Packing-equipped cap and method for manufacturing same

Abstract

The present invention provides a packing-equipped cap that can improve the sealing properties of a mouth of a bottle filled with a liquid when mounted to the mouth, and prevents an additive in a member for forming the packing from scattering as fine dust.　Provided is a packing-equipped cap 10 in which a recessed part to be mounted to a mouth 12a of a bottle 12 filled with a liquid L is formed from a top plate part 10a and a skirt part 10b made of resin, and a multilayer packing 14 is in close contact with the interior of the recessed part. The multilayer packing 14 is formed from: a rubber elastic resin layer 14a that is in close contact with the inner surface of the top plate part 10a; and a clean contact layer 24 that is layered on the rubber elastic resin layer 14a, the surface of the clean contact layer 24 being brought into contact with the liquid L and / or a vaporized substance of the liquid L when the packing-equipped cap 10 is mounted to the mouth 12a of the bottle 12. The clean contact layer 24 is formed form a high-density polyethylene resin having no additives added thereto and is formed to be thinner than the rubber elastic resin layer 14a. A side surface of the multilayer packing 14 is in close contact with the inner surface of the skirt part 10b.

Description

Cap with packing and its manufacturing method

[0001] The present invention relates to a cap with a packing and a method for manufacturing the same.

[0002] Gaskets are inserted into caps attached to the mouths of bottles filled with liquid for various purposes. For example, Patent Document 1 below proposes a gasket-equipped cap in which a polyethylene gasket with a density of 0.935 to 0.970 g / cc is attached to the inner surface of the top plate of a metal cap. It is described that when this gasket-equipped cap is attached to the mouth of a polyester (PET) container, the initial opening torque is significantly reduced. Furthermore, Patent Document 2 below proposes a gasket-equipped cap in which a thermoplastic elastomer gasket is attached to the inner surface of the top plate of the cap. It is described that when this gasket-equipped cap is used as a cap for a reagent bottle or a water bottle, it can reliably seal the container without worrying about liquid leakage.

[0003] Patent No. 2701417 Patent No. 3028934

[0004] The polyethylene gasket with a density of 0.935 to 0.970 g / cc provided in the gasket-equipped cap of the above-mentioned Patent Document 1 has a high hardness, so when the cap is fitted onto the neck of a bottle, the contact area between the bottle neck and the gasket is reduced, and when the cap is opened after being fitted onto the neck of a bottle, the initial opening torque is reduced. However, when this gasket-equipped cap is used as a cap for a reagent bottle or a water bottle, the reduced contact area between the bottle neck and the cap gasket may cause leakage of the reagent or water.

[0005] Furthermore, with the thermoplastic elastomer gasket provided in the gasket-equipped cap of Patent Document 2, when the cap is fitted to the mouth of a reagent bottle or water bottle, the gasket is pressed and deformed by the mouth surface, improving the seal between the mouth and the gasket and sufficiently preventing leakage of reagents or water. However, because thermoplastic elastomers typically contain various additives such as heat stabilizers, lubricants, and antioxidants, the additives in the gasket can scatter as fine dust, which can contaminate liquids such as reagents. In particular, gasket-equipped caps attached to the mouths of bottles filled with liquids such as cleaning solutions used to clean precision components such as semiconductors or photoresist solutions must reliably prevent the generation of fine dust from the gasket.

[0006] Furthermore, since the gasket-equipped cap is attached to the mouth of a bottle filled with chemicals such as various organic solvents, acids, or alkalis, the gasket may be made of a rubber-elastic layer of a thermoplastic elastomer, etc., laminated with a polypropylene resin layer or a polyester resin layer. However, the polypropylene resin layer has poor barrier properties against organic solvents, and the polyester resin layer has poor durability against acids and alkalis.

[0007] The present invention aims to solve the above-mentioned problems and provide a cap with a gasket that is durable against the liquid and / or vapor of that liquid filled into the bottle, improves the sealing performance of the mouth of the bottle into which the liquid is filled, and prevents additives in the material that forms the gasket from scattering as fine dust, and a method for manufacturing the same.

[0008] The gasket-equipped cap, which has been made to achieve the above-mentioned object, is a gasket-equipped cap comprising: a cap body having a recess formed by a resin top plate portion and a resin skirt portion, the recess being attached to the mouth of a bottle into which a liquid is to be filled; and a multilayer gasket that is in intimate contact with the inside of the recess, the multilayer gasket being provided with a rubber-elastic resin layer that is in intimate contact with the inner surface of the top plate portion; and a clean contact layer that is laminated on the rubber-elastic resin layer on the opening side of the recess, the clean contact layer having a surface that comes into contact with the liquid and / or vaporized form of the liquid when the gasket-equipped cap is attached to the mouth of the bottle, the clean contact layer being additive-free and having a density of 0.930 g / cm ３ The multilayer packing is made of the above polyethylene resin, is formed thinner than the rubber elastic resin layer, and the side surface of the multilayer packing is in close contact with the inner surface of the skirt portion.

[0009] The rubber elastic resin layer is made of a thermoplastic elastomer and has a thickness of 1 to 3 mm, and the clean contact layer has a density of 0.930 to 0.961 g / cm ３ It is preferable that the sheet is made of polyethylene resin and has a thickness of 20 to 350 μm.

[0010] A gas barrier layer containing an ethylene-vinyl alcohol copolymer resin or a polyamide resin is preferably provided between the rubber elastic resin layer and the clean contact layer, as this can prevent liquids such as organic solvents filled in the bottle from volatilizing and permeating to the outside.

[0011] The cap body and the multilayer packing are preferably formed as an integral body, so that the entire multilayer packing can be maintained in a clean state when mounted inside the cap body.

[0012] The method for manufacturing a cap with a packing that has been made to achieve the above object is to manufacture a cap with a packing that includes a cap body having a recess formed by a resin top plate portion and a resin skirt portion, the recess being attached to the mouth of a bottle into which a liquid is to be filled, and a multi-layer packing that is tightly attached to the recess, the method comprising the steps of: ３The gasket-equipped cap is made of the above polyethylene resin, and when the gasket-equipped cap is attached to the mouth of the bottle, it has a clean contact layer on one side that comes into contact with the liquid and / or the vaporized form of the liquid, and a rubber elastic resin layer on the other side of the clean contact layer that is thicker than the clean contact layer, and after forming a multi-layer gasket with one side of the rubber elastic resin layer as the exposed surface, the multi-layer gasket is inserted into a mold for melt-molding the cap body so that the exposed surface of the rubber elastic resin layer is in close contact and one side of the clean contact layer is in a position where it becomes the exposed surface, and molten resin is injected into the mold.

[0013] The packing of the packing-equipped cap according to the present invention has a clean contact layer including a packing surface that comes into contact with the liquid to be filled into the bottle and / or the vapor of this liquid, and has a density of 0.930 g / cm 3 that is highly chemical resistant. ３ The packing used in the present invention is durable against the liquid and / or vapor of the liquid filled in the bottle because of the polyethylene resin used in the present invention. Moreover, because the clean contact layer is made of polyethylene resin containing no additives, it is possible to prevent the scattering of fine dust particles, such as additives contained in the rubber elastic resin layer, as well as from the clean contact layer, and to prevent the fine dust particles from mixing into the liquid filled in the bottle.

[0014] Furthermore, when the gasket-equipped cap of the present invention is attached to the mouth of a bottle into which liquid is to be filled, the tip surface of the mouth presses against the multilayer gasket, causing the rubber elastic resin layer to deform, which in turn causes the entire multilayer gasket to deform, increasing the contact surface with the tip of the bottle's mouth and improving the sealing performance of the multilayer gasket at the mouth of the bottle.

[0015] It is a cross-sectional view showing an example of a cap with a packing to which the present invention is applied. It is a cross-sectional view showing an example of a mold used in a method for manufacturing a cap with a packing to which the present invention is applied. It is a cross-sectional view showing another example of a cap with a packing to which the present invention is applied.

[0016] An example of a gasket-equipped cap according to the present invention is shown in FIG. 1. The gasket-equipped cap 10 shown in FIG. 1 (hereinafter simply referred to as cap 10) comprises a cap body formed of a resin top plate 10a and a skirt portion 10b, and a multilayer gasket 14 fitted into a recess surrounded by the top plate 10a and the skirt portion 10b. This cap 10 is threaded onto a threaded portion formed on the outer surface of the mouth portion 12a of a bottle 12 to be filled with liquid L. The cap 10 is made of resin, and the threaded portion that threads onto the threaded portion of the mouth portion 12a of the bottle 12 is formed on the inner wall surface of the opening side of the recess formed by the inner surface of the top plate 10a and the inner surface of the skirt portion 10b. The bottle 12 may be made of resin or metal as long as it is durable against liquid L. The bottle 12 may also have an inner wall surface coated with a coating agent that is durable against liquid L. The resin forming the cap body may be the same as or different from the resin forming the bottle 12, but a melt-moldable resin is preferred.

[0017] 1, a multilayer packing 14 is in intimate contact with the inner surface of the top plate 10a and the inner surface of the skirt 10b, improving the strength of the cap 10. The multilayer packing 14 is formed from a rubber-elastic resin layer 14a in intimate contact with the inner surface of the top plate 10a and a multilayer thin film layer 14b laminated on the rubber-elastic resin layer 14a and thinner than the rubber-elastic resin layer 14a. As shown in the partially enlarged cross-sectional view of the multilayer packing 14, the multilayer thin film layer 14b is composed of a coating layer 16 laminated in intimate contact with the rubber-elastic resin layer 14a, a gas barrier layer 20 bonded to the coating layer 16 via an adhesive layer 18, and a clean contact layer 24 bonded to the gas barrier layer 20 via an adhesive layer 22.

[0018] When the cap 10 is attached to the neck 12a of the bottle 12, the rubber-elastic resin layer 14a deforms due to the pressure of the tip of the neck 12a, expanding the contact area between the multilayer packing 14 and the tip of the neck 12a and improving the sealing of the neck 12a. The resin forming the rubber-elastic resin layer 14a is preferably a thermoplastic polyethylene resin or a thermoplastic elastomer. Specific examples of thermoplastic elastomers include styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and hydrogenated elastomers. The thickness of the rubber-elastic resin layer 14a is preferably 1.0 to 3.0 mm, more preferably 1.5 to 2.5 mm, and even more preferably 1.5 to 2.0 mm per layer.

[0019] The multilayer thin film layer 14b laminated on the rubber elastic resin layer 14a preferably has a thickness of 45 to 500 μm, more preferably 50 to 300 μm, and even more preferably 50 to 250 μm per layer. The coating layer 16 constituting this multilayer thin film layer 14b is laminated in close contact with the surface of the rubber elastic resin layer 14a, and serves as a sealant layer that bonds the multilayer coating layer 14b and the rubber elastic resin layer 14a together. The coating layer 16 is preferably formed from an olefin resin and has a density of 0.910 g / cm. ３ The above polyethylene resins can be suitably used. The resin forming the coating layer 16 may contain additives such as antioxidants.

[0020] A gas barrier layer 20 is laminated on the coating layer 16 via an adhesive layer 18. The gas barrier layer 20 is intended to prevent leakage of gas evaporated from the liquid L filled in the bottle 12 and the inflow of air into the bottle 12, and is formed of a resin containing an ethylene-vinyl alcohol copolymer resin or a polyamide resin. The ethylene content of the ethylene-vinyl alcohol copolymer resin is preferably 20 to 60%, more preferably 25 to 45%. When such an ethylene-vinyl alcohol copolymer resin is used, the blending amount of the ethylene-vinyl alcohol copolymer resin in the gas barrier layer 20 is preferably 50% by mass or more. When a polyamide resin is used, the blending amount of the polyamide resin in the gas barrier layer 20 is preferably 50% by mass or more. The thickness of the gas barrier layer 20 is preferably 5 to 100 μm, more preferably 5 to 75 μm, and even more preferably 5 to 50 μm in one layer.

[0021] A clean contact layer 24 is laminated on the gas barrier layer 20 via an adhesive layer 22. The clean contact layer 24 has a surface that comes into contact with the liquid L and / or vaporized form of the liquid L filled in the bottle 12 when the cap 10 is screwed onto the mouth portion 12a of the bottle 12. The clean contact layer 24 contains no additives and has a density of 0.930 g / cm ３The polyethylene resin is formed from the above-mentioned polyethylene resin. The term "additive-free" here means that no additives such as antioxidants, lubricants, or mold release agents are added, although residues of radial initiators and polymerization catalysts added during the production of the polyethylene resin may be present. Specifically, the content of each of the neutralizing agent, antioxidant, and light resistance stabilizer, as determined by liquid chromatography of the polyethylene resin, is 0.01% by mass or less. High-density polyethylene resins, in particular, have linear molecular chains with little ethylene branching, are highly crystalline, and are highly resistant to solvents and chemicals at room temperature. Furthermore, because they are additive-free, there is no risk of additives scattering as fine dust. The clean contact layer 24 made of this polyethylene resin not only prevents the scattering of fine dust such as additives from itself, but also prevents the scattering of additives even if they are blended into the rubber elastic resin layer 14a, coating layer 16, gas barrier layer 20, and adhesive layers 18 and 22 that make up the multilayer packing 14.

[0022] The density of the polyethylene resin forming the clean contact layer 24 is 0.930 g / cm ３ The upper limit of the density of polyethylene resin is 0.970 g / cm3 due to its processability etc. ３ From the viewpoint of processability of polyethylene resin, the density is 0.930 to 0.965 g / cm ３ and more preferably 0.940 to 0.965 g / cm ３ and even more preferably 0.945 to 0.961 g / cm ３ The melt flow rate (MFR) of this polyethylene resin is preferably 4.0 g / 10 min or less. The thickness of the clean contact layer 24 is preferably 20 to 350 μm, more preferably 20 to 250 μm, and even more preferably 20 to 200 μm in one layer. The polyethylene resin may contain an ethylene-α-olefin copolymer, and examples of the α-olefin include propylene, butene-1,4-methyl-pentene-1, hexene-1, and octene-1.

[0023] It is preferable that this clean contact layer 24 prevent, as much as possible, the exposed surface that comes into contact with the liquid L and / or vapor of the liquid L filled in the bottle 12 when the cap 10 is screwed onto the mouth 12a of the bottle 12 from coming into contact with other objects during the manufacturing process of the packing cap and becoming contaminated with dust, etc. For this reason, it is preferable that the packing cap shown in Figure 1 is an integrally molded body of the cap body and the multilayer packing 14, so that the entire multilayer packing 14 can be maintained in a clean state when attached to the cap body.

[0024] An example of a method for manufacturing the packing cap shown in Fig. 1 is described with reference to Fig. 2. First, a rubber elastic resin layer 14a and a multilayer thin film layer 14b are laminated together as shown in Fig. 2(a). As shown in the partially enlarged cross-sectional view of Fig. 2(a), the multilayer thin film layer 14b is formed from a coating layer 16 laminated in close contact with the rubber elastic resin layer 14a, a gas barrier layer 20 bonded to the coating layer 16 via an adhesive layer 18, and a clean contact layer 24 bonded to the gas barrier layer 20 via an adhesive layer 22.

[0025] The multilayer packing 14 shown in Fig. 2(a) is inserted into a die for melt molding the cap body while the exposed surface of its clean contact layer 24 is kept out of contact. As shown in Fig. 2(b), the die for melt molding is composed of a lower die 32 and an upper die 34. The lower die 32 has a mounting surface 32a on which the multilayer packing 14 is placed, and the multilayer packing 14 is placed on the mounting surface 32a of the opened lower die 32 so that the exposed surface of the clean contact layer 24 is in close contact with the mounting surface 32a.

[0026] Next, the lower mold 32 and the upper mold 34 are closed, and molten resin is injected through the molten resin injection port 36 of the upper mold 34 to fill the cavity 38 formed by the lower mold 32 and the upper mold 34. The mold is then cooled, and the lower mold 32 and the upper mold 34 are opened, thereby removing the cap 10 in which the multilayer packing 14 is tightly attached within the recess formed by the top plate portion 10a and the skirt portion 10b as shown in FIG.

[0027] The multilayer packing 14 described so far is formed from a rubber elastic resin layer 14a, a coating layer 16 laminated in close contact with the rubber elastic resin layer 14a, a gas barrier layer 20 joined to the coating layer 16 via an adhesive layer 18, and a clean contact layer 24 joined to the gas barrier layer 20 via an adhesive layer 22. However, if the gas barrier property of the mouth of the bottle 12 into which the liquid L is filled is not a major issue, the multilayer packing 14 may be formed from a rubber elastic resin layer 14a and a clean contact layer 24 laminated in close contact with the rubber elastic resin layer 14a, as shown in Figure 3.

[0028] In the gasket-equipped cap according to the present invention, the surface of the multilayer gasket 14 is formed with a clean contact layer 24, which prevents fine dust from scattering from the gasket itself and also prevents fine dust from scattering from the rubber-elastic resin layer 14a, thereby improving the cleanliness of the gasket. Furthermore, the multilayer gasket 14 has a rubber-elastic resin layer 14a. When the gasket-equipped cap is attached to the mouth 12a of the bottle 12, the end surface of the mouth 12a presses against the multilayer gasket 14, deforming the rubber-elastic resin layer 14a, which in turn deforms the entire multilayer gasket 14, expanding the contact surface with the tip of the mouth 12a of the bottle 12 and improving the sealing performance of the multilayer gasket 14 around the mouth 12a. Furthermore, the clean contact layer 24 on the surface of the multilayer gasket 14 is formed of high-density polyethylene, which is resistant to various organic solvents, acids, alkalis, and other chemicals. Therefore, the gasket-equipped cap of the present invention can be suitably used as a gasket-equipped cap to be attached to the mouth 12a of a bottle 12 filled with cleaning liquid or photoresist solution used to clean precision components such as semiconductors, or filled with various organic solvents, acids, alkalis, or other chemicals.

[0029] Examples of the present invention will be described in detail below, but the scope of the present invention is not limited to these examples.

[0030] Example 1 (Production of multilayer packing 14) The multilayer packing 14 was produced by decorative molding. First, the multilayer thin film layer 14b was formed by inflation molding. The multilayer thin film layer 14 was formed in the following order: clean contact layer 24, adhesive layer 22, gas barrier layer 20, adhesive layer 18, and coating layer 16. The materials used for each layer and the thickness of each layer are as follows: clean contact layer 24: density 0.956 g / cm ３ Polyethylene resin (MFR: 0.34 g / 10 min) Thickness: 28 μm Adhesive layer 22: Density 0.910 g / cm ３ Maleic acid-modified polyethylene resin (MFR: 3.7 g / 10 min) Thickness: 3.5 μm Gas barrier layer 20: Ethylene-vinyl alcohol copolymer resin (ethylene content: 44%) Thickness: 7 μm Adhesive layer 18: Density 0.910 g / cm ３ Maleic acid-modified polyethylene resin (MFR: 3.7 g / 10 min) Thickness: 3.5 μm Coating layer 16: Density 0.930 g / cm ３ Polyethylene resin (MFR: 1.1 g / 10 min) Thickness: 28 μm

[0031] Next, the multilayer thin film layer 14b is placed in the lower mold of a mold of a predetermined shape so that the exposed surface of the clean contact layer 24 is in close contact with the lower mold, and after closing the upper mold of the mold, a rubber elastic resin layer 14a having an MFR of 1.2 g / 10 min and a density of 0.885 g / cm is formed. ３ An olefin-based thermoplastic elastomer of 1000 ppm was injected into the mold, and the rubber elastic resin layer 14a was integrated with the multilayer thin film layer 14b to obtain a 2 mm thick multilayer packing 14. The obtained multilayer packing 14 was removed from the mold using an ejector pin. When the ejector pin was operated, the multilayer thin film layer 14b was trimmed to follow the shape of the rubber elastic resin layer 14a, so a separate trimming step was not required.

[0032] (Fabrication of Cap 10) The cap 10 was fabricated by insert molding. The resulting multilayer packing 14 was inserted into a mold for melt molding of the cap body, as shown in FIG. 2. The mold for melt molding is composed of a lower mold 32 and an upper mold 34, as shown in FIG. 2(b). The lower mold 32 is formed with a mounting surface 32a on which the multilayer packing 14 is to be placed, and the multilayer packing 14 is placed so that the exposed surface of the clean contact layer 24 is in close contact with the mounting surface 32a of the opened lower mold 32. Next, the lower mold 32 and the upper mold 34 are closed, and a molten resin having an MFR of 3.8 g / 10 min and a density of 0.938 g / cm is injected from a molten resin injection port 36 of the upper mold 34. ３ Molten polyethylene resin is injected into the cavity 38 formed by the lower mold 32 and the upper mold 34. The mold is then cooled, and the lower mold 32 and the upper mold 34 are opened to remove the cap 10, in which the multilayer packing 14 is tightly attached to the recess of the cap body formed by the top plate portion 10a and the skirt portion 10b as shown in Figure 1.

[0033] Example 2 The cleanliness of the obtained multilayer packing 14, and the sealing property and strength of the obtained packing-equipped cap 10 were tested.

[0034] (Cleanliness) Cleanliness test Cleanliness is evaluated based on the cleanliness using the following formula (1). The test cap 10 equipped with the multilayer packing 14 is used to fill a test container with a capacity of a (ml) with ultrapure water (a / 2 (ml)) and then cap the container. After shaking for 15 seconds and leaving it to stand for 24 hours, the test is carried out using a particle counter. In formula (1), a is the capacity of the test container, b is the amount of liquid sampled from the test container, and c is the number of particles contained in the total amount of sampled liquid counted by the particle counter. Results: Measurement of the multilayer packing 14 obtained in Example 1 revealed a particle diameter of 0.2 μm and a particle count of 2.2 particles / ml. A cleanliness level of 5 particles / ml or less is considered to be sufficient to improve the quality and yield of semiconductors and liquid crystals, and this was a satisfactory cleanliness level.

[0035] 1 was filled to the brim with water, and the cap 10 with the packing obtained in Example 1 was screwed onto the mouth 12a. The bottle was then held at a test pressure of 200 KPa for 30 minutes, and the presence or absence of leakage was checked. Result: There was no leakage from the cap 10 with the packing obtained in Example 1.

[0036] 1 is filled with liquid L to 98% or more, and the cap 10 with a packing is screwed onto the mouth 12a. The bottle is then stored in an atmosphere of -18°C or below. After the temperature of the liquid L and the bottle 12 reaches -18°C or below, the bottle is dropped from a height of 1.2 m and checked for leakage. Results There was no leakage from the cap 10 with a packing obtained in Example 1.

[0037] The packing cap according to the present invention can be used as a cap for the mouth of a bottle filled with a liquid that requires high cleanliness.

[0038] 10: Cap with packing, 10a: Top plate portion, 10b: Skirt portion, 12: Bottle, 12a: Mouth portion, 14: Multilayer packing, 14a: Rubber elastic resin layer, 14b: Multilayer thin film layer, 16: Coating layer, 18, 22: Adhesive layers, 20: Gas barrier layer, 24: Clean contact layer, 32: Lower mold, 34: Upper mold, 32a: Mounting surface, 36: Molten resin injection port, 38: Cavity, L: Liquid

Claims

1. A packing cap comprising a cap body having a recess formed by a resin top plate and skirt portion to be attached to the mouth of a bottle into which a liquid is to be filled, and a multi-layer packing intimately attached to the recess, wherein the multi-layer packing is provided with a rubber-elastic resin layer intimately attached to the inner surface of the top plate, and a clean contact layer laminated on the rubber-elastic resin layer on the opening side of the recess, the surface of which comes into contact with the liquid and / or vaporized form of the liquid when the packing cap is attached to the mouth of the bottle, and wherein the clean contact layer is additive-free and has a density of 0.930 g / cm ３ a cap with a packing, which is made of the above polyethylene resin and is formed thinner than the rubber elastic resin layer, and the side of the multilayer packing is in close contact with the inner surface of the skirt portion.

2. The rubber elastic resin layer is made of a thermoplastic elastomer and has a thickness of 1 to 3 mm, and the clean contact layer has a density of 0.930 to 0.961 g / cm ３ 2. The packing-equipped cap according to claim 1, characterized in that it is made of polyethylene resin and has a thickness of 20 to 350 μm.

3. The gasket-equipped cap according to claim 1, characterized in that a gas barrier layer containing an ethylene-vinyl alcohol copolymer resin or a polyamide resin is provided between the rubber elastic resin layer and the clean contact layer.

4. The packing cap according to claim 1, wherein the cap body and the multi-layer packing are integrally molded.

5. When manufacturing a cap with a gasket, the cap body has a recess formed of a resin top plate and skirt portion, which is attached to the mouth of a bottle into which a liquid is to be filled, and the cap has a multi-layer gasket that is tightly attached to the recess, the cap is free of additives and has a density of 0.930 g / cm ３ A method for manufacturing a cap with a gasket, characterized in that a multi-layer gasket is formed from the above polyethylene resin, having a clean contact layer on one side that comes into contact with the liquid and / or vaporized form of the liquid when the cap with a gasket is attached to the mouth of the bottle, and a rubber elastic resin layer on the other side of the clean contact layer that is thicker than the clean contact layer, with one side of the rubber elastic resin layer being an exposed surface, and then the multi-layer gasket is inserted into a mold for melt molding the cap body so that the exposed surface of the rubber elastic resin layer is in close contact and one side of the clean contact layer is in a position where it is an exposed surface, and molten resin is injected into the mold.

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