Pressure vessel and method for manufacturing a pressure vessel

Abstract

To provide a resin liner and a pressure container which improve: pressure resistance performance through simply and inexpensively eliminating a welded section; and dimensional accuracy.SOLUTION: A pressure container comprises: a thermoplastic resin liner body made up of a cylindrical straight body section and dome sections, installed on both ends of the straight body section, respectively having a shape with a diameter thereof reduced with a distance from the straight body section; and an outer shell which is a reinforcement layer made of a hardened reinforced fiber composite material covering an outer peripheral surface of the liner body. The liner body is manufactured through rotational casting. The thermoplastic resin material used for the liner body is made of a resin composite which: consists of, per 100 parts by weight of thermoplastic resin, equal to or more than 1 part and equal to or less than 30 parts by weight of plate-like inorganic filler having a volume means particle diameter of 1 μm or more and 30 μm or less and an aspect ratio of equal to or more than 100 and equal to or less than 200 and equal to or more than 0.01 parts and equal to or less than 0.05 parts by weight of crystal core agent; and has a ratio of a mold shrinkage factor in a flow direction to the same in a direction perpendicular to the flow direction of equal to or more than 0.6 and equal to or less than 1.0 and tensile breaking elongation of equal to or more than 10% and equal to or less than 400%.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pressure vessel excellent in pressure resistance, which is formed by a resin liner for a pressure vessel that can be rotationally molded and has excellent dimensional accuracy, and an outer shell in which the outer surface of the resin liner is covered with a reinforcing layer made of a cured product of a fiber-reinforced composite material, and a method for manufacturing the same.

Background Art

[0002] Conventionally, as fuel tanks used in the fields of automobiles, space and aircraft, and tanks for storing and transporting natural gas and hydrogen gas used in the industrial field, from the viewpoint of excellent light weight and durability (high toughness) during pressurization, as shown in FIG. 1, a pressure vessel in which a container body (liner) made of a thermoplastic resin is reinforced with an outer shell made of a fiber-reinforced resin material is used. As the reinforcing fibers used for the outer shell, glass fibers, carbon fibers, etc. are mainly used. Among them, carbon fibers with high specific strength are preferably used as tanks for transferring natural gas and hydrogen and accumulators because they can reduce the weight of the pressure vessel and improve the strength and rigidity design.

[0003] As a pressure vessel, for example, as shown in FIG. 2, a resin liner having a cylindrical straight body portion 201 and hemispherical dome portions 202 provided at both ends of the straight body portion, and an outer shell formed outside the liner body are generally used. Further, for the outer shell, a fiber-reinforced resin material in which a long reinforcing fiber bundle is impregnated with a matrix resin is wound around the outside of the liner body by a filament winding method (hereinafter sometimes abbreviated as the FW method), and the pressure vessel is produced by heating and curing.

[0004] Currently, as shown in Fig. 3, for the liner of a pressure vessel, the mainstream is an injection-molded liner half-part 301 formed by injection molding, with two of them facing each other and joined and integrated by welding using a laser or heat. However, there are issues such as an increase in liner quality control items and a cost increase due to low productivity. Therefore, direct blow molding, rotational molding, etc., which do not require post-processing, have been considered as cost reduction methods. Manufacturers have emerged that focus on the rotational molding method, which is cheaper than direct blow molding and has no welded parts, and study liner prototypes. The rotational molding method as shown in Fig. 4 is a method in which a thermoplastic resin material (powder and pellet shapes) is filled into a mold, the mold is rotated uniaxially, and at the same time, the mold is heated while swinging up and down around the rotation axis, and after the resin is fused to a predetermined thickness, it is cooled and solidified to obtain a product.

[0005] For example, as a resin liner molding material with improved rotational molding processability, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2021-020971) is known. Patent Document 1 discloses a molding material for rotational molding composed of an unmelted product of a first powder containing a thermoplastic resin and an inorganic additive and a second powder composed of a long-chain fatty acid and its metal salt.

[0006] Also, as a polyamide resin composition for rotational molding excellent in low-temperature impact resistance and surface properties, Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2019-131827) is known. Patent Document 2 discloses a polyamide resin composition containing an aliphatic polyamide having a relative viscosity at 25°C of 2.45 or less and a polyolefin having a specific density.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] In the rotational molding method, due to the differences in the molding shrinkage behavior of the thermoplastic resin material during cooling and solidification in the resin flow direction (hereinafter sometimes abbreviated as the MD direction) and the orthogonal direction (hereinafter sometimes abbreviated as the TD direction), it is difficult to control dimensional accuracy and the crystallization rate. As a result, there are problems such as excessive residual of the polymer amorphous part during cooling and easy thermal deformation. Therefore, each manufacturer is earnestly studying to solve the problems of molding shrinkage anisotropy and crystallization rate control during rotational molding.

[0009] However, although the inventions described in Patent Document 1 or 2 above improve the workability and surface properties during rotational molding, "molding shrinkage anisotropy" and "crystallization rate control", which are essential for improving dimensional accuracy, have not been sufficiently improved on the material side. Therefore, they have not reached a satisfactory level for actual use.

[0010] Therefore, the present invention aims to provide a thermoplastic resin liner capable of rotational molding and having excellent dimensional accuracy.

Means for Solving the Problems

[0011] To solve the above problems, the pressure vessel and the method for manufacturing a pressure vessel according to the present invention have any of the following configurations. That is, A thermoplastic resin liner body including a cylindrical straight body portion and dome portions provided at both ends of the straight body portion and narrowing as they move away from the straight body portion, and an outer shell in which the outer surface of the liner body is covered with a reinforcing layer made of a cured product of a reinforcing fiber composite material. The pressure vessel is formed, the liner body is manufactured by rotational molding, and the thermoplastic resin material used for the liner is a resin composition containing 1 to 30 parts by weight of a plate-shaped inorganic filler having a volume average particle diameter of 1 μm or more and 30 μm or less and an aspect ratio of 100 or more and 200 or less, and 0.01 to 0.05 parts by weight of a crystal nucleating agent, based on 100 parts by weight of the thermoplastic resin. The pressure vessel is characterized in that the ratio of the flow direction / orthogonal direction of the molding shrinkage rate is 0.6 or more and 1.0 or less, and the tensile break elongation is 10% or more and 400% or less.

[0012] It is preferable that a test piece having a width of 15 mm, a length of 70 mm, and a thickness of 1 mm is cut out from the straight barrel portion of the liner body of the present invention and the heat sag deformation amount when heat-treated at 100 °C for 60 minutes is 1 mm or more and 5 mm or less.

[0013] It is preferable that the temperature change ΔT (=Tm [melting point: °C] - Tmc [cooling crystallization temperature: °C]) when a part of the liner body of the present invention is measured by DSC is 10 °C or more and 40 °C or less.

[0014] The thermoplastic resin material used for the liner body of the present invention is preferably selected from any one of polyamide resin, polyethylene resin, polyester resin, and fluororesin.

[0015] The plate-like inorganic filler is preferably selected from any one of glass flakes, mica, and kaolin.

[0016] Further, the method for manufacturing a pressure vessel of the present invention has the following configuration. That is, A method for manufacturing a pressure vessel formed of a thermoplastic resin liner body having a cylindrical straight body portion and dome portions provided at both ends of the straight body portion and narrowing as they move away from the straight body portion, and an outer shell covering an outer surface of the liner body with a cured product of a reinforcing fiber composite material. The thermoplastic resin material used for the liner body is a resin composition containing 1 to 30 parts by weight of a plate-like inorganic filler having a volume average particle diameter of 1 μm or more and 30 μm or less and an aspect ratio of 100 or more and 200 or less, and 0.01 to 0.05 parts by weight of a crystal nucleating agent with respect to 100 parts by weight of the thermoplastic resin. First, the thermoplastic resin, the inorganic filler, and the crystal nucleating agent are melt-kneaded and pelletized in advance, and then introduced into a mold. The molding temperature is set to be equal to or higher than Tm (melting point) + 10 [°C] and equal to or lower than Tm + 100 [°C] of the thermoplastic resin material, the molded product removal temperature is set to be equal to or higher than Tg (glass transition temperature) + 10 [°C] and equal to or lower than Tg + 50 [°C] of the thermoplastic resin material, the mold heating rate is 20 °C / min to 40 °C / min, and the mold cooling rate is 20 °C / min to 35 °C / min. The liner body is molded by rotational molding under these molding conditions, and then a reinforcing fiber composite material is wound around the liner body and cured to form an outer shell.

Advantages of the Invention

[0017] According to the present invention, by using a thermoplastic resin liner that is rotationally molded and has improved dimensional accuracy, a pressure vessel with significantly improved pressure resistance performance and cost competitiveness can be obtained.

Brief Description of the Drawings

[0018]

Figure 1

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Figure 9

Mode for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described in detail.

[0020] The pressure vessel according to the present invention includes a cylindrical straight body portion, and dome portions provided at both ends of the straight body portion and having a shape that narrows as it moves away from the straight body portion, and a liner body made of a thermoplastic resin, and an outer shell formed by covering the outer surface of the liner body with a reinforcing layer made of a cured product of a reinforcing fiber composite material.

[0021] <Thermoplastic resin> As the thermoplastic resin used for the liner body of the present invention, there is no particular usage restriction, but it is preferably a polyamide resin, a polyester resin, a polyethylene resin, and a fluororesin that are excellent in rotational molding processability.

[0022] Examples of the polyamide resin used in the present invention include nylon synthesized mainly from amino acids, lactams, diamines, and dicarboxylic acids.

[0023] Typical examples of the raw materials include amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and para-aminomethylbenzoic acid; lactams such as ε-caprolactam and ω-laurolactam; aliphatic, alicyclic, and aromatic diamines such as tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, metaxylylenediamine, paraxylylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, bis(4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminopropyl)piperazine, and aminoethylpiperazine; and aliphatic, alicyclic, and aromatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid.

[0024] Examples of the polyamide resin include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polypentamethylene adipamide (nylon 56), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (nylon 66 / 6T), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6I), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6T / 6I), polyxylylene adipamide (nylon XD6), and mixtures or copolymers thereof. Particularly preferred examples include nylon 6, nylon 66, nylon 610, nylon 6 / 66 copolymer, nylon 6 / 12 copolymer, and the like.

[0025] Examples of the polyester resin used in the present invention include those obtained by a condensation reaction using a dicarboxylic acid (or its ester-forming derivative), a diol (or its ester-forming derivative), and / or a hydroxycarboxylic acid (or its ester-forming derivative) as main raw materials.

[0026] Examples of the dicarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, bis(p-carboxyphenyl)methane, anthracenedicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 5-sodium sulfoisophthalic acid; aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, dodecanedioic acid; alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acid; and ester-forming derivatives thereof.

[0027] In addition, as the diol component, aliphatic glycols having 2 to 20 carbon atoms, namely, ethylene glycol, propylene glycol, 1,4 - butanediol, neopentyl glycol, 1,5 - pentanediol, 1,6 - hexanediol, decamethylene glycol, cyclohexanedimethanol, cyclohexanediol, etc., long - chain glycols having a molecular weight of 400 to 6000, namely, polyethylene glycol, poly - 1,3 - propylene glycol, polytetramethylene glycol, etc., and ester - forming derivatives thereof, etc. can be mentioned. Examples of these polymers or copolymers include polybutylene terephthalate, polybutylene (terephthalate / isophthalate), polybutylene (terephthalate / adipate), polypropylene terephthalate, polypropylene (terephthalate / isophthalate), polyethylene terephthalate, polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), bisphenol A (terephthalate / isophthalate), polybutylene naphthalate, polybutylene (terephthalate / isophthalate), polypropylene naphthalate, polyethylene naphthalate, polycyclohexanedimethylene terephthalate, polycyclohexanedimethylene (terephthalate / isophthalate), poly(cyclohexanedimethylene / ethylene) terephthalate, poly(cyclohexanedimethylene / ethylene)(terephthalate / isophthalate), etc.

[0028] In addition, a thermotropic liquid - crystalline thermoplastic polyester resin composed of structural units selected from aromatic oxycarbonyl units, aromatic dioxy units, aromatic dicarbonyl units, ethylenedioxy units, etc. can also be used.

[0029] Examples of the aromatic oxycarbonyl unit herein include structural units formed from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 4'-hydroxydiphenyl-4-carboxylic acid. Examples of the aromatic dioxy unit include structural units formed from 4,4'-dihydroxybiphenyl, hydroquinone, and t-butylhydroquinone. Examples of the aromatic dicarbonyl unit include structural units formed from terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. Examples of the aromatic iminooxy unit include, for example, structural units formed from 4-aminophenol. Specific examples include thermotropic liquid crystalline polyesters such as p-oxybenzoic acid / polyethylene terephthalate and p-oxybenzoic acid / 6-oxy-2-naphthoic acid.

[0030] Preferred polyester resins include polyalkylene terephthalates such as polyethylene terephthalate, polybutylene terephthalate, and polypropylene terephthalate, polyalkylene naphthalates such as polyethylene-2,6-naphthalate and polybutylene-2,6-naphthalate, polyesters exhibiting thermotropic liquid crystallinity, and polyesters selected from polylactic acid. More preferred are polyesters selected from polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyesters exhibiting thermotropic liquid crystallinity, and polylactic acid.

[0031] Examples of the polyethylene resin used in the present invention mainly include low-density polyethylene (hereinafter abbreviated as LDPE), high-density polyethylene (hereinafter abbreviated as HDPE), and linear low-density polyethylene. LDPE is polymerized from ethylene under high pressure using a radical polymerization catalyst, has low crystallinity, and a density of 0.92 g / cm 3 HDPE is produced by a method of polymerizing ethylene using a Ziegler catalyst, has high crystallinity, and a density of 0.95 g / cm 3 Linear low-density polyethylene is a type of low-density polyethylene. Since its molecular structure is branched, it has higher toughness and strength than LDPE. Since the liner of the present invention preferably has high heat resistance, HDPE is preferably used.

[0032] The fluororesin used in the present invention is not particularly limited, but those having a reactive functional group introduced therein can be preferably exemplified. The reactive functional group is not particularly limited, and specifically, vinyl group, epoxy group, carboxyl group, acid anhydride group, ester group, aldehyde group, carbonyldioxy group, halocarbonyl group, alkoxycarbonyl group, amino group, hydroxyl group, styryl group, methacryl group, acrylic group, ureido group, mercapto group, sulfide group, isocyanate group, hydrolyzable silyl group, etc. can be exemplified. Among them, epoxy group, carboxyl group, acid anhydride group, amino group, and hydroxyl group are preferable, and further, carboxyl group and acid anhydride group are more preferable. Two or more of these reactive functional groups may be contained.

[0033] As a method for introducing a reactive functional group into a fluororesin, a method of blending a compound or resin compatible with the fluororesin and containing the functional group, a method of copolymerizing with a polymerizable monomer containing the functional group or a functional group convertible to the functional group when polymerizing the fluororesin, a method of using an initiator containing the functional group or a functional group convertible to the functional group when polymerizing the fluororesin, a method of reacting the fluororesin with a polymerizable monomer containing the functional group or a functional group convertible to the functional group in the presence of a radical generator, a method of modifying the fluororesin by techniques such as oxidation and thermal decomposition, etc. can be mentioned. Among them, a method of introducing a functional group into the main chain or side chain of the fluororesin by copolymerization, and a method of reacting the fluororesin with a polymerizable monomer containing a functional group in the presence of a radical generator are preferable from the viewpoints of quality, cost, and control of the introduction amount.

[0034] The polymerizable monomer containing the functional group is not particularly limited. Examples thereof include acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, crotonic acid, hymic acid, acid anhydrides thereof, glycidyl acrylate, glycidyl methacrylate, glycidyl ethyl acrylate, glycidyl itaconate, vinyl acetate, vinyl propionate, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and the like.

[0035] When the fluororesin containing the reactive functional group is used in alloy with other resins, the amount of the functional group contained in the fluororesin containing the reactive functional group is preferably 0.01 mol% or more, more preferably 0.05 mol% or more, and still more preferably 0.1 mol% or more per 1 g of the fluororesin containing the reactive functional group. The upper limit of the amount of the functional group is not particularly limited as long as the original properties of the fluororesin are not impaired. Considering the deterioration of fluidity and the like, it is preferably 10 mol% or less. It can be exemplified as a range.

[0036] The structure of the fluororesin used in the present invention is not particularly limited, but it is preferably composed of at least one fluorolefin. For example, homopolymers such as tetrafluoroethylene or chlorotrifluoroethylene, copolymers with hexafluoropropylene, perfluoro(alkyl vinyl ether), vinylidene fluoride, vinyl fluoride, and furthermore, copolymers with non-fluorinated ethylenic monomers that do not contain fluorine such as ethylene, propylene, butene, and alkyl vinyl ethers can also be exemplified. More specifically, polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene-hexafluoropyrene copolymer (EFEP), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), etc. can be mentioned. Among them, from the viewpoints of high heat resistance and easy melt molding processing, ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) are preferred, and ETFE is more preferred.

[0037] <Reinforced fiber composite material> The reinforced fiber composite material of the reinforcing layer that covers the outer surface of the liner body of the present invention is a cured product obtained by impregnating a heat-curable resin into a bundle of reinforcing fibers and heating and curing it.

[0038] As the heat-curable resin used in the present invention, there is no particular use restriction if it is liquid, but examples include epoxy resins, unsaturated polyester resins, phenol resins, urea resins, and melamine resins. In particular, from the point of high adhesive strength, an epoxy resin using compounds such as phenols, amines, carboxylic acids, and intramolecular unsaturated carbons as precursors is preferred.

[0039] Examples of glycidyl ether type epoxy resins using phenols as precursors include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, epoxy resins having a biphenyl skeleton, phenol novolak type epoxy resins, cresol novolak type epoxy resins, resorcinol type epoxy resins, epoxy resins having a naphthalene skeleton, triphenylmethane type epoxy resins, phenol aralkyl type epoxy resins, dicyclopentadiene type epoxy resins, diphenylfluorene type epoxy resins, and their various isomers, alkyl and halogen substituted products. Also included in this type are compounds obtained by modifying epoxy resins composed of phenols with urethane or isocyanate.

[0040] Examples of glycidyl amine type epoxy resins using amines as precursors include tetraglycidyldiaminodiphenylmethane, glycidyl compounds of xylenediamine, triglycidylaminophenol, and positional isomers, alkyl group and halogen substitution products of glycidyl aniline.

[0041] Examples of epoxy resins using carboxylic acids as precursors include glycidyl compounds of phthalic acid, and various isomers of glycidyl compounds of hexahydrophthalic acid and dimer acid.

[0042] Examples of epoxy resins using unsaturated carbon in the molecule as a precursor include, for example, alicyclic epoxy resins.

[0043] As the curing agent used for heat-curing the thermosetting resin of the present invention, there is no particular limitation as long as it can cure the thermosetting resin. It may be a curing agent that undergoes an addition reaction such as an amine or an acid anhydride, or a curing catalyst that causes addition polymerization such as cationic polymerization or anionic polymerization, and two or more kinds of curing agents may be used in combination. As the curing agent, preferably, compounds having an amino group, an acid anhydride group, or an azide group are suitable. For example, dicyandiamide, alicyclic amines, aliphatic amines, aromatic amines, amino benzoate esters, various acid anhydrides, phenol novolak resins, cresol novolak resins, imidazole derivatives, phenolic compounds such as t-butyl catechol, and Lewis acid complexes such as boron trifluoride complexes and boron trichloride complexes can be mentioned.

[0044] The fibers constituting the reinforcing fiber bundle used in the reinforcing fiber composite material of the present invention are not particularly limited as the type of reinforcing fiber, and examples include carbon fibers, metal fibers, organic fibers, and inorganic fibers. Two or more of these may be used.

[0045] Examples of carbon fibers include PAN-based carbon fibers made from polyacrylonitrile (PAN) fibers as raw materials, pitch-based carbon fibers made from petroleum tar or petroleum pitch as raw materials, cellulose-based carbon fibers made from viscose rayon or cellulose acetate as raw materials, vapor-grown carbon fibers made from hydrocarbons as raw materials, and graphitized fibers thereof. Among these carbon fibers, PAN-based carbon fibers are preferably used in terms of excellent balance between strength and elastic modulus.

[0046] Examples of metal fibers include fibers made of metals such as iron, gold, silver, copper, aluminum, brass, and stainless steel.

[0047] Examples of the organic fiber include fibers made of organic materials such as aramid, polybenzoxazole (PBO), polyphenylene sulfide, polyester, polyamide, and polyethylene. Examples of the aramid fiber include para-aramid fiber excellent in strength and elastic modulus, and meta-aramid fiber excellent in flame retardancy and long-term heat resistance. Examples of the para-aramid fiber include polyparaphenylene terephthalamide fiber, copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber, etc., and examples of the meta-aramid fiber include polyphenylene isophthalamide fiber, etc. As the aramid fiber, para-aramid fiber having a higher elastic modulus than the meta-aramid fiber is preferably used.

[0048] Examples of the inorganic fiber include fibers made of inorganic materials such as glass, basalt, silicon carbide, and silicon nitride. Examples of the glass fiber include E glass fiber (for electricity), C glass fiber (for corrosion resistance), S glass fiber, T glass fiber (high strength, high elastic modulus), etc. Basalt fiber is a fiber obtained by fiberizing the mineral basalt and is a fiber having very high heat resistance. Basalt generally contains 9 to 25% by weight of FeO or FeO2 which is an iron compound, and 1 to 6% by weight of TiO or TiO 2 which is a titanium compound, but it is also possible to increase the amount of these components in the molten state and fiberize them.

[0049] Since the reinforced fiber composite material of the present invention is often expected to serve as a reinforcing material, it is desirable to exhibit high mechanical properties. In order to exhibit high mechanical properties, it is preferable that the reinforcing fiber contains carbon fiber.

[0050] In the reinforced fiber composite material of the present invention, the reinforcing fiber is usually composed of arranging one or more bundles of reinforcing fiber bundles formed by bundling a large number of single fibers. The total number of filaments (the number of single fibers) of the reinforcing fiber when arranging one or more bundles of reinforcing fiber bundles is preferably 1,000 to 2,000,000.

[0051] From the viewpoint of productivity, the total number of filaments of the reinforcing fiber is more preferably 1,000 to 1,000,000, even more preferably 1,000 to 600,000, and particularly preferably 1,000 to 300,000. The upper limit of the total number of filaments of the reinforcing fiber may be such that the productivity, dispersibility, and handleability can be maintained well in consideration of the balance with the dispersibility and handleability.

[0052] <Inorganic filler (plate-like)> The thermoplastic resin material used for the liner of the embodiment of the present invention contains a plate-like inorganic filler having an aspect ratio of 100 or more and 200 or less. When the aspect ratio of the plate-like inorganic filler is less than 100, the effect of improving the anisotropy of the molding shrinkage is poor. As a result, a large amount of inorganic filler exceeding 30 parts by weight with respect to 100 parts by weight of the thermoplastic resin must be blended. In this case, the fluidity in the mold during rotational molding is significantly reduced, resulting in molding defects, which is not preferable.

[0053] From the viewpoint of improving the molding shrinkage anisotropy with a small blending amount and improving the dimensional accuracy, the aspect ratio of the plate-like inorganic filler is preferably 100 or more, more preferably 120 or more, and even more preferably 130 or more. The upper limit of the aspect ratio of the plate-like inorganic filler is preferably 200 or less, more preferably 180 or less, and even more preferably 150 or less from the viewpoint of suppressing the breakage of the inorganic filler during melt-kneading processing and the handleability.

[0054] Here, the "aspect ratio" is calculated by obtaining the volume average particle diameter and the number average thickness of the plate-like inorganic filler, and "volume average particle diameter (μm) / number average thickness (μm)". The "volume average particle diameter" is obtained by weighing 100 mg of the inorganic filler, dispersing it in water, and then using a laser diffraction / scattering particle size distribution measuring device (LA-300 manufactured by HORIBA, Ltd.). The "number average thickness" refers to the number average value obtained by measuring the thicknesses of 10 randomly selected inorganic fillers observed at a magnification of 2000 times with a scanning electron microscope (SEM) (JSM-6360LV manufactured by JEOL Ltd.). In the thermoplastic resin material used for the liner of the embodiment of the present invention, the content of the plate-like inorganic filler having an aspect ratio of 100 or more and 200 or less is 1 to 30 parts by weight with respect to 100 parts by weight of the thermoplastic resin. When the content of the plate-like inorganic filler is less than 1 part by weight, the anisotropy of the molding shrinkage of the resin composition increases, and problems such as dimensional defects of the resin liner and inability to assemble with the die parts occur. On the other hand, when the content of the plate-like inorganic filler exceeds 30 parts by weight, it is not preferable because the fluidity in the mold during rotational molding decreases. In order to achieve both rotational molding processability and dimensional accuracy, the content of the plate-like inorganic filler is preferably 27 parts by weight or less, more preferably 25 parts by weight or less, and even more preferably 20 parts by weight or less.

[0055] From the viewpoint of not impairing the smoothness of the liner surface, the volume average particle diameter of the plate-like inorganic filler used in the embodiment of the present invention is preferably 30 μm or less, and more preferably 25 μm or less. By using a plate-like inorganic filler having a volume average particle diameter of 30 μm or less, the surface smoothness of the liner obtained by rotational molding from the resin composition of the embodiment of the present invention is improved, which is preferable. The lower limit of the volume average particle diameter is not particularly limited, but is preferably 1 μm or more, and more preferably 10 μm or more.

[0056] As the plate-like inorganic filler used in the embodiment of the present invention, glass flakes, mica, and kaolin are preferably used, and particularly mica is preferably used in terms of dimensional stability and fluidity during molding.

[0057] The mica used in the embodiments of the present invention may be naturally occurring muscovite, biotite, phlogopite, sericite, or synthetic mica produced artificially. Two or more of these micas may be included. Examples of the method for producing mica include hydro jet pulverization, wet pulverization using a stone mortar, dry ball mill pulverization, pressure roller mill pulverization, air jet mill pulverization, and dry pulverization using an impact pulverizer such as an atomizer. Further, the surface may be treated with a silane coupling agent or the like for the purpose of improving the adhesion between mica and the thermoplastic resin. Further, mica that has been heat-treated for the purpose of removing impurities and hardening mica may also be used.

[0058] <Nucleating agent> For the thermoplastic resin material used for the liner of the embodiment of the present invention, a small amount of a nucleating agent is blended in order to improve the crystallization rate accompanying the cooling and solidification during rotational molding. If the crystallization of the liner obtained by rotational molding is insufficient, troubles such as thermal deformation in a high-temperature environment above the glass transition temperature of the thermoplastic resin will occur, which is not preferable.

[0059] In the thermoplastic resin material used for the liner of the embodiment of the present invention, the content of the nucleating agent is 0.01 parts by weight or more and 0.05 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin. If the content of the nucleating agent is less than 0.01 parts by weight, the effect of improving the crystallization rate of the liner molded product is not sufficient, and problems such as thermal deformation will occur. On the other hand, even if more than 5 parts by weight of the nucleating agent is blended, no further improvement effect on the crystallization rate can be obtained, and the resin toughness may also decrease, which is not preferable.

[0060] The nucleating agent used in the present invention is intended to dramatically improve the crystal nucleation rate in the crystal growth process of the thermoplastic resin. Specifically, organic nucleating agents such as polyether ether ketone and inorganic nucleating agents such as talc are preferably used.

[0061] <Method for manufacturing a resin liner for a pressure vessel> Among these, as a manufacturing method of the liner body constituting the pressure vessel, it is important to perform it by the rotational molding method shown in Fig. 5. As the rotational method of rotational molding, there are mainly two types: "uniaxial rotation + rocking motion" 501 and "biaxial rotational motion" 502. The former is a molding method in which the mold rotates on a platform that swings left and right like a pendulum, and is optimal for obtaining large-sized molded products with a simple structure. The latter is a molding method in which the two axes are interlocked and rotate with a movement on a planetary motion, and is optimal for obtaining molded products with a complicated shape having many unevennesses because of good transferability to the mold. In the present invention, in order to ensure the assembling accuracy between the liner and the base portion, it is preferable to perform rotational molding by the "biaxial rotational motion" method capable of coping with a complicated shape.

[0062] Further, as the heating method of rotational molding, there are "direct firing type", "hot air circulation oven type" and "medium circulation type", and in the present invention, the "medium circulation type" can be preferably used in terms of enabling more precise temperature control.

[0063] When heating and melting unevenness occurs in the process of charging a molding material into a mold in rotational molding, melting it in the mold, and transferring and shaping it to the mold surface by rotational motion, a large number of voids are generated inside the molded product, leading to a decrease in product strength, which is not preferable. Therefore, in order to uniformly heat and melt the thermoplastic resin material in the mold, it is necessary to control the mold heating rate at 20°C / min to 40°C / min and the mold temperature to be Тm (melting point) + 10 [°C] or higher of the thermoplastic resin material. If the mold heating rate is less than 20°C / min, heating and melting unevenness is likely to occur, and if it exceeds 40°C / min, thermal deterioration of the material is likely to progress, which is not preferable. The upper limit of the molding temperature in the mold is Тm + 100 [°C], and if the temperature is raised above that, significant thermal decomposition of the thermoplastic resin material progresses, which is not preferable.

[0064] Furthermore, when cooling and solidifying in the mold of the next process and demolding, if the molded product is not gradually cooled, problems such as deformation of the molded product will occur when taking out the molded product. Therefore, it is necessary to control the cooling rate of the molded product removal temperature in the mold within the range of 20 °C / min to 35 °C / min, and the mold temperature when taking out the molded product at Tg (glass transition temperature) + 10 °C or higher of the thermoplastic resin material. If the mold cooling rate is lower than 20 °C / min, the surface of the molded product will not be sufficiently solidified and mold seizure will occur during demolding. If it exceeds 35 °C / min, the molded product will be in a rapid cooling state and most of the inside of the molded product will be in an amorphous state, which is not preferable because it will cause liner thermal deformation in the curing process during the manufacture of pressure vessels. The upper limit of the molded product removal temperature is Tg + 50 [°C]. Raising the temperature above this is not preferable because it becomes difficult for the resin to cool and solidify in the mold.

[0065] <Manufacturing method of thermoplastic resin material used for resin liner of pressure vessel> The thermoplastic resin material used for the liner of the embodiment of the present invention is usually obtained by melt-kneading. Examples of melt-kneading include methods of supplying to a commonly known melt-kneading machine such as a single-screw or twin-screw extruder, Banbury mixer, kneader, and mixing roll, and kneading at a processing temperature of Tm (melting point) + 5 to 100 [°C] of the resin material. At this time, there is no particular limitation on the mixing order of the raw materials. After all the raw materials are blended, melt-kneading is performed by the above method; after some of the raw materials are blended, melt-kneading is performed by the above method, and then the remaining raw materials are blended and melt-kneaded; or after some of the raw materials are blended, the remaining raw materials are mixed using a side feeder during melt-kneading by a single-screw or twin-screw extruder. Any method may be used. Also, for a small amount of additive components, it is of course possible to add them before molding after kneading and pelletizing other components by the above method and then subjecting them to molding.

[0066] <Manufacturing method of outer shell> A method for manufacturing a pressure vessel formed of a thermoplastic resin liner body having a cylindrical straight body portion of the present invention and dome portions provided at both ends of the straight body portion and narrowing as they move away from the straight body portion, and an outer shell covering an outer surface of the liner body with a cured product of a reinforcing fiber composite material. A method (referred to as a filament winding method) for forming an outer shell covering the outer surface of the liner body with a cured product of a reinforcing fiber composite material will be described below. This manufacturing method includes a step (a) of preparing a molded product intermediate formed of a reinforcing layer composed of a plurality of reinforcing fiber composite materials by winding a reinforcing fiber composite material impregnated with a liquid thermosetting resin composition around a liner, a step (b) of holding the molded product intermediate at room temperature and flowing the thermosetting resin composition impregnated in the reinforcing fiber composite material, and a step (c) of heating the molded product intermediate after step (b) to obtain a cured product of the reinforcing fiber composite material impregnated with the thermosetting resin. In the present invention, room temperature refers to a temperature in the range of 5°C to 35°C.

[0067] In step (a) of preparing the molded product intermediate, the reinforcing fiber composite material is drawn out, impregnated with the thermosetting resin composition, and then wound around the liner. The liner can be freely selected according to the use of the filament winding molded product. For example, in the manufacture of a hollow pipe member, a cylindrical liner that can be demolded after curing the molded product, or various shaped liners that can be demolded by melting by heating or the like can be used. In the manufacture of a pressure vessel, a metal or resin liner or the like that ensures sealing performance against a predetermined contained substance can be used. As a method of winding the reinforcing fiber composite material impregnated with the thermosetting resin composition around the liner, from the viewpoints of moldability and mechanical properties of the molded product, etc., it is preferable to supply the reinforcing fiber composite material from a head portion that can move relatively freely with respect to the liner and arrange the reinforcing fiber composite material so as to satisfy the required performance of the filament winding molded product.

[0068] In step (b) of holding the molded article intermediate at room temperature, since the molded article intermediate is held at room temperature, in at least part of the step, the state in which the thermosetting resin composition impregnated in the reinforced fiber composite material has fluidity is maintained. In a state where the thermosetting resin composition can flow, the bubbles that have entered the reinforcing layer of the reinforced fiber composite material obtained in step (a) are caused by the buoyancy acting on the bubbles and the winding tightness remaining in the fibers when the fibers are wound around the core, etc. It appears on the surface layer of the reinforcing layer of the reinforced fiber composite material. Therefore, by holding the molded article intermediate at room temperature, at least part of the bubbles in the reinforcing layer of the reinforced fiber composite material can be removed, and the voids remaining in the filament winding molded article can be reduced. The holding of the molded article intermediate can be performed while rotating the liner of the molded article intermediate as the rotation center. Thereby, it is possible to prevent the thermosetting resin composition having fluidity from dripping and falling off due to gravity. The dropping of the thermosetting resin composition may increase the fiber volume content (Vf: %) of the filament winding molded article and deteriorate the product performance. In addition, the dropped thermosetting resin composition is often discarded, deteriorating the product yield. By rotating the molded article intermediate during holding, the influence due to the dropping of the thermosetting resin composition can be eliminated.

[0069] In the holding of the molded article intermediate, the holding temperature is room temperature, but preferably within the range of room temperature, and can be set to any temperature ±5°C determined according to the type and use conditions of the thermosetting resin composition. When the range of this arbitrary temperature ±5°C exceeds the range of room temperature, the excess part shall be rounded down. Depending on the type and use conditions of the thermosetting resin composition, when the temperature is high, the gelation of the thermosetting resin composition may proceed rapidly, and there is a risk that a sufficient resin flow time cannot be ensured. Also, when the temperature is low, the viscosity of the thermosetting resin composition decreases, and compared with the case where the temperature is high, it may take a long time to obtain the same degree of void reduction effect. Therefore, the holding temperature is not particularly limited as long as it is room temperature, but it is preferably within a range determined according to the type and use conditions of the thermosetting resin composition used.

[0070] In step (c) of obtaining a cured product of a fiber-reinforced composite material impregnated with a thermosetting resin, the molded product intermediate after holding at room temperature is heated to cure the thermosetting resin composition, but the method is not limited, and heating can be performed using any method such as a heater or an induction heating coil. During heating, the molded product intermediate can be held while being rotated. By rotating and holding the molded product intermediate, it is possible to prevent the thermosetting resin composition from falling off.

[0071] The step (a) of preparing the molded product intermediate, the step (b) of holding the molded product intermediate at room temperature, and the step (c) of obtaining a cured product of a fiber-reinforced composite material impregnated with a thermosetting resin are not limited in the place of implementation. That is, the molded product intermediate may be moved between step (a) and step (b), or the steps may be continuously performed without moving. Also, the molded product intermediate may be moved between step (b) and step (c), or the steps may be continuously performed without moving. Further, when the molded product intermediate is moved between step (b) and step (c), the place of movement can also be the place where step (a) was performed.

[0072] The filament winding molded product obtained in the present invention can be widely used in aerospace applications, leisure applications, and general industrial applications, including pressure vessels, rolls, propeller shafts, flywheels, fishing rods, and golf club shafts. In particular, it can be suitably used for applications such as pressure vessels that require strength. The pressure vessel manufactured by the present invention is not limited to hydrogen gas vehicles and natural gas vehicles, but is also suitably used for ships, aircraft, etc., and stationary types used on the ground, air respirators used by hospitals and firefighters, etc. Also, the substances stored in this pressure vessel may be gases such as nitrogen, oxygen, argon, liquefied petroleum gas, and hydrogen, or those obtained by liquefying the above substances.

[0073] <Molding shrinkage rate> The thermoplastic resin material used for the liner of the embodiment of the present invention needs to reduce the shrinkage anisotropy during mold cooling and solidification, and the ratio of the flow direction (MD) / orthogonal direction (TD) of the molding shrinkage rate, which is an index of shrinkage anisotropy, needs to be in the range of 0.6 or more and 1.0 or less. When the MD / TD ratio is greater than 1.0, the screw dimension accuracy for attaching the base part of the liner is insufficient and it cannot be attached. On the other hand, when the MD / TD ratio is less than 0.6, a large amount of plate-like inorganic filler is blended and mold transfer failure occurs.

[0074] The molding shrinkage rate of the present invention is calculated by using a plate with a film gate shape of (length) 70 mm × (width) 70 mm × (thickness) 2.0 mm, and calculating the dimensional change rate of the injection molded product with respect to the mold dimensions in the resin flow direction (MD) and the orthogonal direction (TD) with respect to the resin flow direction, and is represented by the ratio of MD / TD. The molding conditions such as the molding temperature, mold temperature, and pressure are appropriately changed according to the thermoplastic resin material used.

[0075] <Elongation at break> ASTM No. 1 dumbbell test specimens were prepared by injection molding using the thermoplastic resin material of the embodiment of the present invention, tensile tests (n = 5 each) were carried out in accordance with ASTM3039, and the elongation at break was measured. In order to impart excellent pressure resistance to the liner of the present invention, the elongation at break needs to be 10% or more. When it is less than 10%, the pressure resistance performance is significantly impaired, which is not preferable. The upper limit of the elongation at break of the thermoplastic resin material is 400%, and above that, it exceeds the measurement limit of the tensile test and cannot be measured.

[0076] <Heat sag deformation amount> The thermoplastic resin material used for the liner of the embodiment of the present invention needs to be sufficiently crystallized in the mold, and the heat sag deformation amount, which is an index of the completion of crystallization, needs to be 5 mm or less, preferably 3 mm or less, and more preferably 2 mm or less. The lower limit value of the heat sag deformation amount of the present invention is 1 mm. To make it less than 1 mm, a large amount of inorganic filler is blended, which significantly impairs the resin tensile elongation, so it is not preferable. Further, when the heat sag deformation amount of the thermoplastic resin material of the present invention is 5 mm or more, in the step of winding the reinforcing fiber impregnated with the thermosetting resin around the resin liner and performing the curing treatment, the resin liner thermally contracts, and as shown in FIG. 6, a gap is generated between the resin liner and the base part, and it leaks when pressurized inside the liner, so it is not preferable.

[0077] The heat sag deformation amount of the present invention is measured by cutting out a heat sag test piece of (width) 15 mm × (length) 70 mm × (thickness) 1 mm from the liner body, holding one end 10 mm, fixing it in a cantilever state so that the test piece is horizontal, treating it in a hot air oven at 100 °C for 60 minutes, and then measuring the distance that the tip on the side opposite to the held part droops due to its own weight from the horizontal state with a height gauge.

[0078] <ΔT in DSC measurement> The thermoplastic resin material used for the liner in the embodiment of the present invention needs to promptly complete crystallization during the cooling and solidification of rotational molding. As an index for material design, it is preferable to control ΔT (= melting point (Tm) - crystallization temperature during cooling (Tmc)) in DSC measurement within the range of 10 °C or more and 40 °C or less. If ΔT is less than 10 °C, the cooling and solidification are too fast, and voids are likely to form inside the molded product. If ΔT is greater than 40 °C, the cooling and solidification are slow, and crystallization does not proceed sufficiently, leaving a large amount of amorphous state inside the molded product, which causes a decrease in heat resistance, so it is not preferable.

[0079] The melting point (Tm) and the crystallization temperature during cooling (Tmc) of the present invention were measured using a differential scanning calorimeter (DSC Q20) manufactured by TA Instruments. 5 to 7 mg of the sample to be measured was weighed, and the temperature was raised from 20°C to 400°C at a rate of 20°C / min under a nitrogen atmosphere, and then the temperature was lowered from 400°C to 50°C at a rate of 20°C / min. The peak of the endothermic peak that appears during heating is Tm (melting point), and the peak of the exothermic peak that appears during cooling is the crystallization temperature during cooling (Tmc).

Example

[0080] Examples are shown below to more specifically explain the present invention, but the present invention is not limited to the descriptions of these examples. The physical property evaluations in each example and comparative example were carried out according to the following methods.

[0081] 〔DSC characteristics (Tm, Tmc, Tg)〕 Using a differential scanning calorimeter (DSC Q20) manufactured by TA Instruments, 5 to 7 mg of the thermoplastic resin material used in each example and comparative example was weighed, and the melting point (Tm), the crystallization temperature during cooling (Tmc), and the glass transition temperature (Tg) were measured under the following measurement conditions. <Measurement conditions> · Under a nitrogen atmosphere (flow rate: 50 mL / min) · Heating rate 20°C / min · Cooling rate 20°C / min · Reached heating temperature 400°C (held for 3 minutes), reached cooling temperature 50°C

[0082] 〔Molding shrinkage rate〕 Using an injection molding machine SE75DUZ manufactured by Sumitomo Heavy Industries, under the conditions that the resin temperature is Tm + 10°C or higher and the mold temperature is Tg + 20°C or higher, the thermoplastic resin materials of each example and comparative example were used to mold a plate of (length) 70 mm × (width) 70 mm × (thickness) 2.0 mm (gate shape: film gate). Using this plate, the amount of dimensional change due to the shrinkage of the actual molded product with respect to the initial mold dimensions was measured in the resin flow direction (MD) and the direction orthogonal to the resin flow direction (TD), and the ratio of MD / TD was determined.

[0083] 〔Tensile physical properties〕 Using the Sumitomo Heavy Industries injection molding machine SE75DUZ, under the conditions that the resin temperature is Tm + 10°C or higher and the mold temperature is Tg + 20°C or higher, ASTM No. 1 dumbbells of the thermoplastic resin materials of each example and comparative example were molded. Using this ASTM No. 1 dumbbell, a tensile test (n = 5 for each) was carried out in accordance with ASTM 3039, and the tensile elongation at break was measured.

[0084] [Heat sag deformation amount] A heat sag test piece of (width) 15 mm × (length) 70 mm × (thickness) 1 mm was cut out from the resin liner body, one end of 10 mm was held, and while fixing it in a cantilever state so that the test piece was horizontal, it was treated in a hot air oven at 100°C for 60 minutes. Then, the distance that the tip on the side opposite to the held part sagged by its own weight from the horizontal state was measured with a height gauge.

[0085] [Measurement of clearance between the nozzle and the resin liner] As shown in FIGS. 6 and 7, the resin liner and the nozzle parts were assembled, and shim tapes with different thicknesses were inserted into the clearance part (701) to measure the clearance amount.

[0086] [Manufacturing method of thermoplastic resin material] After dry-blending each component shown in each example and comparative example, using a Nippon Steel Works TEX30α type twin-screw extruder (screw diameter 30 mm, L / D = 45, 5 kneading parts, co-rotating fully meshing type screw) equipped with a vacuum vent, at a screw rotation speed of 200 rpm and a discharge rate of 30 Kg / hr, the cylinder temperature was set so that the resin temperature at the die exit was the melting point + 10°C or higher, and melt-kneaded, and pelletized with a strand cutter. Using these pellets, DSC measurement, molding shrinkage rate, and tensile physical property evaluation were carried out.

[0087] [Manufacturing method of resin liner] Using a two-axis motion rotary molding device manufactured by Suiko (heating method: oil jacket), under the rotary molding conditions of each example and comparative example, the resin liner shape shown in FIG. 7 (wall thickness: 2 mm Obtained (±0.1 mm, screw part: inner diameter φ13 mm, outer diameter φ24 mm).

[0088] [Method for manufacturing a pressure vessel by filament winding method and pressure resistance test (pressure resistance)] Install the liner obtained above on the filament winding forming device, and feed the resin containing a liquid thermosetting resin composition (epoxy resin: curing agent = 100:32 mass ratio, uniformly mixed at 25°C normal temperature) while impregnating one tow of carbon fiber "TORAYCA" (registered trademark) T700SC-24K manufactured by Toray Industries, Inc. into the resin while feeding the yarn. It was wound around in a range of 60 mm width at a winding angle of ±83° with respect to the axial direction of the core, and laminated to a thickness of 1 mm to prepare an intermediate molded product. After the fiber winding, the intermediate was rotated at a speed of 7 rpm and held in an environment of 20°C for 15 minutes. At the start of the holding, the viscosity of the resin was 1100 mPa·s.

[0089] After the holding, the intermediate molded product was heated at a temperature of 80°C for 2 hours and at a temperature of 110°C for 4 hours to cure the resin, and a pressure vessel for pressure resistance test was obtained. Next, the pressure vessel obtained above was installed in the pressure vessel hydraulic rupture test device shown in Fig. 8, water was fed and pressurized by a hydraulic pump, and the rupture pressure at the time of container rupture was measured (N = 3), and the following criteria were provided to evaluate the pressure resistance performance. <Pressure resistance performance / Judgment criteria> 〇: Rupture pressure 70 MPa or more △: Rupture pressure 60 MPa or more and less than 70 MPa ×: Rupture pressure less than 60 MPa

[0090] 〔Raw materials〕 In the examples and comparative examples, the raw materials shown below were used.

[0091] <Reference Example 1> Thermoplastic resin Nylon 6 resin: CM1056 (manufactured by Toray Industries, Inc., grade for high viscosity and high impact blow molding, "AMILAN" (registered trademark)) Polyethylene resin: HB-216R (manufactured by Japan Polyethylene Corporation, high density polyethylene for large hollow blow molding, "NOVATECH" (registered trademark)) Fluororesin: P-66P (manufactured by AGC, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer for blow molding, "Fluоn" (registered trademark))

[0092] <Reference Example 2> Plate-like inorganic filler Mica 1: Volume average particle diameter: 25 μm, aspect ratio: 150 Mica 2: Volume average particle diameter: 60 μm, aspect ratio: 50 Glass flake: Volume average particle diameter: 30 μm, aspect ratio: 200 The above volume average particle diameter was determined by a laser diffraction / scattering particle size distribution measuring device LA-300 manufactured by HORIBA. The thickness was observed at a magnification of 2000 times using a scanning electron microscope (SEM) (JSM-6360LV manufactured by JEOL Ltd.). Ten samples were randomly selected from the image, the thickness was measured, and the number average value was determined. The aspect ratio was calculated as volume average particle diameter (μm) / number average thickness (μm).

[0093] <Reference Example 3> Crystal nucleating agent Talc: FH104 (manufactured by Fuji Talc Co., Ltd., median diameter 4 μm, ultrafine powder grade) <Reference Example 4> Liquid thermosetting resin composition Epoxy resin main agent: Bisphenol A type liquid epoxy resin ("jER" (registered trademark) 828 (manufactured by Mitsubishi Chemical Corporation)) Hardener: Mixture of poly(propylene glycol) diamine, isophorone diamine, cyclohexylamine, and polypropylene glycol ("ARADUR" (registered trademark) 3486 (manufactured by Huntsman Japan Co., Ltd.))

[0094]

Table 1

[0095]

Table 2

[0096] As described above, by comparing the examples and comparative examples, it can be seen that the resin liner and pressure vessel of the present invention achieve a dramatic improvement in pressure resistance performance by improving the shrinkage anisotropy and crystallization characteristics during rotational molding.

Explanation of Signs

[0097] 101 Pressure vessel 102 Reinforced fiber composite material 103 Liner container 104 Base part 201 Cylindrical straight body part 202 Hemispherical dome parts provided at both ends of the straight body part 301 Injection-molded liner half part 302 Injection-molded liner (welded and joined half parts) 501 Uniaxial rotation + rocking motion 502 Biaxial rotation 601 Rotational molding liner 602 Base part 701 Clearance part

Claims

1. A pressure vessel formed by a thermoplastic resin liner body having a cylindrical straight body portion and dome portions provided at both ends of the straight body portion and narrowing as they move away from the straight body portion, and an outer shell covering the outer surface of the liner body with a cured product of a reinforcing fiber composite material, wherein the liner body is manufactured by rotational molding, and the thermoplastic resin material used for the liner is a resin composition containing 1 to 30 parts by weight of a plate-like inorganic filler having a volume average particle diameter of 1 μm or more and 30 μm or less and an aspect ratio of 100 or more and 200 or less, and 0.01 to 0.05 parts by weight of a crystal nucleating agent, per 100 parts by weight of the thermoplastic resin, and having a ratio of the flow direction / orthogonal direction of the molding shrinkage rate of 0.6 or more and 1.0 or less and a tensile break elongation of 10% or more and 400% or less. The pressure vessel is characterized by this.

2. A test piece having a width of 15 mm, a length of 70 mm, and a thickness of 1 mm is cut out from the straight body portion of the liner body, and the heat sag deformation amount when heat-treated at 100°C for 60 minutes is 1 mm or more and 5 mm or less. The pressure vessel according to Claim 1 is characterized by this.

3. The temperature change ΔT (=Tm [melting point: °C] - Tmc [cooling crystallization temperature: °C]) when a part of the liner body is measured by DSC is 10°C or more and 40°C or less. The pressure vessel according to Claim 1 or 2 is characterized by this.

4. The thermoplastic resin material used for the liner body is selected from any one of polyamide resin, polyethylene resin, polyester resin, and fluororesin. The pressure vessel according to any one of Claims 1 to 3 is characterized by this.

5. The plate-like inorganic filler is selected from any one of glass flakes, mica, and kaolin. The pressure vessel according to any one of Claims 1 to 4 is characterized by this.

6. A method for manufacturing a pressure vessel formed by a thermoplastic resin liner body having a cylindrical straight body portion and dome portions provided at both ends of the straight body portion and narrowing as they move away from the straight body portion, and an outer shell covering the outer surface of the liner body with a cured product of a reinforcing fiber composite material. The thermoplastic resin material used for the liner body is composed of a resin composition containing 1 to 30 parts by weight of a plate-like inorganic filler having a volume average particle diameter of 1 μm or more and 30 μm or less and an aspect ratio of 100 or more and 200 or less, and 0.01 to 0.05 parts by weight of a crystal nucleating agent, per 100 parts by weight of the thermoplastic resin. First, the thermoplastic resin, the inorganic filler, and the crystal nucleating agent are melt-kneaded and pelletized in advance, and then introduced into a mold. The mold temperature rising rate is 20 °C / min to 40 °C / min, the molding temperature is Tm (melting point) + 10 [°C] or more and Tm + 100 [°C] or less of the thermoplastic resin material, the mold cooling rate is 20 °C / min to 35 °C / min, and the molded product removal temperature is Tg (glass transition temperature) + 10 [°C] or more and Tg + 50 [°C] or less of the thermoplastic resin material. The liner body is molded by rotational molding under these molding conditions, and then a reinforcing fiber composite material is wound around the liner body and cured to form an outer shell.

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