JP2022119264A - Pressure vessels and methods of manufacturing pressure vessels - Google Patents

Abstract

To provide a resin liner with excellent strength, rigidity, and heat resistance and a pressure vessel with excellent pressure resistance in a simple and inexpensive manner.SOLUTION: A pressure vessel having a cylindrical straight-body section and a dome section provided at both ends of the straight-body section and having a shape that shrinks as it moves away from the straight-body section, the straight-body section and the dome section being formed of a liner body made of thermoplastic resin and an outer shell in which the outer surface of the liner body is covered with a reinforcement layer made of a hardened reinforced fiber composite material. The pressure vessel is characterized in that the liner body is manufactured by direct blow molding and the pinch-off portion formed in the dome section has a tensile strength of 100 MPa or more, a flexural modulus of 6 GPa or more, and a load deflection temperature (load 0.45 MPa) of 200°C or more.SELECTED DRAWING: Figure 1

Description

The present invention is a resin liner for pressure vessels that can be directly blow molded and has excellent strength, rigidity and heat resistance, and an outer shell in which the outer surface of the resin liner is covered with a reinforcing layer made of a cured reinforced fiber composite material. The present invention relates to a formed pressure vessel having excellent pressure resistance.

Conventionally, from the standpoint of light weight and excellent durability (high toughness) when pressurized, thermal BACKGROUND ART A pressure vessel in which a container body (liner) made of plastic resin is reinforced with an outer shell made of a fiber-reinforced resin material is used. Glass fiber, carbon fiber, etc. are mainly used as the reinforcing fiber used for the outer shell. Among them, carbon fiber, which has a high specific strength, can be designed to improve the strength and rigidity while reducing the weight of the pressure vessel.

As a pressure vessel, for example, a resin liner (Fig. 2) having a cylindrical straight body portion and hemispherical dome portions provided at both ends of the straight body portion; A pressure vessel with an outer shell is commonly used. In addition, the outer shell is formed by winding a fiber-reinforced resin material in which a matrix resin is impregnated into a long reinforcing fiber bundle around the outside of the liner body by a filament winding method (hereinafter sometimes abbreviated as FW method), and heat-cured. A pressure vessel is created by Especially in recent years, pressure vessels designed to be filled with fuel for natural gas vehicles and fuel cell vehicles have been attracting attention as pressure vessel applications. We are searching for ways to reduce the cost of pressure vessels.

Currently, as shown in Fig. 3, injection molding (half-split) + welding (laser or heat) is the mainstream for pressure vessel liners. However, direct blow molding and rotational molding, which do not require post-processing, have been investigated as cost reduction methods.

Recently, many manufacturers are considering making prototype liners using the direct blow molding method. In the direct blow molding method, part of a cylindrical hot parison generally made of thermal resin is sandwiched between a pair of molds to create a striped pinch-off portion extending in the axial direction of the liner (Fig. 4). is formed. At the pinch-off part, part of the hot parison is constrained by the mold, creating a part with a thickness different from that of other parts. there were. Therefore, each manufacturer is earnestly studying to solve the problem of pinch-off during direct blow molding.

For example, Patent Document 1 (International Publication No. WO2018/207771) is known as a resin liner having a pinch-off shape with improved pressure resistance. Patent Literature 1 discloses a pressure vessel using a resin liner that softens the valley shape of the pinch-off portion that occurs during direct blow molding.

Further, Patent Document 2 (International Publication No. WO2013/172226) is known as a blow-molded product using a resin material having excellent pinch-off adhesion. Patent Document 2 discloses a blow-molded product using a resin composition in which an EVOH resin having excellent blow moldability is blended with an olefin-based resin.

Patent Document 3 (International Publication No. WO2006/112252) is known as a method for manufacturing a liner for pressure-resistant containers using a liquid crystal polyamide resin with excellent pinch-off adhesion. In Patent Document 3, a liquid crystal polyamide resin is used for a pressure-resistant container liner that is directly blow molded. A pressure vessel liner having a pinch-off portion with a tensile elongation of 1% or more is disclosed.

Patent Document 4 (Japanese Patent Application Laid-Open No. 7-32460) is known as a blow-molded product in which oxidative deterioration of a resin material is suppressed. Patent Document 4 discloses a blow-molded product obtained by pinching off a parison between molds and then blowing the parison with an inert gas.

International publication WO2018/207771 International publication WO2013/172226 International publication WO2006/112252 JP-A-7-32460

However, although the inventions described in Patent Documents 1 to 4 above improve the pinch-off adhesion during direct blow molding, the strength, rigidity, and heat resistance of the pinch-off portion are not at a level that is satisfactory for practical use. There is no mention of a thermoplastic resin liner having a pinch-off portion tensile strength of 100 MPa or more, a flexural modulus of 6 GPa or more, and a deflection temperature under load of 200° C. (load 0.45 MPa) or more.

Accordingly, an object of the present invention is to provide a thermoplastic resin liner that can be directly blow molded and has excellent strength, rigidity and heat resistance.

In order to solve the above problems, a pressure vessel and a method for manufacturing a pressure vessel according to the present invention have any of the following configurations. i.e.
A liner main body comprising a cylindrical straight body portion and dome portions provided at both ends of the straight body portion and tapering away from the straight body portion, wherein the straight body portion and the dome portion are made of a thermoplastic resin. and an outer shell in which the outer surface of the liner body is covered with a reinforcing layer made of a hardened reinforced fiber composite material, wherein the liner body is manufactured by direct blow molding, and The pressure vessel is characterized in that the pinch-off portion formed in the dome portion has a tensile strength of 100 MPa or more, a bending elastic modulus of 6 GPa or more, and a deflection temperature under load (0.45 MPa load) of 200° C. or more.

The thermoplastic resin used for the liner body of the present invention is preferably a polyamide resin composition containing 15 to 200 parts by weight of fibrous filler with respect to 100 parts by weight of polyamide resin.

The thickness of the pinch-off portion formed in the dome portion of the present invention is preferably 1.15 to 1.30 times the thickness of the dome portion.

It is preferable that the fibrous filler contained in the polyamide resin composition of the present invention is a modified cross-section glass fiber having a modified cross-section ratio of 1.3 or more and 10 or less.

The polyamide resin contained in the polyamide resin composition of the present invention is preferably nylon 11 or nylon 12.

The peak intensity ratio (the peak intensity of the direct blow molded product/the peak intensity of the resin material before direct blow molding) measured by FT-IR on the inner surface of the liner body of the present invention at a measurement wavelength of 1700 ^-1 to 1750 cm ^-1 is 0. It is preferably 0.005 or less.

Moreover, the manufacturing method of the pressure vessel of this invention has the following structures. i.e.
A cylindrical straight body portion and dome portions provided at both ends of the straight body portion and having a shape that tapers away from the straight body portion, wherein the straight body portion and the dome portion are formed of a thermoplastic resin liner. A method for manufacturing a pressure vessel comprising a main body and an outer shell in which the outer surface of the liner main body is covered with a reinforcing layer made of a hardened reinforced fiber composite material, wherein the liner main body is made of a thermoplastic resin. Extruded at an extrusion speed of 0.10 kg/sec to 0.50 kg/sec to form a hot parison, the upper and lower ends of the hot parison are fixed with a mold, and direct blow molding is performed under molding conditions of the melting point of the thermoplastic resin + 10 ° C. or higher. and winding a reinforcing fiber composite material around the liner body and curing it to form an outer shell.

The molds of the present invention are a pair of molds for fixing the upper and lower ends of the hot parison from the left and right, and it is preferable to form a pinch-off portion that presses and integrates the upper and lower ends of the parison except for the central portions.

In the direct blow molding of the present invention, it is preferable to blow an inert gas having an oxygen concentration of 1% or more and 10% or less into the hot parison.

According to the present invention, by using a direct blow molded thermoplastic resin liner with improved strength, rigidity and heat resistance of the pinch-off portion, it is possible to obtain a pressure vessel with significantly improved pressure resistance and cost competitiveness. can.

It is the schematic which showed the component structure of a pressure vessel. It is the schematic which showed the shape of the resin liner. 1 is a schematic diagram of an injection molded and welded resin liner; FIG. This is a molded product showing the pinch-off shape of a direct blow molded resin liner. It is the schematic which showed the direct blow molding apparatus. 4 is a graph showing FT-IR analysis results of the inner surface of a resin liner. This is a molded product showing the degree of pinch-off depression. FIG. 4 is a schematic diagram of a shape of a resin liner that is direct blow molded in an example. 1 is a schematic diagram of an apparatus for carrying out a pressure vessel pressure test; FIG.

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

A 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 the distance from the straight body portion increases, and the straight body portion and the mirror are provided. A pressure vessel in which a part is formed of a liner body made of a thermoplastic resin 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.

<Thermoplastic resin>
The thermoplastic resin used for the liner body of the present invention is a polyamide resin composition containing a fibrous filler.

Examples of polyamide resins used in the polyamide resin composition include nylons synthesized using amino acids, lactams, diamines and dicarboxylic acids as main raw materials.

Representative examples of raw materials thereof 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; methylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4-/2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, metaxyl diamine, 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, aminoethylpiperazine and other aliphatic, alicyclic, Aromatic diamines and adipic acid, spelic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfo Aliphatic, alicyclic and aromatic dicarboxylic acids such as isophthalic acid, hexahydroterephthalic acid and hexahydroisophthalic acid are included.

Polyamide resins include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polypentamethylene adipamide (nylon 56), polyhexamethylene Bacamide (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 mixtures thereof. Copolymers and the like are preferably used. Particularly preferred are nylon 6, nylon 66, nylon 610, nylon 6/66 copolymer, nylon 6/12 copolymer, and the like.

Furthermore, as the polyamide resin used in the present invention, an aliphatic polyamide (nylon 11, melting point 185 ° C.) obtained by condensation polymerization of 11-aminoundecanoic acid obtained from castor oil, which is a vegetable oil, or starting from synthetic chemical butadiene Aliphatic polyamide (nylon 12, melting point 175°C) obtained by polycondensation of lauryl lactam, which is a monomer to be synthesized, has the lowest melting point and water absorption, so it is preferably used in terms of excellent blow molding processability and dimensional accuracy. can be done.

Examples of fibrous fillers contained in the polyamide resin composition of the present invention include glass fibers, milled glass fibers, carbon fibers, ceramic fibers, and mineral fibers. Among these, examples of mineral fibers include potassium titanate whiskers, zinc oxide whiskers, calcium carbonate whiskers, wollastonite whiskers, asbestos fibers, and gypsum fibers. Ceramic fibers include, for example, alumina fibers and silicon carbide fibers. Preferred fibrous fillers in embodiments of the present invention are those with a fiber length of 1-150 μm and a fiber diameter of 1-25 μm before compounding, commonly referred to as staple fibers. By using such a short fiber filler, the anisotropy of the filler can be relaxed, and an isotropic warpage reduction effect can be imparted. The content of the fibrous filler is 15-200 parts by weight, preferably 25-200 parts by weight, per 100 parts by weight of the polyamide resin. If the content of the fibrous filler is less than 15 parts by weight, it is difficult to obtain the reinforcing effect of the filler. .

Furthermore, it is preferable to use modified cross-section glass fiber as the fibrous filler used in the present invention, because it is possible to achieve both reduction in warpage in the direction perpendicular to the flow direction of the molded article and high strength. Here, the cross-sectional shape of the modified cross-section glass fiber is preferably flat, cocoon-shaped, oval, elliptical, semi-circular or arc-shaped, rectangular or similar cross-sectional shape, and particularly flat cross-sectional shape. It is more preferable to have The ratio of the major diameter (longest linear distance in the cross section) to the minor diameter (longest linear distance in the direction perpendicular to the major diameter) in the cross section perpendicular to the length direction of a glass fiber with a flat cross section (heteromorphic ratio) ) is preferably 1.3 to 10, more preferably 1.5 to 5. If the deformation ratio of the fibrous filler is less than 1.3, the effect of improving the strength is poor, and the upper limit of the deformation ratio is 10 from the viewpoint of productivity.

The following compounds can be added to the polyamide resin composition used in the present invention for the purpose of modification. Polyalkylene oxide oligomer compounds, thioether compounds, ester compounds, plasticizers such as organic phosphorus compounds, crystal nucleating agents such as organic phosphorus compounds, polyether ether ketones, montanic acid waxes, lithium stearate, aluminum stearate Metal soaps such as ethylenediamine/stearic acid/sebacic acid polycondensates, release agents such as silicone compounds, coloring inhibitors such as hypophosphite, (3,9-bis[2-(3-(3 - phenolic such as t-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane) Antioxidants, phosphorus-based antioxidants such as (bis(2,4-di-cumylphenyl)pentaerythritol-di-phosphite), water, lubricants, UV inhibitors, colorants, foaming agents, etc. Usual additives can be blended into the PPS resin composition. If any of the above compounds exceeds 20% by weight of the entire composition, the inherent properties of the (A) PPS resin are impaired, so it is preferable to add 10% by weight or less, more preferably 1% by weight or less.

Furthermore, for the purpose of improving the adhesion between the fibrous filler and the polyamide resin and suppressing the warp deformation of the resin liner when absorbing water, the fibrous filler contains at least one selected from epoxy group, amino group, isocyanate group, hydroxyl group, and mercapto group. It is possible to treat the surface with an alkoxysilane compound having one functional group. Specific examples of such compounds include epoxy group-containing alkoxysilanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Compound; Mercapto group-containing alkoxysilane compounds such as γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane; γ-ureidopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane, γ-(2-ureidoethyl ) Ureido group-containing alkoxysilane compounds such as aminopropyltrimethoxysilane; γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropylmethyldimethoxysilane, γ-isocyanatopropylmethyldiethoxy silane, isocyanato group-containing alkoxysilane compounds such as γ-isocyanatopropylethyldimethoxysilane, γ-isocyanatopropylethyldiethoxysilane, γ-isocyanatopropyltrichlorosilane; γ-(2-aminoethyl)aminopropylmethyldimethoxysilane , γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and other amino group-containing alkoxysilane compounds; and γ-hydroxypropyltrimethoxysilane, γ-hydroxypropyltriethoxysilane, and other hydroxyl groups. Containing alkoxysilane compound etc. are mentioned.

<Method for producing polyamide resin composition>
The polyamide resin composition used in the present invention is usually obtained by melt-kneading. The melt-kneader is supplied to a commonly known melt-kneader such as a single-screw or twin-screw extruder, a Banbury mixer, a kneader, and a mixing roll, and kneaded at a processing temperature of +5 to 100°C of the melting peak temperature of the polyamide resin. A typical example is a method of In this case, there are no particular restrictions on the order in which the raw materials are mixed, and all the raw materials are mixed and then melt-kneaded by the above method. Either a method of melt-kneading, or a method of blending a part of the raw materials and then mixing the rest of the raw materials using a side feeder during melt-kneading with a single-screw or twin-screw extruder may be used. As for the small amount of the additive component, it is of course possible to knead the other components by the above-described method, pelletize the pelletized product, and then add the pelletized product before molding.

<Reinforcing fiber composite material>
The reinforcing fiber composite material of the reinforcing layer covering the outer surface of the liner body of the present invention is a hardened product obtained by impregnating a reinforcing fiber bundle with a thermosetting resin and curing it by heating.

The thermosetting resin used in the present invention is not particularly limited as long as it is liquid, and examples thereof include epoxy resins, unsaturated polyester resins, phenol resins, urea resins, and melamine resins. In particular, epoxy resins having compounds such as phenols, amines, carboxylic acids, and intramolecular unsaturated carbons as precursors are preferable because of their high adhesive strength.

Glycidyl ether-type epoxy resins having phenols as precursors include bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol S-type epoxy resin, epoxy resin having a biphenyl skeleton, phenol novolac-type epoxy resin, cresol novolac-type epoxy resin. Resins, resorcinol-type epoxy resins, epoxy resins having a naphthalene skeleton, trisphenylmethane-type epoxy resins, phenol aralkyl-type epoxy resins, dicyclopentadiene-type epoxy resins, diphenylfluorene-type epoxy resins, and their various isomers, alkyl, and halogen substitutions body, etc. Compounds obtained by modifying epoxy resins made of phenols with urethane or isocyanate are also included in this type.

Glycidylamine-type epoxy resins using amines as precursors include positional isomers of tetraglycidyldiaminodiphenylmethane, glycidyl compounds of xylenediamine, triglycidylaminophenol, and glycidylaniline, and alkyl- and halogen-substituted products. mentioned.

Examples of epoxy resins having a carboxylic acid as a precursor include various isomers of glycidyl compounds of phthalic acid, hexahydrophthalic acid, and glycidyl compounds of dimer acid.

Examples of epoxy resins having intramolecular unsaturated carbon as a precursor include alicyclic epoxy resins.

The curing agent used for curing the thermosetting resin of the present invention by heating is not particularly limited as long as it cures the thermosetting resin. It may be a curing agent that undergoes an addition reaction such as amine or anhydride, or a curing catalyst that causes addition polymerization such as cationic polymerization or anionic polymerization, or two or more curing agents may be used in combination. A compound having an amino group, an acid anhydride group, or an azide group is preferably suitable as the curing agent. For example, dicyandiamide, alicyclic amines, aliphatic amines, aromatic amines, aminobenzoic acid esters, various acid anhydrides, phenolic novolac resins, cresol novolak resins, imidazole derivatives, phenolic compounds such as t-butylcatechol, etc. and Lewis acid complexes such as boron trifluoride complexes and boron trichloride complexes.

As for the fibers that constitute the reinforcing fiber bundle used in the reinforcing fiber composite material of the present invention, the types of reinforcing fibers are not particularly limited, and carbon fibers, metal fibers, organic fibers, and inorganic fibers are exemplified. You may use 2 or more types of these.

Examples of carbon fibers include PAN-based carbon fibers made from polyacrylonitrile (PAN) fibers, pitch-based carbon fibers made from petroleum tar or petroleum pitch, and cellulose-based carbon made from viscose rayon, cellulose acetate, or the like. fibers, vapor-grown carbon fibers made from hydrocarbons, and graphitized fibers thereof; Among these carbon fibers, PAN-based carbon fibers are preferably used because they have an excellent balance between strength and elastic modulus.

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

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

Examples of inorganic fibers include fibers made of inorganic materials such as glass, basalt, silicon carbide, and silicon nitride. Glass fibers include, for example, E glass fiber (for electrical use), C glass fiber (for corrosion resistance), S glass fiber, and T glass fiber (high strength and high modulus of elasticity). Basalt fiber is a fibrous material made from mineral basalt, and is a fiber with extremely high heat resistance. Basalt generally contains 9 to 25% by weight of iron compounds FeO or FeO2 and 1 to 6% by weight of titanium compounds TiO or TiO2. Fiberization is also possible.

Since the fiber-reinforced resin base material in the first and second forms of the present invention is often expected to serve as a reinforcing material, it is desirable to exhibit high mechanical properties. Preferably, the reinforcing fibers contain carbon fibers.

In the fiber-reinforced resin substrates according to the first and second embodiments of the present invention, the reinforcing fibers are usually configured by arranging one or more reinforcing fiber bundles in which a large number of single fibers are bundled. The total number of reinforcing fiber filaments (number of single fibers) when one or more reinforcing fiber bundles are arranged is preferably 1,000 to 2,000,000.

From the viewpoint of productivity, the total number of filaments of the reinforcing fibers is more preferably 1,000 to 1,000,000, still more preferably 1,000 to 600,000, and 1,000 to 300,000. Especially preferred. The upper limit of the total number of filaments of the reinforcing fibers should be such that good productivity, dispersibility, and handleability can be maintained in consideration of the balance between dispersibility and handleability.

The pinch-off portion formed in the dome portion of the liner body of the present invention will be described below.

At the time of direct blow molding, part of a cylindrical hot parison made of thermoplastic resin is sandwiched between a pair of molds, forming a streaky pinch-off portion (Fig. 4) extending in the axial direction of the liner into the dome portion. It is formed. Since part of the parison resin is constrained by the mold at the pinch-off part, a part with a different thickness from other parts is created, and the pinch-off part extending in the axial direction becomes thin, which tends to reduce the strength of the pinch-off part. The thickness of the pinch-off portion must be 1.15 times greater than the thickness of the dome portion.

If the pinch-off portion formed in the dome portion of the present invention is not firmly adhered, the pressure resistance performance of the pressure vessel is significantly reduced. 0.45 MPa) should be 200°C. The upper limits are a tensile strength of 300 MPa, a bending elastic modulus of 25 GPa, and a deflection temperature under load of 260° C. at the pinch-off portion when 200 parts by weight of the fibrous filler is contained in 100 parts by weight of the polyamide resin.

<Method for manufacturing pressure vessel>
A method for manufacturing a 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 the distance from the straight body portion increases, the straight body portion and A method for manufacturing a pressure vessel, wherein the dome portion is formed of a liner body made of a thermoplastic resin and an outer shell in which the outer surface of the liner body is covered with a reinforcing layer made of a hardened reinforced fiber composite material. , The liner body is formed by extruding a thermoplastic resin at an extrusion speed of 0.10 kg / sec to 0.50 kg / sec to make a hot parison, fixing the upper and lower ends of the hot parison with a mold, and increasing the melting point of the thermoplastic resin + 10 A method of manufacturing a pressure vessel, characterized by molding by direct blow molding under molding conditions of ℃ or higher, winding a reinforcing fiber composite material around the liner body, and curing the liner body to form an outer shell.

<Method for manufacturing pressure vessel resin liner>
Of these methods, it is important to use the direct blow molding method (FIG. 5) as the method for manufacturing the liner body constituting the pressure vessel of the present invention. Direct blow molding is a hot parison type in which air is directly blown into the molten extruded hot parison before it cools, and is also called extrusion blow molding. The resin heated and melted by the extruder is extruded into a tubular shape (hot parison) from the die head, and the molten parison is sandwiched between the molds. In the present invention, the air is usually blown from the upper side of the mold, but a method of blowing from the lower side and lateral direction of the mold may also be used. In the direct blow molding method, dents called pinch-offs (Fig. 4) occur in the process of sandwiching the hot parison between the molds. When pressure is applied from the inside of the molded product, cracks develop from the pinch-offs and break easily. Therefore, in the present invention, it is necessary to control the hot parison extruding speed within the range of 0.10 kg/sec to 0.5 kg/sec in order to improve the depression of the pinch-off portion. If the hot parison extrusion speed is less than the lower limit of 0.10 kg/sec, the melt residence time in the extruder becomes long, and the resin is thermally deteriorated, resulting in a decrease in strength, which is not preferable. If the hot parison extrusion speed exceeds the upper limit of 0.50 kg/sec, the hot parison discharge speed is too high and resin burning may occur due to shear force, which is not preferable. Further, in the present invention, the temperature for forming the hot parison should be the melting point of the thermoplastic resin plus 10° C. or higher in order to strengthen the adhesion of the pinch-off portion. However, if the hot parison forming temperature is higher than the melting point +100° C., the thermal decomposition of the resin progresses and the viscosity of the resin decreases, and the hot parison draws down, making molding impossible. Further, in the present invention, it is preferable to use an inert gas (nitrogen, helium, argon, etc.) with an oxygen concentration of 10% or less in the hot parison blowing process during direct blow molding in order to improve strength by improving oxidation deterioration of the resin liner. . If air is used in the hot parison blowing process, the resin liner may deteriorate due to oxidation and become brittle, which is not preferable.

<Manufacturing method of outer shell>
It comprises a cylindrical straight body part of the present invention and dome parts provided at both ends of the straight body part and having a shape that narrows as it separates from the straight body part, and the straight body part and the dome part are thermoplastic. A method for manufacturing a pressure vessel formed of a resin liner body and an outer shell in which the outer surface of the liner body is covered with a reinforcing layer made of a hardened reinforced fiber composite material, wherein the outer surface of the liner body is A method of forming an outer shell covered with a reinforcing layer made of a hardened reinforcing fiber composite material (referred to as a filament winding method) will be described below.

This manufacturing method is a step 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), a step (b) in which the molded product intermediate is held at room temperature and the thermosetting resin composition impregnated in the reinforcing fiber composite material is flowed, and after step (b), the molded product intermediate is It is constituted by the step (c) of heating to obtain a cured product of the reinforcing fiber composite impregnated with the thermosetting resin. In the present invention, normal temperature means a temperature in the range of 5°C to 35°C.

In step (a) of preparing an intermediate molded product, the reinforcing fiber composite material is pulled out, impregnated with a thermosetting resin composition, and then wound around a liner. The liner can be freely selected depending on the application of the filament winding molded product. For example, in the manufacture of hollow pipe members, it is possible to use cylindrical liners that can be de-cored after the molded product has been cured, and liners of various shapes that can be de-cored by being melted by heating. be. In the production of the pressure vessel, it is possible to use a liner or the like made of metal or resin that ensures a sealing performance with respect to a predetermined content. As a method of winding the reinforcing fiber composite material impregnated with the thermosetting resin composition around the liner, it is possible to move freely relative to the liner from the viewpoint of moldability and mechanical properties of the molded product. It is preferable to supply the reinforcing fiber composite material from the head portion and arrange the reinforcing fiber composite material so as to satisfy the required performance of the filament winding molded product.

In the step (b) of holding the molded product intermediate at room temperature, the thermosetting resin composition impregnated in the reinforcing fiber composite material is at least part of the process by holding the molded product intermediate at room temperature. A state of fluidity is maintained. In a state where the thermosetting resin composition can flow, the air bubbles that have entered the reinforcing layer of the reinforcing fiber composite material obtained in step (a) are affected by the buoyancy acting on the air bubbles and when the fibers are wound around the core. It is exposed on the surface layer of the reinforcing layer of the reinforcing fiber composite material due to tightening of the winding or the like caused by the tension remaining in the fibers. Therefore, by keeping the molded product intermediate at room temperature, at least some of the air bubbles in the reinforcing layer of the reinforcing fiber composite material can be removed, and the voids remaining in the filament winding molded product can be reduced. The intermediate molded product can be held while rotating about the liner of the intermediate molded product. As a result, the fluid thermosetting resin composition can be prevented from dripping and falling off due to gravity. Detachment of the thermosetting resin composition may increase the fiber volume content (Vf: %) of the filament-wound molded product, degrading product performance. In addition, the dropped thermosetting resin composition is often discarded, resulting in poor product yield. By rotating the molded product intermediate while holding it, it is possible to eliminate the influence of falling off of the thermosetting resin composition.

In holding the molded product intermediate, the holding temperature is room temperature, preferably within the range of room temperature, and an arbitrary temperature ± 5 ° C. determined according to the type of thermosetting resin composition and the conditions of use. can be done. When this arbitrary temperature range of ±5°C exceeds the normal temperature range, the excess shall be rounded down. Depending on the type and conditions of use of the thermosetting resin composition, when the temperature is high, gelation of the thermosetting resin composition proceeds rapidly, and there is a risk that sufficient resin flow time cannot be secured. In addition, when the temperature is low, the viscosity of the thermosetting resin composition decreases, and it may take a longer time to obtain the same degree of void reduction effect as compared to when the temperature is high. Therefore, the holding temperature is not particularly limited as long as it is normal temperature, but it is preferably within a range determined according to the type of the thermosetting resin composition to be used and the conditions of use.

In the step (c) of obtaining a cured product of the reinforcing fiber composite material impregnated with the thermosetting resin, the thermosetting resin composition is thermally cured by heating the molded product intermediate after being kept at room temperature, but the method is limited. It can be heated using any method such as a heater or an induction heating coil. During heating, the molded product intermediate can be held while rotating. By rotating and holding the molded product intermediate, the thermosetting resin composition can be prevented from coming off.

The step (a) of preparing a molded product intermediate, the step (b) of maintaining the molded product intermediate at room temperature, and the step (c) of obtaining a cured product of a reinforcing fiber composite material impregnated with a thermosetting resin, There are no restrictions on where it can be implemented. In other words, the intermediate molded product may be moved between step (a) and step (b), or the steps may be performed continuously without moving. Moreover, the molded product intermediate may be moved between the step (b) and the step (c), or the steps can be performed continuously without moving. Furthermore, when the intermediate molded product is moved between the step (b) and the step (c), it can be moved to the place where the step (a) was performed.

The filament winding molded article obtained by the present invention can be widely used for 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 also ships, aircraft, etc. It is preferably used for Substances stored in this pressure vessel may be gases such as nitrogen, oxygen, argon, liquefied petroleum gas and hydrogen, and liquefied substances of the above substances.

<Method for analyzing oxidation deterioration of resin liner>
In order to improve the strength and toughness at the time of pinch-off adhesion, the resin liner of the present invention has a peak strength ratio due to material oxidation deterioration in the range of 1700 cm ^-1 to 1750 cm ^-1 in FT-IR measurement. The peak strength/the peak strength of the resin material before direct blow molding) should be 0.005 or less, more preferably 0.002 or less. As the FT-IR measurement method of the present invention, specifically, about 1 g of the surface of the molded product is cut out at three locations, and an ATR method (attenuation Total reflection method: Detector DLaTGS, incident angle 45°, Ge prism, resolution 4 cm ⁻¹ ). Then, the degree of oxidative deterioration was quantitatively evaluated based on the magnitude of the absorption peak intensity in the wavelength range of 1700 cm ⁻¹ to 1750 cm ⁻¹ , which is likely to be observed when the resin thermally decomposes due to oxidative deterioration. FIG. 6 shows the ^{FT -} IR analysis results of the resin liner under oxidatively deteriorated blow molding conditions and under oxidative deterioration suppressed blow molding conditions. It can be seen that there is a difference in the absorption peak intensity, and that the absorption peak is hardly observed under the blow molding conditions in which oxidative degradation is suppressed.

<Tensile test at pinch-off portion of resin liner>
The pinch-off portion of the dome portion of the direct blow molded resin liner (thickness 3 mm) was cut into strips of width 15 mm x length 125 mm, and subjected to a tensile test (n = 5 each) in accordance with ASTM D3039. ) was performed and the tensile strength was measured.

<Bending test at pinch-off portion of resin liner>
The pinch-off portion of the dome portion of the direct blow molded resin liner (thickness 3 mm) was cut into strips of width 15 mm x length 125 mm, and a bending test was performed in accordance with ASTM D790 (each n = 3 ) was performed and the flexural modulus was measured.
<Measurement of deflection temperature under load at pinch-off portion of resin liner>
The pinch-off portion of the dome portion of the direct blow molded resin liner (thickness 3 mm) was cut into strips of width 15 mm x length 125 mm, and the deflection temperature under load (load 0.00) was measured according to ASTM D648. 45 MPa, each n=3) was performed, and the deflection temperature under load was measured.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the description of these examples. Evaluation of physical properties in each example and comparative example was carried out according to the following methods.

[Method for manufacturing resin liner]
Using an accumulator-type extrusion blow molding device manufactured by Tahara, under the blow molding conditions of each example and comparative example, the resin liner shape shown in FIG. outer diameter φ24 mm) was obtained.
<Extrusion blow molding equipment/equipment specifications>
・Extruder screw diameter: φ80mm
・Extruder screw arrangement: Deep groove full flight specification ・Accumulation pump capacity: 4000cc
・Extruder screw speed: 35 rpm
・Die shape: Die purge <Molding conditions>
・Hot parison length: 70mm
・Hot Parison Weight: 2000g
・Hot parison blowing gas: Air or inert gas (using nitrogen gas)

[Hot parison extrusion speed measurement method]
Under the blow molding conditions of each example and comparative example, the time when the hot parison was extruded to a length of 70 mm (parison weight of 2000 g) was measured with a stopwatch (N = 3), and the extrusion speed (kg / sec) was measured. Calculated.

[Method for measuring hot parison formation temperature]
The surface temperature of the parison (70 mm in length) extruded under the blow molding conditions of each example and comparative example was measured by infrared thermography (non-contact type). The measurement was made at two points on the parison extruding side and the side opposite to the parison extruding direction (hereinafter referred to as the anti-extrusion side).

[FT-IR measurement of resin liner (degree of oxidation deterioration of resin material)]
About 1 g of the inner surface of the resin liner obtained above was cut out at three points, and measured by the ATR method using an FT-IR device (Bruker: TENSOR II). Then, the absorption peak intensity ratio in the wavelength range of 1700 cm ^-1 to 1750 cm ^-1 (the peak intensity of the resin liner molded product / the peak intensity of the resin raw material before blow molding), which is likely to be observed due to the thermal decomposition of the resin due to oxidative deterioration. The degree of oxidative deterioration was quantitatively evaluated by the size of . In addition, it can be said that the resin liner that is less oxidatively deteriorated as the numerical value is smaller.
<Measurement conditions>
・Light source: Glover (SiC)
・Detector: DLaTGS
・Resolution: 4 cm ^-1
・Accumulated times: 128 times ・Attached equipment: Thunder dome, single-reflection ATR, incident angle 45°, Ge prism used

[Tensile test of resin liner/pinch-off part (pinch-off adhesion)]
The pinch-off portion of the dome portion of the resin liner obtained above was cut into strips of width 15 mm x length 125 mm from two locations on the parison extrusion direction side and the parison counter extrusion direction side, and cut in accordance with ASTM D3039. Tensile tests (n=5 each) were performed to measure the tensile strength. Incidentally, it can be said that the resin liner with a higher pinch-off adhesion has a higher numerical value.

[Bending test of resin liner/pinch-off part (rigidity of pinch-off part)]
The pinch-off portion of the dome portion of the direct blow molded resin liner (thickness 3 mm) was cut into strips of width 15 mm x length 125 mm, and a bending test was performed in accordance with ASTM D790 (each n = 3 ) was performed and the flexural modulus was measured. Incidentally, it can be said that the resin liner having a higher pinch-off portion rigidity has a higher numerical value.

[Measurement of load deflection temperature of resin liner/pinch-off part (heat resistance of pinch-off part)]
The pinch-off portion of the dome portion of the direct blow molded resin liner (thickness 3 mm) was cut into strips of width 15 mm x length 125 mm, and the deflection temperature under load (load 0.00) was measured according to ASTM D648. 45 MPa, each n=3) was performed, and the deflection temperature under load was measured. In addition, it can be said that the larger this value is, the less likely the pinch-off portion is to be thermally deformed in the resin liner.

[Pressure vessel manufacturing method by filament winding method and pressure resistance test (pressure resistance)]
The liner obtained above is installed in a filament winding forming apparatus, and a liquid thermosetting resin composition (epoxy main agent: curing agent = 100:32 mass ratio) is uniformly mixed at 25 ° C. and normal temperature to the winding core. ) was supplied to one yarn bundle of carbon fiber “Torayca” (registered trademark) T700SC-24K manufactured by Toray Industries, Inc. while being impregnated with the resin. It was wound in a range of width 60 mm at a winding angle of ±83° with respect to the axial direction of the winding core, and laminated to a thickness of 1 mm to prepare an intermediate molded article. After the fiber winding, the intermediate was held at 20° C. for 15 minutes while rotating at a speed of 7 rpm. At the start of holding, the viscosity of the resin was 1100 mPa·s.

After the holding, the molded product intermediate 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 obtain a pressure vessel for pressure testing. Next, the pressure vessel obtained above was installed in the pressure vessel hydraulic burst test apparatus shown in FIG. , the pressure resistance performance was evaluated according to the following criteria.
<Pressure resistance/judgment criteria>
○: Bursting pressure 100 MPa or more △: Bursting pressure 80 MPa or less ×: Bursting pressure 50 MPa or less

〔material〕
In the examples and comparative examples, the following raw materials were used.

<Reference Example 1> Thermoplastic resin used for direct blow molding Glass fiber reinforced nylon 6 resin-1: CM1046K4 (manufactured by Toray Industries, Inc., grade for blow molding containing 20% glass fiber, glass fiber deformation ratio 1.0, ( Registered Trademark) Amilan)
Glass fiber reinforced nylon 6 resin-2: Only the glass fiber containing CM1046K4 is changed to modified cross-section glass fiber (manufactured by Nittobo Co., Ltd. CSG-3PA-830, deformation ratio 4.0) Nylon 6 resin: CM1056 (Toray Industries, Inc. ), grade for high-viscosity, high-impact blow molding, does not contain fibrous filler, (registered trademark) Amilan)

<Reference Example 2> Liquid thermosetting resin composition Epoxy main agent: Bisphenol A type liquid epoxy resin (“jER” (registered trademark) 828 (manufactured by Mitsubishi Chemical Corporation))
Curing agent: mixture of poly(propylene glycol) diamine, isophorone diamine, cyclohexylamine, polypropylene glycol (“ARADUR” (registered trademark) 3486 (manufactured by Huntsman Japan Co., Ltd.))

As described above, by comparing the examples and the comparative examples, the resin liner and the pressure vessel of the present invention improved the pinch-off dent as shown in FIG. It can be seen that a pinch-off portion that exhibits heat resistance is formed, and a dramatic improvement in pressure resistance performance is realized.

101 Pressure vessel 102 Reinforcing fiber composite material 103 Liner container 104 Base part 201 Cylindrical straight body part 202 Semispherical dome parts 301 provided at both ends of the straight body part Injection molded liner (half split part)
302 Injection molded liner (welded half parts)
401 Direct blow molding liner 402 Pinch-off dented portion 501 Single screw extruder 502 Direct blow molding die 503 Hot parison 701 Direct blow molding liner with large pinch-off dent 702 Direct blow molding liner with small pinch-off dent

Claims (9)

A liner main body comprising a cylindrical straight body portion and dome portions provided at both ends of the straight body portion and tapering away from the straight body portion, wherein the straight body portion and the dome portion are made of a thermoplastic resin. and an outer shell in which the outer surface of the liner body is covered with a reinforcing layer made of a hardened reinforced fiber composite material, wherein the liner body is manufactured by direct blow molding, and A pressure vessel, wherein a pinch-off portion formed in the dome portion has a tensile strength of 100 MPa or more, a bending elastic modulus of 6 GPa or more, and a deflection temperature under load (0.45 MPa load) of 200° C. or more. 2. The pressure vessel according to claim 1, wherein the thermoplastic resin used for the liner body is a polyamide resin composition containing 15 to 200 parts by weight of fibrous filler with respect to 100 parts by weight of polyamide resin. 3. The pressure according to claim 1, wherein the thickness of the pinch-off portion formed in the dome portion is 1.15 to 1.30 times the thickness of the dome portion. container. 4. The pressure vessel according to claim 2 or 3, wherein the fibrous filler contained in the polyamide resin composition is a modified cross-section glass fiber having a modified cross-section ratio of 1.3 or more and 10 or less. The pressure vessel according to any one of claims 2 to 4, wherein the polyamide resin contained in the polyamide resin composition is either nylon 11 or nylon 12. The peak intensity ratio (the peak intensity of the direct blow molded product/the peak intensity of the resin material before direct blow molding) measured by FT-IR on the inner surface of the liner body at a measurement wavelength of 1700 ^-1 to 1750 cm ^-1 is 0.005 or less. The pressure vessel according to any one of claims 1 to 5, characterized in that: A cylindrical straight body portion and dome portions provided at both ends of the straight body portion and having a shape that tapers away from the straight body portion, wherein the straight body portion and the dome portion are formed of a thermoplastic resin liner. A method for manufacturing a pressure vessel formed of a main body and an outer shell in which the outer surface of the liner main body is covered with a reinforcing layer made of a hardened reinforced fiber composite material,
The liner body is formed by extruding a thermoplastic resin at an extrusion speed of 0.10 kg/sec to 0.50 kg/sec to form a hot parison, fixing the upper and lower ends of the hot parison with a mold, and adding the melting point of the thermoplastic resin + 10 ° C. Molded by direct blow molding under the above molding conditions,
A method of manufacturing a pressure vessel, comprising winding a reinforcing fiber composite material around the liner body and curing the material to form an outer shell. 8. The method according to claim 7, wherein the molds are a pair of molds for fixing the upper and lower ends of the hot parison from the left and right, and form a pinch-off portion that presses and integrates the upper and lower ends of the parison other than the central portions. A method of manufacturing the described pressure vessel. 9. The method of manufacturing a pressure vessel according to claim 7, wherein in the direct blow molding, an inert gas having an oxygen concentration of 1% or more and 10% or less is blown into the hot parison.

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