JP3591034B2 - Gas cylinder and manufacturing method thereof - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to various gas cylinders, particularly to gas cylinders suitable for being mounted on automobiles and the like, and to a method for producing the same.
[0002]
[Prior art]
In recent years, vehicles using natural gas as fuel have attracted attention in the United States and other countries as low-emission vehicles. Such an automobile is equipped with a gas cylinder generally called a CNG tank (Compressed Natural Gas Tank).
[0003]
Such gas cylinders for automobiles are conventionally made of metal such as steel or aluminum alloy, but those made of metal are heavy and reduce fuel consumption. In addition, since the calorific value per unit weight of natural gas is only about half that of gasoline, trying to increase the distance that can be run without refueling to the level of a gasoline-powered vehicle uses about twice as much natural gas as gasoline. And this also increases the gross vehicle weight and reduces fuel economy. Therefore, reduction of the weight of gas cylinders is being studied as a measure to improve fuel efficiency.
[0004]
Incidentally, Japanese Patent Publication No. 5-88665 describes a gas cylinder in which a plastic inner shell having gas barrier properties is covered with a pressure-resistant outer shell made of FRP (fiber reinforced plastic). Since this gas cylinder is essentially made of plastic, it is considerably lighter than a metal cylinder. If this gas cylinder is used as a natural gas cylinder for automobiles, an improvement in fuel efficiency can be expected.
[0005]
However, since FRP is more brittle than metal, cracks or the like may occur when a large impact force is applied from the outside. When the crack propagates, the pressure resistance and strength of the outer shell made of FRP may be rapidly reduced. Even if the damage is not significant, if the impact force is applied to the same location many times, the cracks and the reinforcing fibers may be damaged, and the pressure resistance and strength may be reduced.
[0006]
[Problems to be solved by the invention]
The object of the present invention is to pay attention to the above-mentioned problems, and to provide the outer shell made of FRP of a gas cylinder with toughness, while maintaining high pressure resistance, suppressing the propagation of cracks and damage to reinforcing fibers, and improving the impact resistance. And to improve fatigue resistance.
[0007]
It is another object of the present invention to enable such a gas cylinder to be manufactured easily and at low cost.
[0008]
[Means for Solving the Problems]
A gas cylinder of the present invention that meets the above object is a gas cylinder having an inner shell having gas barrier properties and a pressure-resistant FRP outer shell provided so as to cover the inner shell, wherein the outer shell has the following constituent elements. [A], [B], and [C], and the component [A] is integrally formed in a state of being included in the component [B], and also appears on the cut surface of the outer shell. A portion (10) consisting of only the component [C] appears around the molded portion.
[A]: reinforcing fiber bundle [B]: cured product of thermosetting resin [C]: elastomer and / or thermoplastic resin
The method for producing a gas cylinder according to the present invention includes the following components [A], [B], and [C] around an inner shell having gas barrier properties, and the component [A] includes the component [B]. ], And forming a pressure-resistant FRP shell using a yarn prepreg in which the component [C] is present near the surface.
[A]: Reinforcing fiber bundle [B]: Thermosetting resin [C]: Elastomer and / or thermoplastic resin
FIG. 1 shows a gas cylinder according to one embodiment of the present invention. In FIG. 1, a gas cylinder 1 has an inner shell 2 having a gas barrier property and a pressure-resistant FRP outer shell 3 provided so as to cover the inner shell 2. This gas cylinder 1 has a body part A, a head plate part B following it, a nozzle mounting base 4 and a nozzle 5 attached thereto, and a boss 6 provided on the bottom of the cylinder as a whole.
[0011]
In the above, the inner shell 2 has an action of preventing gas leakage. In addition, it also acts as a core when forming a pressure-resistant outer shell as described later.
[0012]
The inner shell 2 is made of, for example, a resin such as a polyethylene resin, a polypropylene resin, a polyamide resin, an ABS resin, a polybutylene terephthalate resin, a polyacetal resin, and a polycarbonate resin. ABS resin is preferable in terms of excellent impact resistance. The resin inner shell 2 can be manufactured by, for example, a well-known blow molding method, and can be integrally connected to the nozzle mounting base 4 at the time of blow molding. By using the composite blow molding method, it is also possible to form a multilayer structure in which a layer of, for example, a polyamide resin having excellent gas sealing properties is sandwiched between layers of, for example, a high-density polyethylene resin having excellent rigidity. Further, the inner shell 2 may be made of FRP. Such an inner shell 2 made of FRP can be manufactured by, for example, injection-molding a resin containing a short fiber having a fiber length of about 2 to 10 mm of a reinforcing fiber used for the outer shell 3 as described later. . Further, the inner shell 2 may be made of a metal, for example, a light alloy such as a thin aluminum alloy or a magnesium alloy.
[0013]
The inner shell 2 has a function of preventing gas leakage as described above. In order to improve such action, it is also preferable to form a gas barrier layer on the inner surface and / or the outer surface. For example, when a nitrogen gas containing fluorine is used as a blowing gas at the time of blow molding, a gas barrier layer made of a fluororesin film can be formed on the inner surface of the inner shell 2. Alternatively, a gas barrier layer can be formed by forming a plating film of a metal such as copper, nickel, and chromium on the outer surface. The metal plating film can be formed by an electrolytic plating method or an electroless plating method. When the inner shell 2 is manufactured by a composite blow molding method, a layer of a polyamide resin or the like having excellent gas barrier properties is disposed on the inner side, and a layer of easy plating, for example, an ABS resin is disposed on the outer side. Molding can also be facilitated.
[0014]
The inner shell may be provided with ring-shaped ribs extending in the circumferential direction at intervals of about 2.5 to 5 cm on the inner surface. Such an inner shell can be obtained, for example, by forming a half-shell inner shell made of plastic with ribs, and joining and integrating them. This rib improves the strength of the inner shell, prevents deformation of the inner shell when the outer shell of the FRP described later is formed, reduces the strength of the outer shell due to meandering and uneven distribution of the reinforcing fibers of the FRP layer forming the outer shell, This is useful for preventing variation in strength and, consequently, reduction in pressure resistance performance.
[0015]
On the other hand, the outer shell 3 is made of FRP from the viewpoint of providing pressure resistance and reducing the weight of the entire gas cylinder 1. The outer shell 3 made of such FRP is formed by forming the above-described inner shell 2 as a so-called mandrel, forming a wound layer of a reinforcing fiber yarn containing a resin therearound by a known filament winding method or tape winding method. It can be configured by the following. At this time, if the outer surface of the inner shell 2 is formed as a rough surface having an average height of about 10 to 200 μm, slippage of the reinforcing fiber yarn during winding can be prevented, and disturbance of the reinforcing fiber distribution can be reduced. preferable.
[0016]
This outer shell is made up of components [A], [B] and [C] as shown in FIG.
The component [A] is a reinforcing fiber bundle. The number of single fibers constituting the fiber bundle is preferably in the range of 1,000 to 500,000 filaments, more preferably 3,000 to 50,000 filaments. Further, in order to obtain a thick fiber bundle, a plurality of fiber bundles may be combined, and conversely, in order to obtain a thin material, the thick material may be separated.
[0017]
As the reinforcing fiber yarn, at least one of high-strength and high-modulus fiber yarns such as carbon fiber yarn, graphite fiber yarn, glass fiber yarn, and organic high-modulus fiber (for example, polyaramid fiber) can be used. These reinforcing fiber yarns are preferably non-twisted fiber yarns that are excellent in opening property, in that stress concentration due to bending can be reduced and voids can be reduced. Among such reinforcing fiber yarns, the specific strength and the specific elastic modulus are excellent (excellent in weight saving effect), and there is almost no occurrence of yarn breakage or fluff during winding, and not only the productivity is improved, but also the yarn Carbon fiber yarns that can prevent a decrease in strength characteristics and a decrease in impact resistance performance due to the incorporation of seams or fluff are preferred.
[0018]
The component [B] is made of (a cured product of) a thermosetting resin.
As the thermosetting resin, an epoxy resin is particularly mentioned, and it is generally used in combination with a curing agent or a curing catalyst. Particularly, an epoxy resin using an amine, a phenol, or a compound having a carbon-carbon double bond as a precursor is preferable. Specifically, various isomers of tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, and triglycidylaminocresol, and phenols are used as epoxy resins with amines as precursors. Bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, a compound having a carbon-carbon double bond as a precursor Examples of the epoxy resin include, but are not limited to, alicyclic epoxy resins. A brominated epoxy resin obtained by brominating these epoxy resins is also used.
[0019]
Examples of the curing agent include acid anhydrides (eg, methylnadic anhydride), amine-based curing agents (eg, metaphenylenediamine, methyldianiline, ethylmethylimidazole, isophoronediamine), polyaminoamide-based curing agents, and phenol-based curing agents (eg, For example, sparakidroxyphenylsulfone), a polymercaptan-based curing agent, and a latent curing agent (such as dicyandiamide) can be used. Further, these curing agents may be used in combination with a boron trifluoride amine complex, which is a so-called curing catalyst, or an imidazole compound. Further, a urea compound obtained by an addition reaction between isocyanate and dimethylamine may be used in combination.
[0020]
Examples of the thermosetting resin used for the component [B] include a maleimide resin, a resin having an acetylene terminal, a resin having a nadic acid terminal, a resin having a cyanate ester terminal, a resin having a vinyl terminal, and a resin having an allyl terminal. It is preferably used. These may be appropriately mixed with an epoxy resin or another resin. Further, a reactive diluent may be used, or a modifier such as a thermoplastic resin or an elastomer may be mixed and used to such an extent that heat resistance is not significantly reduced.
[0021]
As the component [B] of the present invention, a thermosetting resin widely recognized in the industry such as a phenol resin, a resorcinol resin, an unsaturated polyester resin, and a vinyl ester resin can also be used.
[0022]
The component [C] is an elastomer and / or a thermoplastic resin.
As the thermoplastic resin, the main chain has a bond selected from a carbon-carbon bond, an amide bond, an imide bond, an ester bond, an ether bond, a carbonate bond, a urethane bond, a thioether bond, a sulfone bond, an imidazole bond, and a carbonyl bond. A typical example is a thermoplastic resin. In particular, polyvinyl acetate, polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, polyaramid, polybenzimidazole, Polyethylene, polypropylene, cellulose acetate, and cellulose butyrate are suitable for the thermoplastic resin used in the present invention because of their excellent impact resistance. Among them, polyamide, polyimide, polyamideimide, polyetherimide, polyethersulfone, and polysulfone are particularly suitable for the present invention because of their high toughness and good heat resistance. Among them, the toughness of polyamide is particularly excellent, and is most suitable for the present invention.
[0023]
Various elastomers such as synthetic rubbers can be used as the elastomer, but a thermoplastic elastomer is particularly preferably used in the present invention. Examples of the thermoplastic elastomer include thermoplastic elastomers such as polystyrene, polyolefin, polyester, and polyamide.
[0024]
When an epoxy resin is used as the component [B], the solubility of the polystyrene or polyolefin thermoplastic elastomer in the epoxy resin is low, whereas the solubility of the polyester or polyamide thermoplastic elastomer in the resin is low. Since it is high, the bonding between the component [B] and the component [C] can be sufficiently strengthened, and a favorable composite material which does not peel off from each other when a stress is generated is obtained.
[0025]
Here, the polyester-based or polyamide-based thermoplastic elastomer is a block copolymer-type thermoplastic elastomer composed of a hard segment component and a soft segment component, wherein the hard segment component has a polyester or polyamide structure.
[0026]
The components [A], [B], and [C] as described above appear on the cut surface of the outer shell 3 as shown in FIG. 2, for example.
That is, the component [C] 9 exists around the component [A] 8 composed of the reinforcing fiber bundle integrated with the component [B] 7, and substantially between the adjacent components [A]. The portion 10 made of only the resin containing no reinforcing fiber clearly appears.
[0027]
In such a cut surface, the linear length of the connecting geometric centers of two adjacent component [A] and L _1, exists between the two components straight lines adjacent [A] component [C], i.e. when the length across the portion 10 comprising substantially only resin and _{L 2,} these ratios _L 2 / _{L 1,}
1/100 ≦ L ₂ / L ₁ ≦ 1/2
Preferably,
1/50 ≦ L ₂ / L ₁ ≦ １ ／
It is desirable to satisfy
[0028]
If L ₂ / L ₁ is smaller than 1/100, the development of cracks cannot be prevented. If L ₂ / L ₁ is larger than 1/2, the amount of resin increases and the weight of the cylinder increases.
[0029]
The component [A] in FIG. 2 is a cured product of a thermosetting resin, that is, molded integrally with the component [B]. The portion 10 made of only the resin [C] clearly appears.
[0030]
In such a cross-sectional structure, since the portion 10 composed of the component [C] is composed of a resin mainly composed of an elastomer and / or a thermoplastic resin, the component [A] and the component [B] Shows higher toughness than the integrally molded part. Therefore, it is possible to block the propagation of cracks and the propagation of damage to the reinforcing fiber at this portion, and prevent them from spreading. As a result, a decrease in the pressure resistance and strength of the outer shell 3 due to the occurrence of cracks and damage to the reinforcing fibers is suppressed, and the outer shell 3 as a whole can maintain excellent pressure resistance and strength.
[0031]
Further, since the high toughness portion 10 itself has an excellent impact energy absorbing function, the impact resistance of the outer shell 3 is greatly improved.
[0032]
Further, even in the case where the same portion of the outer shell 3 is repeatedly impacted, the damage and the crack of the reinforcing fiber are prevented from being propagated and expanded, so that the fatal damage does not progress.
[0033]
The outer shell 3 of the gas cylinder as described above includes components [A], [B], and [C] around an inner shell 2 having a gas barrier property formed in advance, and the component [A] includes The element [B] is impregnated, and the component [C] is formed by using a yarn prepreg existing near the surface, for example, by a filament winding method. Here, the component [B] is a component before solidification.
[0034]
As the component [C] in the yarn prepreg, it is preferable that the above-described material is formed into a particle.
The shape of the particles is not limited to a spherical shape. Of course, it may be spherical, but may be in various shapes such as fine powder obtained by crushing a resin lump or fine particles obtained by spray drying or reprecipitation. In addition, it may be in the form of a milled fiber in which fibers are cut short, or in the form of a needle or whisker. In particular, when it is desired to use spherical particles, the product obtained by the suspension polymerization method can be used as it is.
[0035]
The size of a particle is represented by a particle size, and the particle size in this case means a volume average particle size determined by a centrifugal sedimentation velocity method or the like.
The particle size of the particles used in the present invention is suitably in the range of 2 μm to 150 μm, and more preferably 5 μm to 100 μm. When the particle size is smaller than 2 μm, when the particles are to be arranged on the outer periphery of the reinforcing fiber bundle, the particles also enter the gap between the single fibers of the reinforcing fiber together with the component [B], and the particles This is because the prepreg may not exist on the surface of the prepreg. On the other hand, when the particle size of the particles is 2 μm or more, when the matrix resin containing the particles is impregnated into the reinforcing fiber bundle, the particles are excluded from the gaps between the single fibers of the reinforcing fibers. Since it is filtered, it will be present off the surface of the yarn prepreg.
[0036]
However, in the case of particles having a large anisotropy such as a milled fiber shape, a needle shape, and a whisker shape, even if the particle size is small, the particles hardly penetrate between filaments and tend to be eliminated on the surface of the yarn prepreg. Even if the particles have a particle size smaller than 2 μm, if the component [B] swells into the particles by mixing with the component [B] and the apparent particle size increases, The above-mentioned concept of the particle diameter is applied to the diameter.
[0037]
In the case of particles having a particle size of more than 150 μm, the physical properties of the composite material in order to disturb the arrangement of the reinforcing fibers or to increase the interval between fiber bundles and the thickness between layers in the composite material obtained by molding to an unnecessarily large value. May be reduced. However, even particles having a particle size exceeding 150 μm are partially dissolved in the constituent element [B] during molding and become small, or are deformed by heating during molding, so that filaments and interlayers of the composite material are deformed. There is also a material in which is narrower than before molding, in which case it can be used as a suitable material.
[0038]
The optimum value of the particle size may vary depending on the outer diameter of the reinforcing fibers used, the number of single fibers, and the like.
[0039]
Further, the component [C] may be formed as a fiber. The fibers may be long fibers or short fibers. Here, long fiber means a fiber having a length of 5 cm or more, and short fiber means a fiber having a length of less than 5 cm. When the component [C] is a fiber, if the single fiber fineness is too large, the interval between the fiber bundles in the composite material and the portion where the component [A] between the layers does not exist become unnecessarily thick, Since the physical properties of the molded article may be deteriorated by disturbing the arrangement of the component [A], the denier is preferably 15 denier or less, more preferably 5 denier or less.
[0040]
When the component [C] is a fiber, it is preferable that the crystallinity of the fiber be 40% or more by an operation such as drawing. If the crystallinity is low, the wet heat resistance may decrease.
[0041]
The component [C] may retain the original shape after molding, or may lose the shape.
[0042]
The yarn prepreg used in the present invention preferably has a flat cross section in a plane perpendicular to the longitudinal direction, whereby a cut surface structure as shown in FIG. It is possible to easily form the outer shell 3 having a small thickness which meets the requirements for the production. It is more preferable that the flat cross section has a major axis length of 2 mm or more and 30 mm or less.
[0043]
In the outer shell 3 of the gas cylinder according to the present invention, the component [C] needs to be present around the component [A] forming a group and its matrix resin . When such a condition is not satisfied, for example, when a large amount of the component [C] exists deep inside the component [A], the energy absorption in the boundary region becomes insufficient, and the FRP constituting the outer shell 3 becomes insufficient. The effect of improving the impact resistance and fracture toughness is small, the arrangement of the reinforcing fibers is disturbed, and the fraction of the matrix resin in the vicinity of the reinforcing fibers is reduced, so that the strength and heat resistance may be impaired.
[0044]
From such a viewpoint, as for the distribution of the component [C] in the yarn prepreg before molding, it is necessary that most of the component [C] be distributed near the surface of the yarn prepreg. When the outer shell 3 is formed from such a yarn prepreg, the component [C] exists in the boundary region between the yarn prepregs, so that an FRP having excellent impact resistance can be obtained. Here, “distributing near the surface” specifically means that 90% or more of the component [C] is present in a portion from the outer peripheral surface of the yarn prepreg to 30% of the minimum thickness of the yarn prepreg. It is more preferable that 90% or more of the component [C] be present in a region from the outer peripheral surface of the yarn prepreg to 20% of the minimum thickness of the yarn prepreg, since the effects of the present invention are more remarkably exhibited.
[0045]
Using such a yarn prepreg, the outer shell 3 of the gas cylinder according to the present invention is formed, for example, by a method shown in FIG.
[0046]
In the method shown in FIG. 3, the reinforcing fiber yarns 12 drawn out from the plurality of creels 11 are aligned as a reinforcing fiber bundle 13, and the reinforcing fiber bundle 13 is passed through a first resin bath 14 to be cured by heat. Matrix resin 15 made of a conductive resin is impregnated. The resin-impregnated reinforcing fiber bundle 16 is then passed through a tank 18 filled with a particulate or powdery component [C] 17, and the component [C] mainly near the surface of the resin-impregnated reinforcing fiber bundle 16. 17 are deposited. Further, the reinforcing fiber bundle 19 to which the component [C] 17 is adhered is passed through a second resin bath 20, and a matrix resin 21 made of a thermosetting resin is adhered to or impregnated from the surface. . The matrix resin 15 and the matrix resin 21 may be the same resin or different resins. Further, the second resin bath 20 can be omitted.
[0047]
The resin-impregnated reinforcing fiber bundle 22 having the component [C] attached in the vicinity of the surface, which has exited the second resin bath 20, is wound around the inner shell 2 at a predetermined winding angle by a filament winding method. , An outer shell 3 is formed. After winding, a desired outer shell 3 is formed by heating and curing the resin.
[0048]
In such a manufacturing method, since the second resin bath 20 can be omitted, the second resin bath 20 can be implemented simply by adding a device for applying the component [C] to the conventional filament winding device, and can be easily performed. In addition, the outer shell 3 excellent in target pressure resistance at low cost can be formed.
[0049]
In addition, the kind of gas filled in the gas cylinder according to the present invention is not particularly limited, and includes nitrogen, oxygen, helium gas and the like in addition to the natural gas as described above.
[0050]
【The invention's effect】
As described above, when using the gas cylinder of the present invention, the outer shell made of FRP is composed of the components [A], [B], and [C], and cracks and reinforcing fiber damage are caused in the portion composed of the component [C]. Therefore, it is possible to obtain a gas cylinder excellent in pressure resistance, impact resistance, and fatigue resistance while achieving the weight reduction effect of the FRP.
[0051]
Further, according to the method for producing a gas cylinder according to the present invention, the component [C] can be easily located at a predetermined position in the outer shell, and a desired gas cylinder can be produced easily and at low cost.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a gas cylinder according to one embodiment of the present invention.
FIG. 2 is an enlarged partial sectional view of a cut surface of an outer shell of the gas cylinder of FIG.
FIG. 3 is a schematic configuration diagram illustrating a method for manufacturing a gas cylinder according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Gas cylinder 2 Inner shell 3 Outer shell 4 Nozzle mounting base 5 Nozzle 6 Boss 7 Component [B]
8 Component [A]
9 Component [C]
Reference Signs List 10 Part composed of component [C] 11 Creel 12 Reinforcement fiber yarn 13 Reinforcement fiber bundle 14 First resin bath 15 Matrix resin 16 Resin impregnated reinforcement fiber bundle 17 Particulate or powdery component [C]
18 Tank for component [C] 19 Reinforcing fiber bundle 20 with component [C] attached Second resin bath 21 Matrix resin 22 Resin-impregnated reinforcing fiber bundle with component [C] attached

Claims (6)

A gas cylinder having an inner shell having gas barrier properties and a pressure-resistant FRP outer shell provided so as to cover the inner shell, wherein the outer shell includes the following components [A], [B], and [C]. And the component [A] is integrally formed in a state included in the component [B], and the component [C] is formed around the integrally formed portion that appears on the cut surface of the outer shell. ], Wherein the gas cylinder has a portion (10) consisting only of the gas cylinder.
[A]: Reinforcing fiber bundle [B]: Thermosetting resin [C]: Elastomer and / or thermoplastic resin The length L transverse to the length L ₁ of the straight line connecting the geometrical centers of two adjacent component [A], the component straight line exists between two adjacent components [A] [C] the ratio L ₂ / L ₁ and _2, which satisfies the _{1/100 ≦ L 2 / L} 1 ≦ 1/2, gas cylinder of claim 1. The constituent element [C] is polyvinyl acetate, polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, polyaramid 3. The gas cylinder according to claim 1, comprising at least one selected from the group consisting of polybenzimidazole, polyethylene, polypropylene, cellulose acetate, cellulose butyrate, polyester-based thermoplastic elastomer and polyamide-based thermoplastic elastomer. Around the inner shell having gas barrier properties, the following components [A], [B], and [C] are included. The component [A] is impregnated with the component [B], and the component [C] A method for producing a gas cylinder, comprising forming a pressure-resistant FRP shell using a yarn prepreg existing near the surface.
[A]: Reinforcing fiber bundle [B]: Thermosetting resin [C]: Elastomer and / or thermoplastic resin The method for producing a gas cylinder according to claim 4, wherein the yarn prepreg is formed by adhering a particulate component [C] to a surface of a component [A] impregnated with the component [B]. The method for producing a gas cylinder according to claim 4, wherein the outer shell is formed by a filament winding method.

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