Inner plug forming the nozzle and eye drop container

Abstract

To provide an inner stopper that prevents sorption (adsorption, absorption) of eye drops and prevents a gap from being formed between the inner stopper and a container body, and an eye drop container equipped with the inner stopper.SOLUTION: An inner stopper 10, which is attached to a mouth portion 2 of a container body 1 and constitutes a nozzle has a liquid contacting portion 10a comprising a layer containing a cyclic olefin copolymer (copolymer) and a buffer portion 15 provided around a periphery contacting the mouth portion 2, and the buffer portion 15 comprises a material that does not contain the cyclic olefin copolymer (copolymer).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inner plug constituting a nozzle and an eye drop container provided with the same. [Background technology]

[0002] Conventionally, containers made of resins such as polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) have been widely used as eye drop containers for containing eye drops. Patent Document 1 describes a method of sealing an eye drop container having a container body made of a resin molded product in a predetermined laminated film. The container body has an eye drop container section and a nozzle section protruding from the container section, and is configured so that the eye drops can be dispensed from the eye drop container by pointing the nozzle section toward the eye and pressing the container section with a finger.

[0003] Among the constituent resins of conventional eye drop containers, polyethylene and the like are inexpensive but have the drawback of easily absorbing medicines (active ingredients, etc.). For packaging containers such as packaging bags, cyclic olefin copolymers are known as resins that have excellent non-absorption properties for content ingredients (see, for example, Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-107322 [Patent Document 2] International Publication No. 2003 / 043895 [Patent Document 3] International Publication No. 2004 / 080370 Summary of the Invention [Problem to be solved by the invention]

[0005] To prevent sorption (adsorption or absorption) of eye drops in the container, it is necessary to use a material that does not easily sorb the active ingredient of the eye drops. However, according to the studies of the present inventors, when a cyclic olefin copolymer is used for the inner stopper, it is found that because the cyclic olefin copolymer is harder than the above-mentioned resins such as PE, PP, and PET, a gap is generated between the inner stopper and the container body, and this gap can cause the leakage or inflow of water vapor, medicine, etc.

[0006] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an inner stopper that suppresses sorption (adsorption, absorption) of eye drops while reducing the likelihood of a gap forming between the stopper and the container body, and an eye drop container equipped with the inner stopper. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides an inner plug that is attached to the mouth of a container body to form a nozzle, and that is characterized by having a liquid-contacting part made of a layer containing a cyclic olefin copolymer, and a buffer part provided on the outer periphery that contacts the mouth.

[0008] The inside plug may have a flange portion that contacts the tip surface of the mouth portion and a leg portion that contacts the inner surface of the mouth portion, and the buffer portion may be provided on at least the outer peripheral surface of the leg portion. The outer peripheral portion of the inside plug that contacts the mouth portion may have a portion where the liquid contact portion directly contacts the inner surface of the mouth portion, closer to the storage portion of the container body than the portion that contacts the inner surface of the mouth portion via the buffer portion. The buffer portion may be made of a material selected from polyethylene resin, rubber, and elastomer. The layer containing a cyclic olefin copolymer may contain at least one of COP (a copolymer of different cyclic olefins) and COC (a copolymer of a cyclic olefin and a non-cyclic olefin).

[0009] The present invention also provides an eye drop container comprising the above-mentioned inner stopper and a container body having an opening to which the inner stopper is attached. The container body may have a layer containing a cyclic olefin copolymer at least on the surface that comes into contact with the liquid content. [Effects of the Invention]

[0010] The inner stopper of the present invention has a liquid-contacting part made of a layer containing a cyclic olefin copolymer (copolymer) with excellent non-sorption properties, and a buffer part provided on the outer periphery that comes into contact with the mouth, thereby suppressing sorption (adsorption, absorption) of the eye drops while also reducing the gap between the container body. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing an example in which the inside plug of the first embodiment is attached to the opening of a container body. FIG. [Figure 2] FIG. 10 is a cross-sectional view showing an example in which the inside plug of the second embodiment is attached to the opening of the container body. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings.

[0013] FIG. 1 shows an example in which a stopper 10 according to the first embodiment is attached to the mouth 2 of a container body 1. The eye drop container of the first embodiment is a dropper container including the stopper 10 having a nozzle portion 11 and the container body 1 having the mouth 2 to which the stopper 10 is attached. The container body 1 has a storage portion 5 for storing contents, located in the direction opposite to the direction in which the nozzle portion 11 protrudes from the mouth 2. The contents are liquid or liquid-containing contents. When the stopper 10 is attached to the mouth 2, the stopper 10 forms the nozzle of the container body 1 via the nozzle portion 11. In FIG. 1, the nozzle portion 11 is positioned above and the storage portion 5 is positioned below, representing a typical stationary state. When the eye drop container is in use, the nozzle portion 11 is positioned downward or diagonally downward. Furthermore, when storing the eye drop container, the nozzle portion 11 may be positioned sideways.

[0014] The nozzle portion 11 has a nozzle hole 12 that communicates with the storage portion 5. The contents stored in the storage portion 5 drip out of the container body 1 through the nozzle hole 12. The inside plug 10 of the first embodiment has a flange portion 13 that contacts the tip surface 2a of the mouth portion 2, a leg portion 14 that contacts the inner surface 2b of the mouth portion 2, and an inner cylinder portion 16 from which the nozzle portion 11 extends toward the storage portion 5 inside the leg portion 14. The nozzle hole 12 is formed continuously up to the tip portion 16a of the inner cylinder portion 16. A gap portion 17 is formed between the inner surface of the leg portion 14 and the outer surface of the inner cylinder portion 16.

[0015] 2 shows an example of an inside plug 20 of the second embodiment attached to the mouth 2 of a container body 1. The inside plug 20 of the second embodiment is configured similarly to the inside plug 10 of the first embodiment, except that the inside of the leg portion 24 is filled with resin up to the inner surface of the nozzle hole 22 and does not have the inner tube portion 16 and void portion 17 of the first embodiment. In this case, by molding the leg portion 24 from a resin containing a cyclic olefin copolymer, molding defects can be suppressed even if the leg portion 24 is thick. The nozzle portion 21, flange portion 23, etc. can be configured similarly to the first embodiment.

[0016] The inside plugs 10, 20 have a liquid-contacting portion 10a, 20a made of a layer containing a cyclic olefin copolymer and a buffer portion 15, 25 provided on the outer periphery that contacts the opening 2. The liquid-contacting portion 10a, 20a of the inside plugs 10, 20 is at least a part or all of the area that can come into contact with the liquid contents. Examples of areas that can constitute the liquid-contacting portion 10a, 20a include the inner surface of the nozzle portion 11, 21 in the nozzle hole 12, 22, the inner surface of the flange portion 13, 23, the inner and outer surfaces of the leg portions 14, 24, and the inner and outer surfaces of the inner tube portion 16. Here, the inner surfaces of the nozzle portion 11, 21, the leg portions 14, 24, and the inner tube portion 16 refer to the radially inner surfaces centered on the nozzle hole 12, 22. The inner surface of the flange portion 13, 23 refers to the surface opposite the side of the nozzle portion 11, 21 that protrudes toward the tip portion 11a, 21a. These outer surfaces are the surfaces opposite to their respective inner surfaces. Of inside plugs 10, 20, the portions other than buffer sections 15, 25 may be made entirely of a resin containing a cyclic olefin copolymer as inside plug main body sections 10b, 20b.

[0017] The inside stoppers 10, 20 have a layer containing a cyclic olefin copolymer, which is a resin with excellent non-sorption (non-adsorption) properties. Examples of cyclic olefin copolymers include COP (copolymers of different cyclic olefins) and COC (copolymers of cyclic olefins and acyclic olefins). This can prevent the contents from being adsorbed onto the inside stoppers 10, 20.

[0018] Examples of COP (copolymer of different cyclic olefins) include copolymers of two or more types of cyclic olefins, or hydrogenated products thereof. COP (copolymer of different cyclic olefins) is preferably an amorphous polymer, more preferably a ring-opening polymer of a cyclic olefin obtained by metathesis or the like, or a hydrogenated product thereof. COP (copolymer of different cyclic olefins) contains a higher proportion of alicyclic structures than COC (copolymer of a cyclic olefin and an acyclic olefin) and has excellent non-sorption (non-adsorption) properties.

[0019] Examples of COC (copolymer of cyclic olefin and acyclic olefin) include copolymers of at least one kind of cyclic olefin and at least one kind of acyclic olefin, or hydrogenated products thereof. COC (copolymer of cyclic olefin and acyclic olefin) is preferably an amorphous polymer, and more preferably a copolymer of cyclic olefin and ethylene, or hydrogenated products thereof.

[0020] The cyclic olefin used as a constituent monomer of the cyclic olefin copolymer is an unsaturated hydrocarbon (olefin) having at least one ring structure, such as at least one of vinylcycloalkanes having a cycloalkane of 3 to 20 carbon atoms and derivatives thereof, monocycloalkenes having 3 to 20 carbon atoms and derivatives thereof, and cyclic olefins having a norbornene skeleton (norbornene-based monomers).

[0021] Examples of norbornene-based monomers include bicyclo[2.2.1]-2-heptene (norbornene) and its derivatives. Examples of norbornene derivatives include compounds having a substituent such as an alkyl group, compounds having two or more unsaturated bonds such as norbornadiene, and compounds having three or more ring structures, two of which constitute a norbornene skeleton. Examples of norbornene-based monomers having three or more ring structures include tricyclo[5.2.1.0]-2-heptene (norbornene). 2,6 ]decene (dihydrodicyclopentadiene), compounds in which one or more molecules of cyclopentadiene are added to norbornene or dihydrodicyclopentadiene by the Diels-Alder reaction (e.g., tetracyclododecene, pentacyclopentadecene, hexacycloheptadecene, etc.), hydrogenated products of these, isomers with different double bond positions, alkyl-substituted products, etc.

[0022] Examples of acyclic olefins used as constituent monomers of COC (copolymers of cyclic olefins and acyclic olefins) include α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene, and alkenes such as 3-decene and 3-dodecene.

[0023] The resin component constituting the liquid contact portion 10a, 20a or the inside plug main body 10b, 20b may be at least one type of cyclic olefin copolymer, or may be a mixture of a cyclic olefin copolymer with other resins. The proportion of the cyclic olefin copolymer in the liquid contact portion 10a, 20a or the inside plug main body 10b, 20b may be, for example, 40 to 100% by weight. Examples of other resins that can be blended into the liquid contact portion 10a, 20a or the inside plug main body 10b, 20b include polyolefin resins such as polyethylene resin, and thermoplastic elastomers such as styrene-based elastomers and olefin-based elastomers.

[0024] The thickness of the cyclic olefin copolymer-containing layer (sorption-suppressing layer) in the liquid-contacting portion 10a, 20a is not particularly limited, but is preferably in the range of 50 to 3000 μm. Specific examples of the thickness of the sorption-suppressing layer include 50 μm, 100 μm, 150 μm, 200 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 1000 μm, 1500 μm, 2000 μm, 2500 μm, and 3000 μm, as well as intermediate thicknesses. The sorption-suppressing layer may have portions thicker than the above ranges. For example, when the sorption-suppressing layer is provided from the liquid-contacting portion 10a, 20a to the interior of the inside plug 10, 20, as in the inside plug body 10b, 20b, it may have portions thicker than 3000 μm. The proportion of the sorption-suppressing layer relative to the surface of liquid contact portions 10a, 20a is preferably 80% or more in terms of surface area ratio, and examples thereof include approximately 90%, 95%, and 100%.

[0025] The buffer portions 15, 25 are provided at least on the outer peripheral surfaces of the leg portions 14, 24. The outer peripheral surfaces of the leg portions 14, 24 are an example of the outer peripheral portion that contacts the mouth portion 2 of the inside stopper 10, 20. In FIG. 1, a portion 15a where the buffer portion 15 is formed on the leg portion 14 and a portion 15b where the buffer portion 15 is formed on the flange portion 13 are continuously formed. In FIG. 2, the buffer portion 25 has a portion 25a formed on the leg portion 24, but the buffer portion 25 is not formed on the flange portion 23, and the flange portion 23 directly contacts the tip surface 2a of the mouth portion 2. By providing the buffer portions 15, 25 on at least a portion of the outer peripheral portion that contacts the mouth portion 2 of the inside stopper 10, 20, the buffer portions 15, 25, which are made of a material more flexible than the liquid-contacting portions 10a, 20a or the inside stopper main body portions 10b, 20b, contact the mouth portion 2, thereby reducing the gap between the inside stopper 10, 20 and the container body 1. The buffer portions 15, 25 may be provided on the entire outer periphery of the inside plugs 10, 20 that contact the mouth portion 2.

[0026] Portion 15b of flange portion 13 where buffer portion 15 is formed is formed at least on the side of flange portion 13 facing tip surface 2a of mouth portion 2. The range of portion 15b where buffer portion 15 is formed on flange portion 13 is not particularly limited, and buffer portion 15 may extend to the outer peripheral surface of flange portion 13 in the radial direction, or it is also possible to extend buffer portion 15 to the side from which nozzle portion 11 protrudes from flange portion 13.

[0027] The buffering portions 15, 25 are preferably formed in a continuous ring shape in the circumferential direction around the nozzle holes 12, 22. It is also possible to form the buffering portions 15, 25 in part of the circumferential direction of the inside plugs 10, 20. For example, multiple buffering portions 15, 25 may be formed along the circumferential direction at predetermined intervals. Alternatively, some parts of the circumferential direction may be locally provided with no buffering portions 15, 25, and the remaining parts may be provided with buffering portions 15, 25 in a C-shape in the circumferential direction.

[0028] The buffer sections 15, 25 can be made of a material such as a resin selected from polyethylene resin, rubber, elastomer, etc. The thickness of the buffer sections 15, 25 is not particularly limited, but examples include 50 μm, 100 μm, 150 μm, 200 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 1000 μm, and ranges including intermediate thicknesses among these. However, as long as the buffer sections 15, 25 do not come into contact with the liquid contents, the thickness of the buffer sections 15, 25 may be thicker than the above-mentioned values.

[0029] Examples of polyethylene resins that can be used to form the buffer sections 15, 25 include ethylene homopolymers, linear low-density polyethylene (C4-LLDPE) copolymerized with ethylene and an α-olefin having four carbon atoms (1-butene, etc.), linear low-density polyethylene (C6-LLDPE) copolymerized with ethylene and an α-olefin having six carbon atoms (1-hexene, etc.), linear low-density polyethylene (C8-LLDPE) copolymerized with ethylene and an α-olefin having eight carbon atoms (1-octene, etc.), ethylene-vinyl acetate copolymer (EVA), and ethylene-vinyl alcohol copolymer (EVOH).

[0030] Examples of the rubber or elastomer constituting the buffer sections 15, 25 include thermoplastic elastomers such as natural rubber, synthetic rubber, styrene-based elastomers, and olefin-based elastomers. The resin component constituting the buffer sections 15, 25 may be at least one of polyethylene resin, rubber, and elastomer, or may be a mixture of two or more of polyethylene resin, rubber, and elastomer, or a mixture with other resins. The proportion of polyethylene resin, rubber, or elastomer in the buffer sections 15, 25 is, for example, 50 to 100% by weight. Examples of other resins that can be blended into the buffer sections 15, 25 include polyolefin resins such as polypropylene resin.

[0031] Another layer may be provided between the liquid contact portion 10a, 20a or the inside plug main body 10b, 20b and the buffer portion 15, 25. If there is no problem with the adhesion between the resin layers, the liquid contact portion 10a, 20a or the inside plug main body 10b, 20b may be laminated so as to be in direct contact with the buffer portion 15, 25. When another layer is interposed between the liquid contact portion 10a, 20a or the inside plug main body 10b, 20b and the buffer portion 15, 25, the thickness of the other layer is preferably, for example, 150 μm or less.

[0032] The outer peripheral surfaces of the legs 14, 24 may have portions 14a, 24a where the liquid contact portions 10a, 20a or the inside plug main body portions 10b, 20b come into direct contact with the inside surface 2b of the mouth portion 2, on the side closer to the storage section 5 of the container body 1 than portions 14b, 24b that come into contact with the inside surface 2b of the mouth portion 2 via the buffer portions 15, 25. By having the liquid contact portions 10a, 20a or the inside plug main body portions 10b, 20b come into direct contact with the inside surface 2b of the mouth portion 2 at these portions 14a, 24a, contact between the contents and the buffer portions 15, 25 can be suppressed.

[0033] In the outer periphery of the inside plugs 10, 20 that contacts the mouth 2, the ratio (A) of the area 14a, 24a where the liquid contact portion 10a, 20a or the inside plug main body 10b, 20b contacts the inner surface 2b of the mouth 2 to the area (B) of the area where the inside plugs 10, 20 contact the inner surface 2b of the mouth 2 via the buffer portion 15, 25 is preferably small, in order to enhance the buffering effect of the buffer portion 15, 25. For example, (A) / (B) may be 0.3 or less, 0.2 or less, 0.1 or less, approximately 0.05, approximately 0.02, or approximately 0.01. The buffer portion 15, 25 may extend to the vicinity of the boundary between the outer periphery of the inside plugs 10, 20 that contacts the mouth 2 and the liquid contact portion 10a, 20a. When the buffer portions 15, 25 contact the portions where a gap is formed between the inside plugs 10, 20 and the inner surface of the mouth portion 2, it is preferable that the width of the buffer portions 15, 25 that contact the gap is short.

[0034] The inside plugs 10, 20 may be manufactured by joining the buffer sections 15, 25 by heat sealing, adhesive, or the like after molding the inside plug main sections 10b, 20b. Alternatively, the inside plug main sections 10b, 20b and the buffer sections 15, 25 may be simultaneously resin-molded using two-color molding or the like. Alternatively, the inside plug main sections 10b, 20b may be molded, and then the buffer sections 15, 25 may be resin-molded by insert molding between the inside plug main sections 10b, 20b and a mold. In the case of insert molding, it is preferable that the shape of the inside plug main sections 10b, 20b be maintained during molding of the buffer sections 15, 25. For this reason, it is preferable that the melting point (or heat resistance, etc.) of the material constituting the inside plug main sections 10b, 20b be higher than the molding temperature of the buffer sections 15, 25. When molding the inside plug main sections 10b, 20b using a mold, a gate 26 for injecting resin into the mold may be located, for example, near the end of the flange section 23, as shown in FIG. 2. By arranging gate portions 26 at at least two locations in the circumferential direction of flange portion 23, the flow of resin can be made smoother.

[0035] The container body 1 has a mouth 2 to which the inside stoppers 10, 20 are attached, and a body 4 surrounding the storage section 5. A shoulder 3 whose diameter gradually decreases may be provided between the mouth 2 and the body 4. It is preferable that at least the container body 1 has a layer containing a cyclic olefin copolymer at least on the surface that comes into contact with the liquid content. The resin containing a cyclic olefin copolymer used in the container body 1 may be appropriately designed from the same options as the resin containing a cyclic olefin copolymer used in the liquid-contacting parts 10a, 20a of the inside stoppers 10, 20 or the inside stopper body parts 10b, 20b described above, but these resins may be the same or different resins.

[0036] The container body 1 may have a reinforcing layer, a gas barrier layer, an ultraviolet absorbing layer, an oxygen absorbing layer, a printed layer, etc. Examples of lamination methods for the layers constituting the container body 1 include dry lamination, extrusion lamination, co-extrusion, coating, etc., and can be appropriately selected depending on the materials and combinations of each layer. The container body 1 may be colorless and transparent as a whole, or may be colored partially or entirely in the thickness direction or surface direction. The molding method for the container body 1 is not particularly limited, but examples include blow molding. The type of container for the container body 1 is not particularly limited, but examples include bottle containers.

[0037] The eye drop container may have a cap C to protect the nozzle portion 11, 21. The cap C is preferably connected to at least one of the nozzle portion 11, 21 of the inside stopper 10, 20 or the mouth portion 2, shoulder portion 3, and body portion 4 of the container body 1 in an openable / closable or detachable manner. The capacity of the storage portion 5 is not particularly limited, but is, for example, 20 ml or less, and examples thereof include 3 ml, 5 ml, 10 ml, 15 ml, and 20 ml.

[0038] Examples of eye drops include aqueous eye drops, oily eye drops, eye drops that are dissolved before use, and eye drops in the form of suspensions. The eye drops may contain additives other than the active ingredient, such as solubilizers, stabilizers, isotonicity agents, buffers, pH adjusters, preservatives, and thickeners. Specific examples of active ingredients used in eye drops include prostaglandin-related drugs such as isopropyl unoprostone, latanoprost, travoprost, tafluprost, and bimatoprost; non-steroidal anti-inflammatory drugs such as diclofenac sodium, pranoprofen, bromfenac sodium hydrate, and nepafenac; vitamin B preparations such as cyanocobalamin and flavin adenine dinucleotide sodium; antiallergic ingredients such as ashitazanolast hydrate, amlexanox, ibudilast, epinastine hydrochloride, olopatadine hydrochloride, sodium cromoglycate, ketotifen fumarate, tranilast, pemirolast potassium, and levocabastine hydrochloride; immunosuppressants such as cyclosporine and tacrolimus hydrate; and beta-blockers such as carteolol hydrochloride and thiazolinone hydrochloride. Examples of anti-cataract drugs include glutathione and pirenoxine; antibacterial drugs include gatifloxacin hydrate, dibekacin sulfate, tosufloxacin tosilate hydrate, tobramycin, vancomycin hydrochloride, moxifloxacin hydrochloride, levofloxacin hydrate, lomefloxacin hydrochloride, ofloxacin, chloramphenicol, and norfloxacin; and beta-blocker / carbonic anhydrase inhibitor combination drugs include dorzolamide hydrochloride and brinzolamide.

[0039] The present invention has been described above based on preferred embodiments, but the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention. The drip container having the inner stopper of this embodiment is not limited to an eye drop container, but can also be used for containers containing other contents, such as nasal drops, ear drops, and other medicines or lotions that are administered by dripping the medicinal solution onto the affected area. In a layer containing a cyclic olefin copolymer, it is also possible to blend a cyclic olefin homopolymer or a hydrogenated product thereof in place of or together with the cyclic olefin copolymer. [Example]

[0040] The present invention will be specifically described below with reference to examples.

[0041] (Making the inner stopper) An inside plug was produced in which the inside plug body was made of COP and the buffer part was made of PE, with an annular buffer part on the outer circumferential surface. In Example 1, an inner cylinder was provided inside the leg part of the inside plug body with a gap therebetween. In Example 2, the inside of the leg part of the inside plug body was filled with resin up to the nozzle hole. For comparison, in Comparative Example 1, the buffer part was omitted and the inside plug was produced from PE.

[0042] (Measurement of survival rate) Each brown glass bottle, 24 mm in diameter and 45 mm in height, contained one inner stopper and 3 ml of Shiseido Co., Ltd.'s Revital® Lotion EX I lotion as the liquid content, which was then sealed with aluminum tape. The entire inner stopper was immersed in the liquid content, and the mouth of the brown glass bottle was sealed with aluminum tape on the lid. The bottle was then stored at a temperature of 40°C and a relative humidity of 75%. The tocopherol acetate (vitamin E) concentration (initial concentration) in the liquid content before immersion of the inner stopper was approximately 477 ppm. The tocopherol acetate (vitamin E) concentration (post-immersion concentration) in the liquid content after 28 days of storage was measured. The residual rate was calculated from the initial concentration and post-immersion concentration using the following formula: (Formula 1) Residual rate (%) = (Concentration after immersion / Initial concentration) × 100 (%)

[0043] In Example 1, the concentration after immersion was about 427 ppm, and the residual rate was about 89.5%. In Example 2, the concentration after immersion was about 428 ppm, and the residual rate was about 89.7%. In Comparative Example 1, the concentration after immersion was about 341 ppm, and the residual rate was about 71.5%.

[0044] (Leak test) A container body having a capacity of 6.9 ml and an innermost layer made of a cyclic olefin resin was prepared. An inner stopper of Examples 1 and 2 or Comparative Examples 1 and 2 was attached to the mouth of this container body. The inner stoppers of Examples 1 and 2 and Comparative Example 1 were the same as those used in measuring the residual rate. The inner stopper of Comparative Example 2 was made entirely of a cyclic olefin resin. In Examples 1 and 2, the buffer portion of the inside plug is configured to contact the innermost layer of the cyclic olefin resin at the mouth of the container body.

[0045] The bottom was cut off from the container body's storage section to form an opening for injecting the test liquid described below. The nozzle of the inner stopper attached to the mouth of the container body was sealed with aluminum film. The container was placed upside down, with the nozzle facing downward and the bottom of the container body facing upward, and the test liquid (Ichinen Chemicals Co., Ltd., Heat Seal Checker JIP310, containing red dye) was injected through the opening. After leaving the container in the upside-down position for one week, the contact area between the mouth of the container body and the inner stopper was wiped with a white cloth or similar (wipe), and the presence or absence of leakage was determined by whether the red color of the test liquid was visible on the white wipe.

[0046] In Examples 1 and 2 and Comparative Example 1, there was no leakage at the contact area between the mouth of the container body and the inside plug. In Comparative Example 2, leakage was observed at the contact area between the mouth of the container body and the inside plug.

[0047] (summary) In Examples 1 and 2, in which a buffer portion was provided on the outer periphery of the container body that contacted the mouth, the residual rate of the ingredients was high and there was no leakage at the contact area between the mouth and the inside stopper. In Comparative Example 1, in which the entire inner plug was made of PE, there was no leakage at the contact area between the mouth and the inner plug, but the residual rate of the components was low. In Comparative Example 2, in which the entire inner stopper was made of cyclic olefin resin, the residual rate of the components was presumably as high as in Examples 1 and 2, but leakage of the contents occurred at the contact point between the mouth and the inner stopper. From the above results, it was confirmed that the inner stoppers of Examples 1 and 2 suppress sorption (adsorption, absorption) of eye drops onto the inner stopper, while making it difficult for gaps and leakage to occur between the inner stopper and the container body. [Explanation of symbols]

[0048] C...cap, 1...container body, 2...mouth portion, 2a...tip surface of mouth portion, 2b...inner surface of mouth portion, 3...shoulder portion, 4...body portion, 5...storage portion, 10,20...inner plug, 10a,20a...liquid contact portion, 10b,20b...inner plug body portion, 11,21...nozzle portion, 11a,21a...tip portion of nozzle portion, 12,22...nozzle hole, 13,23...flange portion, 14,24...leg portion, 14a,24a...portion where the leg portion directly contacts the mouth portion, 14b,24b...portion where the leg portion contacts the inner surface of the mouth portion via the buffer portion, 15,25...buffer portion, 15a,25a...portion where the buffer portion is formed on the leg portion, 15b...portion where the buffer portion is formed on the flange portion, 16...inner tube portion, 16a...tip portion of the inner tube portion, 17...gap portion, 26...gate portion.

Claims

1. An inner plug that is attached to the mouth of a container body to form a nozzle, a liquid-contacting part made of a layer containing a cyclic olefin copolymer, and a buffer part provided on an outer periphery that contacts the opening, the buffer part being made of a material that does not contain a cyclic olefin copolymer and is made of a material selected from polyethylene resin, rubber, and elastomer; The inside plug has a flange portion that contacts the tip surface of the mouth portion and a leg portion that contacts the inner surface of the mouth portion, and the buffer portion does not extend to the side where the tip of the nozzle protrudes from the flange portion.

2. A stopper as described in claim 1, characterized in that the buffer portion is provided on at least the outer peripheral surface of the leg portion.

3. The inside plug according to claim 1 or 2, characterized in that the outer peripheral portion of the inside plug that contacts the mouth portion has a portion where the liquid contact portion directly contacts the inner surface of the mouth portion, on a side closer to the storage portion of the container body than the portion that contacts the inner surface of the mouth portion via the buffer portion.

4. The inside plug according to any one of claims 1 to 3, characterized in that the layer containing a cyclic olefin copolymer contains at least one of COP (a copolymer of different cyclic olefins) and COC (a copolymer of a cyclic olefin and a non-cyclic olefin).

5. An eye drop container comprising: the inside plug according to any one of claims 1 to 4; and a container body having an opening to which the inside plug is attached.

6. 6. The eye drop container according to claim 5, wherein the container body has a layer containing a cyclic olefin copolymer at least on a surface that comes into contact with the liquid content.

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