KR100469635B1 - Setting method of metal nozzle in the plastic vessel - Google Patents

Abstract

The present invention relates to a method for binding a metallic nozzle to a plastic liner coupled to a plastic liner of a composite material container used for a storage of compressed natural gas.

The binding method of the present invention has the effect of preventing the leakage of gas in the high-pressure composite container using a metallic nozzle while maintaining a strong bonding force between the nozzle and the plastic liner.

Description

How to bind a metal nozzle for a high pressure container to a plastic container {Setting method of metal nozzle in the plastic vessel}

The present invention relates to a method for binding a metallic nozzle coupled to a plastic liner (liner) of a composite material container used for storage of compressed natural gas. In the present invention, the composite material refers to a material obtained by wrapping a liner of a container with a plastic such as high density polyethylene, and soaking carbon fiber or glass fiber in a polymer resin such as epoxy resin and winding it on the liner. High pressure vessels such as natural gas fuel storage containers for automobiles are manufactured by wrapping the liner in plastic and then wrapping carbon fiber or glass fiber with a polymer resin such as epoxy resin and wrapping it. As the plastic used herein, high density polyethylene, polypropylene, polyester resin, or the like is used.

Such plastic liners are lighter in weight than metal liners, have high corrosion resistance, and are extremely resistant to repeated filling fatigue. It also has the advantage of shortening the charging time compared to the metallic liner. However, when the plastic liner is used, the connection portion between the metal nozzle and the plastic liner is not firm, and thus there is a disadvantage in that gas is easily leaked during long-term use. In particular, when the liner is manufactured by injection molding or rotary molding, a metal nozzle is inserted into the liner, which makes it difficult to use an adhesive.

Compressed natural gas storage containers must withstand high pressures of 200 atm or higher and must be made of materials capable of withstanding high pressures. Conventionally, the liner is made of a metallic material, and it is manufactured by wrapping it with carbon fiber or glass fiber, and recently, a plastic liner is injected using high density polyethylene (hereinafter referred to as HDPE) for light weight and shortening the filling time of gas. It is produced by injection molding or rotary molding and wound by carbon fiber or glass fiber wetted with epoxy resin. Where a plastic liner is used, the adhesion between the plastic liner and the metallic nozzle becomes a problem. As a conventional technique to solve this problem, a method of physically contacting a nozzle and a liner by using a plastic fastener is used. (Registration No. 10-0247116, dated 9/9/99)

Conventional metallic liners are heavy in weight, very susceptible to corrosion, and expensive to manufacture. Composite containers using plastic liners, on the other hand, are lightweight, corrosion resistant, resistant to repetitive filling fatigue, and have a short gas filling time. When the natural gas is injected into the container, the natural gas is injected under pressure, and heat generated by the compression heat and the expansion of the liner inside the container increases the temperature rising speed of the metal liner. Since the heat generation of the liner due to expansion is low, the temperature increase rate of the liner is low, thereby shortening the injection time. For this reason, the development of various composite containers using plastic liners is currently in progress. In case of using the existing metal liner, there is no big problem in firmly joining the liner and the nozzle.However, when the plastic liner is used, the bonding state between the plastic and the metal is a property of the manufacturing process. There may be gaps between the plastics present, and gas leakage may occur between the plastic liner and the metal nozzles due to external shocks, temperature changes, rapid pressure transfers, the effects of repeated loads, and years of use. Existing techniques to solve this problem is to install the above-mentioned plastic fasteners in close contact with the nozzle and the liner. However, these technologies have a complicated structure, which makes it difficult to apply them to actual products and maintain high pressure gas confidentiality. In particular, clamps installed inside the nozzle are very difficult to install and cannot prevent outward gas leakage.

Plastic surfaces generally have low surface energy, i.e. low activity, resulting in poor adhesion and wettability. In particular, the adhesion to the metal is very poor, when the molten resin and the metal meets due to the rapid cooling, residual stress is left around. Therefore, there is a limit to preventing the leakage of gas by the conventional physical adhesion method without chemical modification or surface treatment of plastic and metal.

The present invention relates to a method for firmly binding a metallic nozzle to a plastic liner of a composite container in a composite container.

The present inventors can make the metallic nozzle firmly bind to the composite container by constructing the metallic nozzle in a specific form and by applying the appropriate surface treatment on the metallic nozzle to the plastic liner of the composite container. The present invention was completed by confirming that the used composite material container can be prevented from leaking gas from the container even when used for a long time.

1 is a cross-sectional view of a metal nozzle used in the present invention

2 is a plan view of a metal nozzle used in the present invention.

3 is a cross-sectional view of the high-pressure container showing a state in which the metal nozzle is bound to the composite container in the present invention.

Fig. 4 is a graph in which the adhesion of the nozzles bound by the method of the present invention is tested.

-Explanation of symbols for the main parts of the drawings-

DESCRIPTION OF SYMBOLS 1 Screw part 2 Nozzle head 3 Support hole 4 Hanging jaw part

5: inner bent slope 6: upper fastening support portion 7: nozzle blade portion

8: slope support protrusion 9: hook recess 10: lower fastening support 11: metallic nozzle

12 plastic liner 13 carbon fiber / epoxy resin composite material 14 through hole

The present invention relates to a method of binding a metallic nozzle to a plastic liner in a high pressure natural gas storage container.

In the present invention, the metallic nozzle used was configured as shown in Figs.

In the metallic nozzle used in the present invention, the cylindrical nozzle head 2 and the lower end of the nozzle head 2 having the through hole 14 formed in the center in the vertical direction and the threaded portion 1 formed at the upper end of the inner hole 14 are formed. A plurality of support holes 3 are formed on the outer periphery of the disc, and the locking jaw portion 4 having the inclined surface is formed at the outer end by bending upwardly vertically on the outer surface of the support hole 3. It consists of a nozzle wing portion 7 having an upper fastening support 6 is formed in the inner bending surface 5 is bent upwardly outward.

In addition, the lower side of the support portion 10 is formed in the shape of the sloping support protrusions (8) protruding downwardly outward from the center of the lower end of the nozzle blade (7) and the engaging recess (9) formed on the outer surface of the slope support protrusion (8). It is composed of The metallic nozzle of the present invention is made of aluminum, brass, or the like.

In FIG. 1, the tapered portion is formed in the groove portion of the upper fastening support 6 and the lower fastening support 10 so that the molten plastic resin is injected into and coagulated so that the internal pressure of the container or a sudden external shock or repeated fatigue load The plastic liner 12 did not come out of the nozzle 11.

2 is a plan view of a nozzle used in the present invention. Bonding the metallic nozzle 11 and the plastic liner 12 by insert injection molding, shrinkage occurs when the solidified by cooling in a molten state of high temperature due to the characteristics of the plastic. With this in mind, as shown in Fig. 2, as the support hole 3 is made, the molten plastic filled therein solidifies, and shrinkage occurs in the up and down direction of the nozzle 11, so that the plastic liner 12 is further applied to the nozzle 11. Strongly glued Existing nozzles are easily separated from the adhesive part with the metal because the upper part and the lower part of the plastic are separated from each other and there is no pulling force. However, by using this method, the upper and lower plastics work in one body and have strong adhesive force.

Figure 3 is a cross-sectional view of the container showing a state in which the metallic nozzle is bound to the composite material container in the present invention.

Because metals and plastics have low bonding strength, several pretreatment processes are required. In the present invention, the metallic nozzle 11 is treated with an acid to make fine irregularities on the surface, and the plasma treatment thereon improves the wettability of the surface, thereby improving the adhesion between the metal and the plastic. The acid treatment method is used to form a fine uneven surface on the metal surface. When about 20% of an aqueous hydrochloric acid solution is immersed for about 10 minutes, a fine uneven surface is formed on the metal surface by the corrosive action of hydrochloric acid. A phenol resin or urethane thermosetting adhesive is applied to the surface of the metallic nozzle 11 subjected to plasma treatment. The phenol resin-based thermosetting adhesive is hardened by the hot heat of the molten plastic during injection molding and is chemically combined with the molten resin. In addition, when the metallic nozzle 11 is inserted to inject the plastic liner 12, the molten plastic meets the metallic nozzle 11 and rapidly cools, thereby causing residual stress at the contact surface due to shrinkage of the resin. The liner material can easily fall off, causing gas to leak or liner breakage. Therefore, the metallic nozzle 11 is heated to 70 ° C to 90 ° C and then inserted into the injection molding. At this time, the temperature of the nozzle 11 varies depending on the type of the liner resin, but in the case of high density polyethylene (HDPE), which is generally used in the liner, if the temperature is too high, the crystallinity of the resin is too high, so the contact surface is easily broken (brittle). Since 70 degreeC-90 degreeC is suitable.

The metallic nozzle used in the present invention is constructed by machining, as shown in FIGS. 1 and 2. The pressure vessel is subjected to a high internal pressure and there is a risk of dropping the adhesive portion of the plastic liner 12 and the metallic nozzle 11 due to a sudden external shock or repeated fatigue load. In order to prevent this, the shape of the metallic nozzle 11 is designed as shown in FIGS. 1 and 2 so that the plastic liner 12 is forcibly fastened. As shown by the support hole 3 in FIGS. 1 and 2, a reverse taper was applied to the groove to prevent the liner 12 from falling out of the nozzle 11. After the nozzle 11 is heated, the nozzle 11 is inserted into the mold, the molten resin is injected into the mold, the resin is filled at high pressure, and cooled to prevent the liner 12 of the groove portion from coming out. In addition, since the support hole 3 is formed in the nozzle 11, a liner in which the molten resin cools and contracts in the vertical direction of the support hole 3 is more strongly bonded to the nozzle 11. That is, the resin filled in the support hole 3 serves to strongly bond the nozzle 11 and the liner 12 like rivets while being shrunk by cooling.

The machined nozzles need to be pretreated to increase the adhesion properties of the metallic nozzles 11 and the plastic liner 12. In general, since adhesion is highly dependent on the surface properties of the contact surfaces of the materials, the adhesion is improved by surface modification that only changes the properties of the surface without changing the overall mechanical properties of each material. In the present technology, the metallic nozzle is treated with acid to provide fine irregularities, and the plasma treatment is performed thereon to remove residual carbon contaminants present on the surface, and when the metallic nozzle is aluminum, the thickness of aluminum oxide is increased on the surface layer. The wettability was improved, thereby improving the adhesion between metal and plastic. In addition, the metallic nozzle 11 subjected to the plasma treatment was coated with a thermosetting adhesive. Through this pretreatment process, gas leakage from the simple physically bonded metallic nozzle 11 and the plastic liner 12 was overcome.

At about 70 ° C, the pretreated metallic nozzle 11 is minimized at the contact surface between the plastic liner 12 and the metallic nozzle 11 manufactured by the insert injection molding process to minimize the residual stress caused by the resin shrinkage and to promote adhesion. After heating to ˜90 ° C., the resin was injected into the mold and the resin was injected to minimize the difference in shrinkage due to the temperature difference between the metallic nozzle 11 and the resin, thereby increasing the adhesive strength.

By using the proposed nozzle 11 of the present invention, it is possible to improve the adhesion between the nozzle 11 and the plastic liner 12 which is the most problematic in the composite high pressure vessel, and to prevent the leakage of gas. Due to the shape of the proposed nozzle 11, the plastic liner 12 is not easily separated from the nozzle. The surface treatment of the nozzle 11 and the use of a thermosetting adhesive increase the adhesive force to prevent the leakage of gas. FIG. 4 shows the adhesion to high density polyethylene (HDPE) when surface treatment is not performed on ordinary aluminum and when the aluminum is acid treated by the proposed method and then treated using plasma, and a urethane-based thermosetting adhesive is applied thereon. One result is shown. Adhesion was measured according to ASTM D1876. As shown, the adhesion is improved by about 782% compared to the metal that is not surface treated (denoted as an existing product in FIG. 4). Through this method, the problem of gas leakage at the connection portion between the metallic nozzle 11 and the plastic liner 12, which is a difficult problem commonly occurring in the composite pressure vessel, has been solved. This technology can be applied not only to pressure vessels for natural gas automobiles, but also to other types of pressure vessels, and the material of nozzles can be applied not only to aluminum but also to various other metals. Applicable to

The binding method of the present invention has the effect of preventing the leakage of gas in the high-pressure composite container using a metallic nozzle while maintaining a strong bonding force between the nozzle and the plastic liner.

Claims (2)

In a method of binding a metallic nozzle to a plastic container, a fine uneven surface is formed on the surface of the metallic nozzle, plasma-processed thereon, and a wasteol- or urethane-based thermosetting adhesive is applied thereon, followed by heating during injection molding of the plastic liner. And inserting the metallic nozzle into the metallic nozzle and the plastic liner. The method of claim 1, wherein the plastic liner is high density polyethylene, the metallic nozzle is an aluminum nozzle, and the heating temperature of the metal nozzle is 70 to 90 ° C.