KR20230103477A - Plastic liner for pressure vessel and manufacturing method thereof - Google Patents

Abstract

The present invention provides a plastic liner. The plastic liner comprises: a cylinder-shaped body unit; and a dome unit formed at both ends of the body unit and provided with at least one connection unit, wherein the dome unit is formed by a blow molding method, so that at least one pinch line is formed on the outer surface thereof, and a welding unit is provided on a portion of the pinch line.

Description

Plastic liner for pressure vessel and plastic liner manufacturing method {PLASTIC LINER FOR PRESSURE VESSEL AND MANUFACTURING METHOD THEREOF}

The present invention relates to a plastic liner and a method for manufacturing the same. More specifically, the present invention relates to a plastic liner for pressure vessels through blow molding and a manufacturing method thereof.

Recently, the use of pressure vessels has increased, and type IV pressure vessels usually contain plastic liners. Methods for manufacturing plastic liners include an injection-fusion method in which pellet-shaped resin is put into an injection molding machine, injected, and then fused, a rotational molding method in which powder resin is put into a mold and rotated through two axes, and a pellet-shaped resin is molded through a parison. Blow molding, which is extruded and molded through expansion in a mold, is mainly used.

In particular, the blow molding method is suitable for mass production and is suitable for manufacturing small liners, and is therefore widely used for commercial purposes.

In the blow molding process, a hot parison is vertically extruded on an extruder using an extrusion die, an expanding gas is blown into the parison, the mold is sealed, and the parison is expanded. When the expansion is complete, the excess parison is cut off, which is cut off along the pinch-off portion of the mold. At this time, the pinch line formed on the outer surface of the parison of the mold forms a weak point on the surface of the liner, limiting the use of the plastic liner as a high-pressure pressure vessel such as a hydrogen vessel.

Therefore, it is urgent to develop a method for improving the weakness of the pinch line of the liner manufactured by the blow molding method and using it as a plastic liner for high-pressure containers.

Korean Patent Publication No. 10-2017-0070116 as a background art of the present invention discloses a method and equipment for generating a liner without a pinch line, but specifically, a configuration in which the take-out strength of the liner is increased by improving the pinch line not initiated

An object of the present invention is to provide a plastic liner that can be used as an inner liner of a high-pressure vessel such as a hydrogen pressure vessel by improving the structural weakness of a pinch line in a plastic liner by blow molding to improve the physical properties of the entire liner there is.

Another object of the present invention is to provide a method for manufacturing a plastic liner that can be used as a pressure vessel by improving the structure of a pinch line in a plastic liner formed by blow molding.

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

1. One aspect of the invention relates to a plastic liner.

The plastic liner includes a cylindrical body portion; and

A dome portion formed at both ends of the body portion and provided with at least one connection portion; includes,

The dome portion is formed by a blow molding method, at least one pinch line is formed on an outer surface, and a wet part is provided on a portion of the pinch line.

2. In the first embodiment, the wetting part may be formed by extending a cut-off area provided at one end of the mold so that a part of the parison flows into the expanded area.

3. In the above two specific examples, the protruding surface of the wetted part may be flattened.

4. In the specific example of any one of 1 to 3, the wetted part may be determined according to Equation 1 below.

[Equation 1]

L ≤ 1/2D

Here, L is the length of the wetted part 220, and D is the radius of the dome part.

Here, L is the length of the wetted part and D is the radius of the dome part.

5. In the above 4 embodiments, the wet part is formed along the pinch line, and may have a length of 10 to 50 mm and a height of 3 to 10 mm.

6. In the specific example of any one of 1 to 5, the thickness of the dome portion may be determined according to Equation 2 below.

[Equation 2]

T _o < T _i

Here, T _i is the thickness of the region where the wetted portion is formed, and T _o is the thickness of the remaining portion of the dome portion.

7. In any one of the specific examples of 1 to 6, the wet part may be formed by expanding the parison after one end of the parison having a controlled thickness is introduced into the mold.

8. In the 7th embodiment, the thickness of the parison is controlled by the parison program, the total length is 120 cm or less, the thickness is 1.5 T or less, and the parison with a diameter of 60 to 90 Φ is 30 cm or less in the longitudinal direction The thickness may be increased by 50% or more in

9. In any one embodiment of 1 to 8, the plastic liner may be formed of at least one of PA6, PA66, PA11, PA12 and meta-xylene adipamide (MXD-6).

10. In the embodiment of any one of 1 to 9 above, the plastic liner has an expansion rate of 120% or more in a pressure resistance test, and bursts may be generated in a portion of the body portion in a burst test.

11. Another aspect of the invention relates to pressure vessels.

The pressure vessel may include the plastic liner; and

It includes: a filament composite layer formed by winding on the liner.

12. Another aspect of the present invention relates to a method of manufacturing a plastic liner.

The plastic liner manufacturing method includes (a) extruding the parison by adjusting the thickness of one end of the parison using a parison program;

(b) introducing the parison with the adjusted thickness into a mold having an expanded cut-off area and compressing the mold;

(c) disposing a blow needle at one end of the parison and inflating the parison by introducing gas;

(d) forming a wet part on the outer surface of the parison; and

(e) forming a plastic liner by cooling and curing the parison in a mold;

13. In the 12 embodiments, in step (a), the parison has a thickness controlled by a parison program, has a total length of 120 cm or less, a thickness of 1.5 T or less, and a parison with a diameter of 60 to 90 Φ It may be that the thickness is increased by 50% or more at 30 cm or less in the longitudinal direction.

14. In the 12th or 13th embodiment, in the step (d), the cut-off portion of the mold is expanded to introduce the parison, and after a part of the outer surface of the parison is folded, it is compressed to form a wetted part.

15. In the specific example of any one of 12 to 14, a step of forming a flat surface on one surface of the wetted part by a movable slider in the mold may be further included.

The plastic liner according to the present invention can be used as a plastic liner for high-pressure pressure vessels by effectively preventing the occurrence of weak points in the pinch line generated along the parting line, which is a disadvantage of the blow molding method. The plastic liner has greatly improved physical properties including tensile strength, and can induce rupture of the body part, not the dome part, especially in the burst test.

The plastic liner manufacturing method according to another aspect of the present invention can improve the weakness of the pinch line in the plastic liner manufacturing process of the blow molding method, and can greatly improve the plastic liner manufacturing efficiency because an additional reinforcement process of the pinch line is not required. can

1 is a perspective view of a plastic liner in one embodiment of the present invention.
FIG. 2 is a plan view of the plastic liner of FIG. 1 viewed from a dome portion.
FIG. 3 is a cross-sectional side view of the plastic liner of FIG. 1 taken along line AA′.
4 is a cross-sectional side view of the plastic liner of FIG. 1 taken along line BB'.
5 is a process flow chart of a method for manufacturing a plastic liner according to another aspect of the present invention.
6 is a schematic diagram showing the configuration of a mold in a method for manufacturing a plastic liner according to another aspect of the present invention.
7 shows a parison programming screen in the parison forming step in the plastic liner manufacturing method according to one embodiment of the present invention.
8 is a comparison of pictures of a plastic liner according to Example 1 of the present invention and a plastic liner according to Comparative Example 1.
9 is an optical microscope photograph of a dome portion formed with a wetted portion of a plastic liner according to Example 1 of the present invention and a dome portion of Comparative Example 1.
10 is a partially cut-away photograph of a dome portion of Example 1 of a plastic liner according to one embodiment of the present invention.
11 is a comparison of burst test photos of Example 1 and Comparative Example 1 of a plastic liner according to one embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. However, the following drawings are only provided to aid understanding of the present invention, and the present invention is not limited by the drawings. In addition, since the shape, size, ratio, angle, number, etc. disclosed in the drawings are exemplary, the present invention is not limited to the illustrated details.

Like reference numbers designate like elements throughout the specification. In addition, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted.

When 'includes', 'has', 'consists of', etc. mentioned in this specification is used, other parts may be added unless 'only' is used. In the case where a component is expressed in the singular, the case including the plural is included unless otherwise explicitly stated.

In interpreting the components, even if there is no separate explicit description, it is interpreted as including the error range.

When the positional relationship of two parts is described by 'over', 'over', 'under', 'beside', etc., unless 'immediately' or 'directly' is used, there is a One or more other parts may be located.

Positional relationships such as 'top', 'top', 'bottom', and 'bottom' are described based on the drawings, and do not represent absolute positional relationships. That is, the positions of 'upper' and 'lower' or 'upper surface' and 'lower surface' may be changed depending on the observation position.

In this specification, "a to b" representing a numerical range is defined as "≥a and ≤b".

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a perspective view of a plastic liner 1000 according to one embodiment of the present invention, FIG. 2 is a plan view of the plastic liner 1000 according to FIG. 1 viewed from a dome portion 200, and FIG. 3 is a plastic liner according to FIG. 1 It is a side cross-sectional view taken along line A-A' of 1000, and FIG. 4 is a side cross-sectional view taken along line B-B' of the plastic liner 1000 according to FIG.

1 to 4, a plastic liner 1000 according to one embodiment of the present invention includes a body portion 100 and a dome portion 200.

The body portion 100 may have a cylindrical shape.

The body portion 100 is provided in a cylindrical shape to provide a space for storing gas therein, and can effectively distribute the pressure of the gas filled in the space.

The dome part 200 is formed at both ends of the body part 100 and is provided with at least one connection part 230 .

The connection part 230 provides a connection passage through which gas can flow in or out.

The dome part 200 and the body part 100 are formed by molding by blow molding. Specifically, the parison introduced into the combined mold is expanded according to gas blowing and molded according to the shape of the mold, and the dome portion 200 may have a curved surface formed on an outer circumferential surface.

The wetting part 220 may be formed by extending a cut-off area provided at one end of the mold so that a part of the parison flows into the expanded area.

At least one pinch line 210 is formed on an outer surface of the dome portion 200 .

A pinch line 210 is formed in the dome portion 200 along the fastening portion of the mold, and specifically, the pinch line 210 is formed by compressing the parison forming the liner at the cut-off portion of the mold. is formed

The dome part 200 includes a wet part 220 , and more specifically, the wet part 220 may be provided on a part of the pinch line 210 .

In detail, the wetting part 220 is formed by extending a cut-off area provided at one end of the mold so that a part of the parison flows into the expanded area. A cut-off area is formed at one end of the mold, and when a groove is formed in a part of the cut-off area, a part of the parison flows into the groove, and when the mold is fastened to each other as it is, the parison is formed in the groove. The wet water 220 may be formed by being compressed.

The mating part 220 is formed by folding and compressing a partial surface of the parison by a mold, and combining both surfaces facing each other according to mating.

The wet part 220 protrudes from one side of the outer circumferential surface of the dome part 200 and is formed.

In one embodiment, the wet part 220 may be determined according to Equation 1 below.

Specifically, the length of the wetting part 220 may be determined according to Equation 1 below.

[Equation 1]

L ≤ 1/2D

Here, L is the length of the wet part 220, and D is the radius of the dome part 200.

The wet part 220 may be formed only on a part of the pinch line 210, and when the wet part 220 is provided within the above range, even if the working pressure of the plastic liner 1000 is increased, the dome part 200 It is preferable because it can prevent rupture.

If the wetting part 220 is provided beyond the above range, not only the manufacturing efficiency of the plastic liner 1000 is lowered, but also there is a concern that defects may occur in the process of cutting the parison by the mold.

It is preferable that the wet part 220 is provided only on a part of the pinch line, and is provided within the range of Equation 1 relative to the radius of the dome part 200 to effectively improve the weakness of the pinch line without reducing process efficiency there is.

For example, the wet part 220 is formed along the pinch line 210 and may have a length of 10 to 50 mm and a height of 3 to 10 mm.

The wetting part 220 within the above range is provided to effectively improve the weakness of the pinch line.

A flat surface 221 may be formed on an outer surface of the wet part 220 .

The flat surface 221 may be formed using a movable slider provided in a mold in the process of forming the wet part 220 .

Since the flat surface 221 is formed, the wetting part 220 reduces friction with the outside, thereby reducing the risk of breakage, and then increasing the efficiency of a filament composite winding process for manufacturing a pressure container.

In one embodiment, the plastic liner 1000 is formed using a parison of 1.5T or less and 90 Φ or less. In this case, when the wetted part 220 is provided within the above range, the tensile strength of the dome part 200 is increased to 40 MPa or more, so that rupture of the dome portion 200 can be effectively prevented.

The dome portion 200 may have a thickness determined according to Equation 2 below.

[Equation 2]

T _o < T _i

Here, T _i is the thickness of the portion where the wetted portion 220 is formed, and T _o is the thickness of the remaining portion of the dome portion 200 .

The dome portion 200 may have an increased thickness of a portion where the wetted portion 220 is formed according to Equation 2 above.

Referring to FIG. 4 , the dome portion 200 is formed to be thicker than the rest of the dome portion 200 by adjusting the thickness of the parison. In this case, the dome portion 200 ) to prevent rupture.

The wetting part 220 may be formed by inflating a parison whose thickness is adjusted at one end after being introduced into the mold.

Specifically, the thickness of the parison forming the dome part 200 is controlled by a parison program. For example, a parison with a total length of 120 cm or less, a thickness of 1.5T (average thickness: 1.5 mm) or less, and a diameter of 60 to 90 Φ (diameter 60 to 90 mm) or less is 30 cm or less in the longitudinal direction and the thickness is 50% or more may have been increased.

When the thickness of one end of the parison is adjusted to flow into the mold and blow molding is performed, the thickness around the wetted part 220 in the dome part 200 is adjusted to be thicker than the rest of the dome part 200. Sufficient strength can improve

Specifically, the thickness around the wet part 220 may be increased by increasing the thickness of one end of the parison and adjusting the flow of the molten parison and molding conditions.

In one embodiment, the plastic liner 1000 may be formed of at least one of PA6, PA66, PA11, PA12, and meta-xylene adipamide (MXD-6).

When the parison is manufactured using the polyamide resin of the above type and the plastic liner 1000 is manufactured using the blow molding method, it is easy to mass-produce the plastic liner 1000 and the strength of the liner can be increased. In addition, the plastic liner 1000 may exhibit gas barrier performance.

The plastic liner 1000 has an expansion rate of 120% or more in a pressure resistance test using water, and in a burst test, a portion of the body portion 100 may be ruptured.

The plastic liner 1000 is provided with a wetted portion 220 at the pinch line 210, and a wetted portion 220 of the dome portion 200 whose thickness is adjusted according to the molding conditions of the parison. It is possible to induce rupture of the body part 100 other than (200).

Another aspect of the present invention relates to a pressure vessel.

The pressure vessel may include the plastic liner; and a filament composite layer formed by winding the upper portion of the liner.

The pressure vessel may have improved mechanical properties such as tensile strength by including the above-described plastic liner, and may be manufactured as a type 4 pressure vessel and exhibit a working pressure of 300 to 700 bar.

Another aspect of the present invention relates to a method for manufacturing a plastic liner.

5 is a process flow chart of a method for manufacturing a plastic liner according to another aspect of the present invention.

Referring to FIG. 5 , the plastic liner manufacturing method includes (a) extruding the parison by adjusting the thickness of one end of the parison using a parison program; (b) introducing the parison with the adjusted thickness into a mold having an expanded cut-off area and compressing the mold; (c) disposing a blow needle at one end of the parison and inflating the parison by introducing gas; (d) forming a wet part on the outer surface of the parison; and (e) forming a plastic liner by cooling and curing the parison in a mold.

First, the parison is extruded by adjusting the thickness of one end of the parison using the parison program (S100).

The thickness of the parison may be adjusted so that the surfaces of the parison disposed at the cut-off part of the mold form a pinch line folded with each other, and a wet part may be formed at a part of the pinch line, and the thickness around the wet part It is formed thicker than other parts to improve the tensile strength of the dome part, thereby preventing rupture in the dome part.

In the S100, the thickness of the parison is adjusted by the parison program. For example, a parison having a total length of 120 cm or less, a thickness of 1.5 T or less, and a diameter of 60 to 90 Φ is 30 cm or less in the longitudinal direction. can be increased by more than 50%.

One end of the parison is accurately adjusted in thickness with the parison program during the parison extrusion creation process, introduced into the mold, melted after combining the mold, the parison flows, and the molding conditions are adjusted in the mold to form a wet part in the dome part It can effectively increase the thickness of the area.

When the thickness of the parison is not adjusted in advance using a parison program, it is difficult to increase the thickness of the wetted portion by adjusting molding conditions of the parison.

The parison whose thickness is adjusted is introduced into a mold having an extended cut-off area, and the mold is compressed (S200).

6 is a schematic diagram showing the configuration of a mold in a method for manufacturing a plastic liner according to another aspect of the present invention.

Referring to FIG. 6, in the mold M, a part of the cut-off region C is extended, and specifically, a groove G is formed so that a part surface of the parison P is expanded to form the groove ( G) can be introduced into

A blow needle is disposed at one end of the parison, and gas is introduced to inflate the parison (S300).

When gas is introduced into the parison disposed in the mold to expand the parison and bring it into close contact with the mold, the outline of the parison is formed in a liner form by pressurization of the mold.

A wet part is formed on the outer surface of the parison (S400).

In S400, the cut-off part of the mold is expanded to introduce the parison, and after a part of the outer surface of the parison is folded, it is compressed to form a wetted part.

The parison is inflated in the mold and the parison is introduced into the cut-off area. Specifically, the cut-off portion is expanded to form a groove, and as the parison is introduced into the groove, one surface of the parison is folded, face-bonded to each other, and pressurized by a mold to be pressed together to form a strong wetted part.

The wetted portion is formed to increase the tensile strength of the dome portion, thereby improving the physical properties of the plastic liner and improving the weakness of the pinch line of the dome portion, thereby preventing the dome portion from being ruptured.

At this time, a step of forming a flat surface on one surface of the wet part by providing a movable slider in the mold may be further included.

By forming a flat surface on one surface of the wet part, it is possible to reduce the risk of damage caused by friction with the outside, and then the efficiency of the filament composite winding process for manufacturing the pressure vessel can be increased.

The parison is cooled and hardened in a mold to form a plastic liner (S500).

The parison is cooled to form a plastic liner, and finally, the plastic liner is recovered by releasing it from the mold.

Therefore, the plastic liner manufacturing method provides a plastic liner manufacturing method in which rupture of the dome is prevented by improving the weakness of the pinch line in manufacturing the liner using blow molding.

Hereinafter, preferred examples are presented to aid understanding of the present invention, but the following examples are only illustrative of the present invention, and the scope of the present invention is not limited to the following examples.

Examples 1 to 3.

A blow mold molding machine equipped with lip dies and dies was prepared.

The mold formed a groove in advance at the cut-off portion so that the parison flowed into the groove to form a wetted portion. A parison was manufactured using PA6 as a material by controlling the thickness of the parison through the processing conditions of the tube die in the extruder through the parison program.

A vertically descending parison is put between the open molds, the molds are brought into close contact with each other, the parison is cut off, nitrogen gas is introduced into the mold, and the parison is expanded to contact the inner surface of the mold to form a plastic liner. , After cooling, the mold was separated and taken out.

At this time, the extrusion time of the parison and the molding time in the mold are less than 10 seconds, the temperature of the lip die and the die is maintained at 180 to 250 ° C, and after taking out from the mold, it is cooled at 10 to 20 ° C using a chiller to form a plastic liner was manufactured.

7 shows a parison programming screen in the parison forming step in the plastic liner manufacturing method according to one embodiment of the present invention.

A parison with a total length of 120 cm, a thickness of 1.5T (average thickness: 1 mm) or less and a diameter of 60 Φ (60 mm in diameter) or less was manufactured.

Referring to FIG. 7, in A (Example 1), B (Example 2), and C (Example 3), the parison is formed by increasing the thickness by 50% or more from the total parison length of 50 cm to one end of the parison to 15 cm. did

The parison was placed in a mold in which a groove was formed in an expansion area at a cut-off area, gas was introduced to inflate and compressed, and one end of the parison was cut to finally recover the plastic liner.

Comparative Example 1.

The parison was manufactured in the same manner as in Example 1, but the parison was manufactured by adjusting the parison program according to D of FIG. 7 by increasing the thickness by 25% from a total parison length of 50 cm to a parison end of 15 cm.

Comparative Example 2.

The parison was manufactured in the same manner as in Example 1, but the groove was not formed in the mold so that the conventional pinch line was formed as it was.

Comparative Example 3

The parison was manufactured in the same manner as in Example 2, but the groove was not formed in the mold so that the conventional pinch line was formed as it was.

Comparative Example 4

The parison was manufactured in the same manner as in Example 3, but the groove was not formed in the mold so that the conventional pinch line was formed as it was.

Comparative Example 5

By adjusting the parison program according to D of FIG. 7, the parison was manufactured by increasing the thickness by 25% from the total parison length of 50 cm to the parison end of 15 cm, and the conventional pinch line was formed as it was because no groove was formed in the mold. made it so

Experimental example 1.

The appearances of the plastic liners according to Example 1 and Comparative Example 1 were visually inspected.

8 is a comparison of pictures of a plastic liner according to Example 1 of the present invention and a plastic liner according to Comparative Example 1.

Referring to FIG. 8, it was confirmed that the wetted portion was formed according to Example 1 on the right side of the dome in (B), and protruded to a height of 5 mm and a length of 30 mm.

In particular, it was confirmed that friction with the outside can be reduced when a flat surface is formed using a movable slide in preparation for the wetted part on the left side.

In (A), in the case of Comparative Example 1, it was confirmed that the pinch line was formed on the outer surface of the dome.

9 is an optical microscope photograph of a dome portion formed with a wetted portion of a plastic liner according to Example 1 of the present invention and a dome portion of Comparative Example 1.

Referring to FIG. 9, the conventional parting line overlaps at the pinch line where the parison is folded to form a weak point, but the plastic liner manufactured according to Example 1 does not form a parting line at the pinch line where the parison is folded. Confirmed.

Experimental Example 2

In the dome of the plastic liner prepared in Example 1, the thickness of the wetted portion was compared with the rest of the portion.

10 is a partially cut-away photograph of a dome portion of Example 1 of a plastic liner according to one embodiment of the present invention.

Referring to FIG. 10 , it can be seen that the thickness of the region where the wetted part is disposed is greater than the thickness of the rest of the dome part, and accordingly, it is confirmed that the weakness of the pinch line in the dome part is improved.

Experimental example 3.

Tensile evaluation was performed after taking the liner out of the mold.

division mold modification parison program Tensile strength (MPa) liner performance with groove no groove A B C D Wet part O outside of wet area Expansion rate [%] rupture Example 1 O - O - - - 45 MPa 44 MPa 150 ↑ body part Example 2 O - - O - - 43 MPa 46 MPa 140 ↑ body part Example 3 O - - - O - 41 MPa 45 MPa 120 ↑ body part Comparative Example 1 O - - - - O 35 MPa 42 MPa 55 ↓ dome pinch line Comparative Example 2 - O O - - - 30 MPa 38 MPa 20 ↓ dome pinch line Comparative Example 3 - O - O - - 29 MPa 39 MPa 10 ↓ dome pinch line Comparative Example 4 - O - - O - 30 MPa 38 MPa 5 ↓ dome pinch line Comparative Example 5 - O - - - O 24 MPa 35 MPa 3 ↓ dome pinch line

In Examples 1 to 3, when the wet part was provided through the mold in which the groove was formed, and the thickness of the wet part was adjusted by adjusting the parison program and molding conditions of the mold, the tensile strength of the wet part was 41 MPa or more, resulting in the same parison It was confirmed that the tensile strength was increased by 10 MPa or more compared to Comparative Examples 2 to 5 in which the wet part was formed but not provided, and it was confirmed that the wet part could effectively improve the weakness of the pinch line.

On the other hand, for the expansion rate of the plastic liner, water was injected into the liner at a constant flow rate at the connection part of the liner, and the degree of expansion over time was checked to confirm the final breakage due to permanent deformation.

11 is a comparison of burst test photos of Example 1 and Comparative Example 1 of a plastic liner according to one embodiment of the present invention.

Referring to FIG. 11 and Table 1, water was added until rupture under constant velocity conditions of 0.01 to 0.1 L/sec, and pressure was applied from the start of the test until rupture. The expansion rate was determined as the change in weight according to the added flow rate with respect to the weight corresponding to the liner volume.

In Examples 1 to 3, it was confirmed that an expansion rate of 120% or more and rupture of the body were generated. In the case of Comparative Example 1 in FIG. It was confirmed that a low expansion rate and dome rupture occurred in Comparative Examples 2 to 5 as well.

Therefore, the plastic liner according to the present invention can improve the weakness of the pinch line, which is a disadvantage of the plastic liner manufactured by the blow molding method, to provide a liner that meets the safety standards for high-pressure containers, and the manufactured plastic liner is manufactured by the conventional blow molding method. Unlike plastic liners made of , it can be used for medium and large pressure vessels as well as small ones.

So far, the present invention has been looked at mainly through embodiments. Those skilled in the art to which the present invention pertains will be able to understand that the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the equivalent scope will be construed as being included in the present invention.

1000: plastic liner
100: body part 200: dome part
210: pinch line 220: wet part
221: flat surface 230: connection
M: mold
P: Parison
C: cut-off area
G: Groove

Claims (15)

a cylinder-shaped body; and
A dome portion formed at both ends of the body portion and provided with at least one connection portion; includes,
The plastic liner, characterized in that the dome portion is formed by a blow molding method, at least one pinch line is formed on an outer surface, and a wet part is provided on a part of the pinch line.
The plastic liner according to claim 1, wherein the wet part is formed by extending a cut-off area provided at one end of the mold so that a part of the parison flows into the expanded area.
3. The plastic liner according to claim 2, wherein the wetted portion has a flattened protruding surface.
The plastic liner according to claim 1, wherein the wetted part is determined according to Equation 1 below:
[Equation 1]
L ≤ 1/2D
Here, L is the length of the wetted part, and D is the radius of the dome part.
5. The plastic liner according to claim 4, characterized in that the wetted portion is formed along the pinch line, has a length of 10 to 50 mm, and a height of 3 to 10 mm.
The plastic liner according to claim 1, wherein the dome portion has a thickness determined according to Equation 2 below:
[Equation 2]
T _o < T _i
Here, T _i is the thickness of the area where the wetted part is formed, and T _o is the thickness of the rest of the dome part.
The plastic liner according to claim 1, wherein the wetted part is formed by expanding the parison after one end of the parison having a controlled thickness is introduced into the mold.
The parison according to claim 7, wherein the thickness of the parison is controlled by the parison program, and the parison has a total length of 120 cm or less, a thickness of 1.5 T or less, and a diameter of 60 to 90 Φ in a longitudinal direction of 30 cm or less. A plastic liner, characterized in that is increased by more than 50%.
The plastic liner according to claim 1, wherein the plastic liner is formed of at least one of PA6, PA66, PA11, PA12, and meta-xylene adipamide (MXD-6).
The plastic liner according to claim 1, wherein the plastic liner has an expansion rate of 120% or more in a pressure resistance test and rupture is generated in a part of the body portion in a burst test.
The plastic liner according to any one of claims 1 to 10; and a filament composite layer formed by winding the upper portion of the liner.
(a) extruding the parison by adjusting the thickness of one end of the parison using a parison program;
(b) introducing the parison with the adjusted thickness into a mold having an expanded cut-off area and compressing the mold;
(c) disposing a blow needle at one end of the parison and inflating the parison by introducing gas;
(d) forming a wet part on the outer surface of the parison; and
(e) forming a plastic liner by cooling and curing the parison in a mold;
13. The method of claim 12, wherein the thickness is adjusted by the parison program in step (a), and the parison has a total length of 120 cm or less, a thickness of 1.5 T or less, and a diameter of 60 to 90 Φ in the longitudinal direction of 30 cm. A method for manufacturing a plastic liner, characterized in that the thickness is increased by 50% or more below.
13. The manufacturing of plastic liner according to claim 12, wherein in the step (d), the cut-off portion of the mold is expanded to introduce the parison, and a part of the outer surface of the parison is folded and compressed to form a wetted part. method.
13. The method of claim 12, further comprising forming a flat surface on one surface of the wetted part by a movable slider in the mold after step (e).

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