction coefficient, an ONy film can be produced by adding a slip agent or a filler to the polyamide resin in advance. Examples of the slip agent include acid amides, alkali metal salts and / or alkaline earth metal salts of saturated or unsaturated fatty acids, alkali metal salts and / or alkaline earth metal salts of hydroxy saturated or unsaturated fatty acids, and the like. These lubricants bleed on the film surface and have a function of reducing the surface energy. The filler is not particularly limited as long as it uniformly disperses in the nylon resin and forms fine protrusions on the surface, and includes an organic or inorganic filler. The filler shape is not particularly limited, and may be powder, particle, flake, plate, fiber, needle, cloth, mat, or any other shape. Those are preferred. The average particle diameter of the filler particles is preferably 0.5 to 8 μm. It is desirable that substantially no particles having a particle size of 8 μm or more are contained. Particles having a particle diameter of 8 μm or more not only cause gel generation and deteriorate the appearance of the film, but also easily cause film breakage in the film forming process, which causes a decrease in operability. On the other hand, if the average particle size is less than 0.5 μm, effective projections are hardly formed on the film surface, and the friction coefficient of the present invention cannot be achieved. Specific examples of the filler particles include organic materials such as PMMA, Ny, PTFE, styrene, and cellulose, and inorganic materials such as silica, kaolin, and zeolite, but are not particularly limited, and two or more of these may be used. You can use it.

(Configuration of Laminate Wrapping Material, Laminating Method) The present laminating packaging material preferably has a barrier layer as an intermediate layer, a base material layer on one side of the barrier layer, and a sealant layer on the other side of the barrier layer. . As the base material layer, it is preferable to use at least one ONy film described above, and as the barrier layer, it is preferable to use a pure aluminum foil or an aluminum foil made of a soft material of an aluminum-iron-based alloy. Examples thereof include polyethylene, polypropylene, maleic acid-modified polypropylene, maleic acid-modified polyethylene, an ethylene-acrylate copolymer, an ionomer resin, and polyvinyl chloride for imparting chemical resistance. The layers of the base material layer, the barrier layer, and the sealant layer can be laminated by a known method. For example, lamination can be performed by a dry laminating method using an adhesive such as polyester, polyurethane, or polyester urethane.

The total thickness of the laminate base material including the aluminum foil and the ONy film is preferably 200 μm or less. When the thickness exceeds 200 μm, it becomes difficult to form the corner portion by cold forming, and a molded product having a sharp shape may not be obtained.

The thickness of the aluminum foil layer is preferably 20 to 100 μm. Thereby, it becomes possible to hold | maintain the shape of a molded article favorably, and it can prevent that oxygen, a water | moisture content, etc. penetrate | invade into a packaging material. When the thickness of the aluminum foil layer is less than 20 μm, the aluminum foil layer is likely to break during cold forming of the laminate packaging material, and pinholes and the like are likely to occur even when the laminate packaging is not broken. Or moisture may enter. On the other hand, when the thickness of the aluminum foil layer exceeds 100 μm, the effect of preventing breakage and pinhole generation during cold forming is not greatly improved, and only the total thickness is not preferable.

The present invention will be specifically described below with reference to examples and comparative examples.
Example 1 (Production of Biaxially Stretched Nylon Film) Nylon 6 pellets (relative viscosity 3.48) containing 700 ppm of sodium ethylenebisstearate and 900 ppm of 2 μm silica fine particles were melt-kneaded at 255 ° C. in an extruder. The melt was extruded as a cylindrical film from a die and subsequently quenched with water to produce a raw film. Next, as shown in FIG. 1, the raw film is inserted between a pair of low-speed nip rolls 1 and then heated by the heater 2 and the heater 3 while air is being pressed into the film. By blowing air from the ring 4, MD and TD simultaneous biaxially stretched films 5 by the tubular method were obtained. The draw ratio was 3.0 times for MD and 3.2 times for TD. Next, this stretched film 5 was put into a heat roll type and tenter type heat treatment facility, respectively, and heat treated at 180 ° C. to obtain an ONy film. The ONy film had a thickness of 25 μm.

(Uniaxial tensile breaking strength of ONy film, evaluation method of 50% modulus value) For the evaluation method of uniaxial tensile breaking strength of ONy film and 50% modulus value, Tensylon (RTC-1210-A) manufactured by Orientec was used. The test was carried out at a width of 15 mm, a gap between chucks of 100 mm, and a tensile speed of 200 mm / min. The ONy film was subjected to humidity control for 2 hours in an environment of 23 ° C. × 50%, and then measured in each of four directions of 0 ° (MD) direction / 45 ° direction / 90 ° (TD) direction / 135 ° direction. Based on the obtained stress-strain curve, the breaking strength in each direction and the 50% modulus value were determined.

(Friction coefficient evaluation method of ONy film) Static friction coefficient and dynamic friction coefficient of ONy film were measured by JISK7125 (plastic-film and sheet-friction coefficient test method) using Toyo Seiki-friction measuring machine (TR-2). Thread mass 200 g (contact area 38 cm ² ), sled moving speed 150 mm / min. It carried out in. The ONy film was conditioned for 2 hours in an environment of 23 ° C. × 50%, and then measured for the film to film to determine the static friction coefficient and the dynamic friction coefficient.

(Cold Formability Evaluation Method) The cold formability of the laminate packaging material including the aluminum foil and the ONy film was evaluated. Specifically, first, the obtained ONy film was used as a base layer, and an aluminum foil (thickness 40 μm) and an unstretched polypropylene film [Pyrene Film CT-P1128 (trade name), manufactured by Toyobo Co., Ltd., thickness 30 μm] were each dried. A laminate packaging material was obtained by laminating (dry coating amount: 4.0 g / m ² ). In addition, Toyo Morton Co., Ltd. TM-K55 / Toyo Morton Co., Ltd. CAT-10 (mixing ratio 100/8) was used as an adhesive for dry lamination. The laminate packaging material after dry lamination was aged at 60 ° C. for 72 hours. The laminate packaging material thus obtained was conditioned at 23 ° C. × 50% for 2 hours, and then used a compression mold (38 mm × 38 mm) with a maximum load of 10 MPa from the unstretched polypropylene film side. Molding was carried out cold (room temperature), and the maximum molding depth at which defects such as pinholes and cracks did not occur was evaluated at 0.5 mm pitch.

Comparative example 1 In Example 1, it carried out similarly to Example 1 except having put the stretched film into the heat roll and the tenter type heat treatment equipment, and heat-treating at 210 degreeC.

Comparative example 2 In Example 1, it carried out similarly to Example 1 except having put the stretched film into the heat roll and the tenter type heat treatment equipment, and heat-treating at 220 degreeC.

Comparative Example 3 The same procedure as in Example 1 was performed except that a biaxially stretched nylon film (Harden film-N1102, thickness 25 μm) manufactured by Toyobo was used as the ONy film.

Comparative example 4 In Example 1, it carried out similarly to Example 1 except having put the stretched film into the heat roll and the tenter type heat treatment equipment, and heat-treating at 140 degreeC.

As shown in Table 1, Examples in which both the static friction coefficient and the dynamic friction coefficient of the ONy film were adjusted to 0.30 or less, the breaking strength in all four directions in the uniaxial tensile test was adjusted to 270 MPa or more, and the 50% modulus value was adjusted to 140 MPa or more. In No. 1, excellent moldability could be secured. On the other hand, when either the static friction coefficient or the dynamic friction coefficient of the ONy film is greater than 0.30, or the breaking strength in any of the four directions is less than 270 MPa and the 50% modulus value is less than 140 MPa, the moldability is reduced. It was. Therefore, none of Comparative Examples 1 to 4 was able to ensure excellent moldability. The numerical value of the maximum molding height, which is an index of cold formability, varies depending on the conditions such as the shape of the mold, but when molded and measured under the same conditions, a difference of 0.5 mm is actually useful. A difference comes out in sex.

The laminate packaging material of the present invention is suitably used as a packaging material for a press-through pack that requires high moisture resistance, barrier properties, light shielding properties, puncture resistance, and pinhole resistance.

Process drawing of the tubular extending | stretching apparatus which manufactures the ONy film in the said embodiment.

1 Tubular stretcher nip roll 2 Tubular stretcher preheating heater 3 Tubular stretcher main heat heater 4 Tubular stretcher cooling air ring 5 Tubular stretcher film

Claims (4)

In a cold forming press-through pack packaging material comprising a base material layer, a barrier layer, and a sealant layer, four directions in a uniaxial tensile test (sample width 15 mm, distance between chucks 100 mm, tensile speed 200 mm / min.) Are used as the base material layer. (0 ° (MD), 45 °, 90 ° (TD), 135 °) All the breaking strengths are 270 MPa or more, and the static friction coefficient and the dynamic friction coefficient (23 ° C. × 50% RH, film to film) are all A press-through pack packaging material for cold forming, wherein a biaxially stretched nylon film having a thickness of 0.30 or less is used. The biaxially stretched nylon film has four directions (0 ° (MD), 45 °, 90 ° (TD), 135 °) in a uniaxial tensile test (sample width 15 mm, distance between chucks 100 mm, tensile speed 200 mm / min.). The press-through pack packaging material for cold forming according to claim 1, wherein all 50% modulus values are 140 MPa or more. A container using the cold-forming press-through pack packaging material according to any one of claims 1 to 2 and forming a concave portion by stretch molding or deep drawing so that a sealant layer is an inner surface. A press-through pack, wherein the contents are stored in a concave portion of the container according to claim 3 and sealed.

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