Tube container and method for producing same

Abstract

The purpose of the present invention is to provide: a tube container, a production process of which uses little energy, and which has a coating layer that has excellent conformability to a tube container body, excellent flexibility, and excellent film formation strength; and a method for producing the tube container. The present invention relates to a tube container comprising a metal base material, said tube container having a coating layer on an inner surface thereon, wherein the coating layer is formed of a fluorine-containing two-component curable urethane resin composition.

Description

Tube container and method for manufacturing the same

[0001] The present invention relates to a tube container and a method for manufacturing the same.

[0002] Metal tube containers, such as aluminum tubes, are used as packaging containers for cosmetics, pharmaceuticals, and quasi-drugs because they can completely protect the contents from light (ultraviolet rays), air (gas), and water (water vapor), and offer excellent non-airbag properties, portability, and ease of use.

[0003] A metal tube container typically comprises a metal body that is easily plastically deformable, and a metal main body (hereinafter also referred to as the "tube container body") which is formed by one end of the body and continuously ending at a shoulder and neck. The other end of the body of this tube container is folded and closed, and the neck is closed with a cap that can be opened and closed.

[0004] Metal tube containers are typically used by squeezing them to push out the contents of pharmaceuticals, quasi-drugs, and cosmetics, such as liquids or creams; therefore, they are required to have excellent flexibility.

[0005] Furthermore, in addition to preventing the contents from deteriorating, tube containers often have a coating layer on their inner surface to prevent the contents from corroding the container itself. This coating layer requires not only conformability and flexibility to the tube container but also high film strength.

[0006] For example, Patent Document 1 discloses a method for coating the inside surface of a metal tube container to obtain high chemical resistance. Specifically, the method discloses a method for coating the inside surface of a metal tube container in which a first corrosion-resistant paint is coated on the inner surface of the base material of the metal tube container, and then a second corrosion-resistant paint is coated on the inner surface of the base material of the metal tube container, characterized in that the viscosity of the first corrosion-resistant paint before curing is greater than the viscosity of the second corrosion-resistant paint before curing.

[0007] Japanese Patent Publication No. 2006-160289

[0008] As disclosed in Patent Document 1, a known method for forming a coating layer on the inner surface of a metal tube container involves spray-coating a paint made from a chemical-resistant resin composition using a spray gun. However, since the resin composition is diluted to a viscosity that allows it to be spray-coated using a spray gun, it is common to heat the metal tube container coated with the coating layer in order to promote the curing reaction of the coating layer after painting. Therefore, the manufacturing process of metal tube containers with a coating layer requires a heating step, which increases energy consumption. Furthermore, in recent years, due to environmental concerns, there has been a greater demand than ever for reducing energy consumption in the manufacturing process of various products. For this reason, there has been a desire for tube containers that require less energy in the manufacturing process and have a coating layer with excellent conformability and flexibility to the tube container body, as well as film strength.

[0009] Therefore, the object of the present invention is to provide a tube container having a coating layer that requires less energy in the manufacturing process, has excellent conformability and flexibility to the tube container body, and has excellent film formation strength, as well as a method for manufacturing the same.

[0010] The inventors of this invention conducted diligent research to solve the aforementioned problems and, as a result, found that the problems can be solved by the following configuration example, and thus completed the present invention. The configuration example of the present invention is as follows.

[0011] [1] A tube container made of a metal substrate, having a coating layer on the inner surface of the tube container, wherein the coating layer is formed of a fluorine-containing two-component curable urethane resin composition. [2] The tube container according to [1], wherein the fluorine-containing two-component curable urethane resin composition contains a hydroxyl polymer as a main component and an isocyanate compound as a curing agent, and the mixing ratio of the main component and the curing agent (main component:curing agent) is 3:1 to 9:1. [3] The tube container according to [1] or [2], wherein the curing reaction rate of the coating layer after storing the tube container at room temperature for one week is 70% or more. [4] The tube container according to any one of [1] to [3], wherein the solvent resistance of the coating layer is 5 to 350 MEK rubbing cycles. [5] The tube container according to any of [1] to [4] above, wherein the tube container has a body portion and a shoulder portion and a mouth portion continuous with one end of the body portion, and the cylindrical body member obtained by cutting off the head portion including the shoulder portion and the mouth portion does not exhibit peeling of the coating layer after the crusher test under the following condition (1): Condition (1) Prepare a stand on which a rod is fixed, and place the cylindrical body member on the stand by passing the rod through the open end of the cylindrical body member so that the open end of the cylindrical body member is in the up and down direction. If the outer diameter of the opening of the cylindrical body member is 19.05 mm or more, a cylindrical weight (2 kg) that passes through the center of the bottom surface of the rod is repeatedly dropped from a height of 100 cm above the upper open end of the cylindrical body member, or from a height of 50 cm above the upper open end of the cylindrical body member, until the height of the cylindrical body member is 10 mm or less. The flattened cylindrical body member is stretched out and cut from one open end to the other to unfold the cylindrical body member into a rectangle, and the peeling of the coating layer of the unfolded body member is evaluated. The peeling of the coating layer is evaluated in an area of ​​80% or more that includes the center of the total area of ​​the unfolded rectangular body member. [6] The tube container according to any one of [1] to [5] above, wherein the film thickness of the coating layer is 3 to 25 μm. [7] The tube container according to any one of [1] to [6] above, wherein the metal substrate is an aluminum substrate.[8] A method for manufacturing a tube container according to any one of [1] to [7] above, comprising a coating film forming step of applying a paint containing a fluorine-containing two-component curable urethane resin composition to the inner surface of a tube container made of a metal substrate to form a coating layer, and a room temperature curing step of curing the coating layer at room temperature. [9] A method for manufacturing a tube container according to [8] above, further comprising a heat curing step of heating the coating layer at 150°C or below for 5 minutes or more to cure it, wherein the heat curing step is performed before and / or after the room temperature curing step.

[0012] According to the present invention, it is possible to provide a metal tube container having a coating layer that requires less energy in the manufacturing process, exhibits excellent conformability and flexibility to the tube container body, and has superior film formation strength, as well as a method for manufacturing the same.

[0013] Figure 1 is a schematic diagram showing an example of a side view of a tube container (or tube container body) according to the present invention.

[0014] The present invention relates to a tube container made of a metal substrate, wherein the tube container has a coating layer on its inner surface, and the coating layer is formed from a fluorine-containing two-component curable urethane resin composition.

[0015] <Tube Container> Figure 1 shows one embodiment of the tube container of the present invention. The present invention will be described below based on one embodiment of the tube container of the present invention shown in Figure 1, but the tube container of the present invention is not limited to the form shown in Figure 1. The tube container 10 of one embodiment of the present invention shown in Figure 1 is formed in a cylindrical shape and is provided to contain contents (cosmetics, pharmaceuticals, quasi-drugs, etc.) inside. Specifically, the tube container 10 comprises a metal base material 4 (tube container body) having a body portion 2, a shoulder portion 3 and a mouth portion 1 continuous with one end of the body portion 2, and a coating layer 5 formed on the inner surface of the mouth portion 1, the shoulder portion 3 and the body portion 2, and is a container suitable for containing high viscosity liquids or viscous substances. In this disclosure, the portion of the tube container 10 including the mouth portion 1 and the shoulder portion 3, that is, the portion of the tube container 10 other than the body portion 2, is also referred to as the "head".

[0016] Male threads are engraved on the outer circumference of the mouth portion 1 of the metal base material 4, and these male threads engage with female threads on the inner wall of a cap (not shown) fitted onto the tube container 10 in a detachable manner. In the metal base material 4 of this type of tube container 10, the body portion 2 is made of a plastically deformable material and wall thickness. Examples of materials for forming such a body portion 2 include a thin-film tubular body obtained by plastically deforming a metal ingot selected from aluminum, aluminum alloys, tin, tin alloys, and lead into a thin-layer tubular shape by backward extrusion. In this embodiment, the shoulder portion 3 and mouth portion 1 continuous with one end of the body portion 2 are formed from the same material as the body portion 2, but in the present invention, the material of the shoulder portion 3 and mouth portion 1 is not particularly limited, and it is also possible to fix a plastic mouth portion 1 and shoulder portion 3 to a separately molded metal body portion 2. Among the materials for forming such a body portion 2, aluminum and its alloys are preferred in many applications, and metallic aluminum is more preferred.

[0017] The metal base material of the tube container of the present invention is preferably at least one base material selected from aluminum, aluminum alloy, tin, and tin alloy, and more preferably an aluminum base material.

[0018] The thickness of the metal base material 4 of the body of the tube container body of the present invention can be appropriately selected depending on the desired application and the properties of the contents. However, it is preferably 130 μm or less, more preferably 90 to 120 μm, and even more preferably 95 to 110 μm, in order to facilitate squeezing when using the container to squeeze out the contents and to easily obtain a container with excellent flexibility. A tube container made of a metal base material is preferable because it is easy to make the body of the tube container body with such a thickness, and even with such a thickness, the tube container body is excellent in flexibility and stress cracking resistance.

[0019] The length of the body of the tube container of the present invention can be appropriately selected depending on the desired application. For example, the lower limit of the body length can be selected from 50 mm, 55 mm, 65 mm, 70 mm, 80 mm, 90 mm, 110 mm, 130 mm, 140 mm, and 150 mm, and the upper limit can be selected from 200 mm, 190 mm, 180 mm, 170 mm, 150 mm, 125 mm, 110 mm, 105 mm, 90 mm, and 70 mm.

[0020] In one embodiment of the present invention, the coating layer 5 in the tube container 10 is formed on the inner surface of the metal substrate 4. The coating layer 5 is preferably formed by a spray coating method, in which a paint containing a fluorine-containing two-component curable urethane resin composition is sprayed from a rod-shaped nozzle inserted into the interior from the opening end (bottom portion 10a) toward the inside of the body. The coating layer 5 may be a single layer formed by one spray coating or a multi-layer formed by multiple spray coatings, allowing for the formation of the required film thickness depending on the contents. The coating layer 5 may also be formed by a method other than the spray coating method; for example, it can be formed by applying a paint that forms the coating layer using a brush.

[0021] The thickness of the coating layer on the body of the tube container of the present invention can be appropriately selected depending on the desired application and the properties of the contents. However, from the viewpoint of enabling easy squeezing when using the container to push out the contents, having excellent conformability and flexibility to a metal substrate, and achieving high film formation strength, the thickness is preferably 3 to 25 μm, more preferably 5 to 20 μm, and even more preferably 5 to 15 μm.

[0022] The coating layer of the tube container of the present invention is a layer formed from a fluorine-containing two-component curable urethane resin composition. Specifically, it is a layer obtained by curing a coating film formed by applying a paint obtained by diluting the fluorine-containing two-component curable urethane resin composition. Because the coating layer of the tube container of the present invention is formed from a fluorine-containing two-component curable urethane resin composition, the coating layer can be cured at room temperature (10 to 35°C), eliminating the need for heating equipment (such as a long furnace) required when using conventional thermosetting resin compositions. Therefore, energy consumption and equipment costs can be reduced, and the tube container of the present invention can be manufactured efficiently while reducing the environmental impact.

[0023] The two-component curable urethane resin composition used in the above-mentioned fluorine-containing two-component curable urethane resin composition is a urethane resin that uses a hydroxyl polymer (polyol) as the main component and an isocyanate compound as the curing agent. The hydroxyl polymer (polyol) is one which has two or more hydroxyl groups in its molecule, and examples of which include polyethylene glycol, polypropylene glycol, acrylic polyol, polyester polyol, polyether polyol, polycarbonate polyol, polyurethane polyol, etc. The isocyanate compound is a polyvalent isocyanate that has two or more isocyanate groups in its molecule. For example, aromatic isocyanates such as 2,4-tolylene diisocyanate, xylene diisocyanate, and 4,4-diphenylmethane diisocyanate, or aliphatic (or alicyclic) isocyanates such as 1,6-hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated diphenylmethane diisocyanate are used. Alternatively, adducts or polymers of the above-mentioned isocyanates can also be used. For example, adducts of tolylene diisocyanate, trimers of tolylene diisocyanate, etc.

[0024] The fluorine-containing two-component curable urethane resin composition used in the coating layer of the present invention is a two-component curable urethane resin composition in which a fluorine additive is included. Furthermore, the fluorine additive contained in the fluorine-containing two-component curable urethane resin composition hardens by forming a chemical bond between the two-component curable urethane resin and the fluorine additive through the reaction curing of the resin. A commercially available fluorine additive can be used; for example, NeoFluoriPerl, a fluorine resin additive manufactured by Noda Screen Co., Ltd., can be used.

[0025] A preferred embodiment of the two-component curable urethane resin is one in which the mixing ratio (main component:curing agent) of the main component, a hydroxyl polymer (polyol), and the curing agent, an isocyanate compound, is 3:1 to 9:1, and more preferably, the mixing ratio of the polyol to the isocyanate compound is 5:1 to 9:1.

[0026] In the tube container of the present invention, it is preferable that the curing reaction rate of the coating layer after applying a coating containing the above-mentioned fluorine-containing two-component curable urethane resin composition to the inner surface of the tube container and storing it at room temperature (e.g., 23°C) for one week (7 days) is 70% or more. The coating layer formed on the tube container of the present invention has curing reactivity at room temperature (e.g., 23°C), and if the curing reaction rate is 70% or more under the above conditions, the coating layer formed on the inner surface of the tube container will have better film strength. It is more preferable that the curing reaction rate of the coating layer after storing the tube container of the present invention at room temperature (e.g., 23°C) for one week (7 days) is 72% or more, and even more preferable that it is 74% or more.

[0027] Furthermore, in the tube container of the present invention, a coating film is formed by coating the inner surface of the tube container with a paint containing the above-mentioned fluorine-containing two-component curable urethane resin composition, and after storage at room temperature (e.g., 23°C) for two weeks (14 days), the curing reaction rate of the coating layer is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more.

[0028] The curing reaction rate of the coating layer is considered to be 0% when the curing reaction rate of the coating film formed by applying a paint containing a fluorine-containing two-component curable urethane resin composition to the inner surface of a tube container is taken from the FT-IR spectrum, and the 2255 cm² value originating from the stretching vibration of the isocyanate group is taken from the spectrum. －１ When the curing reaction rate of the coating layer in the state where no peak intensity is observed is considered to be 100%, the peak intensity at which the curing reaction rate is 0% is 2255 cm, which is derived from the stretching vibration of the isocyanate group due to the curing reaction. －１ This is obtained by calculating the percentage decrease in peak intensity. Specifically, the FT-IR spectrum is measured by FT-IR (ATR method), and the 2255 cm⁻¹, which originates from the stretching vibration of the isocyanate group, is obtained from the FT-IR spectrum of the coating film of the coating layer. －１ The ratio of peak intensity A to reference peak intensity B (A / B) was determined, and from the FT-IR spectrum of the coating layer (after curing reaction), the 2255 cm⁻¹ peak intensity, which originates from the stretching vibration of the isocyanate group, was determined. －１ The ratio of the peak intensity A' to the reference peak intensity B' (A' / B') can be determined, and the curing reaction rate can be calculated using the following formula: Curing reaction rate [%] = {1 - ((A' / B') / (A / B))} × 100. Note that the reference peak intensity B is 1720 cm². －１ The peak intensity of the C=O region in the vicinity is preferable.

[0029] The tube container of the present invention preferably has a solvent resistance of 5 to 350 MEK rubbing cycles after the coating layer is formed by coating the inner surface of the tube container with a paint containing the above-mentioned fluorine-containing two-component curable urethane resin composition and storing it at room temperature (e.g., 23°C) for one week (7 days). If the number of MEK rubbing cycles is less than 5, the abrasion resistance and slipperiness of the coating layer on the inner surface of the tube container cannot be obtained, and the film strength is not practical. If it exceeds 350 cycles, the coating layer itself becomes too hard, which may impair its ability to conform to metal substrates and its flexibility. The MEK rubbing test involves rubbing the coating film with a cotton swab impregnated with MEK (methyl ethyl ketone) at a load of 2 pounds (908 g) and a movement speed of 40 mm / sec, and measuring the number of cycles until the coating film peels off. The MEK rubbing test is a solvent resistance test, and the more MEK rubbing cycles there are, the less the solvent swells, indicating higher solvent resistance and curability. Therefore, it can be said that the more MEK rubbing cycles there are, the better the film strength.

[0030] The paint containing the above-mentioned fluorine-containing two-component curable urethane resin composition is obtained by diluting the fluorine-containing two-component curable urethane resin composition with various organic solvents depending on the painting conditions. Examples of such organic solvents include aromatic solvents such as toluene, xylene, and ethylbenzene; ester solvents such as ethyl acetate, ethyl lactate, butyl acetate, isobutyl acetate, propylene glycol methyl ether acetate, and propylene glycol methyl ether propionate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone; ether solvents such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and dipropylene glycol dimethyl ether; alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, and ethylcyclohexane; and petroleum hydrocarbon solvents such as mineral spirits. In addition, known paint formulation components may be added to the above-mentioned paint as needed.

[0031] For example, when a fluorine-containing two-component curable urethane resin composition is applied by a spray coating method, the viscosity (mPa·s) of the paint containing the fluorine-containing two-component curable urethane resin composition is preferably 20 to 200, more preferably 20 to 100, and even more preferably 20 to 70.

[0032] Furthermore, the paint containing the above-mentioned fluorine-containing two-component curable urethane resin composition is acceptable as long as it can be dried at room temperature until the coating film becomes tack-free after being applied to a metal substrate. The drying time of the coating film can be appropriately adjusted depending on the thickness of the formed coating film, the type of solvent, and the drying temperature, but is usually 5 to 15 minutes, preferably 5 to 10 minutes. In addition, the tube container on which the coating layer is formed should have an airflow of 15 to 40 m³ as the drying conditions for the solvent. ３ / h, preferably 25-30m ３ It may be placed in an environment with a fan speed of / h.

[0033] The tube container of the present invention has a body portion and a shoulder portion and a mouth portion continuous with one end of the body portion. Preferably, the cylindrical body member obtained by cutting off the head portion including the shoulder portion and the mouth portion does not exhibit peeling of the coating layer after the crusher test under the following condition (1). Condition (1) A stand on which a rod is fixed is prepared, and the cylindrical body member is placed on the stand by passing the rod through the open end of the cylindrical body member so that the open end of the cylindrical body member is in the up and down direction. If the outer diameter of the opening of the cylindrical body member is 19.05 mm or more, a cylindrical weight (2 kg) that passes through the center of the bottom surface of the rod is repeatedly dropped from a height of 100 cm above the upper open end of the cylindrical body member. If the outer diameter of the opening of the cylindrical body member is less than 19.05 mm, the rod is dropped from a height of 50 cm above the upper open end of the cylindrical body member until the height of the cylindrical body member is 10 mm or less. The crushed cylindrical body member is straightened and cut from one open end to the other to unfold the cylindrical body member into a rectangle, and the delamination of the coating layer of the unfolded body member is evaluated. The evaluation of the delamination of the coating layer is performed over an area of ​​80% or more including the center of the total area of ​​the unfolded rectangular body member. In the crusher test condition (1) above, it is preferable to evaluate the delamination of the coating layer over an area of ​​90% or more including the center of the total area of ​​the unfolded rectangular body member, and most preferably over the entire area of ​​the unfolded rectangular body member.

[0034] The crusher test is a test to evaluate the conformability and flexibility of various layers laminated on the metal substrate of the tube container body to the metal substrate. A tube container in which the coating layer does not peel off in the crusher test under the above test condition (1) is particularly excellent in the conformability and flexibility of the coating layer to the metal substrate and is therefore suitable.

[0035] The cylindrical body member obtained by cutting off the head of the tube container used in the crusher test may have a length of the body in the vertical direction of the opening surface of 50 to 100 mm, and may be adjusted according to the outer diameter of the opening of the cylindrical body member. For example, when performing a crusher test on a tube container with a body length of the tube container greater than 100 mm, the length of the cylindrical body obtained by cutting off the head may be adjusted to 50 to 100 mm according to the outer diameter of the opening of the cylindrical body member, and then the crusher test may be performed.

[0036] The cylindrical body member obtained by cutting off the head of the tube container used in the crusher test may have an outer diameter of the opening (that is, the body outer diameter of the bottom portion 10a of the tube container) of 10 to 35 mm, preferably 10 to 30 mm, more preferably 10 to 25 mm, and even more preferably 10 to 20 mm.

[0037] The tube container of the present invention preferably further has a printing layer on the outer surface of the tube container body. Further, for the purpose of adhesion of the printing layer to the metal substrate, an adhesive layer may be provided between the metal substrate and the printing layer.

[0038] The printing layer is not particularly limited as long as it is a layer provided conventionally for displaying the contents or for design properties, etc. For example, it may be a printing ink layer such as an acrylic-based, epoxy-based, polyester-based, or polyurethane-based layer.

[0039] <Method for manufacturing a tube container> The method for manufacturing the tube container of the present invention is not particularly limited, but preferably includes a coating film forming step of coating a paint containing a fluorine-containing two-component curable urethane resin composition on the inner surface of a tube container made of a metal substrate to form a coating film of a coating layer, and a room temperature curing step of curing and reacting the coating layer at room temperature.

[0040] In the coating film forming step in the production method of the present invention, any known method may be used as long as it involves applying a paint containing a fluorine-containing two-component curable urethane resin composition to form a coating film of a coating layer. For the application method of the above paint, for example, common application methods such as airless spray, spray coating using an air spray; brush coating; knife coating; roller coating; dipping; pulling up; flow coating; potting can be selected, but it is preferable to select spray coating. Further, the paint containing the fluorine-containing two-component curable urethane resin composition used in the coating film forming step may be diluted to a viscosity appropriately required according to the application method of the paint. For example, the suitable viscosity of the paint when the application method is the spray coating method is the same as the content described in the above description of the tube container of the present invention, and the same applies to the diluent used. Also, the suitable tack-free time of the paint used in the above coating film forming step is the same as the suitable tack-free time of the paint described in the above description of the tube container of the present invention.

[0041] In the production method of the tube container of the present invention, it includes the above coating film forming step and the above room temperature curing step. Since the curing reaction of the coating layer proceeds at room temperature (10 to 35°C) in the room temperature curing step, heating equipment (long furnace, etc.) required when using a thermosetting paint containing a conventional thermosetting resin composition becomes unnecessary. Therefore, it is possible to reduce the energy consumption and equipment cost, and the tube container of the present invention can be efficiently produced while reducing the environmental load. Incidentally, the above room temperature curing step may be performed in a humid environment. In the present disclosure, a humid environment means an environment with a relative humidity of 20 to 75%.

[0042] The manufacturing method of the present invention further includes a heat curing step in which the coating layer is heated at 150°C or below for 5 minutes or more to induce a curing reaction, and it is preferable that the heat curing step is performed before and / or after the room temperature curing step. That is, the heat curing step may be performed before the room temperature curing step, or after it, or it may be performed twice, before and after the room temperature curing step. By having the heat curing step, the curing reaction rate of the coating layer on the inner surface of the tube container can be greatly improved in a short time. The temperature required for curing a coating layer using conventional thermosetting paints is generally 180°C or higher, but the heat curing step can promote the curing reaction of the coating layer formed from a fluorine-containing two-component curable urethane resin composition at a temperature of 150°C or lower, so that the curing reaction of the coating layer can be promoted at a lower temperature range than conventional thermosetting paints, and energy consumption can be reduced. Examples of conventional thermosetting paints include epoxy-phenol resins, and the temperature range required for the curing reaction is 230 to 280°C.

[0043] The above heat curing step is preferably a step of heating the coating film of the coating layer formed by applying a paint containing a fluorine-containing two-component curable urethane resin composition to the inner surface of a tube container made of a metal substrate at a temperature of room temperature (10 to 35°C) or higher and 150°C or lower. For example, the above heat curing step may be a step of curing the coating film of the coating layer formed on the inner surface of the tube container in a low-temperature heating environment of 35°C or higher and 65°C or lower, a step of curing the coating film of the coating layer formed on the inner surface of the tube container in a medium-temperature heating environment of 65°C or higher and 100°C or lower, or a step of curing the coating film of the coating layer formed on the inner surface of the tube container in a high-temperature heating environment of 100°C or higher and 150°C or lower.

[0044] The upper limit of the heating time in the above heat curing process may be appropriately determined according to the temperature applied in the heat curing process and is not particularly limited. For example, when the above heat curing process cures the coating film of the coating layer formed on the inner surface of the tube container in a high temperature heating environment exceeding 100°C and not exceeding 150°C, the heating time is preferably 15 minutes or less, and more preferably 10 minutes or less. Also, for example, when the above heat curing process cures the coating film of the coating layer formed on the inner surface of the tube container in a medium temperature heating environment exceeding 65°C and not exceeding 100°C, the heating time is preferably 15 minutes or less, and more preferably 10 minutes or less. Also, for example, when the above heat curing process cures the coating film of the coating layer formed on the inner surface of the tube container in a low temperature heating environment exceeding 35°C and not exceeding 65°C, the heating time is preferably 1 week or more. Also, the above heat curing process may be performed in a humid environment. In the present disclosure, the humid environment is an environment with a relative humidity of 20 to 75%.

[0045] When the manufacturing method of the present invention has a heat curing process, the heat curing process may be performed at any timing as long as the coating film of the coating layer is applied to the tube container of the present invention. For example, when further forming a printing layer on the outer surface of the tube container, a heat treatment necessary for forming the printing layer is performed. When the conditions of the heat treatment of the printing layer overlap with the conditions of the above heat curing process, the above heat curing process may be performed simultaneously with the heat treatment of the printing layer.

[0046] The above room temperature curing process and / or the above heat curing process may include a blowing process with an air volume of 15 to 40 m ３ / h in part or all of each process. The air volume of the above blowing process is preferably 25 to 30 m ３ / h. When the above blowing process is included in part of each process, the above blowing process is preferably performed for 5 to 20 minutes, and more preferably 5 to 15 minutes.

[0047] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[0048] The resin compositions used in the coating layers in the examples and reference examples are as follows: • Fluorine-containing two-component curable urethane resin composition (Shields fluorine-based clear coat agent manufactured by Noda Screen Co., Ltd.) • Modified epoxy-phenol resin composition (AON302T-100 manufactured by Tanaka Chemical Co., Ltd.)

[0049] [Example 1] A coating layer was formed on the inner surface of an aluminum tube (tube container body) with a wall thickness of approximately 0.1 mm by spray coating using a two-component curable urethane resin composition containing fluorine (viscosity 50 mPa·s) to a film thickness of 12 μm (tack-free time 5-10 minutes). The tube container (outer diameter (φ13.8 mm), length (75 mm)) with the coating layer was then prepared by storing it at room temperature (23°C) for one week.

[0050] [Example 2] A tube container according to Example 2 was prepared in the same manner as in Example 1, except that the curing conditions for the coating layer and the storage period of the tube container at room temperature (23°C) were changed from one week to three weeks.

[0051] [Example 3] The tube container according to Example 3 was prepared in the same manner as in Example 1, except that the curing conditions for the coating layer were the tube container stored at room temperature (23°C) for one week and then heated at 150°C for 10 minutes.

[0052] [Reference Example 1] A coating layer was formed on the inner surface of an aluminum tube (tube container body) with a wall thickness of approximately 0.1 mm by spray coating a paint containing a modified epoxy-phenol resin composition to a film thickness of 8 μm. Subsequently, a tube container (outer diameter (φ13.8 mm), length (75 mm)) with a coating layer on its inner surface was fabricated by heating at 280°C for 5 minutes.

[0053] [Reference Example 2] A tube container according to Reference Example 2 was prepared in the same manner as in Reference Example 1, except that the curing conditions for the coating layer were changed from heating at 280°C for 5 minutes to a storage period of 1 week at room temperature (23°C) for the tube container.

[0054] <Curing Reaction Rate> The curing reaction rate was measured by the following method. The coating layers formed from the resin compositions used in the examples and reference examples were measured by FT-IR (ATR method). The curing reaction rate was calculated based on the amount of structure (peak intensity) lost during the curing reaction before and after curing. Specifically, it was calculated by the following method.

[0055] From the FT-IR spectrum of the coating film formed by applying the paint containing the resin composition used to the inner surface of a tube container, a 2255 cm² vibration originating from the stretching vibration of the isocyanate group was observed. －１ The peak intensity A originates from the C=O bond at 1720 cm². －１ The ratio (A / B) of the peak intensity to the reference peak intensity B was determined. Next, the FT-IR spectrum of the formed coating layer was analyzed to determine the 2255 cm² peak intensity originating from the stretching vibration of the isocyanate group. －１ The peak intensity A' originates from the C=O bond and is 1720 cm. －１ The ratio (A' / B') to the reference peak intensity B' was determined, and the curing reaction rate was calculated using the following formula: Curing reaction rate [%] = {1 - ((A' / B') / (A / B))} × 100. The results are shown in Table 1.

[0056] <MEK Rubbing Test> MEK rubbing was performed on the surface of an aluminum tube (tube container body) after the above-mentioned fluorine-containing two-component curing urethane resin composition had been applied to the inner surface to form a coating layer, and the curing reaction time (storage period) shown in Table 1 below had elapsed. In the test, a cotton swab soaked in MEK was used to rub the UV-cured film back and forth at a load of 2 pounds (908 g) and a moving speed of 40 mm / sec, and the number of back-and-forth strokes of the cotton swab when the coating layer was damaged was counted. The results are shown in Table 1.

[0057] <Crusher Test> The crusher test was performed as follows. The tops of the tube containers obtained in each embodiment and reference example were cut off to obtain cylindrical body members corresponding to each embodiment and reference example. The length (body length) of the obtained cylindrical body members was 75 mm, and the outer diameter (φ) of the opening was 13.8 mm. The cylindrical body members according to each embodiment and reference example were placed on a stand on which a rod was fixed, with the rod passing through the rod so that the openings were facing up and down. A cylindrical weight (2 kg) with the rod passing through its center was dropped from a height of 100 cm above the upper opening end of the cylindrical body member, and the weight was dropped repeatedly until the height of the cylindrical body member was 10 mm or less. The crushed cylindrical body member was straightened out, and cut from one opening end to the other using scissors to unfold the cylindrical body member into a rectangle, and the presence or absence of peeling of the coating layer formed on the inner surface of the unfolded rectangular body member was checked. The presence or absence of peeling of the coating layer can be determined by the entire area of ​​the unfolded rectangular body member (approximately 4.33 × 7.5 = 32.475 cm). ２ The area was checked. (Evaluation method) If no peeling of the coating layer was observed, it was marked with "○". If peeling of the coating layer was observed, it was marked with "×". The results are shown in Table 1.

[0058]

[0059] From the results of Example 1 in Table 1 above, the coating layer formed with a paint containing a fluorine-containing two-component curable urethane resin composition showed a curing reaction rate of 74.8% and required 10 rubbing cycles, even when the curing conditions were storage at room temperature for one week, confirming practical coating strength. Furthermore, there was no peeling in the crusher test, and a coating layer with excellent conformability to metal substrates and flexibility was obtained. In addition, the tube container according to Example 2, where the curing conditions were storage at room temperature for three weeks, showed a curing reaction rate of 93.5% for the coating layer and required 56 rubbing cycles, obtaining high coating strength comparable to that of the tube container according to Reference Example 1, which has a coating layer formed with a paint containing a conventional thermosetting resin. Furthermore, there was no peeling in the crusher test, and a coating layer with excellent conformability to metal substrates and flexibility was obtained. Furthermore, the tube container according to Example 3, which was heated at 150°C for 10 minutes after being stored at room temperature for one week as curing conditions, showed a curing reaction rate of 97.5% for the coating layer and 318 rubbing cycles. Compared to the tube container according to Reference Example 1, which had a coating layer formed with a paint containing a conventional thermosetting resin, significantly superior coating film strength was obtained. Moreover, there was no peeling in the crusher test, and a coating layer with excellent conformability to the metal substrate and flexibility was obtained. On the other hand, the tube container according to Reference Example 2, in which the curing conditions for the coating film formed with a paint containing a conventional thermosetting resin were changed from the conventional heating at 280°C for 5 minutes to a storage period of one week at room temperature (23°C), showed a low curing reaction rate of 25% for the coating layer and only 2 MEK rubbing cycles, and practical coating film strength could not be confirmed. Furthermore, peeling was observed in the crusher test, and the conformability and flexibility of the coating layer to the metal substrate could not be confirmed.

[0060] [Examples 4 and 5] Except for the storage period and storage conditions after the formation of the coating layer, a tube container (outer diameter (φ13.8 mm), length (75 mm)) was manufactured in the same manner as in Example 1. In the low-temperature humidification curing process, humidification was performed to achieve a relative humidity of 75%. The curing reaction rate, crusher test, and MEK rubbing test were performed on the coating layer of the obtained tube container using the above method. The results obtained are shown in Table 2 below.

[0061] [Reference Example 3] In the same manner as the method for manufacturing the tube container according to Example 1, the curing reaction rate of the coating layer immediately after its formation was considered to be "0" for the tube container, and this was shown in Table 2 below.

[0062]

[0063] From the results in Table 2 above, the tube container of Example 4, which was stored at room temperature for two weeks, showed a curing reaction rate exceeding 90%, a MEK rubbing count of 50, and high coating strength. Furthermore, there was no peeling in the crusher test, and a coating layer with excellent conformability and flexibility to the metal substrate was obtained. In addition, the tube container of Example 5, which was stored at room temperature for one week and then in a low-temperature, humidified environment at 40°C for one week, showed a curing reaction rate exceeding 95%, a rubbing count of 90, and remarkably excellent coating strength. Furthermore, there was no peeling in the crusher test, and a coating layer with excellent conformability and flexibility to the metal substrate was obtained.

[0064] 1: Mouth section 2: Body section 3: Shoulder section 4: Metal substrate 5: Coating layer 10: Tube container 10a: Bottom section

Claims

1. A tube container made of a metal substrate, wherein the tube container has a coating layer on its inner surface, and the coating layer is formed from a fluorine-containing two-component curable urethane resin composition.

2. The fluorine-containing two-component curable urethane resin composition contains a hydroxyl polymer as a main component and an isocyanate compound as a curing agent, wherein the mixing ratio of the main component and the curing agent (main component:curing agent) is 3:1 to 9:1, as described in claim 1.

3. The tube container according to claim 1 or 2, wherein the curing reaction rate of the coating layer after storing the tube container at room temperature for one week is 70% or more.

4. The tube container according to any one of claims 1 to 3, wherein the solvent resistance of the coating layer is 5 to 350 MEK rubbing cycles.

5. The tube container according to any one of claims 1 to 4, wherein the tube container has a body portion and a shoulder portion and a mouth portion continuous with one end of the body portion, and the cylindrical body member obtained by cutting off the head portion including the shoulder portion and the mouth portion does not exhibit peeling of the coating layer after the crusher test under the following condition (1). Condition (1) A stand on which a rod is fixed is prepared, and the cylindrical body member is placed on the stand by passing the rod through the open end of the cylindrical body member so that the open end of the cylindrical body member is in the up and down direction. If the outer diameter of the opening of the cylindrical body member is 19.05 mm or more, a cylindrical weight (2 kg) that passes through the center of the bottom surface of the rod is repeatedly dropped from a height of 100 cm above the upper open end of the cylindrical body member, or from a height of 50 cm above the upper open end of the cylindrical body member, until the height of the cylindrical body member is 10 mm or less. The flattened cylindrical body member is stretched out and cut from one open end to the other to unfold the cylindrical body member into a rectangle, and the delamination of the coating layer of the unfolded body member is evaluated. The evaluation of the delamination of the coating layer is performed over an area of ​​80% or more of the total area of ​​the unfolded rectangular body member, including the center.

6. The tube container according to any one of claims 1 to 5, wherein the thickness of the coating layer is 3 to 25 μm.

7. The tube container according to any one of claims 1 to 6, wherein the metal substrate is an aluminum substrate.

8. A method for manufacturing a tube container according to any one of claims 1 to 7, comprising: a coating film forming step of applying a paint containing a fluorine-containing two-component curable urethane resin composition to the inner surface of a tube container made of a metal substrate to form a coating layer; and a room temperature curing step of curing the coating layer at room temperature.

9. The manufacturing method according to claim 8, further comprising a heat curing step of heating the coating layer at 150°C or below for 5 minutes or more to cause a curing reaction, wherein the heat curing step is performed before and / or after the room temperature curing step.

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