JP7002105B2 - Film bag and film bag manufacturing method - Google Patents

Description

The present invention relates to a film bag containing a liquid agent and a method for producing the same.

Conventionally, it has been proposed to crosslink the resin of a film used for, for example, a medical bag or the like by irradiation with radiation. This is because the heat resistance of the film can be improved by irradiation.
For example, Patent Document 1 gels a polyethylene film or sheet having a thickness of 100 to 800 μm, a density of 0.890 to 0.935 g / cm ³ , and a melt flow index (MFR) of 0.1 to 8.0 g / 10 min. We propose a medical film or sheet characterized by having a heat seal strength of 1.0 kg / 15 mm width or more by cross-linking in the range of 10 to 50%.

Further, Patent Document 2 is obtained by copolymerizing ethylene with α-olefin having 3 to 12 carbon atoms (a) having a density of 0.850 to 0.920 g / cm ³ , and (b) GPC (gel permeation. The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) obtained by chromatography) is 3 or less, and (c) is low with respect to the average number of branches of 30% by weight of the high molecular weight region fractionated by GPC. A molded product made of a linear ethylene / α-olefin copolymer having an average number of branches of 0.8% by weight in the molecular weight region of 0.8 or more and 1.2 or less is increased to 20% or more by irradiation and / or electron beam irradiation. We are proposing a medical device for draining or preserving cross-linked body fluids and chemicals.

Japanese Patent No. 2956244 Japanese Patent No. 3584556

On the other hand, with respect to the film bag formed by heat-sealing the multilayer film, when the bag receives an impact such as dropping, a phenomenon that liquid leakage occurs from the port member of the bag and its surroundings can be seen. This is because when the port member is fixed to the bag by heat sealing, the contact portion of the film with the port member and the peripheral portion thereof are thinned by melting, and this thin portion is destroyed by the hydraulic pressure from the inside of the bag. ..

As a countermeasure, as described in Patent Documents 1 and 2, the heat resistance of the resin is enhanced and the thinning at the time of heat sealing is suppressed by irradiating the multilayer film with radiation to crosslink the resin. Conceivable. However, if the entire multilayer film is simply irradiated with radiation, the heat resistance of the inner layer that contributes to heat sealing is increased, and there is a possibility that sufficient heat sealing property (strength) cannot be ensured.

Therefore, an object of the present invention is to provide a film bag capable of suppressing film tearing at a mounting portion of a port member without impairing the heat-sealing property.
Another object of the present invention is to provide a manufacturing method capable of manufacturing a film bag with high productivity, which can suppress film tearing at a mounting portion of a port member without impairing the heat sealability. Is.

The film bag of the present invention is formed by using a multilayer film including an inner layer, an outer layer, and an intermediate layer between the inner layer and the outer layer, and has a bag main body having a storage portion for storing a liquid agent, and the above-mentioned. It is fixed to the bag body by a heat seal, includes a mouth member for taking out the liquid agent in the accommodating portion, the resin of the outer layer and the intermediate layer is crosslinked, and the resin of the inner layer is not crosslinked.

In the film bag of the present invention, the gel fraction of the resin in the outer layer and the intermediate layer may be 10 to 100%, and the gel fraction of the resin in the inner layer may be 0 to 5%.
In the film bag of the present invention, the resin in the intermediate layer contains an ethylene-α-olefin copolymer as a base resin exceeding 50 parts by mass and an olefin-based elastomer of 20 parts by mass or more with respect to 100 parts by mass of the resin. And may be contained.

In the film bag of the present invention, the thickness of the inner layer of the multilayer film at the fixed position of the mouth member may be 50% to 85% of the thickness of the inner layer of the plurality of films in the accommodating portion. ..
In the film bag of the present invention, the thicknesses of the intermediate layer and the outer layer of the multilayer film at the fixed position of the mouth member are the thicknesses of the intermediate layer and the outer layer of the plurality of films in the accommodating portion, respectively. It may be 50% to 90%.

The method for producing a film bag of the present invention relates to a multilayer film including a first layer having heat-sealing properties, a second layer, and an intermediate layer between the first layer and the second layer. By irradiating the second layer and the intermediate layer with radiation from the second layer side so as not to hit the first layer, the resin of the second layer and the intermediate layer of the multilayer film is selectively selected. After the irradiation step of cross-linking and the irradiation step, the first layers of the multi-layer film are faced to each other and heat-sealed so that the first layer of the multi-layer film becomes an inner layer. The present invention includes a step of forming a film bag having the above, and a step of attaching the mouth member to the mouth member mounting portion by a heat seal.

In the method for producing a film bag of the present invention, the irradiation step may include a step of irradiating the multilayer film with an electron beam.
In the method for producing a film bag of the present invention, the resin in the intermediate layer contains an ethylene-α-olefin copolymer as a base resin exceeding 50 parts by mass with respect to 100 parts by mass of the resin, and 20 parts by mass or more. It may contain an olefin-based elastomer.

According to the present invention, since the resin of the inner layer is not crosslinked, heat sealing can be performed with sufficient strength by melting the inner layer. On the other hand, in the mouth member mounting portion, thinning of the crosslinked intermediate layer and outer layer can be suppressed, and the intermediate layer and outer layer can be maintained relatively thick. Further, it is possible to suppress the thinning of the inner layer in the mouth member mounting portion. As a result, it is possible to suppress the thinning of the film as a whole at the mouth member mounting portion. As a result, even if the film bag receives an impact due to dropping or the like, it is possible to suppress the film tearing at the mouth member mounting portion.

Further, the irradiation for cross-linking the resin of the intermediate layer and the outer layer is performed in the state of the film, not after the bag is formed. Therefore, by simply irradiating the second layer side (outer layer side) of the multilayer film with radiation under predetermined conditions, the resin on the second layer side of the first layer (inner layer) of the multilayer film is selectively selected. , Can be easily crosslinked.

FIG. 1 is a schematic plan view of a medical bag according to an embodiment of the present invention. 2A and 2B are cross-sectional views of a main part of a peripheral heat seal portion and a port mounting portion of the medical bag, respectively. 3A and 3B are views showing a part of the manufacturing process of the medical bag. 4A and 4B are views showing the next steps of FIGS. 3A and 3B. 5A and 5B are views showing the next steps of FIGS. 4A and 4B. 6A and 6B are diagrams showing the next steps of FIGS. 5A and 5B. FIG. 7 is a schematic perspective view of a medical bag according to another embodiment of the present invention. FIG. 8 is a plan view of the medical bag of FIG. 7. FIG. 9 is a schematic plan view of a medical bag according to still another embodiment of the present invention. FIG. 10 is a graph showing the relationship between the sealing temperature of the plastic film and the sealing strength.

<Overall composition of the bag>
FIG. 1 is a schematic plan view of a medical bag 1 according to an embodiment of the present invention.
The medical bag 1 is a flat rectangular bag body 3 whose peripheral edge 2 is welded by heat sealing, and a port member as an example of a mouth member of the present invention that is attached to the bag body 3 and discharges a liquid agent. Includes 4 and.

The bag body 3 is an example of a peripheral heat seal portion 5 formed continuously on substantially the entire circumference of the peripheral edge portion 2 and a mouth member mounting portion of the present invention formed on the central portion of one side of the peripheral edge portion 2. It has a port mounting portion 6 and an accommodating portion 7 partitioned by a peripheral heat seal portion 5. In the storage unit 7, for example, an infusion preparation such as a basic infusion such as physiological saline and Ringer's solution, and a medical liquid preparation such as a peritoneal dialysate are stored.

The peripheral heat seal portion 5 includes a pair of vertical seals 51 along the vertical direction of the bag body 3 and a pair of horizontal seals 52 along the horizontal direction of the bag body 3. The port mounting portion 6 is formed on one of the horizontal seals 52.
The port member 4 is a boat-shaped port in this embodiment, and is a boat-shaped base member 10 fixed to the port mounting portion 6 by a heat seal, a head 9 to which a cap 14 (for example, a pull-top type cap) is attached, and a base. Includes a round tubular portion 8 that connects the member 10 and the head 9. The base member 10, the head portion 9, and the tubular portion 8 may be integrally molded or may be connected to each other as separate products. The port member 4 is fixed to the bag body 3 by heat-sealing the bag body 3 to the base member 10 inserted into the port mounting portion 6.
Further, in the bag main body 3, a hanging hole 11 is formed in the other lateral seal 52 facing the port mounting portion 6. Further, the horizontal seal 52 may be provided with one non-seal portion 15 having no heat seal on both sides in the lateral direction with the hanging hole 11 interposed therebetween.

<Film layer structure>
2A and 2B are cross-sectional views of the main parts of the peripheral heat seal portion 5 and the port mounting portion 6 of the medical bag 1, respectively. The layer structure of the film constituting the bag body 3 will be described with reference to FIGS. 2A and 2B.
The bag body 3 is composed of, for example, a heat seal of a multilayer film 12 that overlaps with each other. As shown in FIGS. 2A and 2B, the multilayer film 12 is composed of, for example, a three-layer film. The three-layered multi-layer film 12 includes an inner layer 13, an intermediate layer 18, and an outer layer 17, which are laminated in order from the accommodating portion 7 side.

The inner layer 13, the intermediate layer 18, and the outer layer 17 may all be made of a resin (radiation crosslinked resin) having a polymer structure that exhibits a crosslinking reaction when irradiated with radiation. Examples of such resins include polyolefin resins such as polyethylene, polypropylene, poly (4-methylpentene) and polytetrafluoroethylene, polycyclic olefin resins such as ethylene-tetracyclododecene, and polyethylene terephthalates (PET). Polyester-based resins such as ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol copolymer (EVOH), polyvinyl acetate, polyvinyl alcohol, vinyl-based polymer resins such as polyvinyl chloride, nylon-6, Examples thereof include polyamide-based resins such as nylon-12 and nylon-6,6, olefin-based elastomers, and various thermoplastic elastomers such as styrene-based elastomers.

In the bag main body 3 according to this embodiment, the resin of the outer layer 17 and the intermediate layer 18 has a crosslinked structure, and the resin of the inner layer 13 is not crosslinked. Here, "uncrosslinked" does not mean that the polymer constituting the resin of the inner layer 13 does not have any crosslinked structure. For example, even if the cross-linking reaction is not positively caused by irradiation with an electron beam described later (FIGS. 4A and 4B), some cross-linking of the polymer may occur unintentionally in the manufacturing process of the inner layer 13. Even in that case, the inner layer 13 may have a somewhat crosslinked structure as long as the effect of suppressing film tearing at the port mounting portion 6 can be exhibited without impairing the heat-sealing property of the present invention.

The degree of cross-linking of the resin can be compared, for example, by the gel fraction measured according to JIS K 6769. For example, the degree of cross-linking (gel fraction) of the resins of the outer layer 17 and the intermediate layer 18 cross-linked in this embodiment is, for example, 10% to 100%, and the degree of cross-linking (gel) of the resin of the uncross-linked inner layer 13 is, for example. The fraction) is, for example, 0% to 5%.
Further, in the bag body 3 of this embodiment, the thickness of the heat-sealed portion of the multilayer film 12 is thinner than that of the heat-sealed portion of the multilayer film 12.

For example, the thickness of the inner layer 13 at the fixed position (heat-sealed portion) of the port member 4 shown in FIG. 2B is 85% of the thickness of the inner layer 13 at the accommodating portion 7 (non-heat-sealed portion) shown in FIG. 2A. Hereinafter, the thickness is preferably 50% or more. On the other hand, the thickness of the outer layer 17 and the intermediate layer 18 at the fixed position (heat-sealed portion) of the port member 4 shown in FIG. 2B is the thickness of the outer layer 17 and the intermediate layer 18 in the accommodating portion 7 (non-heat-sealed portion) shown in FIG. 2A. It is 90% or less of the thickness, preferably 50% or more (more preferably 70% or more).

More specifically, the thickness of the inner layer 13 in the heat-sealed portion may be 20 μm to 40 μm, and the thickness of the inner layer 13 in the non-heat-sealed portion may be 30 μm to 50 μm. The thickness of the outer layer 17 in the heat-sealed portion may be 5 μm to 25 μm, and the thickness of the outer layer 17 in the non-heat-sealed portion may be 10 μm to 30 μm. The thickness of the intermediate layer 18 in the heat-sealed portion may be 90 μm to 130 μm, and the thickness of the intermediate layer 18 in the non-heat-sealed portion may be 120 μm to 160 μm.

<Film layer structure (preferable form)>
Next, a preferable form of the resin used for the intermediate layer 18 will be described.
Here, only the preferable form of the resin of the intermediate layer 18 will be described, and the description of the resin of the inner layer 13 and the outer layer 17 will be omitted. That is, unlike the intermediate layer 18, there is no resin that is particularly preferable for the resin of the inner layer 13 and the outer layer 17, and a known resin can be appropriately selected. Specifically, since the inner layer 13 is not an object of cross-linking treatment with an electron beam or the like, it does not need to be a radiation cross-linking type resin, and has various properties required as an inner layer of a multilayer film, such as blocking resistance. The resin is not particularly limited as long as it has. On the other hand, the outer layer 17 is not particularly limited as long as it has a melting point high enough to exhibit the heat resistance required for the medical bag 1 and is a crosslinkable resin (for example, polyethylene or the like).

The intermediate layer 18 is a linear low density polyethylene (LLDPE) having a density of 0.945 g / cm ³ to 0.965 g / cm ³ , an olefin elastomer, and a linear low density polyethylene polymerized with a single site catalyst. Is preferably contained.
Examples of the LLDPE used include ethylene-α-olefin copolymers polymerized with a Ziegler catalyst. Examples of the Ziegler catalyst include various Ziegler catalysts (Ziegler-Natta catalysts) used in the production of polyethylene. Examples of the α-olefin in the ethylene-α-olefin copolymer include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and 1-nonene. , 1-decene, 1-undecene, 1-dodecene and other α-olefins having 3 to 12 carbon atoms can be mentioned. These α-olefins may be used alone or in combination of two or more. Further, the α-olefin is preferably propylene or 1-butene, more preferably 1-butene, among the above examples. By appropriately setting the content ratio of α-olefin in the ethylene-α-olefin copolymer, the density can be set in the above range of 0.945 g / cm ³ to 0.965 g / cm ³ . That is, the content ratio of α-olefin in the ethylene-α-olefin copolymer is appropriately set according to the density required for the ethylene-α-olefin copolymer.

The MFR of the LLDPE is preferably 0.8 g / 10 minutes (190 ° C.) to 1.4 g / 10 minutes (190 ° C.).
Examples of the olefin-based elastomer used include linear polyethylene elastomers, ethylene-α-olefin copolymer elastomers, and propylene-α-olefin copolymer elastomers. Further, examples of the α-olefin in the olefin-based elastomer include the above-mentioned α-olefin.

The density of the olefin-based elastomer is preferably 0.875 g / cm ³ to 0.895 g / cm ³ , and the MFR is preferably 0.4 g / 10 minutes (190 ° C.) to 0.6 g / 10. Minutes (190 ° C).
Examples of the linear low density polyethylene polymerized with the single site catalyst used include ethylene-α-olefin copolymer (m-LLDPE) polymerized with a metallocene catalyst. Examples of the α-olefin in the ethylene-α-olefin copolymer include the above-mentioned α-olefin.

The density of m-LLDPE is preferably 0.895 g / cm ³ to 0.915 g / cm ³ , and the MFR is preferably 0.8 g / 10 min (190 ° C.) to 1.2 g / 10. Minutes (190 ° C).
The blending ratio of each resin contained in the intermediate layer 18 is, for example, ethylene-α-olefin copolymer (LLDPE and m-LLDPE) as a base resin with respect to 100 parts by mass of the entire resin of the intermediate layer 18. It exceeds 50 parts by mass, and the olefin-based elastomer is 20 parts by mass or more (preferably 30 parts by mass to 40 parts by mass).

Although the preferred form of the resin used for the intermediate layer 18 has been described above, the above resin is merely an example of the resin used for the intermediate layer 18. If the intermediate layer 18 is a resin whose heat resistance can be improved by cross-linking, in addition to the above resin, as described above, a polyolefin resin other than polyethylene such as polypropylene, a polycyclic olefin resin, and a polyester resin , A resin such as a polyamide resin, and a resin composed of a combination thereof.

<Manufacturing method of medical bag>
Next, a method for manufacturing the medical bag 1 will be described.
In order to manufacture the medical bag 1, first, as shown in FIGS. 3A and 3B, the multilayer film 12 is manufactured by, for example, inflation molding the raw material resin. More specifically, it constitutes the first layer 19 constituting the inner layer 13, the second layer 20 constituting the outer layer 17, and the intermediate layer 18 formed while air is introduced from the three-layer film extruder 22. The multilayer film 12 including the intermediate layer 23 is supplied to the pair of forming rollers 21 (nip rolls). In the pair of forming rollers 21, pressure is applied to the tubular multi-layer film 12, and as shown in FIG. 3B, the first layers 19 (inner layers 13) are formed into a flat shape so as to face each other. Then, the obtained multilayer film 12 is collected by the take-up roller 24.

Next, as shown in FIGS. 4A and 4B, among the one side 31 and the other side 32 of the flat multilayer film 12 drawn out from the take-up roller 24 and flowing, the first layer is first with respect to one side 31. Radiation is applied to the second layer 20 and the intermediate layer 23 from the second layer 20 (outer layer 17) side so as not to hit 19 (inner layer 13). Here, the MD (Machine Direction) shown in FIGS. 4A and 4B is the flow direction of the multilayer film 12. Examples of the radiation to be irradiated include an electron beam, a gamma ray, and the like, and an electron beam is preferably irradiated. In this case, the electron beam irradiation conditions are appropriately set in consideration of the thickness of the second layer 20 and the intermediate layer 23, and the thickness of the second layer 20 (outer layer 17) is, for example, 10 μm to 30 μm. When the thickness of the intermediate layer 23 (intermediate layer 18) is 120 μm to 160 μm, that is, when the total thickness of the second layer 20 and the intermediate layer 23 is 130 μm to 190 μm, the acceleration voltage is 100 kV to 150 kV. The absorbed dose may be set in the range of 70 kGy to 200 kGy. Specifically, the thicker the multilayer film 12, the deeper the penetration depth of the electron beam by setting the acceleration voltage higher, and the second layer 20 (outer layer 17) to the intermediate layer 23 (intermediate layer 23) are deepened. The electron beam can be sufficiently applied up to 18). In addition, by setting the absorbed dose high, the degree of cross-linking by electron beam irradiation can be increased. If, for example, the acceleration voltage is too large, even the inner layer 13 may be exposed to the electron beam, which may affect the sealing characteristics of the inner layer 13. Further, even if the absorbed dose is set too high, a particularly remarkable effect cannot be obtained, and the film processing speed must be lowered, so that there is a concern that the productivity may be lowered.

Then, by irradiating the electron beam under appropriate voltage and absorbed dose conditions, the resins of the second layer 20 (outer layer 17) and the intermediate layer 23 (intermediate layer 18) are selected from the films constituting the multilayer film 12. Crosslink.
After that, the multilayer film 12 is turned over and flown into the electron beam irradiation device again, and the electron beam irradiation performed on one surface 31 of the multilayer film 12 is also performed on the other surface 32. This completes the cross-linking of the resin of the second layer 20 (outer layer 17) and the intermediate layer 23 (intermediate layer 18) on both the one side 31 side and the other side 32 side of the multilayer film 12.

Next, as shown in FIGS. 5A and 5B, by selectively heat-sealing the flowing multilayer film 12 (inflation film), a plurality of bag bodies 3 connected at intervals along the MD direction are formed. To. The plurality of bag bodies 3 may be formed in only one row along the MD direction, or may be formed in two rows or more side by side as shown in FIG. 5A.

Specifically, a vertical seal 51 along the MD and a horizontal seal 52 along the TD (Transverse Direction) perpendicular to the MD are formed at the same time. The vertical seal 51 and the horizontal seal 52 do not necessarily have to be formed at the same time, and may be formed in separate steps. As a result, the peripheral heat seal portion 5 is formed, and the accommodating portion 7 is formed in the region surrounded by the peripheral heat seal portion 5. Further, in the central portion of one of the horizontal seals 52, a port mounting portion 6 formed of through holes formed so that the unwelded portions of the multilayer film 12 face each other is formed. The port mounting portion 6 is formed as an opening slightly larger than the base member 10 of the port member 4. The heat sealing conditions at this time may be, for example, a sealing temperature = 120 ° C. to 150 ° C. and a sealing time = 0.5 seconds to 10 seconds. Then, the bag main body 3 is punched out one by one from the multi-layer film 12 after heat sealing.

Next, as shown in FIGS. 6A and 6B, the port member 4 is inserted into the port mounting portion 6 of each bag body 3, the multilayer film 12 is crimped to the port member 4 by heat sealing, and the port member 4 is pressed. The untreated portion of the peripheral part of the heat seal is closed by the heat seal at this stage. The heat sealing conditions at this time may be, for example, a sealing temperature = 120 ° C. to 150 ° C. and a sealing time = 0.5 seconds to 10 seconds.
After that, the medical bag 1 is obtained by injecting the liquid agent into the accommodating portion 7.

<Effect of medical bag>
According to the obtained medical bag 1, since the resin of the inner layer 13 is not crosslinked, it can be heat-sealed with sufficient strength by melting the inner layer 13. On the other hand, in the port mounting portion 6, the fixing portion 29 (crimping portion of the port member 4) of the port member 4 and the peripheral portion of the port fixing portion 29, the port member 4 is heated in the steps of FIGS. 6A and 6B. In the portion 25 (port peripheral portion) that is thermocompression-sealed as the horizontal seal 52 when crimped, it is possible to suppress the thinning of the crosslinked intermediate layer 18 and outer layer 17, and the intermediate layer 18 and outer layer 17 are relatively thin. Can be kept thick. Further, in the port fixing portion 29 and the port peripheral portion 25, the thinning of the inner layer 13 can be suppressed. As a result, it is possible to suppress the thinning of the film as a whole in the port fixing portion 29 and the port peripheral portion 25. As a result, even if the medical bag 1 is impacted by dropping or the like, the film tearing at the lower side 27 (lower side of the port portion) of the port fixing portion 29 and the lower side 26 (lower side of the seal portion) of the port peripheral portion 25 is suppressed. Can be done.

Further, as shown in FIGS. 4A and 4B, irradiation for cross-linking the resins of the intermediate layer 18 and the outer layer 17 is performed in the state of the multilayer film 12 not after the formation of the bag body 3. Therefore, only by irradiating the second layer 20 side (outer layer 17 side) of the multilayer film 12 under predetermined conditions, the second layer 20 side of the multilayer film 12 is closer to the first layer 19 (inner layer 13). The resin in the portion can be selectively and easily crosslinked.

Although one embodiment of the present invention has been described above, the present invention can also be implemented in other embodiments.
For example, in the above-described embodiment, a drug solution bag containing a medical solution is described as an example of a film bag, but the present invention can also be used for a bag containing foods such as nutritional supplements and drinks. ..

Further, in the above-described embodiment, a single-chamber bag having only one accommodating portion 7 has been described as an example of the film bag. It can also be used for partitioned multi-chamber bags.
Further, in the above-described embodiment, only the multilayer film 12 obtained by inflation molding is exemplified as the multilayer film 12, but the multilayer film 12 may be produced, for example, by T-die coextrusion molding.

Further, in the above-described embodiment, the boat-shaped port is mentioned as the port member 4, but as shown in FIGS. 7 and 8, the port member 4 may be a round port. In the round port member 4, the rubber stopper 16 may be fitted inside the head portion 9.
Further, in the medical bag 1, the peripheral heat seal portion 5 may not be formed over the entire circumference of the bag body 3. For example, as shown in FIG. 9, only the horizontal seal 52 may be selectively formed. The long side of the bag body 3 (the portion where the vertical seal 51 is formed in FIG. 1) is formed as a polygonal line portion 28 in which the overlapping multilayer films 12 are continuously connected. As a result, the accommodating portion 7 is partitioned by the polygonal line portion 28 and the lateral seals 52 and 52.

In addition, various design changes can be made within the scope of the matters described in the claims.

Next, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to the following examples.
(1) Production of Multilayer Film A resin material constituting each of the outer layer, the intermediate layer and the inner layer was produced by melting and mixing based on the blending ratio (parts by mass) shown in Table 1 below. Then, by inflation molding these resin materials, a three-layer film (films 1 to 5) having a layer structure shown in Table 1 was produced. The information on the resin material of the intermediate layer shown in Table 1 is as follows. Although details of the outer layer and inner layer resins are omitted, all of the films 1 to 5 contain a polyethylene-based resin as a base resin in an amount exceeding 50 parts by mass (outer layer: PE1, inner layer PE2). It was used.
-M-LLDPE (Density = 0.905 g / cm ³ , MFR = 1.0 g / 10 minutes (190 ° C))
-Olefin elastomer (density = 0.885 g / cm ³ , MFR = 0.5 g / 10 minutes (190 ° C))
LLDPE (density = 0.957 g / cm ³ , MFR = 1.1 g / 10 minutes (190 ° C))
(2) Irradiation of electron beam By irradiating the electron beam from the outer layer side of the films 1 to 5, the resins of the outer layer and the intermediate layer of the films 1 to 5 were crosslinked. The electron beam was irradiated using an electron beam irradiation device manufactured by Iwasaki Electric Co., Ltd. so that the acceleration voltage was 125 kV and the absorbed dose was 100 kGy.

Further, using each of the films 1 to 5 before and after the irradiation of the electron beam, a medical bag was prepared according to the above description, and high temperature steam sterilization (121 ° C.) was performed. The Young's modulus before and after sterilization was measured according to JIS K 7161 and is as shown in Table 1. Further, the tensile elongation at break and the tensile stress at break (both conforming to JIS K 7127) of each layer of each film 1 to 5 before and after irradiation with the electron beam were measured and found as shown in Table 1.

(3) Manufacture of film bag <Examples 1 to 5>
The films 1 to 5 (electron-irradiated) obtained above were used to produce the film bag shown in FIG. The size of the film bag was such that the storage capacity of the storage portion was about 250 mL, the vertical length (L) of the storage portion was 20 cm, and the horizontal width (W) was 15 cm. Example 1 for a bag made of film 1, Example 2 for a bag made of film 2, Example 3 for a bag made of film 3, Example 4, film 5 for a bag made of film 4. The bag manufactured in the above was designated as Example 5. The heat seal conditions at the time of forming the peripheral heat seal portion and at the time of attaching the port were the seal temperature = 160 ° C./160 ° C. and the seal time = 5 seconds. After making the film bags, 250 mL of the liquid was poured into each bag.

<Comparative Examples 1 to 5>
On the other hand, the film bag shown in FIG. 1 was manufactured by using the films 1 to 5 before irradiating with the electron beam. Comparative Example 1 for a bag manufactured with film 1 (non-irradiated with electron beam), Comparative Example 2, a bag manufactured with film 2 (non-irradiated with electron beam), and a bag manufactured with film 3 (non-irradiated with electron beam). Comparative Example 3 and a bag manufactured by film 4 (without electron beam irradiation) were designated as Comparative Example 4, and a bag manufactured by film 5 (without electron beam irradiation) was designated as Comparative Example 5. Further, the heat seal conditions at the time of forming the peripheral heat seal portion and at the time of attaching the port were all the same as those of Examples 1 to 5 except that the seal temperature was set to 150 ° C./150 ° C. After making the film bags, 250 mL of the liquid was poured into each bag.

(4) Film bag evaluation test <film thickness>
The thickness of each layer of the film at the accommodating portion and the port portion fixed position of the film bag of Examples 1 to 5 and Comparative Examples 1 to 5 was measured. The results are shown in Tables 2 and 3.
<Strength of falling plate>
The falling plate strength of the film bags of Examples 1 to 5 and Comparative Examples 1 to 5 was measured. Specifically, first, each film bag was left in a constant temperature room at 0 ° C. for 24 hours, and then taken out in a sufficiently cooled state. Next, the film bag is placed on an iron plate, and a 6.8 kg metal plate (size: about 37 cm × 37 cm, thickness: 0.5 cm) is placed on the iron plate so that the surface of the metal plate is parallel to the surface of the film bag bag. I dropped it so that it would be. Then, the drop plate strength was determined by measuring the height (drop height) of the metal plate at which the film bag bursts or liquid leakage occurs. The results are shown in Tables 2 and 3.

In Tables 2 and 3, the plate height "0" indicates that the film bag burst or leaked when the metal plate was dropped from a height of 10 cm or less. Further, the plate height "100 + cm" indicates that the film bag did not burst or liquid leakage occurred even when the metal plate was dropped from the height of 100 cm. Further, the "burst" at the fractured portion indicates that the heat-sealed portion of the film bag was peeled off and the liquid agent flowed out from the peeled-off portion.

(5) Evaluation As shown in Tables 2 and 3, Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, Example 3 and Comparative Example 3, Example 4 and Comparative Example 4, and Example 5 When Comparative Example 5 and Comparative Example 5 are compared with each other, the thinning of the inner layer, the intermediate layer and the outer layer after heat sealing is suppressed by irradiating the film with an electron beam so as not to hit the inner layer of the film. As a result, in Examples 1 to 5, the ratio at which the falling plate strength of 30 cm or more can be achieved is clearly increased. That is, in the film bags of Examples 1 to 5, even if the metal plate is dropped from a height of about 30 cm, the film is torn at the lower side of the seal portion (lower side 26 of FIG. 1) and the lower side of the port portion (lower side 27 of FIG. 1). The probability of occurrence is low. Moreover, it was found that by setting the proportion of the olefin-based elastomer in the intermediate layer to 20 parts by mass or more as in Examples 3 to 5, a high-strength film bag can be stably obtained with a high probability. In particular, in Examples 4 and 5 in which the proportion of the olefin-based elastomer in the intermediate layer was 30 parts by mass or more, a plate drop strength of 30 cm or more could be achieved for all the samples.

(6) Measurement of gel fraction Next, in order to grasp the degree of cross-linking of the above-mentioned films 1 to 5, the following measurements were performed.
First, a first film having the same composition as the intermediate layer of the film 4 and having a thickness of 160 μm and a second film having a composition in which two types of LLDPE were blended and having a thickness of 40 μm were prepared. That is, as a sample film for measuring the gel fraction, the thickness of the first film having the same thickness as the total thickness (140 μm + 20 μm) of the intermediate layer and the outer layer to be crosslinked in the films 1 to 5 and the thickness of the inner layer to be uncrosslinked. A second film having the same thickness as (40 μm) was prepared separately.

Next, the first film (outer layer + intermediate layer) and the second film (inner layer) were superposed, and the electron beam was irradiated from the first film side under the conditions of 6 patterns of acceleration voltage and absorbed dose.
After irradiation with the electron beam, the gel fraction of each film was measured separately according to the following test equipment, test conditions and test method.
<Test equipment>
1L glass flask, cooling condenser, oil bath, stirrer set <test conditions>
Solvent: p-xylene 500 mL
Heating conditions: 130 ° C, 4 hours Drying conditions: 140 ° C, 3 hours, vacuum <Test method>
First, each sample film (first film and second film) was cut into small pieces and weighed about 2 g. This was used as the sample charge amount. Next, the sample film was wrapped with a wire mesh (140 mm × 120 mm) having a thickness of 106 μm, and the total amount was precisely weighed. Next, 500 mL of p-xylene was placed in a glass flask and set in an oil bath at 130 ° C. The liquid temperature was confirmed to be 130 ° C., a wire mesh containing a sample was inserted into a glass flask, and the mixture was stirred for 4 hours. Then, the wire mesh was taken out from the glass flask and vacuum dried at 140 ° C. for 3 hours. After cooling the dried wire mesh, the sample film was precisely weighed.

Then, the gel fraction was determined by the formula: gel fraction (wt%) = (p-xylene insoluble content / sample charge amount) × 100. The results are shown in Table 4.

In Table 4, the irradiation conditions (acceleration voltage (kV) and absorbed dose (kGy)) of the gel fraction 3 are the same as the irradiation conditions of the films 1 to 5 used in Examples 1 to 5 described above. Under the irradiation condition of the gel fraction 3, the gel fraction of the first film having the same thickness as the total thickness of the intermediate layer and the outer layer of the films 1 to 5 is 33.1 wt%, which is the same thickness as the inner layer. The gel fraction of the second film having a shaving was 0.5 wt%. From this, it is proved that the inner layer is not crosslinked and the intermediate layer and the outer layer are selectively crosslinked also in the films 1 to 5. Further, it can be seen that if the thickness of the films is 1 to 5, the inner layer can be uncrosslinked and the intermediate layer and the outer layer can be selectively crosslinked even under the irradiation condition of the gel fraction 4.

On the other hand, under the irradiation conditions of gel fractions 5 and 6, the acceleration voltage was too large, resulting in cross-linking to the resin in the inner layer. It can also be seen that under the irradiation condition of gel fraction 2, the absorbed dose is too small and the resins of the intermediate layer and the outer layer are not sufficiently crosslinked.
(7) Seal curve Next, how the relationship between the seal temperature and the seal strength changes with the change of the gel fraction was evaluated by creating a seal curve of a plastic film.

More specifically, the sample film (without electron beam irradiation) prepared in the above-mentioned "(6) Measurement of gel fraction", the gel fraction 3, the gel fraction 5 and the gel fraction 6 electron beam irradiation film are used. Prepare a pair of each, and use a heat sealer so that the direction of the seal bar is the TD direction (horizontal direction) of the film (so that the film can be peeled in the MD direction (film flow direction) in the peeling test described later). ) Heat-sealed. The conditions for heat sealing at this time are as follows.
・ Temperature: 5 ° C increments from 100 ° C to 150 ° C ・ Seal pressure: 0.64 MPa
・ Pressurization time: 4.1 seconds ・ Seal bar size: Width x Length = 20 mm x 190 mm
Then, five heat-sealed portions at each temperature were cut into strips having a width of 15 ± 0.1 mm in the perpendicular direction, and these were used as samples. Then, the sample was left in an environment of 23 ± 2 ° C. and 50 ± 5% RH for 4 hours or more.

Next, a peeling test was performed on each sample. In the peeling test, first, a sample was taken, opened at an angle of 180 ° around the heat-sealed portion, and both ends of the sample were placed on a jig (jig interval 50 mm) of a tensile tester. Next, a peeling test was performed at a head speed of 300 ± 20 mm / min, and the maximum load at that time was recorded as the seal strength (in the case of breakage, it was recorded as breakage). Then, based on the obtained peeling test data, the sealing temperature was set on the horizontal axis and the sealing strength (peeling strength) was set on the vertical axis, and the graph was graphed as a sealing curve. The graph is shown in FIG.

As shown in FIG. 10, a film having a gel fraction of 3 (that is, a film having a gel fraction of 10 to 100% in the outer layer and the intermediate layer and a gel fraction of 0 to 5% in the inner layer). It was found that superior sealing strength was obtained as compared with the films having a gel fraction of 5 and a gel fraction of 6.
Further, the seal curve of the film having the gel fraction 3 has a smaller shift amount to the high temperature side with respect to the seal curve of the film not irradiated with the electron beam than the seal curves of the films having the gel fraction 5 and the gel fraction 6. It turned out that the shape is also similar. Therefore, since the film bag can be manufactured under almost the same manufacturing conditions (sealing conditions, sterilization conditions, etc.) as the film not irradiated with an electron beam, it becomes easy to manufacture a bag having the same specifications.

1 Medical film bag 2 Peripheral part 3 Bag body 4 Port member 5 Peripheral heat seal part 6 Port mounting part 7 Accommodating part 12 Multi-layer film 13 Inner layer 17 Outer layer 18 Intermediate layer 19 1st layer 20 2nd layer 23 Intermediate layer 25 ports Peripheral part 26 Seal part lower side 27 Port part lower side 29 Port fixing part

Claims (7)

A bag body formed by using a multi-layer film including an inner layer, an outer layer, and an intermediate layer between the inner layer and the outer layer, and having an accommodating portion for accommodating a liquid agent.
It is fixed to the bag body by a heat seal and includes a mouth member for taking out the liquid agent in the accommodating portion.
The resin in the outer layer and the resin in the intermediate layer are crosslinked, and the resin in the inner layer is not crosslinked .
The gel fraction of the resin in the outer layer and the intermediate layer is 10 to 100%.
A film bag having a gel fraction of the resin in the inner layer of 0 to 5% . The resin in the intermediate layer contains an ethylene-α-olefin copolymer and 20 parts by mass or more of an olefin-based elastomer as a base resin of more than 50 parts by mass with respect to 100 parts by mass of the resin. The film bag according to claim 1 . The film according to claim 1 or 2 , wherein the thickness of the inner layer of the multilayer film at the fixed position of the mouth member is 50% to 85% of the thickness of the inner layer of the plurality of films in the accommodating portion. bag. The thickness of the intermediate layer and the outer layer of the multilayer film at the fixed position of the mouth member is 50% to 90% of the thickness of the intermediate layer and the outer layer of the plurality of films in the accommodating portion, respectively. , The film bag according to claim 1 or 2 . The multi-layer film including the first layer having heat-sealing property, the second layer, and the intermediate layer between the first layer and the second layer is described so as not to hit the first layer. An irradiation step of selectively cross-linking the resin of the second layer and the intermediate layer of the multilayer film by irradiating the second layer and the intermediate layer with radiation from the second layer side.
After the irradiation step, the first layers of the multi-layer film are heat-sealed facing each other so that the first layer is an inner layer, thereby forming a film bag having a mouth member mounting portion in a part thereof. Process and
The step of attaching the mouth member to the mouth member mounting portion by a heat seal is included.
In the irradiation step, the gel content of the resin in the second layer and the intermediate layer is 10 to 100%, and the gel content of the resin in the first layer is 0 to 5%. A method for manufacturing a film bag, which comprises the step of irradiating the radiation . The method for manufacturing a film bag according to claim 5 , wherein the irradiation step includes a step of irradiating the multilayer film with an electron beam. The resin in the intermediate layer contains an ethylene-α-olefin copolymer and 20 parts by mass or more of an olefin-based elastomer as a base resin of more than 50 parts by mass with respect to 100 parts by mass of the resin. The method for manufacturing a film bag according to claim 5 or 6 .

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