JP2016068952A - Heat-sealable film and easily-open package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film which has excellent heat sealability and easily-openability (easy peelability) to a nonwoven fabric, has high content visibility, and does not impair gas permeability of the nonwoven fabric; and an easily-open package.SOLUTION: An easily-open package has at least one seal layer. The seal layer contains a polyethylene-based resin having a melting point of 90°C or higher and 130°C or lower, and an acrylic resin having an elastic modulus E' of solid viscoelasticity of 1.0 MPa or more measured on condition of an oscillation frequency of 10 Hz and 150°C.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a film having heat-sealability and easy-openability (easy peel) and an easy-open package, and more particularly, good heat-sealability and easy-to-use for nonwoven fabrics useful as packaging materials for medical supplies and the like. The present invention relates to a peelable film and an easy-open packaging.

In recent years, attempts have been made to apply blister packaging to the packaging of medical instruments such as syringes and surgical gloves.
As shown in FIG. 1, blister packaging is performed by packaging a content (40) by bonding a lid (10) to a bottom material (30) formed by thermoforming a plastic sheet to form a storage section. Yes. Usually, the bottom material and the lid material are bonded together by heat sealing at a temperature equal to or higher than the melting point of the bottom material sealing layer.
By using a breathable material such as sterilized paper or polyethylene nonwoven fabric for the lid, the contents can be sterilized with ethylene oxide gas (EOG) after packaging, and sterilization for each package is possible.

  Such a blister package is required to be easily opened at the time of use, that is, easy peelability. Usually, such an easy peel property is achieved by providing an easy peel property to the sealing layer of the bottom material, or providing an easily peelable coat layer on the cover material or applying an adhesive.

  For example, Patent Document 1 discloses a cohesive failure easy peel film in which a seal layer is formed by mixing an ethylene / methacrylic acid copolymer (EMAA) or the like and a polyolefin resin, and a layer made of EMAA or the like is formed in an adjacent layer. It is disclosed.

  In Patent Document 2, a polyethylene resin is used for the seal layer, the intermediate layer is formed by mixing a polypropylene resin and a polyethylene resin, and a polyolefin resin is disposed on the outer layer, so that the balance between the seal layer and the intermediate layer is An easy peel film having both sealing properties and easy opening properties is disclosed.

  However, these films are easy to peel between plastic films such as food packaging, but when they are heat-sealed with a nonwoven fabric, the nonwoven fabric breaks when opened, and the material pieces and fine fibers cause medical supplies etc. Will contaminate the contents.

  As a result of the study of the phenomenon by the present inventors, the melt flow of the sealing layer at the heat sealing temperature causes the resin to enter the voids inside the nonwoven fabric so that the adhesion with the nonwoven fabric becomes too strong. Since the strength of the material was weaker than that of the adhesive film, it was found that the nonwoven fabric was torn upon opening.

  In addition, in the technique described in Patent Document 1, the transparency of the seal layer is poor, and in the field of medical packaging, since air packaging is often performed, the influence of film opacity is exerted compared to vacuum packaging or the like. It is easy to reduce the visibility of the contents for safety and health.

  Patent Document 3 is a medical instrument packaging body, which imparts heat sealability and easy peelability by applying an easily peelable adhesive to a plastic nonwoven fabric.

  However, in the technique described in Patent Document 3, since the adhesive is applied to the nonwoven fabric that is a breathable sheet, the gas permeability of the nonwoven fabric is reduced, and the manufacturing process is increased because an application process is required. There is a problem such as.

JP-A-5-212835 JP-A-6-47878 JP 2007-302292 A

  The present invention has been made in view of the above circumstances, and the solution is to have both good heat-sealability and easy-opening (easy peel) property with respect to the nonwoven fabric, high content visibility, and sterilization of the nonwoven fabric. An object of the present invention is to provide a heat-sealable film and an easy-open packaging body that do not impair gas permeability such as gas.

  As a result of intensive studies, the present inventors have found that the above problem can be easily solved by adopting a specific configuration, and have completed the present invention.

  That is, the present invention relates to a solid viscoelastic elasticity measured in a film having at least one sealing layer, wherein the sealing layer is a polyethylene resin having a melting point of 90 ° C. or higher and 130 ° C. or lower, and a vibration frequency of 10 Hz and 150 ° C. It exists in the heat-sealable film characterized by containing the acrylic resin whose rate is E'1.0MPa or more, and an easy-open packaging body using the same.

According to the present invention, since it is a highly transparent seal layer, the package contents are highly visible, and even when sealed with sterilized paper or non-woven fabric, good heat sealability and easy peel properties are achieved. In addition, since it is not necessary to apply heat-sealing property and easy-peeling property to the nonwoven fabric, it is possible to provide an easy-open packaging body having good air permeability such as sterilization gas. Industrial value is high in the medical packaging field.
For medical product packaging, bag packaging, pouch packaging, deep-drawing packaging, blister packaging, etc. are appropriately selected in consideration of the shape, impact resistance, and ease of storage of the contained items. Can be used in the body.

The side view which shows an example of the package which used the film of this invention for the bottom material

The polyethylene resin of the sealing layer of the film of the present invention is a polyethylene resin such as low density polyethylene, linear low density polyethylene, ultra low density polyethylene, medium density polyethylene, high density polyethylene, ultra high density polyethylene, or ethylene- A copolymer such as a propylene copolymer can be used. These may be used alone or in combination of two or more.
Of these, low density polyethylene resin and linear low density polyethylene resin are desirable from the viewpoint of heat sealability.

These polyethylene resins are preferably those having a melting point of 90 ° C. or higher and 130 ° C. or lower because the heat sealing temperature of the package is generally 120 ° C. to 160 ° C. More preferably, it is 100 degreeC or more and 125 degrees C or less.
The melting point of the polyethylene resin can be measured by a method according to JIS K7121.

  0.1-50 g / 10min is preferable and, as for the melt flow rate (JIS K7210) of the polyethylene-type resin of the sealing layer of the film of this invention, 1-10 g / 10min is more preferable.

The acrylic resin of the sealing layer of the film of the present invention is a homopolymer or copolymer of acrylic acid derivatives such as acrylic acid or its esters, methacrylic acid or its esters, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, etc. It is a coalescence.
Examples of (meth) acrylic acid esters include methyl acrylate, ethyl acrylate, butyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, phenyl methacrylate, and the like. Can be mentioned.

These acrylic resins may be used alone or in combination.
Among these, the use of polymethyl methacrylate (PMMA) resin is preferable from the viewpoint of the high melting point, the high elastic modulus at the heat seal temperature, and the low fluidity.

The elastic modulus E ′ by solid viscoelasticity measurement of the acrylic resin of the sealing layer of the film of the present invention is 1.0 MPa or more and 100 MPa or less under the conditions of the vibration frequency of 10 Hz and 150 ° C.
At 1.0 MPa or more, the seal layer is prevented from being embedded in the nonwoven fabric during heat sealing, and when it exceeds 100 MPa, blending with a polyethylene resin becomes difficult.

  The melt flow rate (JIS K 7210, 230 ° C., load 37.3N) of the acrylic resin of the sealing layer of the film of the present invention is 0.1 to 0.1 from the viewpoint of the film formability and the mixing property with the polyethylene resin. The thing of the range of 100 g / 10min is preferable. More preferably, it is 1-20 g / 10min.

In general, acrylic resins are known to have high transparency, but in the easy peel layer, the close refractive index of incompatible resins contributes to transparency as a film.
For example, the refractive index of PMMA resin is about 1.49, which is close to the refractive index of 1.51 to 1.53 of polyethylene resin, so even if PMMA resin is mixed and dispersed in polyethylene resin, the film is highly transparent Sex can be obtained.

  The sealing layer of the film of the present invention is preferably formed by blending 50% by mass or more and less than 90% by mass of a polyethylene resin and 10% by mass or more and less than 50% by mass of an acrylic resin. More preferably, it is a blend of a polyethylene resin of 60% by mass or more and an acrylic resin of 40% by mass or less.

When the polyethylene resin is 90% by mass or more, the anchor (adhesion) effect to the nonwoven fabric or the like becomes too strong and the easy peel property tends to be insufficient.
On the other hand, when the acrylic resin is 50% by mass or more, the opacity becomes remarkable, and it is impossible to produce a film and a package having both easy peel properties, deep drawability and transparency.

The thickness of the sealing layer of the film of the present invention is not particularly defined, but is preferably 1 μm or more and 100 μm or less, more preferably 3 μm or more and 50 μm or less. If it is less than 1 μm, sufficient easy peel properties are hardly exhibited, and if it is thicker than 100 μm, the manufacturing cost increases.
When a multilayer film is formed by arranging another thermoplastic resin layer, the thickness of the seal layer can be set by adjusting the function and thickness of the other layer.

  As long as the function of the sealing layer of the film of the present invention is not impaired, an additive can be added. Examples of the additive include an anti-blocking agent, a slip agent, a processing aid, an antioxidant, and an ultraviolet absorber.

The film of the present invention can be heat-sealed with sterilized paper, nonwoven fabric, or the like by known techniques and conditions.
And, when opening the package, it can be easily opened by hand (easy peel) due to the interface peeling at the interface between the sealing layer and the sterilized paper, and does not generate a piece of material such as a nonwoven fabric or fiber residue. is there.

  The adhesive strength between the sealing layer and the nonwoven fabric of the film of the present invention is 75 gf / 15 mm width or more at 25 ° C., preferably 90 gf / 15 mm width or more at 25 ° C. The upper limit is 450 gf / 15 mm width or less, preferably 300 gf / 15 mm width or less.

  The elastic modulus of the seal layer of the film of the present invention is preferably 10 MPa or more at room temperature (23 ° C.) from the viewpoints of handling properties, blocking resistance and the like. More preferably, it is 100 MPa or more.

  The film of the present invention has at least one sealing layer as described above, and can be multilayered together with other thermoplastic resin layers.

  Other thermoplastic resin layers are not particularly defined, but if an olefin resin (PO) layer is provided as a layer adjacent to the seal layer from the viewpoint of interlayer adhesion, an increase in film strength due to an increase in film thickness or a seal layer may be provided. The required minimum thickness can be set to reduce the amount of expensive acrylic resin used and to reduce the cost. Moreover, a softness | flexibility can also be provided to a film.

For the polyolefin resin layer adjacent to the seal layer, for example, a resin similar to the polyethylene resin of the seal layer or an ethylene-vinyl acetate copolymer (EVA) can be used.
For the polyolefin resin layer, a polypropylene resin such as homopolypropylene or propylene-α-olefin copolymer can be used. Examples of the α-olefin include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like.

  Further, from the viewpoint of further improving the deep drawability, pinhole resistance, and strength, it is desirable to provide a layer made of polyamide resin (PA). The polyamide resin layer is suitable for the outer layer or the intermediate layer of the film of the present invention.

  Further, from the viewpoint of moisture resistance and imparting appropriate stiffness to the film, it is desirable to provide a layer made of polypropylene resin (PP).

Further, from the viewpoint of imparting oxygen barrier properties, it is desirable to arrange a layer made of saponified ethylene-vinyl acetate copolymer (EVOH) at a position other than the outermost layer.
An adhesive resin (AD) layer may be formed between the respective layers.

Preferred examples of the layer structure include the following examples when the adhesive resin layer is omitted and the outer layer / intermediate layer / seal layer are described in this order.
In particular, the layer constitutions (2) and (4) are useful from the viewpoint of film strength, suitability for deep drawing and production cost.

(1) PO / seal (2) PA / {seal or PO / seal}
(3) PA / EVOH / {seal or PO / seal}
(4) {PE or PP} / PA / {Seal or PO / Seal}
(5) {PE or PP} / PA / EVOH / {Seal or PO / Seal}
(6) {PE or PP} / EVOH / PA / {Seal or PO / Seal}

The heat-sealable film of the present invention can be produced by a known method, for example, a co-extrusion method, a dry lamination method, an extrusion lamination method, a hot melt lamination method, or the like. Of these, the coextrusion method and the extrusion laminating method are desirable.
Non-stretched film formation is desirable for deep drawing packaging applications.
For pouch packaging applications, a method of laminating the film of the present invention produced by non-stretching film and a stretched film such as a biaxially stretched polyester film by a dry laminating method or the like is desirable.

Examples of the nonwoven fabric bonded to the film of the present invention include sterilized paper, a microporous film made of a synthetic resin, and a nonwoven fabric made of a thermoplastic resin.
Moreover, it can use suitably for joining with the nonwoven fabric of 20-100 g / m < ² > of fabric weights.
In addition, these may be a single layer or a multi-layer structure of plural types.
In particular, the effects of the film of the present invention can be utilized when using sterilized paper for medical packaging materials. Examples of commercially available products include DuPont Tyvek, Oji Special Medica J, Asahi Kasei Kogyo Ben Rize, etc. Can be mentioned.

Examples are shown below, but the present invention is not limited to these examples.
Examples 1-4, Comparative Examples 1-5
Each layer resin shown below was coextruded at a resin temperature of 230 ° C. by a T-die method using a single-screw extruder, and then rapidly cooled with a cast roll at 50 ° C., and a non-stretched multi-layer heat sealability with a total thickness of 100 μm. A film was obtained and used for the bottom material.
The layer structure is as follows.
PP (20 μm) / AD (10 μm) / Ny6 (30 μm) / AD (10 μm) / LLDPE (20 μm) / sealing layer (10 μm)

Example 1:
As a sealing layer, linear low density polyethylene (LLDPE) resin (manufactured by Prime Polymer, Moatech 0138N, melting point 119 ° C., MFR about 1.3 g / 10 min) 90% by mass and PMMA resin (manufactured by Mitsubishi Rayon, Acrypet VH, The elastic modulus E 'of 4.95 MPa at 150 ° C. and MFR of about 2.0 g / 10 min) was mixed with 10% by mass.
Sterile paper (Oji Specialty Paper, Medica J) was used as the lid.

Example 2:
A heat-sealable film was produced and evaluated in the same manner as in Example 1 except that the composition of the sheet layer was changed to 80% by mass of LLDPE and 20% by mass of PMMA.

Example 3:
A heat-sealable film was prepared and evaluated in the same manner as in Example 1 except that the composition of the sheet layer was changed to 70% by mass of LLDPE and 30% by mass of PMMA.

Example 4:
A heat-sealable film was produced and evaluated in the same manner as in Example 1 except that the composition of the sheet layer was changed to 60% by mass of LLDPE and 40% by mass of PMMA.

Comparative Example 1:
A heat-sealable film was produced and evaluated in the same manner as in Example 1 except that the composition of the sheet layer was changed to LLDPE 100% by mass.

Comparative Example 2:
A heat-sealable film was prepared and evaluated in the same manner as in Example 1 except that the blending of the sheet layer was changed to 100% by mass of PMMA.

Comparative Example 3:
A heat-sealable film was prepared and evaluated in the same manner as in Example 1, except that the composition of the sheet layer was changed to 80% by mass of LLDPE and 20% by mass of cyclic olefin copolymer (COC) (Mitsui Chemicals, APL6015). Went.

Comparative Example 4:
Example 1 except that the composition of the sheet layer was changed to 90% by mass of high density polyethylene (HDPE) resin (manufactured by Prime Polymer, Hi-Zex Hz3600F, melting point 133 ° C., MFR about 1 g / 10 min) and 10% by mass of PMMA. A heat-sealable film was prepared by the method and evaluated.

Comparative Example 5:
Using the same heat-sealable film as in Example 2 for the bottom material, and using the OPP (20 μm) / adhesive layer / PET (12 μm) / adhesive layer / EVA (40 μm) film as the lid, the same evaluation is performed. Went.

The following evaluation was performed about the obtained heat-sealable film.
Table 1 shows the film configuration and evaluation results.

(1) Transparency evaluation
The heat-sealable film was visually observed and evaluated according to the following criteria.
○: Appearance is uniform and transparent △: Appearance is uneven but transparent ×: Appearance is uneven and color is whitish

(2) Heat seal The heat sealable film and the lid material are heat sealed with a heat sealer at 150 ° C., 3 kg / cm ² , a seal width of 6 mm, and a seal time of 2 seconds. The following (3) and (4) It was used as a sample for evaluation.

(3) Measurement of seal peel strength A heat-sealed sample was cut into a strip having a width of 15 mm, peeled at a peel rate of 100 mm / min in a 180 ° peel test, and the peel strength was measured. From this peel strength, the seal strength was evaluated according to the following criteria.
○: Peel strength 100 gf / 15 mm width or more ×: Peel strength 100 gf / 15 mm width or less

(4) Easy peel (easy peeling) property evaluation About the heat-sealed sample, sterilized paper was peeled from the film by hand peeling, the peeling condition in that case was observed visually, and the following references | standards evaluated.
○: The sterilized paper is not torn, and no pieces of paper or fluff remain in the peeled part. ×: The sterilized paper is torn, and the piece of paper or fluff remains in the peeled part, or cannot be peeled. Absent

(5) Deep drawability evaluation Using a heat-sealable film, with a deep draw wrapping machine, with a molding temperature of 90 ° C., a molding heating time of 2 seconds, and a molding air pressure time of 3 seconds, the shape is 80 mm long × 80 mm wide × 30 mm deep Was formed into a bottom material, about 5 cm square gauze was placed as the contents, and various deep-sealed packaging bodies were prepared using various lid materials, and evaluated according to the following criteria.
○: There is no molding unevenness, and the visibility of the contents is good.
Δ: Although there is molding unevenness, the visibility of the contents is good.
X: There is molding unevenness and the visibility of the contents is poor.

表中の数字は、シール層の樹脂配合比率（質量％）である。

The numbers in the table are the resin blending ratio (mass%) of the seal layer.

  From Table 1, it can be seen that the film of the present invention has good heat sealability and easy peel property against sterilized paper, and has deep drawability and contents visibility required for medical product packaging.

The film of the present invention has good heat-sealability and easy peel even when sealed with sterilized paper or non-woven fabric, and does not generate paper powder or fibers when opened, and ensures breathability of sterilized paper, etc. Therefore, it can be suitably used for a medical package requiring sterilization gas treatment. Moreover, since the sealing layer is colorless and transparent, it is suitable for packaging applications that require visual confirmation of the contents. Furthermore, as a packaging form, both bag packaging and deep drawing packaging can be easily handled.
From these viewpoints, the film of the present invention can be beneficially used, including post-process processing such as manufacturing of medical supplies, quality control, and user-friendliness.

DESCRIPTION OF SYMBOLS 10 Cover material 20 Bottom material 30 Concave part 40 Contents, such as gauze 50 Heat seal part

Claims (3)

  In a film having at least one sealing layer, the sealing layer has a polyethylene-based resin having a melting point of 90 ° C. or higher and 130 ° C. or lower, and an elastic modulus E ′ of solid viscoelasticity measured under conditions of a vibration frequency of 10 Hz and 150 ° C. A heat-sealable film comprising an acrylic resin of 0 MPa or more, and an easy-open packaging body using the heat-sealable film.   The heat-sealable film according to claim 1, wherein the composition of the sealing layer is a polyethylene resin of 50% by mass or more and less than 90% by mass and an acrylic resin of 10% by mass or more and less than 50% by mass, and the same. Easy-open packaging.   The unstretched coextruded heat-sealable film according to claim 1 or 2, wherein at least one layer composed of a polyamide resin is disposed, and a layer composed of a polyolefin-based resin is disposed adjacent to the seal layer, and the same is used. Easy-open packaging.

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