Liner structure for pressure container and manufacturing method thereof

Abstract

Provided in the present invention is a double-layered liner structure comprising: a sub-structure; and a coating layer formed on top of the sub-structure.

Description

Liner structure for pressure vessel and method for manufacturing same

[0001] The present invention relates to a liner structure for a pressure vessel and a method for manufacturing the same. More specifically, the present invention relates to a liner structure for a Type IV pressure vessel and a method for manufacturing the same.

[0002]

[0003] Typically, Type IV pressure vessels are manufactured by winding composite materials onto non-metallic liners such as plastics, and demand is increasing in the medium- to large-sized vessel market, which requires light weight, high volume, and ultra-high pressure, including passenger cars, large buses, trucks, and tube trailers.

[0004] Liners for Type IV pressure vessels require very high sealing properties, and liners are manufactured using methods such as injection molding, fusion molding, rotational molding, injection molding, and blow molding.

[0005] Conventional (400 L class) large-capacity pressure vessels are manufactured by injection, rotation, and blow molding. For example, in the case of injection molding, which individually injects segments such as domes and cylinders and then heat-fuses them to manufacture pressure vessels, since a mold of a fixed length is used, the longer the pressure vessel, the more times injection and heat-fusion must be repeated, which complicates the process and increases manufacturing costs. In addition, there are problems such as increased process costs depending on the number of heat-fusions, decreased manufacturing yields due to poor heat-fusion, and very fragile welded joints formed in high-pressure, high-temperature environments, as well as the problem of foreign substances penetrating the inside of the liner during the manufacturing process.

[0006] Furthermore, pressure vessels manufactured through blow molding and rotational molding can experience leaks at the nozzle and pinch lines, and resin clumping in certain areas can lead to variations in pressure vessel size, making it difficult to manufacture larger vessels. Rotational molding, in particular, has limited usable materials due to the nature of the process, and the lack of materials capable of meeting the performance requirements of high-pressure hydrogen tanks limits its use in pressure vessel manufacturing.

[0007] Therefore, there is an urgent need to develop a method for manufacturing liners that can increase the efficiency of manufacturing large-capacity liners and reduce defects by preventing foreign substances from entering the liner during manufacturing.

[0008] As a background technology of the present invention, a device and method for forming a liner for a hydrogen tank are disclosed in Korean Patent Publication No. 10-2023-0091516.

[0009]

[0010] The purpose of the present invention is to provide an integral liner for a Type 4 pressure vessel. The liner is manufactured by rotational molding or blow molding to prevent foreign substances from entering the interior and to provide a liner structure that allows freedom in the design of the liner shape.

[0011] Another object of the present invention relates to a method for manufacturing the liner structure.

[0012] The above and other objects of the present invention can all be achieved by the present invention described below.

[0013]

[0014] 1. One aspect of the present invention relates to a liner structure.

[0015] The above liner structure forms a double layer including a sub-structure; and a coating layer formed on top of the sub-structure.

[0016] 2. In the above 1 specific example, the substructure may be a monolithic structure.

[0017] 3. In the above 1 or 2 specific examples, the sub-structure may have a uniform thickness.

[0018] 4. In any one of the above embodiments 1 to 3, the sub-structure may include at least one of PE, PS, SAN, ABS, EVA, PMMA, PET, PA, and PC.

[0019] 5. In any one of the above embodiments 1 to 4, the coating layer can be formed by spray coating polyurea or a derivative thereof.

[0020] 6. In any one of the above embodiments 1 to 5, the coating layer may have a different thickness along the longitudinal direction of the liner structure.

[0021] 7. In any one of the specific examples 1 to 6 above, the coating layer may have a thickness deviation (A) of about 20% or less according to the following formula 1.

[0022] [Formula 1]

[0023] Thickness deviation (A)% = [(T max -T min ) / T ave ]×100

[0024] In the above equation 1, T max is the maximum thickness of the coating layer, and T min is the minimum thickness of the silver coating layer, and T ave is the average thickness of the coating layer.

[0025] 8. In any one of the specific examples 1 to 7 above, the thickness of the substructure and the coating layer can be determined according to the following equations 2 and 3.

[0026] [Formula 2] T s < T c

[0027] [Formula 3] T s ≤ about 1mm

[0028] In the above equations 2 and 3, Ts is the thickness of the substructure, and T c is the thickness of the coating layer, and T c > It is about 2.0mm.

[0029] 9. In any one of the specific examples 1 to 8 above, the moisture absorption rate of the sub-structure may be about 0.1% or less.

[0030] 10. In any one of the specific examples 1 to 9 above, the liner structure can exhibit heat resistance at an internal maximum temperature of about 120°C or less under continuous charging conditions at a maximum charging speed of about 1.8 kg / min.

[0031] 11. In any one of the specific examples 1 to 10 above, the sub-structure may have a surface roughness (Ra) of about 1 to about 1.6.

[0032] 12. In any one of the specific examples 1 to 11 above, the liner structure may have a tensile elongation of about 200% to about 300% as per ASTM 638.

[0033] 13. Another aspect of the present invention relates to a method for manufacturing a liner structure.

[0034] The above liner structure manufacturing method comprises the steps of (a) manufacturing a sub-structure;

[0035] (b) a step of forming a coating layer by spraying a coating agent on the upper part of the sub-structure; and

[0036] (c) a step of drying a sub-structure having a coating layer formed thereon; wherein the sub-structure and the coating layer form a double layer.

[0037] 14. In the above 13 specific examples, the sub-structure can be manufactured by rotational molding or blow molding the thermoplastic resin in (a).

[0038] 15. In the above 13 or 14 specific examples, a step of placing a boss portion in a mold during blow molding or rotational molding and molding them together to join the boss portion to one end of the sub-structure may be included.

[0039] 16. In any one of the specific examples 13 to 15 above, the boss portion may be made of metal or plastic.

[0040] 17. In any one of the specific examples 13 to 16 above, the plastic resin in (a) may include at least one of PE, PS, SAN, ABS, EVA, PMMA, PET, PA, and PC.

[0041] 18. In any one of the embodiments 13 to 17 above, the coating agent may include polyurea derivatives thereof.

[0042] 19. In any one of the embodiments 13 to 18, the spray coating may be performed by varying the thickness of the coating layer along the length direction of the liner structure.

[0043] 20. In any one of the specific examples 13 to 19, the spray coating can form a thickness of the coating layer according to the following equations 2 and 3.

[0044] [Formula 2] T s < T c

[0045] [Formula 3] T s ≤ about 1mm

[0046] In the above equations 2 and 3, T s is the thickness of the substructure, and T c is the thickness of the coating layer, and T c > It is about 2.0mm.

[0047] 21. In any one of the specific examples 13 to 20 above, after the coating layer is cured in (b), the thickness can be increased by repeated spray coating.

[0048]

[0049] The liner structure according to the present invention is manufactured as an integral body without separately manufacturing the dome portion or cylinder portion, so that foreign substances do not enter the interior of the liner structure, and therefore, a separate internal washing and drying process is not required after manufacturing the liner structure. After manufacturing the sub-structure first, a coating layer is formed by spray coating on the sub-structure, so that the sub-structure can support the coating layer, and since the thickness of the liner structure can be varied by adjusting the coating conditions, the overall shape of the liner can be designed more freely.

[0050] In addition, the liner structure includes a double-layer thermosetting coating layer to increase stability against heat and impact, and the sub-structure is manufactured using a thermoplastic resin, so it can be manufactured by blow molding or rotational molding, making it easy to manufacture large-capacity pressure vessels.

[0051]

[0052] FIG. 1 is a perspective view of a liner structure according to one specific example of the present invention.

[0053] Figure 2 is a partial cutaway view of the liner structure of Figure 1.

[0054] Figure 3 is a cross-sectional view of the liner structure of Figure 1.

[0055] Figure 4 is a cross-sectional view of a liner structure according to one specific example of the present invention.

[0056] Figure 5 is a process flow diagram of a method for manufacturing a liner structure according to another aspect of the present invention.

[0057]

[0058] Hereinafter, the present invention will be described in more detail with reference to the attached drawings. However, the drawings are provided solely to aid understanding of the present invention and are not intended to limit the present invention. Furthermore, the shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings are exemplary and the present invention is not limited to the details depicted.

[0059] Throughout the specification, identical reference numerals designate identical components. Furthermore, in describing the present invention, detailed descriptions of related known technologies are omitted if they are deemed to unnecessarily obscure the gist of the present invention.

[0060] In the specification, when "includes," "has," and "consists of" are used, other parts may be added unless "only" is used. When a component is expressed in the singular, it includes cases where the plural is included unless there is a special explicit description.

[0061] When interpreting a component, it is interpreted as including the error range even if there is no separate explicit description.

[0062] In this specification, “a to b” indicating a numerical range is defined as “≥a and ≤b”.

[0063] In this specification, all numerical ranges include the 95% standard error range.

[0064]

[0065] FIG. 1 is a perspective view of a liner structure according to one specific example of the present invention, FIG. 2 is a partial cutaway view of the liner structure of FIG. 1, FIG. 3 is a cross-sectional view of the liner structure of FIG. 1, and FIG. 4 is a cross-sectional view of the liner structure according to one specific example of the present invention.

[0066] Hereinafter, a liner structure (1000) according to the present invention will be described with reference to the drawings.

[0067] One aspect of the present invention relates to a liner structure (1000).

[0068] The above sub-structure (100) can support the coating layer (200) to implement the overall shape of the liner structure (1000).

[0069] A coating layer (200) is coated on the above sub-structure (100) to form a liner structure (1000), and a space in which gas is stored can be formed inside the liner structure (1000).

[0070] The above sub-structure (100) may be a monolithic structure, and specifically may be integrally formed through blow molding or rotational molding.

[0071] The present invention solves the problems arising from conventional molding methods, and by manufacturing a sub-structure (100) into a monolithic structure through blow molding or rotational molding, and molding a coating layer (200) to which the function of a pressure vessel is provided again on the sub-structure (100), the sub-structure (100) can be manufactured integrally, and segments such as a dome portion and a cylinder portion are not formed, so that high-speed molding is possible when manufacturing a liner structure (1000), a fusion process can be omitted, and since micro-cracks are not formed on the surface, micro-dented sections in the coating layer (200) are eliminated, thereby solving the problem of reduced durability of the pressure vessel.

[0072] When manufacturing the sub-structure (100) by the above blow molding or rotational molding, the process can be shortened and high-speed molding is possible, but it is difficult to increase the liner capacity and leaks may occur in the nozzle section and pinch line, and in the case of blow molding, since the resin clumps in some areas, deviations may occur by section depending on the product size.

[0073] When a coating layer (200) is added to the upper portion of the sub-structure (100) after forming the sub-structure (100) by blow molding to form a double layer of the sub-structure (100) and the coating layer (200), not only is it possible to manufacture a large-capacity liner structure (1000), but also leaks are prevented and the coating layer (200) can correct the thickness deviation of the sub-structure (100).

[0074] When manufacturing the sub-structure (100) by the above blow molding or rotational molding, it is easy to increase the capacity of the sub-structure (100), and mass production of a large-capacity liner structure (1000) is possible.

[0075] Since the above sub-structure (100) is manufactured by blow molding or rotational molding and a double layer is formed by surface coating or spray coating on the upper part of the sub-structure (100) to form a coating layer (200), a coating layer (200) having a uniform thickness can be made over the entire surface of the sub-structure (100), and furthermore, if there is a deviation in the surface thickness of the sub-structure (100), the thickness deviation can be corrected. In addition, due to the physical properties of the coating layer (200), the stress that increases as the capacity of the sub-structure (100) increases can be distributed over the entire surface, so that a large-capacity liner structure (1000) can be manufactured. The large-capacity liner structure (1000) of the present invention manufactured in this manner can be utilized, for example, as a liner for a hydrogen tank of about 400 L and about 700 bar or more.

[0076] The large-capacity liner structure (1000) of the present invention forms a double-layer structure in which the sub-structure (100) is firmly bonded to the upper coating layer (200), and thus can exhibit higher strength compared to a single liner made of a conventional plastic resin.

[0077] In one specific example, the sub-structure (100) may have a uniform thickness. Specifically, the cylindrical portion may have a uniform thickness. The sub-structure (100) having a uniform thickness can ensure that the pressure applied during gas charging is uniformly distributed throughout the sub-structure (100), thereby improving storage stability during gas charging and discharging.

[0078] For example, the sub-structure (100) may be manufactured by blow molding or rotational molding to have a uniform thickness.

[0079] The large-capacity liner structure (1000) of the present invention possesses barrier performance capable of preventing the diffusion of gas filled in a pressure vessel. Compared to a conventional liner structure composed solely of a coating layer, the sub-structure (100) is reinforced to form a double-layer structure, thereby significantly improving barrier performance. The gas filled in this case may be any one of several gases typically stored in a pressure vessel, or a mixture thereof, for example, hydrogen gas.

[0080] When the gas charged into the pressure vessel contains moisture, there was a problem that the liner structure composed of a conventional single-layer liner had a high moisture absorption rate, which caused a deterioration in the liner's function. However, the large-capacity liner structure (1000) of the present invention can significantly reduce the moisture absorption rate by having a sub-structure (100), thereby preventing brittle fracture due to long-term use and contributing to improved gas storage stability.

[0081] The above sub-structure (100) may include at least one of PE, PS, SAN, ABS, EVA, PMMA, PET, PA, and PC, and more specifically, the PE may be at least one of MDPE, LDPE, HDPE, and LLDPE, and preferably HDPE. For example, the sub-structure (100) including HDPE is very preferably such that the moisture absorption rate is about 0.1% or less (e.g., 0.01%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.10%).

[0082] The above type of thermoplastic resin can be selected to manufacture a sub-structure (100). The above type of thermoplastic resin can be blow molded or rotationally molded in powder form, and can be easily melted by heat to form a sub-structure (100).

[0083] In one specific example, the coating layer (200) may be formed by spray coating polyurea or a derivative thereof.

[0084] The above polyurea may be an elastic polymer produced by a mixed reaction of isocyanate and synthetic resin, and may form a coating layer (200) on the upper portion of the sub-structure (100) to not only improve the strength of the liner structure (1000), but also implement excellent elasticity, impact resistance, water resistance, and heat resistance. The above polyurea is compatible with the above type of thermosetting resin, so that when the polyurea is coated, a solid bonding surface is formed so that it does not separate from the surface of the sub-structure (100), and the double-layer structure can be firmly maintained.

[0085] The above polyurea is fluid, so it can form a coating layer (200) by spray coating, and it is also possible to form a coating layer (200) by applying it with a brush. The formation of the coating layer (200) is not particularly limited as long as it includes polyurea and can vary the thickness of the coating layer.

[0086] The above coating layer (200) may have different thicknesses along the length direction of the liner structure (1000).

[0087] The above coating layer (200) is formed by spray coating on the upper part of the sub-structure (100), and its thickness can be increased or decreased depending on the coating conditions, for example, the number of spray injections.

[0088] It is formed on the upper part of the sub-structure (100) of the above coating layer (200), and the thickness can be adjusted, so that when the thickness of a part of the sub-structure (100) manufactured by blow molding is not uniform, it is possible to correct this and uniformly adjust the thickness of the entire liner structure (1000).

[0089] Since the thickness of the above coating layer (200) can be determined differently, the degree of freedom in designing the overall shape of the liner structure (1000) can be increased by changing the thickness of the coating layer (200).

[0090] In one specific example, the coating layer (200) may have a thickness deviation (A) according to Equation 1 below of about 20% or less (e.g., 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%).

[0091] [Formula 1]

[0092] Thickness deviation (A)% = [(T max -T min ) / T ave ]×100

[0093] In the above equation 1, T maxis the maximum thickness of the coating layer (200), and T min is the minimum thickness of the silver coating layer (200), and T ave is the average thickness of the coating layer (200).

[0094] The thickness deviation of the coating layer (200) may be about 20% or less, for example, about 10 to 20%, preferably about 10%. When the thickness deviation is controlled within the above range, the unevenness according to the thickness of the liner structure (1000) is reduced, so that the overall strength of the liner structure (1000) can be increased, and the occurrence of fatigue failure due to the concentration of stress due to partial strength differences can be prevented. When the thickness deviation of the coating layer (200) is controlled within the above range, the strength of the liner structure (1000) is increased, so that even if the composite is wound with different tensions, such as in a hoop or helical manner, the liner structure (1000) effectively supports it, so that the formation of the composite layer is easy.

[0095] In one specific example, the thickness of the substructure (100) and the coating layer (200) can be determined according to Equations 2 and 3 below.

[0096] [Formula 2] T s < T c

[0097] [Formula 3] T s ≤ about 1mm

[0098] In the above equations 2 and 3, T s is the thickness of the substructure (100), and T c is the thickness of the coating layer (200), and T c > It is about 2.0mm.

[0099] According to the above formula 2, the thickness of the coating layer (200) can be formed thicker than the thickness of the sub-structure (100), and due to the change in the thickness of the coating layer (200), not only can a degree of freedom be granted to the design of the liner structure (1000), but also an uneven portion of the thickness of the sub-structure (100) manufactured by blow molding or rotational molding can be corrected.

[0100] The thickness of the above coating layer (200) may be thicker than the thickness of the sub-structure (100), and specifically, may be greater than about 2.0 mm. Within the above range, strength may be improved, tensile elongation and flexural modulus may be increased, and the liner structure (1000) may be made lighter, while also exhibiting hydrogen-tightness.

[0101] According to the above formula 3, the thickness of the sub-structure (100) may be about 1 mm or less (e.g., 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1 mm), for example, the thickness of the sub-structure (100) is about 0.7 mm to 1 mm, and preferably about 1.0 mm. The above coating layer (200) may be formed to a thickness of greater than about 2.0 mm, preferably greater than about 3.0 mm, more preferably 3.0 to 5.0 mm (e.g., 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5 mm).

[0102] In one specific example, the sub-structure (100) may be about 1.0 mm and the coating layer (200) may be about 3.0 mm, and the effects of the present invention may be better implemented.

[0103] According to the above formula 3, the internal volume of a pressure vessel for hydrogen storage can be improved within the thickness range of the liner structure (1000), and since the liner structure (1000) is a double layer and can secure higher strength than a single layer liner, it is possible to manufacture the thickness of the sub-structure (100) to be about 1 mm or less. In addition, since the tensile elongation is improved, the internal volume of the pressure vessel can be increased during filling, and hydrogen sealing can be provided.

[0104] In one specific example, the water absorption of the sub-structure (100) may be about 0.1% or less (e.g., 0.01%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.10%).

[0105] The above sub-structure (100) is manufactured from a thermoplastic resin, and the thermoplastic resin has a low moisture absorption rate. For example, HDPE has a moisture absorption rate of about 0.1% or less. Even if the hydrogen filled inside the liner structure (1000) contains moisture, the moisture is not absorbed into the sub-structure (100), so that brittle fracture due to long-term use can be prevented.

[0106] The above coating layer (200) may have a gas permeability of about 3.6 mL / min or less (e.g., 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, or 3.6).

[0107] For example, it can be about 1.0 to 3.6 mL / min, preferably about 1.5 to 2.0 mL / min. The coating layer (200) is manufactured as an integral part of the sub-structure (100) to form a gas barrier film and exhibit hydrogen-tightness, and since it can restrict the flow of gas molecules as well as moisture within the above range, it is not breathable and can prevent brittle fracture due to hydrogen even when high-pressure hydrogen is filled inside the liner structure (1000).

[0108] In one specific example, the liner structure (1000) may have an internal maximum temperature of 120°C or less under continuous charging conditions at a maximum charging speed of about 1.8 kg / min.

[0109] The above liner structure (1000) has improved strength and greatly improved heat resistance due to the coating layer (200), so that the maximum internal temperature of the liner structure (1000) can reach 120°C during continuous charging at a maximum charging speed of about 1.8 kg / min based on the KGS standard high-speed and high-pressure charging standard, but even in this case, no change due to heat occurs and the liner structure has heat resistance.

[0110] When the temperature inside the liner reaches a maximum of about 85°C during charging at a maximum charging speed of about 1.8 kg / min according to the KGS standard, it is desirable to forcibly stop charging and proceed with additional charging after cooling. However, the liner structure (1000) according to the present invention has heat resistance and can exhibit thermal stability even when the maximum internal temperature reaches about 120°C, so that continuous high-speed charging is possible, and thus efficiency can be greatly improved during high-speed gas charging.

[0111] The above sub-structure (100) may have a surface roughness (Ra) of about 1 to about 1.6 (e.g., 1, 1.1, 1.2, 1.3, 1.4, 1.5, or 1.6).

[0112] When the above sub-structure (100) has a surface roughness within the above range, a coating layer (200) having a very smooth surface can be formed by spray coating a coating agent, thereby improving coating uniformity and implementing the effects of the present invention.

[0113] The above liner structure (1000) may have a tensile elongation of about 200 to 300% (e.g., 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300%) based on ASTM 638.

[0114] It exhibits a tensile elongation within the above range, has crack resistance, can withstand high pressure, and exhibits elasticity, so that the shape of the liner structure (1000) can be easily restored due to repeated charging and discharging, and the internal volume can be increased.

[0115] In one specific example, a boss portion (300) is coupled to one end of the sub-structure (100), and the coating layer (200) is coated on the upper part of the wing of the boss portion (300) to fix the boss portion (300).

[0116] The above sub-structure (100) can be manufactured by blow molding or rotational molding, and the boss portion (300) can be placed together in the mold so that the boss portion (300) is coupled to the sub-structure (100). A step (320) may be formed on the inner periphery of the boss portion (300) to increase the coupling area with the sub-structure (100), and since the boss portion (300) is placed and molded together during blow molding or rotational molding, no separation occurs between the boss portion (300) and the sub-structure (100) even when the boss portion (300) is made of metal. Since the above sub-structure (100) is combined with the boss portion (300), and a coating layer (200) is formed on the upper portion of the wing (310) of the boss portion (300) to fix the boss portion (300), the boss portion (300) can be more firmly combined with the liner structure (1000).

[0117] The liner structure (1000) according to the present invention is manufactured by manufacturing a large-capacity sub-structure (100) into a monolithic structure through blow molding or rotational molding, forming a coating layer (200) on the upper portion of the sub-structure (100) to form a double layer by combining the sub-structure (100) and the coating layer (200), thereby not only improving the strength of the liner structure (1000), but also increasing the tensile strength so that it does not deform even after repeated charging and discharging, increasing the strength of the liner structure, imparting hydrogen-tightness and gas-barrier properties to prevent bending due to hydrogen or moisture, and preventing brittle fracture of the liner structure (1000).

[0118] Another aspect of the present invention relates to a method for manufacturing a liner structure.

[0119] Figure 5 is a process flow diagram of a method for manufacturing a liner structure according to another aspect of the present invention.

[0120] Referring to FIG. 5, the method for manufacturing the liner structure includes: (a) a step of manufacturing a sub-structure (100); (b) a step of spray-coating a coating agent on the upper portion of the sub-structure (100) to form a coating layer (200); and (c) a step of drying the sub-structure (100) on which the coating layer (200) is formed.

[0121] First, a substructure (100) is manufactured (S100).

[0122] Specifically, a sub-structure (100) can be manufactured by rotationally molding or blow molding a plastic resin in S100. A sub-structure having a monolithic structure can be manufactured through rotationally molding or blow molding.

[0123] Since the above sub-structure (100) is formed integrally and segments of the dome and cylinder portions are not formed, there is no possibility of foreign substances being introduced or remaining inside the sub-structure (100) during the formation process of the sub-structure, so that the efficiency of the pressure vessel manufacturing process as well as the liner structure can be greatly improved.

[0124] The above plastic resin may include at least one of PE, PS, SAN, ABS, EVA, PMMA, PET, PA, and PC, and the above type of resin is a thermoplastic resin that can be formed into powder and melted, has low moisture absorption, high heat resistance, and can manufacture a large-capacity sub-structure (100) by blow molding or rotational molding.

[0125] The above blow molding or rotational molding may include a step of placing the boss portion (300) in a mold and molding them together to join the boss portion (300) to one end of the sub-structure (100). At this time, the boss portion (300) may be made of metal or plastic, and may be located inside or outside the sub-structure (100), and the position of the boss portion (300) may be appropriately selected as needed.

[0126] In the above S100, the boss part (300) can be placed together in the mold and the boss part (300) can be joined to one end of the sub-structure (100) by blow molding or rotational molding, and a separate O-ring or physical mechanical structure for fixing the boss part (300) or a chemical bond such as an adhesive is not required.

[0127] A coating layer (200) is formed by spraying a coating agent on the upper part of the above sub-structure (100) (S200).

[0128] A coating layer (200) can be formed on the upper part of the above sub-structure (100) to form a double layer, and the strength of the liner structure (1000) can be improved.

[0129] In one embodiment, the coating agent may comprise polyurea or a derivative thereof.

[0130] The above polyurea can be melted and spray-coated, and the thickness of the coating layer (200) can be freely controlled depending on the spray-coating conditions. For example, it is also possible to increase the thickness of the coating layer (200) by spray-coating the cured coating layer (200) again after spray-coating.

[0131] By increasing or decreasing the thickness of the coating layer (200) through the above spray coating process, the thickness of the sub-structure (100) can be compensated for in some areas depending on the characteristics of rotational molding or blow molding, thereby making it possible to manufacture the entire liner structure (1000) with a uniform thickness.

[0132] The above polyurea is combined with the sub-structure (100) to increase the strength of the liner structure (1000). Specifically, it can effectively disperse stress transmitted to the sub-structure (100) and improve heat resistance.

[0133] In one specific example, the spray coating can vary the thickness of the coating layer (200) along the length direction of the liner structure (1000).

[0134] For example, when the above sub-structure (100) is manufactured by blow molding, there may be cases where the thickness of some parts is not uniform, but the spray coating can also maintain the uniformity of the thickness of the liner structure by forming the thickness of the coating layer (200) according to the following equations 2 and 3.

[0135] The thickness of the above coating layer (200) can be determined according to the following equations 2 and 3.

[0136] [Formula 2] T s < T c

[0137] [Formula 3] T s ≤ 1mm

[0138] In the above equations 2 and 3, T sis the thickness of the substructure (100), Tc is the thickness of the coating layer (200), and T c > 2.0mm.

[0139] Since the thickness of the coating layer (200) is controlled by spray coating according to the above formula 2, the design of the shape of the liner structure (1000) is free.

[0140] By limiting the thickness of the sub-structure (100) according to the above formula 3, not only can the internal volume of the liner structure (1000) be increased, but also the tensile elongation of the liner structure (1000) can be increased and the strength can be improved.

[0141] When the thickness of the above sub-structure (100) increases, the strength is improved, but a trade-off relationship is established in which the content and lightness are reduced and the cost increases as the thickness increases. Therefore, it is desirable to limit the thickness of the sub-structure (100) according to the above formula 3.

[0142] The above coating layer (200) can extend to the wing of the boss part (300) to more firmly fix the boss part (300) and prevent the boss part (300) from coming off.

[0143] The sub-structure (100) on which the above coating layer (200) is formed is dried (S300).

[0144] When the sub-structure (100) on which the coating layer (200) is formed is dried, the polyurea of ​​the coating layer (200) is cured and can be combined with the thermoplastic resin of the sub-structure (100) to form a solid double layer.

[0145] In one specific example, after the coating layer (200) is cured in the above S200, the thickness of the coating layer (200) can be increased by repeated spray coating.

[0146] After the above coating layer (200) is cured, the thickness of the coating layer (200) can be controlled by repeated spray coating, and the shape of the liner structure (1000) can be more freely deformed depending on the thickness of the coating layer (200).

[0147]

[0148] Hereinafter, preferred examples are presented to help understand the present invention, but the following examples are only to illustrate the present invention and the scope of the present invention is not limited to the following examples.

[0149]

[0150] Example 1

[0151] HDPE powder was injected into the mold, a metal boss was placed, and a sub-structure having a thickness of approximately 1.0 mm, a diameter of approximately 356 mm, and a length of approximately 864 mm was manufactured through rotational molding.

[0152] Polyurea was spray-coated to a thickness of approximately 1.0 mm on the upper part of the above sub-structure using a two-component coating machine.

[0153] Afterwards, the polyurea coating layer was cured by drying at room temperature to manufacture a liner structure with an internal volume of 52 L.

[0154]

[0155] Example 2

[0156] A sub-structure having a diameter of about 618 mm and a length of about 2,130 mm was manufactured using the same method as Example 1, and then polyurea was spray-coated to manufacture a liner structure having an internal volume of about 416 L.

[0157]

[0158] Experimental Example 1

[0159] The liner structure according to the embodiment did not require separate cleaning because the sub-structures were formed integrally and no surface cracks occurred due to the introduction of foreign substances during the fusion process, and no contaminants were introduced into the interior.

[0160] Water was injected into the liner structure according to the embodiment, and a pressure test was performed targeting approximately 30 bar. The pressure was increased to approximately 15 bar, and the pressure was increased by approximately 10% at a final pressure of approximately 30 bar for approximately 5 minutes. As a result, no deformation of the structure was observed.

[0161] After the pressure test, the water was completely removed, air was injected, pressurized again, and soapy water was applied to the surface to check for leaks. As a result, it was confirmed that the airtightness could be maintained.

[0162] It was confirmed that the pressure resistance and airtightness can be maintained only with the liner structure according to the embodiment, and it was confirmed that a large-capacity liner structure of about 416 L can be manufactured, not just with the internal volume of about 52 L.

[0163]

[0164] Experimental Example 2

[0165] In the example, a pressure vessel was manufactured by winding carbon fiber reinforced plastic on a liner structure to form a composite layer, and then, according to the KSG (Korea Gas Safety Code) standard, hydrogen gas at about -40°C was continuously filled at a supply rate of about 21 g / s until the internal pressure reached about 700 bar.

[0166] In all examples, it was confirmed that thermal stability can be secured during high-speed charging because the internal maximum temperature did not reach the heat-resistant temperature of the internal structure, which is approximately 120°C. In addition, it was confirmed that the liner structure was not deformed or damaged due to the strength enhancement by the double layer of the sub-structure and the coating layer, so that the pressure standard of approximately 700 bar for a high-pressure vessel could be satisfied.

[0167]

[0168] Experimental Example 3

[0169] Sample 1 (Comparative Example) Sample 2 (Example) Sample 3 (Example) Sample 4 (Comparative Example) Substructure thickness (mm) 0.8 1.0 1.0 2.0 Coating layer thickness (mm) 2.0 3.0 5.0 7.0 Tensile elongation (%) 250 300 300 80 Inner volume Increase Increase Increase Increase Decrease Hydrogen airtightness Inadequate Satisfactory Satisfactory

[0170] The tensile elongation, change in pressure vessel volume, and hydrogen tightness were confirmed according to the thickness of the substructure and coating layer.

[0171] Table 1 above shows the tensile elongation and change in internal volume according to the thickness of the substructure and coating layer of the liner structure with an internal volume of 52 L. Before the composite material was wound, a specimen was taken from the liner structure of the example and the tensile elongation was measured using a tensile tester according to ASTM 638.

[0172] The thickness of the substructure and coating layer of samples 2 and 3 satisfies the range of Example 1, but samples 1 and 4 exceed the range of Example 1. It was confirmed that samples 2 and 3 exhibited tensile elongation of 300% or more, which is the target of the present invention, and that the bending resistance, crack resistance, and strength could be achieved. In particular, it was confirmed that the internal volume could be increased and hydrogen airtightness could be exhibited when charging under pressure of approximately 700 bar, which is the high-pressure charging standard, due to the improvement in elasticity of the liner structure.

[0173] In the case of sample 4, it was confirmed that the tensile elongation decreased as the thickness of the substructure increased, and the internal volume decreased during high-pressure charging, so that the effect of the present invention could not be exhibited. In the case of sample 1, although the thickness condition of the coating layer of Example 1 was satisfied, it was confirmed that the thickness of the coating layer did not exhibit hydrogen airtightness, so that the thickness of the coating layer had to exceed at least about 2.0 mm. Specifically, it was confirmed that it had to be maintained at least about 2.5 mm, and more specifically, at least about 3.0 mm or more.

[0174] In addition, it was confirmed that although the tensile elongation may increase depending on the thickness of the substructure and coating layer, the internal volume decreases due to a trade-off relationship, so it is necessary to limit the thickness of the subcoating layer and the coating layer to a certain range, and it was confirmed that there is a need to control the thickness of the coating layer considering hydrogen airtightness.

[0175]

[0176] Accordingly, the present invention first manufactures a sub-structure by a blow molding or rotational molding method, which makes it difficult to form a liner with a uniform thickness in the conventional manufacture of large-capacity pressure vessels, and then forms a coating layer on top of the sub-structure to manufacture a liner structure in a double layer, thereby securing tensile elongation and elasticity, and also providing a liner structure that exhibits heat resistance during high-pressure, high-speed charging, thereby enabling high-speed charging exceeding the gas charging standard.

[0177]

[0178] The present invention has been described above, focusing on specific embodiments. Those skilled in the art will appreciate that the present invention can be implemented in modified forms without departing from its essential characteristics. Therefore, the disclosed embodiments should be considered illustrative rather than limiting. The scope of the present invention is set forth in the claims, not the foregoing description, and all differences within the scope equivalent thereto should be construed as being encompassed by the present invention.

Claims

1. Substructure; and A coating layer formed on top of the above sub-structure; forming a double layer, Liner structure.

2. A liner structure according to claim 1, wherein the sub-structure is a monolithic structure.

3. A liner structure according to claim 1, wherein the sub-structure has a uniform thickness.

4. A liner structure according to claim 1, wherein the sub-structure comprises at least one of PE, PS, SAN, ABS, EVA, PMMA, PET, PA, and PC.

5. A liner structure according to claim 1, wherein the coating layer is formed by spray coating polyurea or a derivative thereof.

6. A liner structure in the first paragraph, wherein the coating layer has a different thickness along the longitudinal direction of the liner structure.

7. In the 6th paragraph, the coating layer has a thickness deviation (A) of about 20% or less according to the following formula 1, a liner structure: [Formula 1] Thickness deviation (A)% = [(T max -T min ) / Tave]×100 In the above equation 1, T max is the maximum thickness of the coating layer, and T min is the minimum thickness of the coating layer, and T ave is the average thickness of the coating layer.

8. In the first paragraph, the thickness of the sub-structure and the coating layer is determined according to the following equations 2 and 3: [Formula 2] T s < T c [Formula 3] T s ≤ about 1mm In the above equations 2 and 3, T s is the thickness of the substructure, and T c is the thickness of the coating layer and T c > It is about 2.0mm.

9. A liner structure in accordance with paragraph 1, wherein the moisture absorption rate of the sub-structure is about 0.1% or less.

10. A liner structure having heat resistance at an internal maximum temperature of 120°C or less under continuous charging conditions at a maximum charging speed of about 1.8 kg / min in the first paragraph.

11. A liner structure according to claim 1, wherein the sub-structure has a surface roughness (Ra) of about 1 to 1.

6.

12. A liner structure having a tensile elongation of about 200 to 300% according to ASTM 638 in the first paragraph. 13.(a) Step of manufacturing a sub-structure; (b) a step of forming a coating layer by spraying a coating agent on the upper part of the sub-structure; and (c) a step of drying the sub-structure on which the coating layer is formed; The above substructure and coating layer form a double layer, Method for manufacturing a liner structure.

14. A method for manufacturing a liner structure, wherein in the 13th paragraph, a sub-structure is manufactured by blow molding or rotational molding a thermoplastic resin in the above (a).

15. A method for manufacturing a liner structure, comprising the step of placing a boss portion in a mold during rotational molding or blow molding and molding together to join the boss portion to one end of a sub-structure.

16. A method for manufacturing a liner structure, wherein the boss portion is made of metal or plastic in the 15th paragraph.

17. A method for manufacturing a liner structure according to claim 13, wherein the thermoplastic resin in (a) includes at least one of PE, PS, SAN, ABS, EVA, PMMA, PET, PA, and PC.

18. A method for manufacturing a liner structure, wherein the coating agent comprises polyurea or a derivative thereof in the 13th paragraph.

19. A method for manufacturing a liner structure, wherein the spray coating is formed by changing the thickness of the coating layer along the length direction of the liner structure.

20. In the 19th paragraph, the spray coating is a method for manufacturing a liner structure, wherein the thickness of the coating layer is formed according to the following equations 2 and 3: [Formula 2] T s < T c [Formula 3] T s ≤ about 1mm In the above equations 2 and 3, T s is the thickness of the substructure, Tc is the thickness of the coating layer, and T c > It is about 2.0mm.

21. A method for manufacturing a liner structure, wherein, in the 13th paragraph, after the coating layer is cured in (b), the thickness is increased by repeated spray coating.

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