JP7063028B2 - Heat-sealing multilayer film and medical packaging - Google Patents

Description

The present invention relates to a heat-sealable multilayer film and a medical packaging using the film.

In recent years, deeply squeezed packages and four-sided bags made of plastic films have been widely used as medical packages and food packages. In recent years, there have been many requests for universal design of packaging materials due to global environmental problems, declining birthrate and aging problems, etc., and packaging bodies are required to have many functions.

In addition to the transparency of the container related to the visibility of the contents, strength such as hygiene and pinhole resistance is also required depending on the application. In particular, as a package that can be opened more easily, it is required to impart easy peeling property (easy opening property), and an easy peeling film has been studied by the compounding design of the resin used for the heat seal layer. There is. (Patent Document 1)

Japanese Unexamined Patent Publication No. 2014-162162

However, since the conventional easy-peelable film has almost no slipperiness, the sealant layer and the base material layer of the multilayer sheet adhere to each other in the film forming process, the slitting process, the bag making process, the content filling process, and the like. There is a problem that a so-called blocking phenomenon occurs and the bag making workability and filling workability are remarkably lowered.

An object of the present invention is to provide a heat-sealable multilayer film having excellent transparency and strength and excellent slipperiness, and a medical packaging using the sheet-sealing multilayer film.

As a result of diligent studies to solve the above problems, the present inventor has found that the problems can be solved by the following means.
The first invention is a heat having at least one heat-sealing layer on the surface layer, at least one layer containing a polyamide-based resin, and a layer containing a polyolefin-based resin adjacent to the heat-sealing layer. A heat-sealing multilayer film, wherein the heat-sealing layer is a layer containing a resin composition of an ethylene-methyl acrylate copolymer (A) and an unsaturated fatty acid amide (B). ..

In the first invention, it is preferable that the unsaturated fatty acid constituting the unsaturated fatty acid amide (B) has 18 or more and 22 carbon atoms or less, and the unsaturated fatty acid amide has a melting point of 65 ° C. or more. ..

In the first aspect of the present invention, the coefficient of dynamic friction between the heat seal layer and the polyethylene film is preferably 0.5 or less when measured in accordance with JIS K7125.

In the first invention, it is preferable that the heat seal layer has an easy peel property.

The second invention is a medical packaging body characterized in that the heat-sealing layer of the heat-sealing multilayer film of the first invention and a polyethylene non-woven fabric are heat-sealed.

According to the present invention, it is possible to provide a heat-sealable multilayer film having excellent transparency and strength and excellent slipperiness, and a medical packaging body using the sheet-sealing multilayer film.

Hereinafter, an embodiment of the present invention will be described in detail. The present invention is not limited to the following embodiments.

In the present embodiment, the "main component" means that the content of each component is preferably 50% by mass or more, more preferably 80, based on the whole resin component constituting each layer as a reference (100% by mass). It means that it contains mass% or more, more preferably 95% by mass or more, and particularly preferably 100% by mass.

Further, in the following embodiments, when expressed as "X to Y" (X and Y are arbitrary numbers), it means "X or more and Y or less" and "preferably larger than X" unless otherwise specified. And "preferably smaller than Y". Further, in the following embodiments, when expressed as "X or more" (X is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably larger than X" and "Y or less" (Y). Is an arbitrary number), which means "preferably smaller than Y" unless otherwise specified.

<Heat-sealable multilayer film>
The heat-sealing multilayer film of the present invention has at least one heat-sealing layer on the surface layer, at least one layer containing a polyamide-based resin, and a layer containing a polyolefin-based resin adjacent to the heat-sealing layer. Has.

(Heat seal layer)
The heat-sealing layer imparts flexibility and heat-sealing properties to the multilayer film of the present invention, and contains a polyolefin-based resin which is a heat-sealing resin. Examples of the polyolefin-based resin include polyethylene-based resin, polypropylene-based resin, and cyclic polyolefin-based resin, and from the viewpoint of sheet breakability, it is preferable to use a polyolefin resin having a tensile elongation of 300% or more.

Examples of polyethylene-based resins include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, and ethylene-acrylic acid. Examples thereof include methyl copolymers, ethylene-methyl methacrylate copolymers, polyethylene-based ionomers, and mixtures thereof. Examples of the polypropylene-based resin include homopolypropylene, a random copolymer of propylene and α-olefin, and a block copolymer. Examples of the cyclic polyolefin-based resin include resins having a norbornene skeleton.

These resins can be used alone or in combination. In the mixed composition, for example, low-density polyethylene having good sheet-forming property and high-density polyethylene having good sheet tearing property may be mixed to adjust both physical characteristics, or two kinds of resins having different melting points or non-phase with each other may be used. Melt polyethylene and polypropylene can be mixed to impart easy peeling properties to the heat seal layer.

The thickness of the heat seal layer is preferably 0.5 μm or more, more preferably 1 μm or more, still more preferably 1.5 μm or more, from the viewpoint of heat sealability, rigidity and moldability. Further, it is preferably 30 μm or less, more preferably 27.5 μm or less, and further preferably 25 μm or less.

From the viewpoint of heat sealability, rigidity and moldability, the thickness of the heat seal layer is preferably 5% or more, more preferably 6% or more, based on the thickness ratio of the polyamide resin layer to the thickness. It is preferably 7% or more, more preferably 50% or less, preferably 47.5% or less, and even more preferably 45% or less.
Further, the heat seal layer may be a single layer or a multilayer layer.

The heat-sealable multilayer film of the present invention preferably has a coefficient of dynamic friction with a polyethylene film of 0.5 or less when measured in accordance with JIS K7125. When the dynamic friction coefficient is 0.5 or less, the heat-sealing multilayer film of the present invention is heat-sealed in the molding process, slitting process, bag making process, content filling process, etc. of the heat-sealing multilayer film of the present invention. Since the layers are less likely to adhere or block, workability in each step is improved, which is preferable.

(Easy peel layer)
In the case of a multilayer heat-sealed layer, for example, a polyolefin-based resin layer containing a polyolefin-based resin as a main component and a polyolefin-based resin layer having an easy peel (hereinafter, also referred to as “EP”) function (hereinafter, “EP layer”). ”). In the case of a multilayer layer of the EP layer and the heat-sealing layer having no EP function, it is preferable to position the EP layer on the outermost layer (that is, the side that heat-seals the non-woven fabric).

Further, the resin as the main component of the EP layer has a melting point of usually 120 ° C. or lower, preferably 100 ° C. or lower, more preferably 75 to 85 ° C., and is subject to the conditions of 190 ° C. and 21.18 N load according to JIS K7210. The melt flow rate (MFR) measured in 1 is usually 0.1 g / 10 min to 10 g / min, preferably 1 g / 10 min to 10 g / 10 min, more preferably 2 g / 10 min to 5 g / 10 min. By selecting it, the degree of welding and the degree of impregnation during heat sealing with the polyethylene non-woven film at a temperature of 135 ° C or less on the packaging machine are appropriately controlled, and stable and appropriate easy peel within the above-mentioned sealing temperature range. It develops strength and is less likely to cause problems such as blocking during winding during film production, molding and transportation in a packaging machine, and improves production efficiency and handleability.

The thickness of the EP layer is preferably 2 μm or more, more preferably 3 μm or more, further preferably 4 μm or more, preferably 20 μm or less, and more preferably 15 μm or less. , 12 μm or less is more preferable. When the thickness of the EP layer is 2 μm or more, stable film-forming property can be obtained. Further, when the thickness is 20 μm or less, fluffing and film residue can be less likely to occur at the time of peeling, and a good peeled appearance can be obtained.

In the present invention, the heat seal layer is preferably a layer containing a resin composition of an ethylene-methyl acrylate copolymer (A) and an unsaturated fatty acid amide (B) from the viewpoint of having an EP function. The heat seal layer preferably contains the resin composition as a main component.

(A) Ethylene-methyl acrylate copolymer In the present invention, the heat-sealed layer is mainly composed of an ethylene-α-olefin copolymer, an ethylene-vinyl acetate copolymer (EVA), and an ethylene-acrylate copolymer. Combined (EAA), Ethylene-ethyl acrylate copolymer (EEA), Ethylene-methacrylic acid copolymer (EMAA), Ethylene-methyl methacrylate copolymer (EMMA), Ethylene-methyl acrylate copolymer (EMA) ) And at least one resin composition selected from the group consisting of these ionomers. In particular, from the viewpoint of seal strength and film-forming property, it is preferable to use an ethylene-methyl acrylate copolymer (EMA).

Typical examples of the ethylene-methyl acrylate copolymer (A) preferably used in the present invention include "Lexpearl" manufactured by Japan Polyethylene Corporation and "Elvalois" manufactured by Mitsui and DuPont Polychemical. It can be mentioned as something that can be obtained.

In addition, by blending two types of EMA with different melting points (high melting point EMA and low melting point EMA), it is possible to adjust the sealing temperature with the non-woven fabric and improve the easy peeling property (appearance after peeling). It is preferable because it can be done. The melting point of EMA is preferably 85 ° C. or higher and 120 ° C. or lower, and more preferably 90 ° C. or higher and 100 ° C. or lower. The EMA having a low melting point preferably has a melting point of 60 ° C. or higher and lower than 85 ° C., more preferably 65 ° C. or higher and 80 ° C. or lower. The mixing ratio is preferably 50 to 90% by mass, more preferably 55 to 80% by mass, with a high melting point EMA being 100% by mass as a whole.

(B) Unsaturated fatty acid amide In order to prevent the heat-sealed layer of this multilayer film from fusing or blocking, an unsaturated fatty acid amide-based lubricant can be preferably used. Since the unsaturated fatty acid amide-based lubricant has a double bond in the molecular structure, the molecular structure is easily curved and the molecules are difficult to adhere to each other. Therefore, since it is superior in dispersibility as a saturated fatty acid amide-based lubricant and has a high transparency and slipperiness effect, it can be preferably used. Specific examples thereof include unsaturated fatty acid amides and unsaturated fatty acid bisamides. Among them, unsaturated fatty acid amides having an unsaturated fatty acid having 18 or more and 22 or less carbon atoms and having a melting point of 65 ° C. or more are more preferable.

As specific examples, oleic acid amide, erucic acid amide, ethylene bisoleic acid amide and the like can be used. Further, it is preferable to use an unsaturated fatty acid amide having 18 or more and 22 or less carbon atoms in the constituent unsaturated fatty acid because it is excellent in the initial slipperiness and the effect of improving the slipperiness at a high temperature of 45 ° C. or higher. Further, when an unsaturated fatty acid amide having a melting point of 65 ° C. or higher is used, the blocking resistance is improved, which is preferable. One type of these unsaturated fatty acid amides may be used, or two or more types may be used in combination.

The blending amount of the unsaturated fatty acid amide used in the multilayer film of the present invention is 0.001 part by mass or more and 1 part by mass or less with respect to 100 parts by mass of the ethylene-methyl acrylate copolymer (A). It is preferably 0.01 parts by mass or more and 0.7 parts by mass or less, and more preferably 0.03 parts by mass or more and 0.5 parts by mass or less. By setting the blending amount to 0.001 part by mass or more, wrinkles do not occur in the winding part at the time of film formation, winding becomes good, and by reducing the weight to 1 part or less, transparency and heat after aging are achieved. Good sealing performance.

(Layer containing polyamide resin)
The layer containing the polyamide resin can impart flexibility and strength to the multilayer film of the present invention. The layer containing the polyamide resin preferably contains the polyamide resin as a main component. The multilayer film of the present invention includes at least one layer containing a polyamide-based resin (hereinafter, also referred to as “PA layer”).

The polyamide resin is not particularly limited, but specifically, for example, 4 nylon, 6 nylon, 7 nylon, 11 nylon, 12 nylon, 46 nylon, 66 nylon, 69 nylon, 610 nylon, 611 nylon, and 6T nylon. , 6I Nylon, MXD6 Nylon, 6-66 Nylon, 6-610 Nylon, 6-611 Nylon, 6-12 Nylon, 6-612 Nylon, 6-6T Nylon, 6-6I Nylon, 6-66-610 Nylon, 6 Examples thereof include -66-12 nylon, 6-66-612 nylon, 66-6T nylon, 66-6I nylon, 6T-6I nylon, 66-6T-6I nylon and the like.

Among these, as the polyamide resin, it is preferable to use 6 nylon or 6-66 nylon from the viewpoint of pinhole resistance. Further, two or more PA layers may be provided, and in that case, each layer may be formed of a different type of polyamide resin.

The thickness of the PA layer is not particularly limited, but is preferably 10% or more, more preferably 15% or more of the film layer thickness. Further, 70% or less is preferable, and 60% or less is more preferable. By setting the thickness of the PA layer to 10% or more, sufficient pinhole resistance can be imparted to the film, and by setting it to 70% or less, curling of the sealed portion can be prevented.

A typical example of the polyamide preferably used in the present invention is "Novamid" manufactured by Mitsubishi Engineering Plastics Co., Ltd., which is commercially available.

(Layer containing polyolefin resin)
The layer adjacent to the heat seal layer of the surface layer of the multilayer film of the present invention includes a layer containing a polyolefin resin for the purpose of imparting flexibility and transparency. The layer containing the polyolefin-based resin preferably contains the polyolefin-based resin as a main component. For the polyolefin resin layer adjacent to the heat seal layer, for example, a resin similar to the polyethylene resin of the heat seal layer or an ethylene-vinyl acetate copolymer (EVA) can be used.
Further, as the polyolefin-based resin layer, a propylene-based resin such as homopolypropylene or a 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.

(Other layers)
Further, from the viewpoint of imparting appropriate moisture resistance and rigidity to the film, it is desirable to arrange a layer containing a polypropylene-based resin (PP). Further, the layer containing PP preferably contains PP as a main component.
Further, from the viewpoint of imparting appropriate flexibility, it is desirable to arrange a layer containing a polyethylene-based resin (PE). Further, the layer containing PE preferably contains PE as a main component.

Further, from the viewpoint of imparting oxygen barrier properties, it is desirable to arrange a layer containing an ethylene-vinyl acetate copolymer saponified product (EVOH) in a layer other than the front and back layers. Further, the layer containing EVOH preferably contains EVOH as a main component.

Further, an adhesive resin (AD) layer may be formed between the layers. As the adhesive resin, for example, a polyolefin-based resin modified with an unsaturated carboxylic acid or a derivative thereof can be used.

(Layer composition of multilayer film)
As a preferable layer structure, if the description of the adhesive resin layer is omitted and the back surface layer / intermediate layer / heat seal layer (front surface layer) is described in this order, the following examples can be mentioned. The back surface layer refers to a layer existing on the opposite side of the heat seal layer in the multilayer film. The intermediate layer is a layer existing between the outer layer and the heat seal layer. In particular, the layer configurations (1) and (3) are useful from the viewpoints of film strength, deep drawing suitability, and manufacturing cost. The specific description of the resin in the composition of the layer means a layer containing the resin, and the layer containing the resin preferably contains the resin as a main component.

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

<Manufacturing method of heat-sealing multilayer film>
The heat-sealable multilayer film of the present invention is coextruded by an existing method such as a T-die method or a tubular method using an extruder equipped with a die to obtain an EP layer, a PA layer and a polyolefin-based resin layer as surface layers. Can be produced at the same time. Further, the multilayer film can also be sequentially produced by using a press method, a roll nip method, a dry laminating method, or the like after separately forming the resin constituting each layer into a sheet. Non-stretched film formation is desirable from the viewpoint of processability such as formability. The term "non-stretching" as used herein means that stretching in a specific direction (winding direction or width direction) is not substantially performed, and a predetermined stretching as an unavoidable force for the convenience of film formation is a part. It is a meaning to include the case where it is included.

In addition, even if various additives such as inorganic fillers, organic fillers, antioxidants, weather stabilizers, light stabilizers, lubricants, nucleating agents, or pigments are blended in each layer as long as the characteristics of each layer are not impaired. good.

<Medical packaging>
The medical packaging of the present invention can be manufactured by cutting out the heat-sealing multilayer film of the present invention into a predetermined shape, processing it into the shape of a bottom material, and then heat-sealing it with a lid material. It is preferable to use a non-woven fabric made of polyethylene.
Examples of the nonwoven fabric to be bonded to the heat-sealing multilayer film of the present invention include sterile paper, microporous films made of synthetic resin, nonwoven fabrics made of thermoplastic resin, and the like. Further, it can be suitably used for joining with a non-woven fabric having a basis weight of 20 to 100 g / m ² . It should be noted that these may be a single layer or a multi-layer structure consisting of a plurality of types. In particular, when sterilized paper as a medical packaging material is used, various effects of the film of the present invention can be utilized, and examples of commercially available products include DuPont Tyvek, Oji Special Medica J, and Asahi Kasei Industrial Benlyse. Can be mentioned.
The heat-sealing conditions are not particularly limited, and the conditions for heat-sealing with a conventional non-woven fabric can be adopted.

Hereinafter, examples will be shown, but the present invention is not limited thereto.
Each layer resin shown below is co-extruded at a resin temperature of 230 ° C. using a single-screw extruder using a single-screw extruder, then quenched and formed with a cast roll at 50 ° C., and has a total thickness of 110 μm and has unstretched heat-sealing properties. A multilayer film was obtained and used as a bottom material.
The layer structure is as follows.
PP (10 μm) / AD (9 μm) / Ny6 (25 μm) / AD (18 μm) / LLDPE (38 μm) / heat seal layer (10 μm)
The heat-sealed layer was blended with 60% by mass of a high melting point ethylene-methyl acrylate copolymer (melting point 90 ° C.) and 40% by mass of a low melting point ethylene-methyl acrylate copolymer (melting point 77 ° C.). .. In addition, sterile paper (made by Oji Special Paper, Medica J) was used as the lid material.

(Example 1)
Ethylene bisoleic acid corresponding to 0.3% by mass when the mixture of the high melting point ethylene-methyl acrylate copolymer and the low melting point ethylene-methyl acrylate copolymer is 100% by mass in the heat seal layer. The above multilayer film was prepared by mixing amide (melting point: 117 ° C.) and evaluated.

(Example 2)
Example 1 and the same as Example 1 except that the constituent resin of the heat seal layer was only a high melting point ethylene-methyl acrylate copolymer (melting point 90 ° C.) and 100% by mass of the high melting point ethylene-methyl acrylate copolymer. A heat-sealable multilayer film was prepared by the same method and evaluated.

(Example 3)
A heat-sealing multilayer film was prepared and evaluated in the same manner as in Example 1 except that the unsaturated fatty acid amide compound mixed in the heat-sealing layer was replaced with erucic acid amide (melting point: 81 ° C.).

(Comparative Example 1)
A heat-sealable multilayer film was prepared and evaluated by the same method as in Example 1 except that the unsaturated fatty acid amide compound was not blended in the heat-seal layer.

(Comparative Example 2)
A heat-sealing multilayer film was prepared in the same manner as in Example 1 except that the heat-sealing layer was mixed with stearate amide (melting point: 101 ° C.), which is a saturated fatty acid amide, instead of the unsaturated fatty acid amide. Evaluation was performed.

(Comparative Example 3)
A heat-sealing multilayer film was produced in the same manner as in Example 1 except that the heat-sealing layer was mixed with ethylene bisstearic acid amide (melting point: 145 ° C.), which is a saturated fatty acid bisamide, instead of the unsaturated fatty acid amide. And evaluated.

(Comparative Example 4)
A heat-sealing multilayer film was prepared and evaluated in the same manner as in Example 1 except that ethylene bislauric acid amide (melting point: 157 ° C.), which is a saturated fatty acid bisamide, was mixed with the heat-sealing layer.

The obtained heat-sealable multilayer film was evaluated as follows. Table 1 shows the types of fatty acid amide lubricants blended in the film and the evaluation results.

(1) Heat-sealing property Each heat-sealing property multi-layer film and lid material are used with a heat sealer (TP-701-B) manufactured by Tester Sangyo Co., Ltd. at 150 ° C., 3 kg / cm ² , sealing width 6 mm, and sealing time 2 seconds. Heat-sealed under the conditions. The heat-sealed sample was cut into strips having a width of 15 mm, peeled at a peeling speed of 100 mm / min in a 180 ° peeling test, the peeling strength was measured, and evaluated according to the following criteria.
◯: Peeling strength 100 gf / 15 mm width or more,
X: Peeling strength less than 100 gf / 15 mm width,

(2) Easy peeling
For each heat-sealed sample, the sterilized paper was peeled off from the film by hand peeling, and the peeling state at that time was visually observed and evaluated according to the following criteria.
◯: The sterile paper does not tear, and no pieces of paper or fluff remain on the peeled part.
Δ: The sterile paper does not tear, but some pieces of paper and fluff remain on the peeled part.
×: The sterile paper is torn, leaving a piece of paper or fluff on the peeled part, or cannot be peeled.

(3) Sliding property In order to evaluate the slipperiness of each heat-sealing multilayer film on the heat-sealing layer side, the coefficient of dynamic friction with a polyethylene film (LLDPE, 70 μm) was measured with JIS K7125, and the following criteria were used. Evaluated in.
◯: Dynamic friction coefficient 0.5 or less,
×: The dynamic friction coefficient exceeds 0.5,

(4) Film-forming property At the time of film-forming, the windability of the film with a winder was evaluated according to the following criteria.
〇: The film was rolled up without any problem.
×: Films were blocked from each other, causing problems such as winding misalignment.

(5) Transparency For each sample, a single-layer film having a thickness of 100 μm was collected only by blending the heat seal layer. With respect to the film, all haze was measured with a haze meter (model: NDH5000) manufactured by Nippon Denshoku Kogyo Co., Ltd. according to JISK7361 and 7136, and evaluated according to the following criteria.
◯: Total haze less than 9.0%,
×: Total haze 9.0% or more,

From Table 1, the heat-sealable multilayer films of the present invention of Examples 1 to 3 contain an ethylene-methyl acrylate copolymer (A) and an unsaturated fatty acid amide (B) in the heat-seal layer. It can be seen that both slipperiness and film forming property are good. Further, in Examples 1 and 3, two types of mixtures of a high melting point ethylene-methyl acrylate copolymer and a low melting point ethylene-methyl acrylate copolymer are used for the heat seal layer. The easy peeling property was also good.
On the other hand, in Comparative Examples 1 to 4 in which the heat-sealed layer did not contain the unsaturated fatty acid amide, the slipperiness and the film-forming property were inferior. Further, in Comparative Examples 2 to 4 in which the heat-sealed layer contained the saturated fatty acid amide, the transparency was further inferior.

The film of the present invention is excellent in workability in each manufacturing process because the heat-sealing layer has slipperiness while maintaining good heat-sealing property and easy peeling property even when sealed with sterilized paper or non-woven fabric. From these points of view, the film of the present invention can be beneficially used, including post-process processing such as manufacturing of medical supplies, quality control, and usability for users.

Claims (5)

A heat-sealing multilayer film having at least one heat-sealing layer on the surface layer, at least one layer containing a polyamide-based resin, and a layer containing a polyolefin-based resin adjacent to the heat-sealing layer. The heat-sealed layer is a layer containing a resin composition of an ethylene-methyl acrylate copolymer (A) and an unsaturated fatty acid amide (B), and the ethylene-methyl acrylate copolymer (A). However, a heat-sealable multilayer film which is at least two types of a copolymer having a melting point of 85 ° C. or higher and a covalent polymer having a melting point of less than 85 ° C. The heat-sealing property according to claim 1, wherein the unsaturated fatty acid constituting the unsaturated fatty acid amide (B) has 18 or more and 22 carbon atoms or less, and the unsaturated fatty acid amide has a melting point of 65 ° C. or more. Multilayer film. When the total amount of the ethylene-methyl acrylate copolymer (A) is 100% by mass, the ethylene-methyl acrylate copolymer (A) having a melting point of 85 ° C. or higher is 50 to 90% by mass. Item 2. The heat-sealable multilayer film according to Item 1 or 2. The heat-sealing multilayer film according to any one of claims 1 to 3, wherein the heat-sealing layer has an easy peeling property. A medical packaging body characterized in that the heat-sealing layer of the heat-sealing multilayer film according to any one of claims 1 to 4 and a polyethylene non-woven fabric are heat-sealed.