JP4195673B2 - Sealing device - Google Patents

Description

The present invention relates to a sealed equipment to a fluid containing carbon dioxide or carbon dioxide and sealed, in particular, relates to carbon dioxide dense FuSo location you prevent the leakage of refrigerant in refrigeration and air conditioning system using as the refrigerant.

  Conventionally, in refrigeration air conditioners such as car air conditioners, a fluorocarbon refrigerant HFC-134a is mainly used as a refrigerant from the viewpoint of environmental problems such as ozone layer destruction. However, in recent years, HFC-134a has been pointed out to have an impact on global warming and its use is restricted. As an alternative, carbon dioxide refrigerant, which has a low global warming potential and is also a natural refrigerant, is an alternative candidate.

  In a refrigeration and air conditioning system using a carbon dioxide refrigerant, it is used under high-temperature and high-pressure conditions of a pressure of about 4 to 11 MPa and a temperature of 120 ° C. or higher as compared with a conventional chlorofluorocarbon refrigerant. Moreover, the influence which a carbon dioxide refrigerant has on the sealing material used for the sealing device is also different from the fluorocarbon refrigerant.

For this reason, various studies have been conducted on sealing materials that can be applied to a carbon dioxide refrigerant sealing device. For example, Patent Document 1 describes a sealing material mainly composed of hydrogenated nitrile rubber crosslinked with an organic peroxide. However, it has been found that a sealing material mainly composed of hydrogenated nitrile rubber is still insufficient to reduce the amount of carbon dioxide leaked from the sealing device. Patent Document 2 describes a fluororesin sealing material mainly composed of polytetrafluoroethylene. However, even when polytetrafluoroethylene is used, a sufficient leakage prevention effect has not been obtained due to the resin characteristic of a large carbon dioxide permeability coefficient.
JP 2002-146342 A JP 2001-108108 A

Accordingly, an object of the present invention is to sufficiently withstand use in a required high-temperature and high-pressure environment so that carbon dioxide or a fluid containing carbon dioxide can be used in a sealing device, and carbon dioxide from the sealing device. An object of the present invention is to provide a sealing device using a sealing material capable of suppressing the amount of carbon leakage.

  In order to solve the above problems, the present inventors use a sealing material mainly composed of a fluororesin composed of a chlorotrifluoroethylene homopolymer or copolymer in a sealing device. It has been found that it can withstand use under high temperature and high pressure conditions and can reduce the amount of carbon dioxide permeation compared to the case of using conventional hydrogenated nitrile rubber or polytetrafluoroethylene, and has completed the present invention. It is.

That is, the present invention is as follows.
(1) A sealing device that uses carbon dioxide or a fluid containing carbon dioxide as a sealing target and is used under a high-temperature condition in which the temperature is 120 ° C. or higher.
An O-ring and a backup ring having a bias cut portion;
The backup ring is molded by a sealing material containing as a main component a fluororesin composed of a chlorotrifluoroethylene homopolymer or copolymer, and the bias cut portion is fused by the high temperature condition. Sealing device .

Sealed equipment to a fluid containing carbon dioxide or carbon dioxide according to the invention and sealed, the backup ring and a sealing material blended with a fluorine-based resin comprising a homopolymer or copolymer of chlorotrifluoroethylene as a main component As a result, it can be used under high-temperature and high-pressure conditions (10 MPa, 120 ° C. or higher), and the permeability of carbon dioxide is suppressed to improve the sealing performance. Further, by using a sealant as described above in bar click up ring, the bias cut portion is fused by the high temperature conditions, it was possible to obtain a better sealing performance.

  Rubber compositions tend to have high molecular mobility due to their glass transition point below room temperature and rubber elasticity, and are disadvantageous in terms of gas permeation resistance compared to resin-based materials. On the other hand, polytetrafluoroethylene resins are widely used in harsh environments because of their excellent heat resistance and liquid resistance. However, polytetrafluoroethylene resin has a large carbon dioxide permeability coefficient, and this tendency becomes more prominent when the resin is filled with a filler so as to be suitable for use conditions in a high-pressure environment and the hardness is increased. This is due to voids generated between the resin matrix and the filler contained. On the other hand, a fluororesin composed of a homopolymer or copolymer of chlorotrifluoroethylene is a resin having a resin hardness higher than that of polytetrafluoroethylene resin and a low carbon dioxide permeability. In addition, since it is a fluorine-based resin, it can sufficiently withstand the refrigeration and air-conditioning system of a carbon dioxide refrigerant that becomes high temperature and pressure.

The fluororesin comprising a homopolymer or copolymer of chlorotrifluoroethylene used in the present invention is a polymer or copolymer having chlorotrifluoroethylene as a monomer, such as polychlorotrifluoroethylene, chloro Examples thereof include trifluoroethylene-ethylene copolymer.
In the case of a chlorotrifluoroethylene-ethylene copolymer, the molar ratio of chlorotrifluoroethylene is preferably 20% or more.

The sealing device made of the above sealing material is intended to seal carbon dioxide or a fluid containing carbon dioxide, and is used in, for example, a refrigerating air conditioner such as a car air conditioner using carbon dioxide as a refrigerant, a refrigerating refrigerator, or the like. Gaskets, packings, O-rings, oil seals, mechanical seals, and the like that can be used, but are not limited thereto.
Additional sealant can be used to backup ring for gaskets or packings, enhanced sealing performance. Even if the backup ring is provided with a bias cut, the cut (slit) portion is fused under high temperature and high pressure use conditions, so that an excellent sealing function is exhibited.

  In addition, additives such as a colorant and a filler can be appropriately blended and used without departing from the object of the present invention.

  Hereinafter, this invention is demonstrated using Examples 1-3 and Comparative Examples 1-4. In addition, this invention is not restrict | limited to these Examples.

Example 1:
Example 1 is an example using a sealing material containing as a main component a fluororesin composed of a chlorotrifluoroethylene homopolymer or copolymer.
In this example, polychlorotrifluoroethylene resin (product name: NEOFLON PCTFE) is used as the fluorine-based resin sealing material, and the inner diameter is 40.0 mm, the outer diameter is 43.2 mm, and the height is 2.0 mm. A seal ring was molded. The seal ring was produced by melting and pressurizing neoplastics PTCFE pellets by a generally known compression molding method to form a burette and then cutting to a specified size. Using this seal ring as a sample, the permeation amount (leakage amount) was determined by the following carbon dioxide permeation measurement method. The measurement results are shown in Table 1 and FIG. An example of attachment is shown in FIG.

Example 2:
Example 2 is an example in which a hydrogenated nitrile rubber (HNBR) O-ring and a fluororesin back-up ring made of a chlorotrifluoroethylene homopolymer or copolymer are used in combination.
The hydrogenated nitrile rubber (HNBR) O-ring in this example is composed of 100 parts by weight of the hydrogenating nitrile rubber (Zetpol 0020, manufactured by Nippon Zeon Co., Ltd., 49% by weight of bound acrylonitrile) as a main component. 4 parts by weight of 1,3-bis (t-butylperoxyisopropyl) benzene as the organic peroxide, 15 parts by weight of HAF carbon black and 65 parts by weight of FEF carbon black as the filler, and 10 parts by weight of trimellitic acid trimellitate as the plasticizer 5 parts by weight of N, N′-m-phenylene dimaleimide as a crosslinking aid, 1.5 parts by weight of alkylated diphenylamine as an anti-aging agent, 3 parts by weight of zinc oxide as a metal oxide, 1 part by weight of stearic acid as a lubricant, Using 0.3 parts by weight of polyethylene wax, a total of 204.8 parts by weight, known mixing The rubber composition was kneaded by the above method, pressure-molded under molding conditions of 180 ° C. for 6 minutes, and then post-cured at 150 ° C. for 4 hours in an oven. The shape was a wire diameter of 2 mm and an inner diameter of 40.0 mm.
The backup ring of this example was made of polychlorotrifluoroethylene (PCTFE), and was produced by the same method as in Example 1. Similarly to Example 1, the shape was 40.0 mm inside diameter, 43.2 mm outside diameter, and 2.0 mm height. An example of attachment is shown in FIG.

Example 3:
In Example 3, a hydrogenated nitrile rubber (HNBR) O-ring and a fluororesin backup ring made of a chlorotrifluoroethylene homopolymer or copolymer were used in combination, and the ring was attached to the backup ring. It is the Example which gave the bias cut (slit) which considered the property. A schematic example of the shape of the bias cut is shown in FIG.
A hydrogenated nitrile rubber (HNBR) O-ring in this example was produced in the same manner as in Example 2. The backup ring made of polychlorotrifluoroethylene (PCTFE) (inner diameter 40.0 mm, outer diameter 43.2 mm, height 2.0 mm) is the same as the backup ring of Example 2 except that a bias cut portion is provided. is there. An example of attachment is shown in FIG.

Comparative Example 1:
Comparative Example 1 is an example using an O-ring made of hydrogenated nitrile rubber (HNBR). This hydrogenated nitrile rubber (HNBR) O-ring was produced in the same manner as in Example 2. In this comparative example, only hydrogenated nitrile rubber (HNBR) O-rings are used. An example of attachment is shown in FIG.

Comparative Example 2:
Comparative Example 2 is an example in which a hydrogenated nitrile rubber (HNBR) O-ring and a polytetrafluoroethylene (PTFE) backup ring are used in combination. This hydrogenated nitrile rubber (HNBR) O-ring was produced in the same manner as in Example 2. Moreover, the polytetrafluoroethylene (PTFE) backup ring was produced by cutting from a burette compression-molded and fired by a known method using a polyflon M12 (trade name) manufactured by Daikin Industries. The shape is an inner diameter of 40.0 mm, an outer diameter of 43.2 mm, and a height of 2.0 mm. An example of attachment is shown in FIG.

Comparative Example 3:
Comparative Example 3 is an example in which a hydrogenated nitrile rubber (HNBR) O-ring and a polyamide (PA) backup ring are used in combination. This hydrogenated nitrile rubber (HNBR) O-ring was produced in the same manner as in Example 2. Moreover, the polyamide (PA) backup ring was produced by cutting using a polypenco 66N (trade name) manufactured by Nippon Polypenco. The shape is an inner diameter of 40.0 mm, an outer diameter of 43.2 mm, and a height of 2.0 mm. An example of attachment is shown in FIG.

Comparative Example 4:
Comparative Example 4 is an example in which a hydrogenated nitrile rubber (HNBR) O-ring and a polytetrafluoroethylene (PTFE) backup ring are used in combination, and the backup ring includes a bias cut. This hydrogenated nitrile rubber (HNBR) O-ring was produced in the same manner as in Example 2. The backup ring made of polytetrafluoroethylene (PTFE) is the same as the backup ring of Comparative Example 2 except that it includes a bias cut portion. An example of attachment is shown in FIG.

In addition, the evaluation test with respect to the permeation amount (leakage amount) of carbon dioxide and the permeation coefficient of carbon dioxide in the present invention was performed as follows.
[Measurement of carbon dioxide permeation]
Using a sealed test container consisting of a main body and a lid body with a capacity of 300 ml, the main body and the lid body are screwed and sealed with each sample (O-ring and backup ring) as a sealing device, and the internal pressure is 8 MPa at 150 ° C. Carbon dioxide was filled so that the entire test container was left in a thermostatic bath at a temperature of 150 ° C. Then, by measuring the difference from the total weight at the start of the test after 400 hours had elapsed for each test container, the reduced amount was determined as the amount of carbon dioxide permeated from each sample.
[CO2 gas permeability coefficient]
Using a resin sheet of 90 mm × 90 mm × thickness 0.2 mm or a rubber sheet of 90 mm × 90 mm × thickness 2 mm as a test piece, using a gas permeation tester manufactured by Toyo Seiki Co., Ltd., JIS K 7126 “Plastic Film and Sheet” Gas Permeability Test Method] Measurement was performed at a temperature of 24 ° C. and a pressure of 0.1 MPa by the test method of Method A.

  The measurement results of carbon dioxide permeation amounts for Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 1 and FIG.

  Measurement results of carbon dioxide permeability coefficient and Rockwell hardness when polychlorotrifluoroethylene (PCTFE), polytetrafluoroethylene (PTFE), polyamide (PA) and hydrogenated nitrile rubber (HNBR) are used as the sheet material Is shown in Table 2.

From the above measurement results, the following could be confirmed.
(1) As can be seen from Example 1, in a sealing device for fixing using a fluororesin made of a chlorotrifluoroethylene homopolymer or copolymer as a sealing material, the hydrogenated nitrile rubber shown in Comparative Example 1 is used. It was found that the amount of carbon dioxide permeated can be greatly reduced compared to the case of using it. This is because the carbon dioxide permeability coefficient of PCTFE resin is smaller than that of hydrogenated nitrile rubber.

(2) As can be seen from Example 2, a hydrogenated nitrile rubber O-ring is used as a sealing device for fixing, and a fluorine-based resin made of a chlorotrifluoroethylene homopolymer or copolymer is used as the backup ring as a sealing material. As compared with the case where only the hydrogenated nitrile rubber O-ring shown in Comparative Example 1 is used, it was found that the amount of carbon dioxide permeated can be greatly reduced. In addition, it was found that the carbon dioxide permeation amount can be significantly reduced compared with the case of using polytetrafluoroethylene as the backup ring shown in Comparative Example 2.

(3) In Comparative Example 3, a hydrogenated nitrile rubber O-ring is used as a fixing sealing device, and polyamide having a small carbon dioxide permeability coefficient is applied as a sealing material. The effect of reducing carbon permeation is not seen. This is because the hardness of the polyamide resin is as hard as R120 in terms of Rockwell hardness, and the deformation to the seal groove is not sufficient and the gap cannot be sufficiently sealed. On the other hand, the PCTFE resin used in Example 2 is easy to be deformed because its hardness is lower than that of polyamide resin and R80, has good filling properties for the seal groove, and is effective in combination with the low permeability to carbon dioxide of the material. It is expressed.
The polytetrafluoroethylene used in Comparative Example 2 has a Rockwell hardness as low as R20, but the carbon dioxide permeability coefficient as a raw material is inferior to that of hydrogenated nitrile rubber and PCTFE resin, so that the effect cannot be obtained. I think.

(4) As shown in Example 3, as a sealing device for fixing, a backup ring using a hydrogenated nitrile rubber O-ring and a fluororesin made of a chlorotrifluoroethylene homopolymer or copolymer as a sealing material. And even when a bias cut was made, it was found that the amount of carbon dioxide permeated can be greatly reduced as compared with Comparative Example 1 and Comparative Example 2. This effect is remarkable even when compared with the example of applying the polytetrafluoroethylene back-up ring with bias cut of Comparative Example 4. This is because the PCTFE resin has a melting point of 220 ° C. and lower than the melting point of polytetrafluoroethylene, which is 327 ° C., so that high temperature and high pressure conditions, which are the use environment, act to cause fusion of the bias cut portion. For this reason, the bias-cut ring acts as an integral unbroken seal ring, and exhibits an effect coupled with its low permeability to carbon dioxide. On the other hand, in the polytetrafluoroethylene in Comparative Example 4, such a fusion phenomenon is not observed.

It is a graph which shows the measurement result of the amount of carbon dioxide leaks about Examples 1-3 and comparative examples 1-4. It is sectional drawing of the groove part by which the sealing member of Example 1 and Comparative Example 1 was mounted | worn. It is sectional drawing of the groove part by which the O-ring and backup ring of Example 2, 3 and Comparative Examples 2-4 were mounted | worn. It is sectional drawing of the groove part by which only the O-ring of the comparative example 1 was mounted | worn. It is a schematic partial view of the bias cut provided in the backup ring.

Explanation of symbols

1 Seal member 2 O-ring 3 Backup ring 4 Bias cut

Claims (1)

It is a sealing device that is used under high temperature conditions where carbon dioxide or a fluid containing carbon dioxide is to be sealed, and the temperature is 120 ° C. or higher,
An O-ring and a backup ring having a bias cut portion;
The backup ring is molded by a sealing material containing as a main component a fluororesin composed of a chlorotrifluoroethylene homopolymer or copolymer, and the bias cut portion is fused by the high temperature condition. Sealing device .

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