JP6185117B2 - Manufacturing method of pressure vessel - Google Patents

Description

  The present invention relates to a method for manufacturing a pressure vessel.

  In a pressure vessel in which a reinforcing material layer is applied to the liner surface by filament winding or the like, when a vacuum test is performed to evacuate the inside of the vessel (for example, a vacuum test stipulated in the EN 14427 standard or ISO 11119-3 standard), both layers If the adhesive strength is weak, the interface peels and the liner buckles.

  One method for increasing the adhesive strength is to interpose an adhesive resin between the two layers. Patent Document 1 discloses that an adhesive layer is provided between a hollow container formed of a liner and a reinforcing material layer. The intervening technique is described.

JP 2008-164131 A

  The present inventor has confirmed through tests that good adhesiveness can be obtained between the liner and the reinforcing material layer when an adhesive resin made of polyethylene having a functional group is used for a liner made of polyethylene resin. However, the adhesive resin has better adhesion as the amount of functional groups (MA content) increases, but there is a problem that the unit price of the material becomes higher.

  Further, most commercially available adhesive resins have a higher melt flow rate (MFR) value than that of general-purpose polyethylene resins, that is, those having good resin fluidity. If this adhesive resin is transported by an extrusion screw device in a blow molding process, the fluidity is too good, so the transport amount becomes difficult to be constant, surging occurs and the parison extrusion amount tends to be uneven. There is. The general extrusion screw device used in the blow molding process is mostly designed in consideration of the MFR value of general-purpose polyethylene resin, and the extrusion screw device is adapted to the characteristics of the adhesive resin having a high MFR value. It is not a good idea in terms of economy to redesign the.

  The present invention was created to solve such problems, and it is possible to achieve both good securing of the liner and the reinforcing material layer and reduction of the manufacturing cost of the container, and an adhesive resin in the blow molding process. An object of the present invention is to provide a method for producing a pressure vessel capable of stabilizing the extrusion amount.

In order to solve the above problems, the present invention is a pressure vessel manufacturing method in which a reinforcing material layer is formed on an outer side of a liner via an adhesive layer, and the polyethylene resin is conveyed by a first extrusion screw device, A portion corresponding to methyl acrylate after fusion by fusing an ethylene-methyl acrylate copolymer having a melt flow rate of 2.0 g / min and a mass content of methyl acrylate of 24 wt% and a polyethylene resin. Is produced, an adhesive resin having a high load melt flow rate of 20 to 60 g / 10 min after fusing is produced and conveyed by a second extrusion screw device, The polyethylene resin conveyed by the extrusion screw device is the liner, and the adhesive resin conveyed by the second extrusion screw device is the above-mentioned liner. A parison is formed as a bonding material layer and blow-molded, and the reinforcing material layer is formed by filament winding using a thermosetting resin having a curing temperature equal to or higher than the melting point of the adhesive resin as an impregnating resin. And

According to the present invention, good adhesion between the liner and the reinforcing material layer can be ensured. In addition, since the adhesive resin of polyethylene having a functional group that is commercially available is more expensive than polyethylene having no functional group, it should be an adhesive layer to which polyethylene having no functional group is added. Thus, the manufacturing cost of the pressure vessel can be reduced. At the time of blow molding, the extrusion amount of the adhesive resin can be stabilized, and surging of the adhesive layer can be suppressed.
Further, in the step of thermosetting the reinforcing material layer, the adhesive resin of the adhesive material layer is also heated again, and the adhesiveness between the liner and the reinforcing material layer can be further enhanced.

  In the present invention, both the ethylene-methyl acrylate copolymer pellets and the polyethylene resin pellets are supplied on the supply port side of the second extrusion screw device.

  Since the present invention employs a so-called dry blend method in which both pellets are mixed and supplied, adjustment of the adhesive resin can be easily performed.

  Further, the present invention is characterized in that pellets obtained by previously fusing ethylene-methyl acrylate copolymer and polyethylene resin at a predetermined ratio are supplied on the supply port side of the second extrusion screw device.

  Since the present invention supplies pellets obtained by previously fusing an adhesive resin made of polyethylene having a functional group and a polyethylene resin in a predetermined ratio, the ratio of both members is stable, and the MA content of the adhesive resin and the HL- The MFR value is stable.

  ADVANTAGE OF THE INVENTION According to this invention, coexistence of ensuring favorable adhesiveness of a liner and a reinforcing material layer and reduction of the manufacturing cost of a container can be aimed at. Further, the extrusion amount of the adhesive resin can be stabilized in the blow molding process.

It is sectional drawing of a pressure vessel. It is the schematic of a blow molding apparatus. It is a table | surface which shows the adhesion test result of the pressure vessel of this invention. It is a graph which shows the relationship between MA content of adhesive resin, and MFR numerical value.

  The pressure container of the present invention is suitable as a container for storing low-pressure gas such as LPG, but can also be applied as a container for storing high-pressure gas such as hydrogen gas. As shown in FIG. 1, a pressure vessel 1 of the present invention is formed on a liner 2 that forms the core of a container housing, an adhesive layer 3 formed on the outside of the liner 2, and an outside of the adhesive layer 3. And a reinforcing material layer 4.

"Liner 2"
The liner 2 has, for example, a cylindrical barrel portion 5 having a substantially constant cross section, and dome portions 6 formed at both ends of the barrel portion 5. Projections are formed on the tops of the respective dome portions 6. That is, a base 7 as the projection is projected from one dome 6 so as to be coaxial with the axis O of the pressure vessel 1, and a support as the projection is provided at the other dome 6. 8 is protrudingly provided. On the inner periphery of the base 7, a metal base 9 is attached as an integral molding, for example, when the liner 2 and the adhesive layer 3 described later are blow-molded.

  The liner 2 is made of a polyethylene resin, and a high density polyethylene resin is particularly preferable. General-purpose high-density polyethylene resins generally have a high load melt flow rate (HL-MFR) “JIS K6922-1 (1997), condition D (measured at a temperature of 190 ° C. and a load of 211.8 N) of 6“ g / 10 min. It is a grade.

"Adhesive layer 3"
The adhesive layer 3 is formed of an adhesive resin made of polyethylene having a functional group with an MA content of 8 to 17 wt%.
The MA content is the amount of the functional group with respect to the entire resin amount.

  The liner 2 and the adhesive layer 3 are integrally formed by blow molding. In FIG. 2, pellets P <b> 1 for constituting the liner 2 (FIG. 1) are put into a hopper 13, conveyed while being kneaded by a first extrusion screw device 11, and supplied to a die head 10. Also, pellets P2 for constituting the adhesive layer 3 (FIG. 1) are put into the hopper 14, conveyed while being kneaded by the second extrusion screw device 12, and supplied to the die head 10. Both materials supplied to the die head 10 are extruded in a cylindrical shape downward from the die head 10 as a parison P having a multilayer sectional structure in which the liner 2 is located on the inner side and the adhesive layer 3 is located on the outer side. Is done.

  The pellet P1 is a polyethylene resin pellet, and a commercially available polyethylene resin pellet can be used. On the other hand, there are the following two types of pellets P2. The first is a case where the pellet P2 is composed of a mixed pellet of an adhesive resin pellet made of polyethylene having a commercially available functional group and a commercially available polyethylene resin pellet (referred to as a dry blend method). .

  The inventors have confirmed through tests that the adhesive resin has a higher amount of functional groups, that is, a higher MA content, so that the adhesiveness between the liner 2 and the reinforcing material layer 4 becomes better. However, on the other hand, as the MA content increases, the numerical value of HL-MFR increases and the fluidity of the resin increases. Therefore, when only the commercially available adhesive resin pellets are introduced into the second extrusion screw device 12, It was found that the amount of conveyance is difficult to be constant because the property is too good, surging occurs, and the extrusion amount of the parison P tends to be uneven. Since it is desirable to use the second extrusion screw device 12 having a design specification substantially equivalent to that of the first extrusion screw device 11 designed for a general-purpose polyethylene resin, the present invention has a functional group. By adding a general-purpose polyethylene resin to the adhesive resin made of polyethylene, the numerical value of HL-MFR is lowered, and the numerical value that the MA content is 8 to 17 wt% is obtained from the balance with the adhesiveness. According to the first mixed pellet method, both pellets are fused in the process of being transported and kneaded by the second extrusion screw device 12 to produce an adhesive resin having an MA content of 8 to 17 wt%. .

  The second is a case where the pellet P2 is a pellet obtained by fusing a commercially available adhesive resin and a commercially available polyethylene resin at a predetermined ratio. That is, it is a case where it has already been produced in an adhesive resin having an MA content of 8 to 17 wt% at the pellet stage. In the case of the first mixed pellet, mixing failure may occur due to the difference in particle size and specific gravity of both pellets, which may cause fluctuations in MA content and HL-MFR. If the problem is solved, the MA content and the numerical value of HL-MFR are stabilized.

“Reinforcement layer 4”
The reinforcing material layer 4 is a filament for supporting a base 7 and a support 8 of the liner 2 on a rotating device (not shown), and rotating the liner 2 around the axis O to wind a roving composed of a bundle of strands around the surface of the liner 2. It is formed by the winding method. The roving is, for example, glass roving.

  The impregnation resin for roving is made of a thermosetting resin having a curing temperature equal to or higher than the melting point of the adhesive resin. Therefore, in the step of thermosetting the reinforcing material layer 4 at a temperature equal to or higher than the curing temperature of the impregnating resin, the adhesive resin of the adhesive layer 3 is remelted.

"Example"
This inventor produced the pressure vessel 1 as a container for LPG as follows.
As the polyethylene resin constituting the liner 2, “HB112R manufactured by Nippon Polyethylene Co., Ltd.” was used. HL-MFR of HB112R is 6g / 10min.
As the adhesive resin constituting the adhesive layer 3, “Nippon Polyethylene Corporation HB112R” and “Nippon Polyethylene Corporation Lexpearl (registered trademark) EMA EB050S” were used. EB050S has an MA content of 24 wt% and an MFR of 2.0 g / 10 min. The melting point is 73 ° C.
The liner 2 and the adhesive layer 3 were formed by blow molding, and the reinforcing material layer 4 was formed by a filament winding method. During filament winding, roving is wound around the liner 2 while applying a predetermined internal pressure inside the liner 2. The adhesive resin of the adhesive layer 3 was produced by a dry blend method. The impregnation resin for roving in the reinforcing material layer 4 was a thermosetting resin. Specifically, as an impregnation resin, a vinyl ester resin is cured with an organic oxide that is cured at an intermediate temperature and an accelerator, and a predetermined internal pressure is applied to the liner 2 at 80 ° C. for 40 minutes in a drying furnace. Heat cured.

FIG. 3 is a table showing adhesion test results regarding the adhesion state between the liner 2 and the reinforcing material layer 4. The test method is to form a test piece of the reinforcing material layer 4 of φ20 locally by making an annular cut in the reinforcing material layer 4 of the pressure vessel 1 and pull the test piece at a maximum value of 7 N / mm ^2. did. First, when the MA content of the adhesive resin constituting the adhesive layer 3 is 24 wt%, that is, when the adhesive resin is composed only of EB050S, the test result is cohesive failure, and a predetermined adhesive strength is obtained. I found out. Next, in the case of an adhesive resin produced by adding HB112R to EB050S, cohesive failure was observed when the MA content was 18 wt%, 17 wt%, 16 wt%, 15 wt%, 10 wt%, 8 wt%, and 7 wt%, 5 wt% % Showed interfacial peeling. From the above test results, it was found that a predetermined adhesive strength can be obtained when the MA content is set to 8 to 24 wt% at which no interfacial peeling occurs. Moreover, when the vacuum test of EN14427 standard was performed on the pressure vessel of each sample having an MA content of 8 to 24 wt%, it was found that the liner 2 was not buckled and a predetermined adhesive strength was obtained. .

  FIG. 4 is a graph showing the relationship between the MA content of the adhesive resin produced by adding HB112R to EB050S and the HL-MFR value. Samples with MA contents of 5.3 wt%, 11.2 wt%, 11.9 wt%, 13.3 wt%, 19.2 wt% were prepared, and the numerical value of each HL-MFR was measured. / 10 min, 35.7 g / 10 min, 42.0 g / 10 min, 55.0 g / 10 min, 91.1 g / 10 min. From the above five-point measurement, the correlation graph S between the MA content and HL-MFR shown in FIG. 4 is obtained. From this correlation graph S, the HL-MFR when the MA content is 8 wt% is approximately 20 g / 10 min. It turns out that there is.

When the adhesive layer 3 of each sample having the MA content of 24 wt%, 18 wt%, 17 wt%, 16 wt%, 15 wt%, 10 wt%, and 8 wt% described in FIG. With regard to surging such as fluctuations in the sample, 17 wt%, 16 wt%, 15 wt%, 10 wt%, 8 wt% samples were found to have less surging than 24 wt%, 18 wt% samples, and the parison extrusion amount was stable I found out. As described above, from the adhesion test result and the parison extrusion stability test result, the adhesive layer 3 is preferably formed of an adhesive resin made of polyethylene having a functional group with an MA content of 8 to 17 wt%.
In particular, it was found that samples of 15 wt%, 10 wt%, and 8 wt% were more stable with respect to the degree of surging, and it was found that the extrusion amount of the parison was more stable. Therefore, the adhesive layer 3 is more preferably formed of an adhesive resin made of polyethylene having a functional group with an MA content of 8 to 15 wt%. In addition, HL-MFR when MA content is 15 wt% is about 60 g / 10min from the graph of FIG. That is, when MA content was 8-15 wt%, it turned out that HL-MFR is 20-60 g / 10min.

  As described above, if the adhesive layer 3 is formed of an adhesive resin made of polyethylene having a functional group with an MA content of 8 to 17 wt%, preferably an MA content of 8 to 15 wt%, the liner 2 and the reinforcement are strengthened. Good adhesiveness of the material layer 4 can be ensured. Moreover, since the adhesive resin of the polyethylene which has a functional group marketed is expensive more than the polyethylene which does not have a functional group, it is set as the adhesive material layer 3 which added the polyethylene which does not have a functional group. Thereby, the manufacturing cost of the pressure vessel 1 can be reduced. Furthermore, in the blow molding process, the extrusion amount of the adhesive resin can be stabilized, and the occurrence of surging of the adhesive layer 3 can be suppressed.

  Further, when the reinforcing material layer 4 is formed by filament winding using a thermosetting resin as an impregnating resin, the adhesive resin of the adhesive material layer 3 is also heated again in the step of thermosetting the reinforcing material layer 4, The adhesiveness between the liner 2 and the reinforcing material layer 4 is further enhanced.

  The preferred embodiments of the present invention have been described above. The present invention is not limited to that described in the drawings, and various design changes can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Pressure vessel 2 Liner 3 Adhesive material layer 4 Reinforcement material layer 10 Die head 11 1st extrusion screw device 12 2nd extrusion screw device 15 Mold P Parison

Claims (3)

A method of manufacturing a pressure vessel in which a reinforcing material layer is formed on the outside of a liner via an adhesive layer,
The polyethylene resin is conveyed by the first extrusion screw device,
A portion corresponding to methyl acrylate after fusion by fusing an ethylene-methyl acrylate copolymer having a melt flow rate of 2.0 g / min and a mass content of methyl acrylate of 24 wt% and a polyethylene resin. in the mass content of 8～15Wt%, and high load melt flow rate after the fusion generates an adhesive resin of 20 to 60 g / 10min, which was conveyed by the second extrusion screw device,
Forming a parison using the polyethylene resin conveyed by the first extrusion screw device as the liner and the adhesive resin conveyed by the second extrusion screw device as the adhesive layer, and blow molding;
The method of manufacturing a pressure vessel, wherein the reinforcing material layer is formed by filament winding using a thermosetting resin having a curing temperature equal to or higher than a melting point of the adhesive resin as an impregnating resin.   2. The method for producing a pressure vessel according to claim 1, wherein both the pellets of ethylene-methyl acrylate copolymer and the pellets of polyethylene resin are supplied on the supply port side of the second extrusion screw device.   2. The pressure vessel according to claim 1, wherein pellets obtained by previously fusing ethylene-methyl acrylate copolymer and polyethylene resin at a predetermined ratio are supplied on the supply port side of the second extrusion screw device. Method.

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