JP5510169B2 - Film for deep drawing - Google Patents

Description

  The present invention relates to a deep drawing film.

Thermoplastic resins typified by polyolefin resins can be kept in a fixed shape by thermoforming such as vacuum molding and pressure forming, and the molded products are used as packaging materials for packaging various articles. ing. In particular, polyolefin resins are widely used as packaging materials for packaging medical devices and pharmaceuticals because they can be sterilized by radiation. As an example of a packaging method using such a packaging material, for example, the packaging material is provided with a recess by deep drawing which is a kind of thermoforming, the medical device is accommodated in the recess, and the opening of the recess is formed in a sheet shape. The method of sealing with a cover material is mentioned. In the case of a medical instrument, radiation sterilization is usually further performed after sealing.
However, polyolefin resins, in particular polyethylene resins, have poor thermoformability, and when a concave portion is formed on the film by deep drawing, there is a problem that adhesion to a mold, deformation in shape, and the like occur. In order to solve such a problem, Patent Document 1 discloses a layer made of a specific ethylene-propylene copolymer composition as a film having good radiation resistance, heat-forming property, etc. and suitable for packaging of medical devices and the like. A laminate having at least one layer (layer A) and at least one layer (layer B) composed of a composition obtained by blending an ethylene-propylene block copolymer and a specific ethylene-α-olefin copolymer at a specific ratio has been proposed. ing.

  On the other hand, as a method for improving the properties of the film, a method of blending a modifier is known. For example, Patent Document 1 proposes a method for improving the workability of a vinyl chloride resin by blending a methyl methacrylate polymer or a methyl methacrylate-alkyl acrylate copolymer having a specific reduced viscosity. Patent Document 2 proposes a method for improving the processability of a vinyl chloride resin by blending polytetrafluoroethylene having a specific molecular weight.

Japanese Patent Publication No. 7-020690 Japanese Patent Publication No. 40-5311 Japanese Patent Laid-Open No. 5-117472

A film containing a polyolefin-based resin as a main component has a problem that the thickness becomes extremely thin when deep drawing is performed. This problem is particularly noticeable when the shape of the recess is complicated or when the depth of the recess is deep. Therefore, the molded product is likely to have a problem such as a hole being formed when it is transported after accommodating a medical instrument to form a package. In extreme cases, holes may be formed at the molding stage.
The laminate described in Patent Document 1 is said to have good heat-forming properties and various physical properties after molding (breaking strength, impact strength, etc.). However, the laminate composed only of the A layer and the B layer has insufficient physical properties after molding, and it is necessary to supplement its function by bonding with other films (C layer). Actually, in the example of Patent Document 3, a polyamide (nylon) film is further dry-laminated as a C layer to a two-layer laminate of A layer / B layer, and a three-layer laminate of A layer / B layer / C layer. It is said. Such a film is time-consuming to manufacture and increases in cost.
In addition, the method of patent documents 2-3 is aimed at modification | reformation of a vinyl chloride resin, and is not mentioned about polyolefin resin. In addition, vinyl chloride resin is a material that is not suitable for radiation sterilization because of changes in color and physical properties, generation of odor, and the like when irradiated with radiation.
The present invention has been made in view of the above circumstances, and is a film that can be sterilized by radiation, has high uniformity in thickness after deep drawing, and is easy to manufacture, and a medical device packaging method using the film The purpose is to provide.

The present invention for solving the above problems has the following configuration.
[1] Ethylene having a melt mass flow rate (JIS K7210: temperature 190 ° C.) of 1 to 3 g / 10 min as a main component and a melt mass flow rate (JIS K 7210: temperature 190 ° C.) of 1 g to 3 g / 10 min A resin composition (A) containing a modifier comprising a copolymer in a proportion of 0% by mass or more and less than 30% by mass with respect to the total amount of all components excluding the modifier, and a melt mass flow rate ( Three layers formed by an inflation method using an acid group-containing polymer (JIS K7210: temperature 190 ° C.) of 1 to 3 g / 10 min and a resin (B) made of at least one selected from its ionomer resin A film,
The first outer layer constituting one surface of the three-layer film and the second outer layer constituting the other surface are each composed of the resin composition (A), and the first outer layer, the second outer layer, The intermediate layer disposed between is made of the resin (B),
The film for deep drawing, wherein the thickness of the first outer layer and the thickness of the second outer layer are each equal to or less than the thickness of the intermediate layer, and the total thickness of the three-layer film is less than 160 μm.
[2] The film for deep drawing according to [1], wherein the acid group-containing polymer is an ethylene-methacrylic acid copolymer.
[3] The ethylene copolymer is selected from an ethylene-propylene copolymer and an ethylene-butene copolymer having a density of 0.860 g / cm ³ or more and less than 0.900 g / cm ³ , [1] or [2 ] The film for deep drawing described in the above.
[4] The film for deep drawing according to any one of [1] to [3], wherein the thickness of the first outer layer and the thickness of the second outer layer are the same.
[5] The film for deep drawing according to any one of [1] to [4], which is a packaging material for medical devices.
[6] A step of deep-drawing the film for deep drawing according to any one of [1] to [5] to form a recess, a medical device is accommodated in the recess, and an opening of the recess is formed. A medical device packaging method comprising: a step of sealing with a lid material to form a package; and a step of subjecting the package to radiation sterilization.

  ADVANTAGE OF THE INVENTION According to this invention, the radiation sterilization is possible, the uniformity of the thickness after deep-drawing shaping | molding is high, and the manufacturing method of the medical instrument using this film which can manufacture easily can be provided.

It is a schematic sectional drawing of the film for deep drawing of this invention. It is a schematic sectional drawing which shows an example of a package body.

<Drawing film>
The deep drawing film of the present invention (hereinafter sometimes simply referred to as a film) is a three-layer film formed by the inflation method using the following resin composition (A) and the following resin (B). The first outer layer constituting one surface of the three-layer film and the second outer layer constituting the other surface are each composed of a resin composition (A), and the first outer layer and the second outer layer The intermediate layer disposed therebetween is made of the resin (B).

[Resin composition (A)]
The resin composition (A) is mainly composed of polyolefin having a melt mass flow rate (hereinafter abbreviated as MFR) (JIS K7210: temperature 190 ° C.) of 1 to 3 g / 10 min, and MFR (JIS K7210: temperature 190). ° C) containing a modifier composed of an ethylene-based copolymer of 1 g to 3 g / 10 min in a proportion of 0% by mass or more and less than 30% by mass with respect to the total amount of all components excluding the modifier. .
MFR is an index indicating the fluidity of the resin. Hereinafter, unless otherwise specified, MFR indicates a value measured at a temperature of 190 ° C. and a test load of 21.18 N in accordance with JIS K7210.

The MFR of the polyolefin contained in the resin composition (A) is preferably 1 to 2 g / 10 minutes.
As the polyolefin, film formation by an inflation method can be used, and there is no particular limitation as long as the MFR is within a predetermined range. For example, low density polyethylene, medium density polyethylene, linear low density polyethylene (LLDPE) Polyethylene such as homopolypropylene, polypropylene such as block polymerized polypropylene and random polymerized polypropylene; and the like. Among these, LLDPE is preferable, and metallocene LLDPE synthesized using a metallocene catalyst is particularly preferable.
The “low density” generally has a density of 0.94 g / cm ³ or less.
The density of the polyolefin is particularly preferably 0.910 to 0.940 g / cm ³ from the viewpoints of moldability, flexibility, and film strength.
A commercially available polyolefin may be used, or a polyolefin synthesized by a known method may be used. The MFR of the polyolefin can be adjusted by the polymerization degree, the monomer type, and the like.

The resin composition (A) contains MFR 1 to 3 g / 10 min polyolefin as a main component. Here, the “main component” means that the ratio of the olefin is 50% by mass or more based on the total amount of all components excluding the modifier from the resin composition (A). The proportion is preferably 80% by mass or more, particularly preferably 100% by mass. That is, the resin composition (A) is composed of a polyolefin having an MFR of 1 to 3 g / 10 min and a modifier of 0% by mass or more and less than 30% by mass with respect to the polyolefin, and does not contain other components. Is preferred.
The polyolefin contained in the resin composition (A) may have one or more MFR of 1 to 3 g / 10 min.

The modifier blended in the resin composition (A) is composed of an ethylene copolymer having an MFR of 1 g to 3 g / 10 minutes. The MFR of the ethylene copolymer is more preferably 1 to 2 g / 10 minutes.
Here, the “ethylene copolymer” means a copolymer having ethylene as a main monomer and monomers other than ethylene as a comonomer.
In the ethylene copolymer, the proportion of ethylene units is preferably 50 to 90 mol%, more preferably 80 to 90 mol%. “Unit” indicates a repeating unit constituting the polymer.
The monomer other than ethylene used as a comonomer is not particularly limited as long as it is copolymerizable with ethylene, and examples thereof include olefins such as propylene and butene. Among these, propylene or butene is preferable from the viewpoint of processability and versatility. That is, the ethylene copolymer is preferably an ethylene-propylene copolymer or an ethylene-butene copolymer.
The ethylene copolymer preferably has a density of 0.860 to 0.900 g / cm ³ from the viewpoint of compatibility with the polyolefin and processability.
As the ethylene copolymer, a commercially available one may be used, or one synthesized by a known method may be used. The MFR of the ethylene copolymer can be adjusted by the polymerization degree, polymerization ratio, monomer type, and the like.

The compounding amount of the modifier is 0% by mass or more and less than 30% by mass, and 0% by mass or more and 25% by mass or less with respect to the total amount of all components excluding the modifier from the resin composition (A). preferable. When the blending amount of the modifying agent is 30% by mass or more, film blocking occurs at the time of inflation film formation, and stable productivity is poor. It also leads to cost increase.
When blending the modifier, that is, when the blending amount of the modifying agent exceeds 0% by mass, if the blending amount is small, the effect of the modifying agent cannot be obtained sufficiently, rather than when not blending. Deep drawability may deteriorate. Therefore, the blending amount of the modifier is 0% by mass, or preferably 10% by mass to 25% by mass, more preferably 0% by mass, or more preferably 15% by mass to 25% by mass.
One or more modifiers may be contained in the resin composition (A).

  The resin composition (A) may contain components other than the predetermined MFR olefin and the modifier as long as the effects of the present invention are not impaired. Examples of the other components include an antiblocking agent.

[Resin (B)]
Resin (B) consists of at least 1 sort (s) chosen from the acid group containing polymer whose MFR is 1-3g / 10min, and its ionomer resin.
The acid group-containing polymer is a polymer containing an acid group in the structure, and the acid group is preferably a carboxy group.
The acid group-containing polymer is not particularly limited as long as film formation by an inflation method can be used and the MFR is within a predetermined range. For example, acid-modified polyolefin, ethylene-α, β-unsaturated Examples thereof include carboxylic acid copolymers.
Examples of the acid-modified polyolefin include maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, and maleic anhydride-modified ethylene copolymer polypropylene. Examples of the ethylene-α, β-unsaturated carboxylic acid copolymer include ethylene-methacrylic acid copolymer (EMAA) and ethylene-acrylic acid copolymer (EAA).
An ionomer resin is a resin in which molecules of an acid group-containing polymer are bonded (ion-crosslinked) with metal ions such as sodium, potassium, and zinc, and examples thereof include EMAA-Na, EMAA-Zn, and EMAA-K. .
The resin (B) is preferably at least one selected from an ethylene-methacrylic acid copolymer and its ionomer resin, since it is particularly excellent in deep drawability, and in particular, an ionomer resin of an ethylene-methacrylic acid copolymer. Is preferred.
Resin (B), from the viewpoint of physical properties strength such as puncture resistance, it is preferable that a density of 0.92~1g / cm ^3, particularly preferably 0.93~0.96g / cm ^3.
As the resin (B), a commercially available product may be used, or a resin synthesized by a known method may be used. The MFR of the resin (B) can be adjusted by the acid group content, the degree of polymerization, and the like.
The acid group content of the resin (B) is preferably more than 0% and 10% or less, and more preferably 5% or more and 10% or less. If the acid group content exceeds 10%, the MFR may be too high. The acid group content is determined by infrared absorption spectroscopy and differential thermal analysis.
As resin (B), 1 type may be used independently and 2 or more types may be used together.

The three-layer film constituting the film of the present invention will be described more specifically with reference to FIG. FIG. 1 is a schematic cross-sectional view of the three-layer film. The three-layer film includes two outer layers (first outer layer 1 and second outer layer 2), and an intermediate layer 3 disposed therebetween. Consists of
The first outer layer 1 and the second outer layer 2 are each made of a resin composition (A), and the intermediate layer 3 is made of a resin (B).
The thicknesses of the first outer layer 1 and the second outer layer 2 are each equal to or less than the thickness of the intermediate layer 3, and the total thickness of the three-layer film is less than 160 μm. By securing the ratio of the intermediate layer to a certain extent, sufficient strength can be ensured even if the entire film is thin. Moreover, the inflation film-forming using the resin composition (A) and the resin (B) can be stably carried out by setting the total thickness to less than 160 μm.
The ratio between the thickness of the first outer layer 1 and the second outer layer 2 and the thickness of the intermediate layer 3 is preferably 1: 1 to 1: 5, more preferably 1: 1 to 1: 3.
The total thickness of the three-layer film is less than 160 μm, and the lower limit thereof is preferably 50 μm or more, more preferably 80 μm or more in consideration of film forming suitability.

The thickness of the first outer layer 1 and the second outer layer 2 is not particularly limited as long as the thickness is less than or equal to the thickness of the intermediate layer 3 and the total thickness of the film is less than 160 μm, but 25 μm to 60 μm preferable.
Further, the thickness of the first outer layer 1 and the thickness of the second outer layer 2 may be different, but are preferably the same from the viewpoint of obtaining a film that hardly causes curling.
The thickness of the intermediate layer 3 is preferably 50 μm to 110 μm.

  Film formation of the film of the present invention can be carried out according to a conventional method using a known inflation film forming apparatus except that the resin composition (A) and the resin (B) are used and the layer structure is as described above.

In the present invention, the resin composition (A) and the resin (B) are used, and the layer structure is as described above, whereby the film formation by the inflation method can be carried out stably and satisfactorily, and the resulting three layers The film is excellent in deep drawability.
That is, since the MFR of the olefin and the modifying agent and the resin (B) constituting the resin composition (A) are close to each other, the compatibility of each component is good, and layer unevenness or the like hardly occurs even during inflation film formation. In addition, in the inflation method, it is possible to suppress the temperature at the time of film formation as compared with other film formation methods (for example, the T-die method), and therefore, an ethylene system having the above MFR as a modifier in olefin. Even if the copolymer is blended, the film is difficult to block during film formation, and stable production is possible.
In addition, since the MFR of these components is within the above range, it is possible to form a film with a general-purpose inflation equipment of the upper blown air cooling method, and local drawdown due to overheating at the time of inflation film formation. It is possible to avoid and form a film while maintaining a uniform thickness. Moreover, the local thickness reduction at the time of carrying out the deep drawing forming of the film obtained is also suppressed.
Further, in the intermediate layer made of the resin (B), a three-dimensional structure centering on the acid group portion of the acid group-containing polymer or the crosslinked portion of the ionomer resin is formed. Therefore, having the intermediate layer at a predetermined ratio improves the strength of the entire film, and it is possible to avoid peeling between molecular chains due to shear stress during deep drawing and locally thinning, deep drawing. Local thickness reduction at the time is suppressed.
When a modifier is blended to some extent in the outer layer, the flexibility of the outer layer is improved, and the effect of suppressing local thickness reduction is improved by improving the extensibility during molding.
Since local thickness reduction is suppressed, a package packaged using the film is less prone to problems such as holes being formed during transportation and storage.
Furthermore, by making the thicknesses of the two outer layers the same, the resulting film has less curl. This is useful from the viewpoint of suitability for processing in a film forming machine and a mold filling machine.

Deep drawing is a method of forming a heated film with a mold, such as vacuum forming or pressure forming. The film of the present invention is a film excellent in deep-drawing formability, in which local thickness reduction is suppressed when deep drawing is performed, and is suitable for deep drawing.
In addition, the film is particularly useful as a packaging material for medical devices because the material constituting each layer can be sterilized by radiation.
An example of a method for packaging a medical instrument using the film of the present invention as a packaging material for the medical instrument will be described with reference to FIG. However, the present invention is not limited to this.
The method includes a step of deep drawing the film of the present invention to form a recess 11 a to form a bottom material 11, a medical instrument 12 is accommodated in the recess 11 a, and the opening of the 11 a is sealed with a lid 13. A package 10 and a step of subjecting the package 10 to a radiation sterilization process.

The opening of the recess 11a can be sealed by laminating the lid member 13 on the surface of the bottom material 11 on the opening side of the recess 11a and heat-sealing.
The lid member 13 is not particularly limited, and a known lid member for the package having the above-described configuration can be used. As an example, a sealant layer provided with a release layer can be mentioned. Such a lid material is laminated so that the surface on the peeling layer side is in contact with the bottom material 11, and the peeling layer is agglomerated and peeled from the sealant layer at the time of peeling.
After the medical device 12 is sealed and packaged in this manner, it is sterilized by radiation.
The package 10 obtained in this way maintains the sterility of the contents (medical device 12). Moreover, since the bottom material 11 has suppressed local thickness reduction, it is hard to produce malfunctions, such as a pinhole vacant at the time of transport.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the following description.
<Examples 1-5, Comparative Examples 1-6>
Using an outer layer forming material composed of resin (A) or a blend of a resin (A) and a modifier shown in Table 1, and an intermediate layer forming material composed of a resin (B) shown in Table 1, A three-layer film was formed using a conventional inflation film forming machine.
Among the materials for forming the outer layer, the blend of the resin (A) and the modifier is obtained by stirring the resin (A) and the modifier in the blending amount shown in Table 1 with respect to the resin (A) at room temperature using a blender. It was prepared by doing.
Film formation is the amount of extrusion of the outer layer forming material and the intermediate layer forming material so that the total thickness (μm) and layer ratio (outer layer / intermediate layer / outer layer) of the resulting three-layer film are the values shown in Table 1, respectively. The outer layer temperature was 170 ° C., the intermediate layer temperature was 150 ° C., and the line speed was 6 m / min.

Each example was evaluated as follows.
[Evaluation of film formability]
The presence or absence of blocking during film formation, bubble stability, and the appearance of the obtained film were visually observed to evaluate film formation. Specifically, the case where no blocking occurred, the bubble stability was good, and the appearance was good was evaluated as “OK”, and the others were evaluated as “NG”. The results are shown in Table 1.

[Evaluation of curls]
With respect to the three-layer film in which the film forming property was “OK” in Test Example 1, the difficulty of curling was evaluated by a 150 mm cross-cut method. Specifically, a three-layer film is cut into a length of 500 mm and a width of 500 mm to obtain a test piece, and the test piece is cut into a length of 150 mm so that each center intersects at right angles at a 45 ° angle with respect to the flow direction. The height of the substrate at the orthogonal part was measured with a metal ruler, and the average value thereof was calculated. Those having an average value of 30 mm or more were evaluated as x, and those having an average value of less than 30 mm were evaluated as ◯. The results are shown in Table 1.

[Evaluation of deep drawability]
In Test Example 1, a three-layer film having a film forming property of “OK” was subjected to pressure molding under the following shaping conditions to provide a concave portion having the following shape, and the thickness of the thinnest portion after molding was measured. The same operation was further performed 4 times, and an average value of 5 times in total was calculated for the thickness of the thinnest part. The results are shown in Table 1.
<Molding conditions> Heating temperature: 90 ° C. (direct heating), cycle time: 12.7 shots / min, heating time: 1 second, foam time: 1.5 seconds (multi-back R535 used).
<Recess> Cross-sectional shape: an ellipse having a minor axis of 40 mm x a major axis of 140 mm, depth: 25 mm.

The abbreviations in Table 1 are as follows.
MFR is a value measured at a temperature of 190 ° C. in accordance with JIS K7210.
[Resin (A)]
A-1: Prime polymer “Evolue SP2520” (metallocene LLDPE, MFR 1.9 g / 10 min, density 0.925 g / cm ³ ).

[Modifier]
X-1: Mitsui Chemicals, Inc. “Toughmer A-1085S” (ethylene-butene copolymer containing ethylene as a main monomer and butene as a comonomer component), MFR 1.9 g / 10 min, density 0.885 g / cm ³ ) .
X-2: an ethylene-butene copolymer having ethylene as a main monomer and butene as a comonomer component), Mitsui Chemicals, Inc. “Toughmer A-4085S” (MFR 3.6 g / 10 min, density 0.885 g / cm ³ ) .

[Resin (B)]
B-1: EMAA, Mitsui DuPont Polychemical Co., Ltd. “Nucleel N0903HC” (MFR 2.7 g / 10 min, density 0.94 g / cm ³ ).
B-2: Mitsui DuPont Polychemical Co., Ltd. “Himiran 1650” (ionomer resin in which EMAA molecules are bonded by zinc ions), MFR 1.3 g / 10 min, density 0.95 g / cm ³ ).
B-3: Mitsui DuPont Polychemical Co., Ltd. “Himiran 1702” (ionomer resin in which EMAA molecules are bonded by zinc ions), MFR 16 g / 10 min, density 0.95 g / cm ³ ).
B-4: Mitsui DuPont Polychemical Co., Ltd. “Evaflex” (ethylene-vinyl acetate copolymer, MFR ³ g / 10 min, density 0.93 g / cm ³ ).

As shown in the above results, in Examples 1 to 5, film formation by the inflation method could be carried out stably. Also, the moldability is good, and in particular, Example 1 in which 20% by mass of the modifier is blended in the outer layer and Examples 2-3 in which the modifier is not blended in the outer layer have a moldability evaluation result of 30 μm or more. And was excellent.
On the other hand, the comparative example 1 which mix | blended the modifier X-2 with MFR 3.6g / 10min, the comparative example 2 which used B-3 whose MFR is 16 as resin (B), and 30 mass% of modifiers Comparative Example 3 blended, Comparative Example 4 having a total thickness of 160 μm, and Comparative Example 5 in which the thickness of the intermediate layer was thinner than the thickness of the outer layer could not be stably formed by the inflation method.
Moreover, the comparative example 6 which used B-4 (EVA) as resin (B) was bad in moldability compared with Example 1 in which all except resin (B) correspond.

  DESCRIPTION OF SYMBOLS 1 ... 1st outer layer, 2 ... Middle layer, 3 ... 2nd outer layer, 10 ... Packaging, 11 ... Bottom material, 12 ... Medical instrument, 13 ... Cover material

Claims (6)

An ethylene-based copolymer having a melt mass flow rate (JIS K7210: temperature 190 ° C.) of 1 to 3 g / 10 min as a main component and a melt mass flow rate (JIS K 7210: temperature 190 ° C.) of 1 g to 3 g / 10 min. A resin composition (A) containing a modifier composed of a coalescence in a proportion of 0% by mass or more and less than 30% by mass with respect to the total amount of all components excluding the modifier, and a melt mass flow rate (JIS K7210: A three-layer film formed by an inflation method using an acid group-containing polymer having a temperature of 190 ° C.) of 1 to 3 g / 10 min and a resin (B) made of at least one selected from its ionomer resin ,
The first outer layer constituting one surface of the three-layer film and the second outer layer constituting the other surface are each composed of the resin composition (A), and the first outer layer, the second outer layer, The intermediate layer disposed between is made of the resin (B),
The film for deep drawing, wherein the thickness of the first outer layer and the thickness of the second outer layer are each equal to or less than the thickness of the intermediate layer, and the total thickness of the three-layer film is less than 160 μm.   The film for deep drawing according to claim 1, wherein the acid group-containing polymer is an ethylene-methacrylic acid copolymer. The depth according to claim 1 or 2, wherein the ethylene copolymer is selected from an ethylene-propylene copolymer and an ethylene-butene copolymer having a density of 0.860 g / cm ³ or more and less than 0.900 g / cm ^3. Drawing film.   The deep drawing film according to any one of claims 1 to 3, wherein a thickness of the first outer layer and a thickness of the second outer layer are the same.   The film for deep drawing according to any one of claims 1 to 4, which is a packaging material for medical instruments.   A step of forming a recess by deep-drawing the film for deep drawing according to any one of claims 1 to 5, and housing a medical instrument in the recess, and sealing the opening of the recess with a lid material And packaging the medical device, and a step of subjecting the packaging to radiation sterilization.

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