Composition and liner for high-pressure gas storage tank containing the same

Abstract

The present invention aims to provide a composition excellent in gas barrier properties and low-temperature impact resistance and a liner for a high-pressure gas storage tank containing the same. Specifically, the present invention relates to a composition and a liner for a high-pressure gas storage tank, which have excellent gas barrier properties and excellent impact resistance and are easily moldable by dispersing resin particles that complement the low-temperature impact resistance in a gas barrier resin.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of priority based on Korean Patent Application No. 10 - 2022 - 0061337 filed on May 19, 2022, and all contents disclosed in the literature of the Korean patent application are included as part of this specification. The present invention aims to provide a composition and a liner for a high - pressure gas storage tank including the same. Specifically, the present invention aims to provide a composition and a liner for a high - pressure gas storage tank that are excellent in processability, gas barrier property, and low - temperature impact resistance.

Background Art

[0002] Conventionally, metal materials have been used as high - pressure gas storage tanks, especially as liners for storage tanks. However, since the liner for the metal material storage tank is heavy, it is not easy to transport and the cost during transportation is high. Therefore, recently, resins have been used as liner compositions for weight reduction. Resins used for liners for weight reduction include polyamide, polyethylene, etc. However, polyethylene - based liners have deteriorated gas barrier properties compared to polyamide - based liners, and polyamide - based liners have excellent gas barrier properties compared to polyethylene - based liners, but have problems such as deteriorated impact resistance and chemical resistance.

[0003] In addition, in the case of existing blend resin compositions, there are problems such as deteriorated processability and limitations in processing methods during product processing. Therefore, there is a current need to develop a composition for a liner resin for a high - pressure gas storage tank that is excellent in gas barrier property and low - temperature impact resistance, has improved processability, and can be applied to a wider range of processing methods such as rotomolding.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, the present invention aims to provide a composition excellent in processability, gas barrier properties, and low-temperature impact resistance, and a liner for a high-pressure gas storage tank containing the same. Specifically, the present invention aims to provide a composition in which thermoplastic elastomer particles that complement the low-temperature impact resistance are dispersed in a gas barrier resin, and a liner for a high-pressure gas storage tank containing the same.

Means for Solving the Problems

[0005] It contains a gas barrier resin (A) and a thermoplastic elastomer (B) dispersed in particulate form in the gas barrier resin (A), and has a low-temperature impact strength measured by ASTM D256 of 10 kJ / m 2 or more, an oxygen permeability measured by ASTM D3985 of 1.0 cm 3 / (m 2 ·day) or less, and a melt flow index measured by ASTM D1238 may be 3.0 g / 10 min or more.

[0006] The content of the thermoplastic elastomer (B) may be 11 to 50% by weight based on the combined weight of the gas barrier resin (A) and the thermoplastic elastomer (B). The gas barrier resin (A) may include one or more selected from the group consisting of polyamide, polyvinyl alcohol (PVOH), and ethylene-vinyl alcohol copolymer (EVOH).

[0007] The ethylene-vinyl alcohol copolymer may have an ethylene content exceeding 10 mol%. The polyamide may be one or more selected from the group consisting of nylon-4, 6, nylon-6, nylon-6, 6, nylon-6, 10, nylon-7, nylon-8, nylon-9, nylon-11, nylon-12, nylon-46, MXD6, and amorphous polyamide, or a copolymer or mixture of two or more thereof.

[0008] The thermoplastic elastomer (B) can include one or more selected from the group consisting of polyether block amide (TPA), polyester copolymer (TPC), thermoplastic polyurethane (TPU), styrene block copolymer (TPS), and thermoplastic polyester elastomer (TPEE).

[0009] The composition may consist of a gas barrier resin (A) and a thermoplastic elastomer (B) dispersed in the gas barrier resin (A) in particulate form.

[0010] Also, the composition may have a low-temperature impact strength measured by ASTM D256 of 10 kJ / m 2 or more to 25 kJ / m 2 or less.

[0011] Also, the composition may have an oxygen permeability measured by ASTM D3985 of more than 0 to 1.0 cm 3 / (m 2 ·day) or less.

[0012] Also, the composition may have a melt flow index measured by ASTM D1238 of 3.0 g / 10 min or more to 10.0 g / 10 min or less.

[0013] A liner for a high-pressure gas storage tank according to an embodiment of the present invention can include the composition.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a composition in which thermoplastic elastomer particles that reinforce low-temperature impact resistance are dispersed in a gas barrier resin, achieving both excellent gas barrier properties and excellent impact resistance, and a liner for a high-pressure gas storage tank including the same.

[0015] Also, according to the present invention, it is possible to provide a composition for a liner for a high-pressure gas storage tank with improved processability and applicable to a wide range of processing methods.

Brief Description of the Drawings

[0016]

Figure 1

BEST MODE FOR CARRYING OUT THE INVENTION

[0017] In the present invention, terms such as first, second, etc. are used to describe various components, and said terms are used only for the purpose of distinguishing one component from another.

[0018] Also, the terms used in this specification are used only for the purpose of explaining exemplary embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "including", "comprising", or "having" are intended to specify the presence of implemented features, numbers, steps, components, or combinations thereof, and it should be understood that the presence or addition of one or more other features, numbers, steps, components, or combinations thereof is not precluded in advance.

[0019] Furthermore, in the present invention, when each layer or element is referred to as being "formed on" each layer or element, it means that each layer or element is directly formed on each layer or element, or that other layers or elements can be additionally formed between each layer, on the object, or on the substrate.

[0020] The present invention can be subject to various modifications and can have various forms, but specific examples are illustrated and described in detail below. However, this is not intended to limit the present invention to a specific disclosed form, and it should be understood that all modifications, equivalents, or alternatives included in the spirit and technical scope of the present invention are included.

[0021] Hereinafter, the composition according to the embodiment of the invention and the liner for a high-pressure gas storage tank including the same will be described in detail. According to an embodiment of the invention, the composition of the invention can include a gas-barrier resin (A) and a thermoplastic elastomer (B) dispersed in a particulate form in the gas-barrier resin (A).

[0022] The gas-barrier resin (A) can include one or more selected from the group consisting of polyamide, polyvinyl alcohol (PVOH), and ethylene-vinyl alcohol copolymer (EVOH).

[0023] Specifically, the gas-barrier resin (A) may be an ethylene-vinyl alcohol copolymer (EVOH). The ethylene-vinyl alcohol copolymer is a copolymer composed of ethylene monomer units and vinyl alcohol monomer units, and the content of ethylene monomer units may be 10 mol% or more. Specifically, the content of ethylene monomer units in the ethylene-vinyl alcohol copolymer may be 35 mol% or more, 38 mol% or more, 40 mol% or more, 42 mol% or more, or 44 mol% or more and 50 mol% or less, or 46 mol% or less. Also, the weight-average molecular weight (Mw) of the ethylene-vinyl alcohol copolymer (EVOH) may be 30,000 to 250,000 g / mol. Specifically, the weight-average molecular weight of EVOH may be 100,000 to 150,000 g / mol.

[0024] When the content of ethylene monomer units in the ethylene-vinyl alcohol copolymer is excessively low, there is a problem that the moldability deteriorates, and when the content of ethylene monomer units is excessively high, there may be a problem that the gas-barrier property deteriorates.

[0025] Specifically, the gas barrier resin (A) may be a polyamide. The polyamide may be one or more selected from the group consisting of nylon-4, 6, nylon-6, nylon-6, 6, nylon-6, 10, nylon-7, nylon-8, nylon-9, nylon-11, nylon-12, nylon-46, MXD6, and amorphous polyamide, or a copolymer or a mixture of two or more thereof.

[0026] However, the polyphenylene sulfide compound has a problem that it is not suitable for improving the burst strength to withstand a high filling pressure. When used as the gas barrier property value of the liner for a high-pressure gas storage tank, it is not suitable because there is a risk that the reinforcing layer breaks inside.

[0027] The thermoplastic elastomer (B) can include one or more selected from the group consisting of polyether block amide (TPA), polyester copolymer (TPC), thermoplastic polyurethane (TPU), styrene block copolymer (TPS), and thermoplastic polyester elastomer (TPEE). Specifically, the thermoplastic elastomer (B) may be thermoplastic polyurethane (TPU).

[0028] LDPE and POE, which are a kind of elastomers that have been used in the past, are not well mixed with barrier resins such as EVOH and PA. In order for the elastomer to be dispersed in the barrier resin in a particulate state, the use of a compatibilizer is essential. However, when a compatibilizer is added to the barrier resin, there is a problem that the viscosity of the blend resin composition increases due to the additives contained in the compatibilizer, resulting in a decrease in processability. However, the elastomer to be used in the present invention is well mixed with the barrier resin, so the use of a compatibilizer is not required. Therefore, there is an advantage that the viscosity of the blend resin composition is relatively low, and thus the processability can be excellent.

[0029] The weight average molecular weight (Mw) of the thermoplastic polyurethane (TPU) may be 50,000 to 500,000 g / mol. Specifically, the weight average molecular weight (Mw) may be 200,000 to 300,000 g / mol.

[0030] The content of the thermoplastic elastomer (B) may be 11 to 50% by weight based on the combined weight of the gas barrier resin (A) and the thermoplastic elastomer (B). Specifically, it may be 11% by weight or more, 20% by weight or more, 30% by weight or more, 35% by weight or more, or 40% by weight or more to 60% by weight or less, 55% by weight or less, or 50% by weight or less. When the content of the thermoplastic elastomer (B) is mixed in an excessively small amount, there is a problem that the low-temperature impact resistance deteriorates. When it is mixed in an excessively large amount, there may be a problem that the gas barrier property is lost.

[0031] Moreover, the composition of the present invention does not further contain a compatibilizer. When a compatibilizer is included, as described for the elastomer, there is a tendency for the viscosity of the blend resin composition to increase, making it difficult to adjust the viscosity and deteriorating the processability. On the other hand, when no compatibilizer is included, a blend resin composition with a relatively low viscosity can be produced, so a composition with relatively excellent processability can be provided. That is, the composition of the present invention may consist of a gas barrier resin (A) and a thermoplastic elastomer (B) dispersed in a particulate form in the gas barrier resin (A).

[0032] The composition according to the present invention has a low-temperature impact strength of 10 kJ / m when stored at a temperature of -40°C for 4 hours according to ASTM D256. 2 or more. Specifically, the low-temperature impact strength is 10 kJ / m. 2 or more, 15 kJ / m. 2 or more, 16 kJ / m. 2 or more, 17 kJ / m. 2 or more, or 18 kJ / m. 2 or more to 25 kJ / m. 2 or less, 22 kJ / m. 2 or less, or 20 kJ / m. 2 or less may also be acceptable.

[0033] In addition, the composition according to the present invention has an oxygen permeability of 1.0 cm measured by ASTM D3985 under the conditions of a liner thickness of 1 mm, a temperature of 23.0 °C, and a relative humidity of 65%. 3 / (m 2 ·day) or less. Specifically, it may be more than 0, or 0.1 cm 3 / (m 2 ·day) or more, and 1.0 cm 3 / (m 2 ·day) or less, 0.5 cm 3 / (m 2 ·day) or less, or 0.2 cm 3 / (m 2 ·day) or less.

[0034] Furthermore, the composition according to the present invention may have a melt flow index measured by ASTM D1238 of 3.0 g / 10 min or more at a temperature of 190 °C and a load of 2.16 kg. Specifically, it may be 3.0 g / 10 min or more, 4.0 g / 10 min or more, 4.5 g / 10 min or more, 5.0 g / 10 min or more, 5.5 g / 10 min or more, or 6.0 g / 10 min or more, and 10.0 g / 10 min or less, 8.0 g / 10 min or less, or 7.0 g / 10 min or less.

[0035] This is because by adding the thermoplastic elastomer (B) to the gas barrier resin (A) in the above-described composition, the composition of the present invention may have improved processability while having excellent gas barrier properties and excellent low-temperature impact resistance.

[0036] In addition, the liner for a high-pressure gas storage tank according to the present invention can contain the above composition. Thereby, the liner for a high-pressure gas storage tank according to the present invention is excellent in gas barrier properties, impact resistance, and processability.

[0037] In order to apply the composition according to the present invention to the liner of a high-pressure gas storage tank, a processing method such as the rotomolding method can be used.

[0038] Hereinafter, preferred embodiments are presented for the understanding of the invention. However, the following embodiments are merely illustrative of the invention and do not limit the invention thereto.

[0039] Production Example: Production of a Composition for a Liner for a High-Pressure Gas Storage Tank In Example 1, a composition was produced by mixing 59% by weight of ethylene vinyl alcohol copolymer (EVOH) and 41% by weight of thermoplastic polyurethane (TPU) as a thermoplastic elastomer. In Example 2, a composition was produced by mixing 64% by weight of ethylene vinyl alcohol copolymer (EVOH) and 36% by weight of thermoplastic polyurethane (TPU) as a thermoplastic elastomer. In Example 3, a composition was produced by mixing 69% by weight of ethylene vinyl alcohol copolymer (EVOH) and 31% by weight of thermoplastic polyurethane (TPU) as a thermoplastic elastomer.

[0040] In Comparative Example 1, a composition was produced with 100% by weight of ethylene vinyl alcohol copolymer (EVOH). In Comparative Example 2, a composition was produced by mixing 90% by weight of ethylene vinyl alcohol copolymer (EVOH) and 10% by weight of thermoplastic polyurethane (TPU) as a thermoplastic elastomer. In Comparative Example 3, a composition was produced by mixing 10% by weight of ethylene vinyl alcohol copolymer (EVOH) and 90% by weight of thermoplastic polyurethane (TPU) as a thermoplastic elastomer.

[0041] In the above Examples 1 to 3 and Comparative Examples 1 to 3, the ethylene vinyl alcohol copolymer (EVOH) having a weight average molecular weight (Mw) of 134,790 g / mol was used. The Melt Blend resin, which is the composition of Examples 1 to 3 and Comparative Example 3, was produced using a twin-screw extruder (27 mm Φ) from Leistritz. As the processing temperature, the temperature of the sample input section of the twin-screw extruder was 170 °C, the average temperature inside the extruder was 200 °C, and the temperature of the extrusion port was 210 °C. The screw speed was set at 200 - 250 rpm, and the feeding speed was 8 - 9 kg / h.

[0042] Experimental Example: Evaluation of the Composition for the Liner of a High-Pressure Gas Storage Tank The oxygen permeability, low-temperature impact strength, and melt flow index of the compositions of Examples 1 to 3 and Comparative Examples 1 to 3 produced above were evaluated. The respective evaluation methods are as follows.

[0043] The oxygen permeability was measured according to the measurement method ASTM D3985 under the conditions of a liner thickness of 1 mm, a temperature of 23.0 °C, and a relative humidity of 65%. The low-temperature impact strength was measured according to the measurement method ASTM D256 after storage at a temperature of -40 °C for 4 hours. The melt flow index was measured according to the measurement method ASTM D1238 by applying a load of 2.16 kg at a temperature of 190 °C. The measurement results are shown in Table 1 below.

[0044]

Table 1

[0045] It was revealed that in Comparative Examples 1 and 2, the low-temperature impact strength deteriorated compared to the examples. In Comparative Example 3, although the low-temperature impact strength was measured as N.B. (Non-brake) and was excellent, it was revealed that the oxygen permeability was high and the gas barrier property deteriorated.

Claims

1. A composition comprising a gas-barrier resin (A) and a thermoplastic elastomer (B) dispersed in particulate form in the gas-barrier resin (A), The low-temperature impact strength measured by ASTM D256 is 10 kJ / m ２ or more, The oxygen permeability measured by ASTM D3985 is 1.0 cm ３ / (m ２ ·day) or less, having a melt flow index measured by ASTM D1238 of 3.0 g / 10 min or more.

2. The composition according to claim 1, wherein the content of the thermoplastic elastomer (B) is 11 to 50% by weight based on the combined weight of the gas-barrier resin (A) and the thermoplastic elastomer (B).

3. The composition according to claim 1, wherein the gas-barrier resin (A) comprises one or more selected from the group consisting of polyamide, polyvinyl alcohol (PVOH), and ethylene-vinyl alcohol copolymer (EVOH).

4. The composition according to claim 3, wherein the ethylene-vinyl alcohol copolymer has an ethylene content of more than 10 mol%.

5. The composition according to claim 3, wherein the polyamide is one or more selected from the group consisting of nylon-4,6, nylon-6, nylon-6,6, nylon-6,10, nylon-7, nylon-8, nylon-9, nylon-11, nylon-12, nylon-46, MXD6, and amorphous polyamide, or a copolymer or mixture of two or more thereof.

6. The composition according to claim 1, wherein the thermoplastic elastomer (B) comprises one or more selected from the group consisting of polyether block amide (TPA), polyester copolymer (TPC), thermoplastic polyurethane (TPU), styrene block copolymer (TPS), and thermoplastic polyester elastomer (TPEE).

7. The composition according to claim 1, wherein the composition consists of a gas-barrier resin (A) and a thermoplastic elastomer (B) dispersed in particulate form in the gas-barrier resin (A).

8. The composition according to claim 1.

9. The composition according to claim 1. The composition has a low-temperature impact strength measured by ASTM D256 of 10 kJ / m ２ or more to 25 kJ / m ２ or less.

10. The composition according to claim 1, having a melt flow index measured by ASTM D1238 of 3.0 g / 10 min or more and 10.0 g / 10 min or less. The composition has an oxygen permeability of more than 0 to 1.0 cm ３ / (m ２ ·day) or less as measured by ASTM D3985.

11. A liner for a high-pressure gas storage tank, comprising the composition according to any one of claims 1 to 10. ​ ​ ​ ​

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