Polyethylene resin composition, and film and medical container comprising same

Abstract

Provided are: a polyethylene resin composition which does not cause fusion of an inner surface even after sterilization treatment at 121°C and which provides excellent weak seal strength stability; a film comprising the polyethylene resin composition; and a medical container using the film.　This polyethylene resin composition comprises: 60%-95% by weight of a high-density polyethylene (A) satisfying characteristics (a)-(d); and 5%-40% by weight of a linear low-density polyethylene (B) satisfying characteristics (e)-(g). (a) The density is 955-970 kg / m3. (b) The melt flow rate (MFR) measured at 190°C and a load of 21.18 N is 0.1-30 g / 10 min. (c) The number of long-chain branches having carbon atoms equal to or more than the number of carbon atoms of a hexyl group is less than 0.5 per 1,000 carbon atoms. (d) The ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) is 3.0 or less. (e) The density is 870-930 kg / m3. (f) The MFR is 0.1-20.0 g / 10 min. (g) The Mw / Mn is 3.0 or less.

Description

Polyethylene resin composition, and film and medical container made thereof

[0001] The present invention relates to a polyethylene resin composition, a film made thereof, and a medical container using the film.

[0002] In the medical field, it is common for multiple pharmaceutical components to be mixed and administered into the body. However, depending on the combination of pharmaceutical components being mixed, chemical reactions or other factors may occur during storage, which can lead to deterioration. Therefore, a single plastic container is often equipped with an isolation means to store each pharmaceutical component in a separate storage compartment, which is then mixed immediately before administration. In this case, easily peelable multi-chamber containers, which separate the storage compartments with adhesive and then connect the adhesive by pressing and peeling the adhesive with hands or an instrument immediately before use to mix the pharmaceuticals, have attracted attention because of their ease of operation and aseptic performance. These containers offer advantages, such as isolating components that react with each other, preventing mistakes in the type and amount of pharmaceuticals being mixed and preventing contamination during mixing.

[0003] The film (laminated film) that constitutes such medical containers must have adhesive joints between the storage compartments that are stable and difficult to peel off during transportation and storage, but must be relatively easy to peel off when used (mixed). Therefore, the peripheral edges of the infusion bag must have sufficient heat seal strength (strong sealability) to prevent leakage of the drug, and the separating sections between the storage compartments must have heat seal strength (easy peelability, weak sealability) that allows them to be easily opened by hand, etc., and control of seal strength is a key technical point.

[0004] In recent years, methods have been proposed for controlling seal strength by using a mold with specific shaped projections and recesses to provide a heat-sealed portion with strong fusion and weak fusion sections at a specific area ratio (see, for example, Patent Documents 1 to 3). However, even these methods are complicated in that it is difficult to balance the seal strength unless the strong fusion and weak fusion sections are maintained in a specific positional relationship. Furthermore, when heat sterilization is performed, the strength of the strong fusion and weak fusion sections changes, making it impossible to control the seal strength, and improvements have been desired.

[0005] Another proposed method involves using a blend of resins that are poorly compatible and have a relatively large difference in melting point (e.g., a polyethylene-based resin composition and a polypropylene-based resin) to form a phase-separated structure in the sealant layer, and then heat-sealing at a temperature at which only the low-melting-point resin phase melts, thereby controlling the fused region at the seal interface and controlling the seal strength (see, for example, Patent Documents 4 to 7). However, films with a sealant layer made of a mixture of polyethylene-based resin and polypropylene-based resin have problems with poor cleanliness, such as the elution of fine particles into chemical solutions, compared to films made solely of polyethylene-based resin. Another drawback is higher material costs compared to films made solely of polyethylene-based resin.

[0006] Also, a method has been proposed for obtaining a container that has excellent transparency and stable weak seal strength even after sterilization at 121°C by using a resin composed of a material containing a polyethylene resin with specific physical properties as the inner layer (sealant layer) (see, for example, Patent Document 8). According to this method, the weak seal strength is stable even after sterilization at 121°C, but it has been found that parts of the container that come into contact other than the sealed part (such as the inner layers of the container) fuse together, so improvement is required.

[0007] None of the above methods have been proposed to provide a film in which the inner layers of the film do not fuse together (internal fusion) after heat sterilization, and which has a good balance of high transparency and stable weak seal strength (weak sealability).

[0008] Japanese Patent Publication No. 8-24314 Japanese Patent Publication No. 2004-476 Japanese Patent No. 4689416 Japanese Patent No. 2675075 Japan National Patent No. 3076862 Japanese Patent Publication No. 8-229099 Japanese Patent No. 5144573 Japanese Patent Publication No. 2017-018290

[0009] The object of the present invention is to provide a polyethylene resin composition which overcomes these conventional drawbacks and which does not fuse to the inner surface even after sterilization and has excellent stability of weak seal strength, a film made from the composition, and a medical container using the film.

[0010] As a result of extensive research, the inventors discovered that the above-mentioned problems can be solved by using a weak heat-sealing layer made of polyethylene containing a specific amount of polyethylene-based resin having specific physical properties, and by using a laminated film including the weak heat-sealing layer as a medical container, and thus completed the present invention.

[0011] That is, the present invention resides in the following [1] to [6]. [1] A polyethylene resin composition comprising 60 to 95% by weight of a high-density polyethylene (A) satisfying the following properties (a) to (d) and 5 to 40% by weight (the total of (A) and (B) being 100% by weight) of a linear low-density polyethylene (B) satisfying the following properties (e) to (g): (a) a density of 955 to 970 kg / m ３ (b) The melt flow rate (hereinafter referred to as MFR) measured at 190°C under a load of 21.18 N is 0.1 to 30 g / 10 min. (c) １３ (d) In molecular weight measurement by gel permeation chromatography, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 3.0 or less. (e) The density is 870 to 930 kg / m ３ (f) The MFR is 0.1 to 20.0 g / 10 min. (g) In molecular weight measurement by gel permeation chromatography, the ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) is 3.0 or less. [2] A film made of the resin composition described in [1] above. [3] The film described in [2] above, which has a seal portion (easy peel seal portion) formed by heat sealing the films together, and after sterilization at 121°C, the seal temperature range at which the easy peel seal portion shows a seal strength of 1 to 4 N / 15 mm is 5°C or more, and the light transmittance measured in pure water at a wavelength of 450 nm is 60% or more. [4] A laminated film having a weak heat seal layer and another resin layer, which is made of the film described in [2] or [3]. [5] The other resin layers include an intermediate layer adjacent to the weak heat seal layer and a heat-resistant layer adjacent to the intermediate layer, and the intermediate layer has a density of 870 to 920 kg / m ３The heat-resistant layer is made of a polyethylene resin having a density of 930 to 970 kg / m ３ [6] The laminate film according to [4], which is made of a polyethylene resin having a structure in which the weak heat seal layers of the laminate film are heat-sealed together, and which, after sterilization at 121°C, has a seal temperature range of 5°C or more at which the seal strength of the easy peel seal portion is 1 to 4 N / 15 mm, and which has a light transmittance of 60% or more measured at a wavelength of 450 nm in pure water. [7] A medical container having a storage section for storing a medicinal solution, the medical container having a bag-shaped storage section with the weak heat seal layer of the film according to [2] or [3] or the laminate film according to any of [4] to [6] as an inner layer. [8] The medical container according to [7], wherein the storage section is divided into two or more compartments by a seal portion formed by heat-sealing the films or laminate films together.

[0012] The film made of the resin composition of the present invention has excellent molding stability during water-cooled inflation molding, and further maintains stable weak seal strength even after sterilization at 121°C, and does not fuse to the inner surface. Therefore, the film can be suitably used for medical containers such as medical infusion bags.

[0013] The polyethylene resin, resin composition, film made thereof, and medical container using this film according to the present invention are described below. [1] High-density polyethylene (A) The high-density polyethylene (A) used in the present invention is an ethylene homopolymer or a copolymer of ethylene and an α-olefin.

[0014] The high-density polyethylene (A) has a density of 955 to 970 kg / m according to JIS K6922-1. ３ , preferably 955 to 960 kg / m ３ The density is 955 kg / m ３ If the density is less than 970 kg / m, the film will have insufficient heat resistance, such that the inner wall of the container (weak heat seal layer) will be fused during sterilization at 121°C. ３ If the thickness exceeds 100 μm, the transparency of the film will decrease, which is not preferable.

[0015] The high-density polyethylene (A) has an MFR of 0.1 to 30 g / 10 min, preferably 1.0 to 20 g / 10 min, and more preferably 1.0 to 10 g / 10 min, measured in accordance with JIS K6922-1 at 190°C under a load of 21.18 N. An MFR of less than 0.1 g / 10 min is undesirable because it increases the load on the extruder during molding and causes surface roughness and thickness unevenness in the width direction during molding. An MFR of more than 30 g / 10 min is undesirable because it reduces the transparency of the film when formed.

[0016] The high-density polyethylene (A) is １３ The number of hexyl or higher branches (LCB) per 1000 carbon atoms determined by C-NMR spectroscopy is less than 0.5. If the LCB is 0.5 or more, the resulting film will be deformed and the heat resistance will be insufficient, which is undesirable.

[0017] The high-density polyethylene (A) has a ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 3.0 or less, as measured by gel permeation chromatography. If the ratio Mw / Mn exceeds 3.0, the transparency of the film formed therefrom decreases, which is undesirable.

[0018] The high-density polyethylene (A) can be produced by, for example, a slurry method, a solution method, a gas-phase method, or the like. When producing the high-density polyethylene (A), a metallocene catalyst or a vanadium-based catalyst composed of an organic transition metal compound containing a cyclopentadienyl derivative and a compound and / or an organic metal compound that reacts with the organic transition metal compound to form an ionic complex can generally be used. The high-density polyethylene (A) can be produced by homopolymerizing ethylene or copolymerizing ethylene and an α-olefin using the catalyst. The α-olefin may be any of those commonly referred to as α-olefins, and is preferably an α-olefin having 3 to 12 carbon atoms, such as propylene, butene-1, hexene-1, octene-1, or 4-methyl-1-pentene. Examples of copolymers of ethylene and an α-olefin include ethylene-hexene-1 copolymer, ethylene-butene-1 copolymer, and ethylene-octene-1 copolymer.

[0019] The high-density polyethylene (A) can be obtained by, for example, the method described in Japanese Patent No. 3319051. [2] Linear low-density polyethylene (B) The linear low-density polyethylene (B) used in the present invention refers to a copolymer of ethylene and an α-olefin, and the linear low-density polyethylene (B) has a density of 870 to 930 kg / m according to JIS K6922-1. ３ , preferably 875 to 920 kg / m ３ , more preferably 875 to 910 kg / m ３ The density is 870 kg / m ３ If the density is less than 930 kg / m, the heat resistance will be insufficient, and when the film is made, the sealing surface (weak heat sealing layer) will fuse during sterilization at 121°C, making it difficult to peel the adhesive portion between the storage chambers, which is not preferable. ３ If the thickness exceeds 100 μm, the transparency and stability of the weak seal strength when made into a film are reduced, which is not preferable.

[0020] The linear low-density polyethylene (B) has an MFR of 0.1 to 20 g / 10 min, preferably 0.5 to 10 g / 10 min, and more preferably 1.0 to 5 g / 10 min, measured in accordance with JIS K6922-1 at 190°C under a load of 21.18 N. An MFR of less than 0.1 g / 10 min is undesirable because it increases the load on the extruder during molding and causes surface roughness during molding and thickness unevenness in the width direction during film formation. Furthermore, an MFR of more than 20 g / 10 min is undesirable because it reduces the melt tension and reduces molding stability.

[0021] The linear low-density polyethylene (B) has a ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 3.0 or less, as measured by gel permeation chromatography. Mw / Mn exceeding 3.0 is undesirable because it reduces the stability of weak seal strength.

[0022] The linear low-density polyethylene (B) can be produced by a production method such as a high-pressure method, a solution method, or a gas-phase method, and is particularly preferably produced by a high-pressure method. When producing the linear low-density polyethylene (B), generally, a metallocene catalyst or a vanadium-based catalyst composed of an organic transition metal compound containing a cyclopentadienyl derivative and a compound and / or an organic metal compound that reacts with the organic transition metal compound to form an ionic complex can be used, and the linear low-density polyethylene (B) can be produced by copolymerizing ethylene and an α-olefin in the presence of the catalyst.

[0023] The α-olefin may be any of those generally called α-olefins, and is preferably an α-olefin having 3 to 12 carbon atoms such as propylene, butene-1, hexene-1, octene-1, 4-methyl-1-pentene, etc. Examples of copolymers of ethylene and α-olefins include ethylene-hexene-1 copolymer, ethylene-butene-1 copolymer, and ethylene-octene-1 copolymer.

[0024] The linear low-density polyethylene (B) can be obtained by the methods described in, for example, JP 2009-275059 A, JP 2013-81494 A, etc. [3] Polyethylene resin composition The polyethylene resin composition of one embodiment of the present invention can be obtained by a conventionally known method, for example, a method of mixing the above-mentioned high-density polyethylene (A) and linear low-density polyethylene (B) using a Henschel mixer, V-blender, ribbon blender, tumbler blender, etc., or by further melt-kneading a mixture obtained by such a method using a single-screw extruder, twin-screw extruder, kneader, Banbury mixer, etc., followed by granulation.

[0025] The blending ratio of high-density polyethylene (A) and linear low-density polyethylene (B) is 60 to 95% by weight of high-density polyethylene (A) and 5 to 40% by weight of linear low-density polyethylene (B). The resulting film has excellent stability in weak seal strength. Preferably, the high-density polyethylene (A) is 65 to 90% by weight and the linear low-density polyethylene (B) is 10 to 35% by weight, and more preferably, the high-density polyethylene (A) is 65 to 78% by weight and the linear low-density polyethylene (B) is 22 to 35% by weight. If the high-density polyethylene (A) content is less than 60% by weight, the resulting film will have insufficient heat resistance, resulting in inner surface fusion and a decrease in the stability of the weak seal strength, which is undesirable. If the high-density polyethylene (A) content is more than 95% by weight, the resulting film will have reduced transparency and a decrease in the stability of the weak seal strength, which is undesirable. If the linear low-density polyethylene (B) content is less than 5% by weight, the resulting film will have reduced transparency and a decrease in the stability of the weak seal strength, which is undesirable. If the content exceeds 40% by weight, the heat resistance of the film formed will be insufficient, causing inner surface fusion and reducing the stability of the weak seal strength, which is not preferable.The polyethylene resin composition contains the high-density polyethylene (A) and the linear low-density polyethylene (B) in a ratio of 100% by weight.

[0026] The polyethylene resin composition may be blended with commonly used known additives, such as antioxidants, antistatic agents, lubricants, antiblocking agents, antifogging agents, organic or inorganic pigments, ultraviolet absorbers, dispersants, etc., as needed, within the scope of not significantly impairing the effects of the present invention. The method for blending the additives with the resin composition of the present invention is not particularly limited, and examples include a method of directly adding the additives in the pelletizing step after polymerization, and a method of preparing a high-concentration masterbatch in advance and dry-blending this at the time of molding.

[0027] The polyethylene resin composition may also be blended with other thermoplastic resins such as polypropylene, ethylene-propylene copolymer rubber, poly-1-butene, etc., within a range that does not impair the effects of the present invention. [4] Film The film of one embodiment of the present invention is a film made from a polyethylene resin composition containing 60 to 95% by weight of a high-density polyethylene (A) satisfying the following properties (a) to (d) and 5 to 40% by weight of a linear low-density polyethylene (B) satisfying the following properties (e) to (g) (the total of (A) and (B) being 100% by weight). (a) Density of 955 to 970 kg / m ３ (b) The melt flow rate (hereinafter referred to as MFR) measured at 190°C under a load of 21.18 N is 0.1 to 30 g / 10 min. (c) １３ (d) In molecular weight measurement by gel permeation chromatography, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 3.0 or less. (e) The density is 870 to 930 kg / m ３ (f) The MFR is 0.1 to 20.0 g / 10 min. (g) In molecular weight measurement by gel permeation chromatography, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 3.0 or less.

[0028] The thickness of the film is not particularly limited and can be determined appropriately as needed, but is preferably 0.01 to 1 mm, more preferably 0.1 to 0.5 mm.

[0029] The above-mentioned film has a seal portion (easy-peel seal portion) formed by heat-sealing films together, and it is preferable that the seal temperature range at which this easy-peel seal portion shows a seal strength of 1 to 4 N / 15 mm is 5°C or more from the viewpoint of stability of weak seal strength, and it is also preferable that the light transmittance after sterilization is 60% or more from the viewpoint of transparency.

[0030] The easily peelable seal portion is a portion where, when the films are heat-sealed together, the adhesive state is maintained when held under normal conditions, and when the easily peelable seal portion is pressed and peeled off by hand or with an instrument, etc. The seal strength of the easily peelable seal portion varies depending on the shape and use of the bag when made into a bag-like container, but is usually preferably set in the range of 0.5 to 10 N / 15 mm.

[0031] The seal strength of the easily peelable seal portion is adjusted by the seal temperature (heating temperature of the heat seal bar), seal pressure, and seal time. Usually, the seal pressure and seal time are fixed and the seal temperature is adjusted so as to obtain the desired seal strength. There are no particular restrictions on the seal pressure and seal time, but usually the seal pressure is 1 to 6 kg / cm. ２ The sheeting time is set in the range of 0.5 to 10 seconds. [5] Laminated Film The laminated film according to one embodiment of the present invention comprises the above-mentioned film, a weak heat seal layer, and another resin layer.

[0032] The film may be a single-layer film as long as it has a weak heat-sealable layer made of the resin blend, but to make it into a film or medical container with various properties such as heat resistance, transparency, gas barrier property, etc., it may be a laminated film (multilayer film) having other resin layers.

[0033] The layer structure of the laminated film is not particularly limited. For example, starting from the weak heat seal layer (Layer A), the layer structure may be Layer A / Layer C (two-layer structure), Layer A / Layer B / Layer C (three-layer structure), or even a layer structure in which a layer is further constructed within Layer B of the Layer A / Layer B / Layer C structure, such as Layer A / Layer B / C / C / C / Layer B. Other layers may also be provided as needed between Layer B and Layer C, or between Layer A and Layer B. Examples of such other layers include an adhesive layer, a gas barrier layer, and an impact-resistant layer. For example, a five-layer structure such as Layer A / Adhesive layer / Layer B / Gas barrier layer / Layer C may also be used. A new layer may also be provided outside Layer C. The symbol / between layers indicates that the layers are adjacent.

[0034] There are no particular restrictions on the resins constituting the layers other than the weak heat seal layer (Layer A), and any commonly used resin may be used, such as polyethylene, ethylene-α-olefin copolymer, polypropylene, propylene-α-olefin random copolymer, propylene-α-olefin block copolymer, polybutene, poly4-methylpentene, cyclic polyolefin, styrene-based thermoplastic elastomer, ethylene-vinyl acetate copolymer, soft vinyl chloride resin, and mixtures of these resins.

[0035] Examples of adhesives that constitute the adhesive layer include polyurethane adhesives, vinyl acetate adhesives, hot melt adhesives, or adhesive resins such as maleic anhydride-modified polyolefins and ionomer resins. When an adhesive layer is included in the layer structure, the essential constituent layers such as layer A, layer B, and layer C can be laminated by co-extrusion with these adhesives.

[0036] The gas barrier layer may be made of a blend of a polyolefin resin and an ethylene-vinyl alcohol copolymer, or a composition in which a layered silicate such as montmorillonite or mica is added to a polyolefin resin.

[0037] The thickness of the entire laminated film is not particularly limited and can be appropriately determined as needed, but is preferably 0.01 to 1 mm, more preferably 0.1 to 0.5 mm.

[0038] The thickness ratio of each layer is not particularly limited, but for example, in the case of a three-layer film, it is generally preferable to use a resin with excellent heat resistance for the C layer to make it thinner and a resin with excellent transparency for the B layer to make it thicker, in order to prevent deformation or fusion due to sterilization treatment, etc., as this will result in a good balance between transparency and heat resistance. The thickness ratio of each layer is preferably A layer:B layer:C layer = 1-30:40-98:1-30 (where the total is 100). When a polyethylene-based resin is used for the B layer, it is preferable to use a polyethylene-based resin having a density of 920 kg / m ３ When a polyethylene resin is used for the C layer, it is preferable to select the following resins because the transparency is good. In this case, from the viewpoint of heat resistance, the density is 930 kg / m ３ It is preferable to select a material with a density of 945 kg / m or more.３ More preferably, it is equal to or greater than this.

[0039] From the viewpoint of stability of weak seal strength, it is preferable that the laminated film has a seal temperature range of 5°C or more at which the seal portion (easy-peel seal portion) formed by heat-sealing the weak heat seal layers of the film to each other has a seal strength of 1 to 4 N / 15 mm even after sterilization at 121°C, and it is also preferable that the light transmittance after sterilization is 60% or more from the viewpoint of transparency.

[0040] The method for producing the laminated film is not particularly limited, but examples include methods for producing a multilayer film or sheet using a water-cooled or air-cooled coextrusion multilayer inflation method, a coextrusion multilayer T-die method, a dry lamination method, and an extrusion lamination method. Among these, the water-cooled coextrusion multilayer inflation method or the coextrusion multilayer T-die method is preferred. In particular, the water-cooled coextrusion multilayer inflation method offers many advantages in terms of transparency, hygiene, and the like. [6] Medical Container One aspect of the present invention is a medical container having a storage section for containing a medicinal solution, the storage section being made of a film or laminated film in a bag-like shape, and the weak heat-sealable layer (Layer A) being the inner layer. Another aspect of the present invention is a medical container in which the storage section is divided into two or more compartments by a seal formed by heat-sealing the weak heat-sealable layers of the film or laminated film.

[0041] From the viewpoint of stability of weak seal strength, it is preferable that the medical container have a seal temperature range of 5°C or more at which the seal portion formed by heat-sealing the films together (easy-peel seal portion) exhibits a seal strength of 1 to 4 N / 15 mm even after sterilization at 121°C, and it is also preferable that the light transmittance after sterilization is 60% or more from the viewpoint of transparency.

[0042] In a medical container, the seal strength of the easily peelable seal portion is adjusted so that the adhesive state is maintained when the medical container is stored under normal conditions, and that when any of the storage chambers of the medical container is pressurized by hand or an instrument, the easily peelable seal portion peels off to allow communication between adjacent storage chambers. The seal strength of the easily peelable seal portion varies depending on the shape and use of the medical container, but is usually set in the range of 0.5 to 10 N / 15 mm.

[0043] The seal strength of the easily peelable seal portion is adjusted by the seal temperature (heating temperature of the heat seal bar), seal pressure, and seal time. Usually, the seal pressure and seal time are fixed and the seal temperature is adjusted so as to obtain the desired seal strength. There are no particular restrictions on the seal pressure and seal time, but usually the seal pressure is 1 to 6 kg / cm. ２ The sheet time is set in the range of 0.5 to 10 seconds.

[0044] In the medical container of the present invention, the desired seal strength can be imparted to the easily peelable seal portion by appropriately changing the sealing temperature. Here, to prevent fluctuations in the seal strength of the easily peelable seal portion, it is preferable that the temperature dependency of the seal strength (heat seal curve) is as gentle as possible. Specifically, the temperature range required to obtain a seal strength of 1 to 4 N / 15 mm is preferably 5°C or more. The heat seal curve characteristics depend on the properties of the polyethylene resin composition used in the weak heat seal layer; generally, the lower the density and the higher the blend ratio of the linear low-density polyethylene (B) blended, the gentler the heat seal curve tends to be.

[0045] The peripheral edge of the medical container of the present invention may be formed by conventional methods. For example, when using a film formed by a coextrusion multilayer T-die method, dry lamination method, extrusion lamination method, or the like, the weak heat-sealable layers may be overlapped so that they face each other, and then the resulting film may be sandwiched between a pair of heat-sealing bars and uniformly heated and pressurized to achieve heat fusion. When using a cylindrical film formed by a water-cooled or air-cooled coextrusion multilayer inflation method, only both ends of the film need be heat-sealed; the entire circumference of the container does not necessarily need to be heat-sealed. In this case, the port portion, which serves as an inlet / outlet for the drug solution, may be formed by heat-sealing simultaneously with the formation of the storage portion, or the formation of the storage portion and the port portion may be performed in separate processes. The port portion may be formed using a mold for integral molding with the storage portion, or by heat-sealing the port portion to the storage portion, among other methods.

[0046] The heat seal strength of the peripheral edge of the medical container of the present invention varies depending on the shape and use of the container, but is preferably set within the strength range of 20 to 60 N / 15 mm.

[0047] The medical container of one embodiment of the present invention can be used in general medical applications, such as a bag for liquid / liquid mixing of amino acid infusion and glucose infusion, and a bag for solid (powder) / liquid mixing of antibiotics and their dissolving solutions.

[0048] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. A. Resins The properties of the resins used in the examples and comparative examples were evaluated by the following methods.

[0049] <Density> The density was measured by the density gradient tube method in accordance with JIS K6922-1.

[0050] <MFR> MFR (melt flow rate) was measured in accordance with JIS K6922-1.

[0051] <Molecular Weight, Molecular Weight Distribution> The weight average molecular weight (Mw), number average molecular weight (Mn), and the ratio of weight average molecular weight to number average molecular weight (Mw / Mn) were measured by GPC. A GPC apparatus (HLC (registered trademark)-8121GPC / HT (trade name) manufactured by Tosoh Corporation) and a column (TSKgel (registered trademark) GMHhr-H(20)HT (trade name) manufactured by Tosoh Corporation) were used, with the column temperature set to 140°C and 1,2,4-trichlorobenzene used as the eluent. A measurement sample was prepared at a concentration of 1.0 mg / ml, and 0.3 ml was injected for measurement. The molecular weight calibration curve was calibrated using a polystyrene sample with a known molecular weight. Mw and Mn were determined as values ​​converted into linear polyethylene.

[0052] <Long Chain Branching> The number of long chain branches per 1,000 carbon atoms was measured by carbon nuclear magnetic resonance ( １３ The carbon nuclear magnetic resonance (C-NMR) method of the polymer １３The C-NMR spectrum was measured, and the number of long chain branches per 1,000 carbon atoms in the polymer was calculated using the following method. The measurement temperature was set to 130°C, and a mixed solution of 1,2-dichlorobenzene / 1,2-dichlorobenzene-d4 = 75 / 25 (volume ratio) was used as the solvent.

[0053] <Method for Calculating the Number of Long Chain Branches (LCBs)> In an NMR spectrum processed with a Gaussian window function, the sum of the peak areas of all peaks having a peak top between 5 and 50 ppm was set to 1000, and the number of long chain branches (the number of branches having 7 or more carbon atoms) was calculated from the peak area of ​​the peak derived from a methine carbon atom bonded to a branch having 7 or more carbon atoms. Under these measurement conditions, the number of long chain branches (the number of branches having 7 or more carbon atoms) was calculated from the peak area of ​​the peak having a peak top near 38.22 to 38.27 ppm. The peak area of ​​the peak was defined as the signal area in the range from the chemical shift of the valley between the adjacent peak on the high magnetic field side to the chemical shift of the valley between the adjacent peak on the low magnetic field side. Note that under these measurement conditions, the peak top position of the peak derived from a methine carbon atom bonded to a hexyl branch was 38.21 ppm in the measurement of an ethylene-1-octene copolymer.

[0054] In the examples and comparative examples, resins produced by the following methods and commercially available products were used. (1) High-density polyethylene A-1 [Preparation of organically modified clay] 300 ml of industrial alcohol (manufactured by Japan Alcohol Sales Co., Ltd., (trade name) Ekinen (registered trademark) F-3) and 300 ml of distilled water were placed in a 1-liter flask, and 15.0 g of concentrated hydrochloric acid and dioleylmethylamine ((C １８ H ３５ ) ２ (CH ３) N, 63.7 g (120 mmol) of (trade name) Lipomin (registered trademark) MO (manufactured by Lion Specialty Chemicals Co., Ltd.) was added, heated to 45 ° C, and 100 g of synthetic hectorite (trade name Laponite RD, manufactured by BYK Corporation) was dispersed therein, and the mixture was then heated to 60 ° C and stirred for 1 hour while maintaining that temperature. The slurry was filtered, washed twice with 600 ml of water at 60 ° C, and dried in a dryer at 85 ° C for 12 hours to obtain 130 g of organically modified clay. This organically modified clay was then jet milled to a median diameter of 15 μm. [Preparation of polymerization catalyst] After replacing the air in a 300 mL flask equipped with a thermometer and a reflux condenser with nitrogen, 25.0 g of the organically modified clay obtained in [Preparation of organically modified clay] and 108 mL of hexane were added, followed by the addition of 0.392 g (1 mmol) of bis(indenyl)zirconium dichloride and 142 mL of 20% triisobutylaluminum, followed by stirring for 3 hours at 60° C. After cooling to room temperature, the supernatant was removed and washed twice with 220 mL of hexane, and then 220 mL of hexane was added to obtain a catalyst suspension (solid weight content: 12.0 wt %). [Production of A-1] A 2-L autoclave was charged with 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 200 mg (corresponding to 24 mg of solids) of the catalyst suspension obtained in [Preparation of Polymerization Catalyst]. The temperature was raised to 85°C, and then an ethylene / hydrogen mixed gas was continuously fed thereto so that the partial pressure became 0.90 MPa (hydrogen concentration in the ethylene / hydrogen mixed gas: 300 ppm). After 90 minutes, the pressure was released, and the slurry was filtered and dried to obtain 190 g of polymer. The MFR of this polymer was 3.0 g / 10 min, and the density was 945 kg / m ３ The results of the evaluation of the basic characteristics of A-1 are shown in Table 1.

[0055] A-2 [Preparation of Organically Modified Clay] An organically modified clay compound was prepared in the same manner as in A-1. [Preparation of Polymerization Catalyst] A polymerization catalyst was prepared in the same manner as in A-1. [Production of A-2] 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 200 mg (corresponding to 24 mg of solids) of the catalyst suspension obtained in [Preparation of Polymerization Catalyst] were added to a 2 L autoclave, and the temperature was raised to 85°C. Then, an ethylene / hydrogen mixed gas was continuously supplied so that the partial pressure became 0.90 MPa (hydrogen concentration in the ethylene / hydrogen mixed gas: 450 ppm). After 90 minutes, the pressure was released, and the slurry was filtered and dried to obtain 205 g of polymer. The MFR of this polymer was 1.0 g / 10 min, and the density was 952 kg / m ３ The results of the evaluation of the basic characteristics of A-2 are shown in Table 1.

[0056] A-3 [Preparation of Organically Modified Clay] An organically modified clay compound was prepared in the same manner as in A-1. [Preparation of Polymerization Catalyst] A polymerization catalyst was prepared in the same manner as in A-1. [Production of A-3] 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 200 mg (corresponding to 24 mg of solids) of the catalyst suspension obtained in [Preparation of Polymerization Catalyst] were added to a 2 L autoclave, and the temperature was raised to 85°C. Then, an ethylene / hydrogen mixed gas was continuously supplied so that the partial pressure became 0.90 MPa (hydrogen concentration in the ethylene / hydrogen mixed gas: 800 ppm). After 90 minutes, the pressure was released, and the slurry was filtered and dried to obtain 205 g of polymer. The MFR of this polymer was 6.2 g / 10 min and the density was 956 kg / m ３ The results of the evaluation of the basic characteristics of A-3 are shown in Table 1.

[0057] A-4 [Preparation of Organically Modified Clay] An organically modified clay compound was prepared in the same manner as in A-1. [Preparation of Polymerization Catalyst] A polymerization catalyst was prepared in the same manner as in A-1. [Production of A-4] 1.2 L of hexane, 1.0 mL of 20% triisobutylaluminum, and 200 mg (corresponding to 24 mg of solids) of the catalyst suspension obtained in [Preparation of Polymerization Catalyst] were added to a 2 L autoclave, and the temperature was raised to 85°C. Then, an ethylene / hydrogen mixed gas was continuously supplied so that the partial pressure became 0.90 MPa (hydrogen concentration in the ethylene / hydrogen mixed gas: 1000 ppm). After 90 minutes, the pressure was released, and the slurry was filtered and dried to obtain 180 g of polymer. The MFR of this polymer was 5.5 g / 10 min and the density was 959 kg / m ３ The results of the evaluation of the basic characteristics of A-4 are shown in Table 1.

[0058] A-5: The following commercially available products were used.

[0059] Nipolon Hard (registered trademark) 1000 (product name), manufactured by Tosoh Corporation (MFR = 20 g / 10 min, density = 964 kg / m) ３ The results of the evaluation of the basic characteristics of A-5 are shown in Table 1.

[0060]

[0061] (2) Linear Low-Density Polyethylene B-1 [Preparation of Organically Modified Clay] 30 ml of 37% hydrochloric acid and 106 g of N,N-dimethylbehenylamine were added to 1,500 ml of water to prepare an aqueous solution of N,N-dimethylbehenylammonium hydrochloride. 300 g of montmorillonite with an average particle size of 7.8 μm (prepared by pulverizing Kunipia® F, a product of Kunimine Industries, using a jet mill) was added to the aqueous solution of hydrochloride and allowed to react for 6 hours. After completion of the reaction, the reaction solution was filtered, and the resulting cake was dried under reduced pressure for 6 hours to obtain 370 g of a modified clay compound. [Preparation of Polymerization Catalyst] 3.3 L of heptane, 1.13 mol (0.9 L) of a heptane solution of triethylaluminum (20 wt.% diluted product) per aluminum atom (1.13 mol per aluminum atom), and 50 g of the modified clay compound obtained above were added to a 20 L stainless steel container under a nitrogen atmosphere and stirred for 1 hour. Diphenylmethylene(4-phenyl-indenyl)(2,7-di-t-butyl-9-fluorenyl)zirconium dichloride was added to the suspension at a concentration of 1.25 mmol per zirconium atom, and the mixture was stirred for 12 hours. 5.8 L of an aliphatic saturated hydrocarbon solvent (IP Solvent 2835, manufactured by Idemitsu Petrochemical Co., Ltd.) was added to the resulting suspension to prepare a catalyst (zirconium concentration: 0.125 mmol / L). [Production of B-1] Using a tank-type reactor equipped for high-temperature, high-pressure polymerization, ethylene, 1-hexene, and hydrogen were continuously injected into the reactor, with the total pressure set to 90 MPa, the ethylene concentration to 53.9 mol%, the 1-hexene concentration to 46.0 mol%, and the hydrogen concentration to 0.12 mol%. The reactor was stirred at 1,500 rpm, and the polymerization catalyst obtained above was continuously fed from the feed port of the reactor, and the polymerization reaction was carried out while maintaining the average temperature at 200° C. The resulting polymer had an MFR of 3.0 g / 10 min and a density of 880 kg / m ３ The results of the evaluation of the basic characteristics of B-1 are shown in Table 2.

[0062] B-2 [Preparation of organically modified clay] An organically modified clay compound was prepared in the same manner as in B-1. [Preparation of polymerization catalyst] A polymerization catalyst was prepared in the same manner as in B-1. [Production of B-2] Using a tank-type reactor equipped for high-temperature, high-pressure polymerization, ethylene, 1-hexene, and hydrogen were continuously injected into the reactor, and the total pressure was set to 90 MPa, the ethylene concentration to 66.7 mol%, the 1-hexene concentration to 33.2 mol%, and the hydrogen concentration to 0.12 mol%. The reactor was then stirred at 1,500 rpm, and the polymerization catalyst obtained above was continuously fed from the reactor's feed port, and the polymerization reaction was carried out while maintaining an average temperature of 220°C. The resulting polymer had an MFR of 1.0 g / 10 min and a density of 900 kg / m ３ The results of the evaluation of the basic characteristics of B-2 are shown in Table 2.

[0063] B-3 [Preparation of organically modified clay] An organically modified clay compound was prepared in the same manner as in B-1. [Preparation of polymerization catalyst] A polymerization catalyst was prepared in the same manner as in B-1. [Production of B-3] Using a tank-type reactor equipped for high-temperature, high-pressure polymerization, ethylene, 1-hexene, and hydrogen were continuously injected into the reactor, and the total pressure was set to 90 MPa, the ethylene concentration to 82.6 mol%, the 1-hexene concentration to 17.2 mol%, and the hydrogen concentration to 0.23 mol%. The reactor was then stirred at 1,500 rpm, and the polymerization catalyst obtained above was continuously fed from the reactor's feed port, and the polymerization reaction was carried out while maintaining an average temperature of 220°C. The resulting polymer had an MFR of 2.0 g / 10 min and a density of 920 kg / m ３ The results of the evaluation of the basic characteristics of B-3 are shown in Table 2.

[0064] B-4: The following commercially available products were used.

[0065] Nipolon (registered trademark)-Z ZF230 (MFR = 2.0 g / 10 min, density = 920 kg / m), manufactured by Tosoh Corporation ３ The results of the evaluation of the basic characteristics of B-4 are shown in Table 2.

[0066]

[0067] (S)-1: The following commercially available products were used.

[0068] Petrothene (registered trademark) 173 (product name), manufactured by Tosoh Corporation (MFR = 0.3 / 10 min, density = 924 kg / m ３ The results of the evaluation of the basic characteristics of (S)-1 are shown in Table 3.

[0069]

[0070] <Resin Composition> The above-mentioned high-density polyethylene (A), linear low-density polyethylene (B), and commercially available resin (S) were dry-blended in the ratios described in the Examples and Comparative Examples. B. Thermoplastic Films and Medical Containers The films and medical containers used in the Examples and Comparative Examples were produced and sterilized by the following method. <Production of Thermoplastic Films and Medical Containers> Using a three-layer water-cooled inflation molding machine (manufactured by Placo), a three-layer film having a film width of 135 mm and a film thickness of 250 μm was molded at a cylinder temperature of 180 to 230°C, a water bath temperature of 15°C, and a take-up speed of 6 m / min. The middle layer was made of polyethylene (trade name) Nipolon (registered trademark)-P FY12 (MFR = 1.7 g / 10 min, density = 916 kg / m) manufactured by Tosoh Corporation. ３ The heat-resistant layer was made of polyethylene (trade name) Nipolon-P FY13 (MFR = 1.0 g / 10 min, density = 950 kg / m) manufactured by Tosoh Corporation. ３ ) was used. The thickness of each layer was molded so that the heat-resistant layer and weak heat-sealing layer were 20 μm, and the middle layer was 210 μm. Next, a 180 mm long sample was cut from the three-layer film, and the center was heat-sealed to form an easily peelable seal. One chamber was filled with 75 ml of ultrapure water and heat-sealed with a 20 ml headspace. Next, the other chamber was filled with 75 ml of ultrapure water and heat-sealed with a 20 ml headspace, thereby producing a medical container with two storage chambers. <Sterilization Treatment> The medical container was sterilized for 20 minutes at 121°C using a steam sterilizer (manufactured by Hisaka Works, Ltd.).

[0071] The properties of the resin compositions, laminated films, and medical containers used in the examples and comparative examples were evaluated by the following methods. <Transparency> Test pieces measuring 10 mm wide x 50 mm long were cut from the sterilized medical containers, and the light transmittance at a wavelength of 450 nm in pure water was measured using an ultraviolet-visible spectrophotometer (Model V-730, manufactured by JASCO Corporation). A medical container with good transparency was considered to have a light transmittance of 65% or more maintained after sterilization. <Inner Surface Weldability (Heat Resistance)> Test pieces measuring 15 mm wide x 100 mm long were cut from the sealed portion of the medical container after sterilization, and the peel strength was measured using a tensile tester (Model RTE-1210, manufactured by Orientec Co., Ltd.). A peel strength of less than 3 N / 15 mm maintained after sterilization was considered to have a good medical container with no inner surface weldability.

[0072] ◯: Peel strength of the sealed portion after sterilization was less than 3 N / 15 mm. ×: Peel strength of the sealed portion after sterilization was 3 N / 15 mm or more. <Seal Strength After Sterilization> The easily peelable seal portion after sterilization was cut into 15 mm wide strips perpendicular to the sealing direction, and a 180° peel was performed at a speed of 100 mm / min. The maximum value obtained during peeling was recorded as the peel strength. (The test was performed five times, and the average value was calculated.) <Sealing Temperature Range> Samples were prepared by heat-sealing the inflation film (cylindrical) with the sealant layers facing each other at a sealing pressure of 2 kg / cm2, a sealing time of 2 seconds, and varying the sealing temperature in 1-5°C increments. Each sample was then sterilized at 121°C for 20 minutes, after which the seal strength was measured using the method described above in the <Sealing Strength> section. The relationship between seal strength and sealing temperature was shown. The sealing temperature range at which the seal strength was 1 to 4 N / 15 mm was calculated, and a sealing temperature range of 5°C or higher was used as a guideline for indicating that there was little fluctuation in the seal strength of the easily peelable seal portion and that a stable weak seal strength was obtained.

[0073] Example 1: Using the resins shown in Tables 1 and 2, three-layer films were molded using a water-cooled inflation molding machine, and molding stability was evaluated. The film thickness was 250 μm. The resulting films were then heat-sealed, and medical containers filled with ultrapure water were prepared. These were then subjected to high-pressure steam sterilization at 121°C. The transparency and inner surface fusion of the film after sterilization were calculated, and the sealing temperature range was calculated using the method described above in the "Sealing Temperature Range" section. The results are shown in Table 4.

[0074]

[0075] Examples 2 to 5 and Comparative Examples 1 to 7 Three-layer films and medical containers were produced and evaluated in the same manner as in Example 1, except that the resins used in the weak heat-sealing layer were changed to those shown in Tables 1 to 3. The results are shown in Table 5.

[0076]

[0077] While the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

[0078] The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2024-020619 filed on February 14, 2024 are hereby incorporated by reference as the disclosure of the present invention.

Claims

1. A polyethylene resin composition comprising 60 to 95% by weight of a high-density polyethylene (A) satisfying the following properties (a) to (d) and 5 to 40% by weight (the total of (A) and (B) being 100% by weight) of a linear low-density polyethylene (B) satisfying the following properties (e) to (g): (a) a density of 955 to 970 kg / m ３ (b) The melt flow rate (hereinafter referred to as MFR) measured at 190°C under a load of 21.18 N is 0.1 to 30 g / 10 min. (c) １３ (d) In molecular weight measurement by gel permeation chromatography, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 3.0 or less. (e) The density is 870 to 930 kg / m ３ (f) The MFR is 0.1 to 20.0 g / 10 min. (g) In molecular weight measurement by gel permeation chromatography, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 3.0 or less.

2. A film made from the resin composition according to claim 1.

3. The film according to claim 2, which has a seal (easy-peel seal) formed by heat-sealing the films together, and after sterilization at 121°C, the seal temperature range at which the easy-peel seal shows a seal strength of 1 to 4 N / 15 mm is 5°C or more, and the light transmittance measured in pure water at a wavelength of 450 nm is 60% or more.

4. A laminated film having a weak heat seal layer made of the film of claim 2 and another resin layer.

5. As other resin layers, an intermediate layer adjacent to the weak heat seal layer and a heat resistant layer adjacent to the intermediate layer are provided, and the intermediate layer has a density of 870 to 920 kg / m ３ The heat-resistant layer is made of a polyethylene resin having a density of 930 to 970 kg / m ３ 5. The laminated film according to claim 4, which is made of a polyethylene resin represented by the formula:

6. The laminated film according to claim 4, wherein the laminated film has a seal portion (easy-peel seal portion) formed by heat-sealing the weak heat-sealing layers of the laminated film together, and after sterilization at 121°C, the seal temperature range at which the easy-peel seal portion shows a seal strength of 1 to 4 N / 15 mm is 5°C or more, and the light transmittance measured in pure water at a wavelength of 450 nm is 60% or more.

7. A medical container having a storage section for storing a medicinal solution, the storage section being in the form of a bag with an inner layer being a weak heat seal layer of the film described in claim 2 or 3 or the laminated film described in any one of claims 4 to 6.

8. The medical container according to claim 7, wherein the storage section is divided into two or more sections by a seal section formed by heat-sealing films or laminated films together.

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