WO2005068578A1

WO2005068578A1 - Container comprising a gasket made from a polymer material and use of this gasket

Info

Publication number: WO2005068578A1
Application number: PCT/EP2004/000252
Authority: WO
Inventors: Hans-Ulrich Hahn
Original assignee: Honeywell Specialty Seelze Gmbh
Priority date: 2004-01-15
Filing date: 2004-01-15
Publication date: 2005-07-28

Abstract

A container for containing a high-purity etchant is disclosed, which comprises an opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer.

Description

Container comprising a gasket made from a polymer material ^' and use of this gasket

The present invention relates to a container for containing a high-purity etchant. The present invention also relates to the use of a gasket for sealing a container for containing a high-purity etchant.

BACKGROUND OF THE INVENTION

In manufacturing electronic elements liquid chemicals are often used for which a high purity is required. Especially in producing highly integrated microchips a high purity degree is required due to the continuously decreasing sizes of said microchips which are produced by the use of process chemicals. In general, the requirements as to the purity of such process chemicals, e.g. process chemicals for the electronic industry, have remarkably increased in recent years. In this regard it is not sufficient to provide respective chemicals in desired purities, but it is also necessary to avoid any contamination of said chemicals during storage, transport or handling. Also, security is an important aspect in view of storage and transport, respectively, since some chemicals may be aggressive or even toxic. An accidental leakage, for example resulting from a damaging of the transport container or untight portions thereof, must thus be prevented to the highest possible reliability. For economic reasons, only large containers are usually employed for delivering chemicals which should be constituted so that no contamination may occur and that even a rough treatment during handling may not lead to leaks, cracks or the like. Moreover, none of the parts of the container, for instance the plug used to close said container and a gasket additionally employed to achieve a tight sealing, should be expensive.

Usually, packages for chemicals like canisters, casks and IBCs (intermediate-bulk-containers) made from plastic materials are closed with plugs being made of plastic, too. For sealing, often gaskets are placed between the plug and the edge of the opening of the package. As a sealing material, rubber elastomers like ethylene/propylene/diene copolymer (EPDM) , Viton® and natural butyl rubber (NBR) as well as low density polyethylene (LDPE) materials are used. However, said materials are not universally applicable, e.g. in the field of semiconductors problems may arise. That is, metal ions contained in said materials might be extracted so that a contamination of the stored matter, often a liquid, results. As one example, LDPE materials are typically not resistant to sulfuric acid. Also, LDPE materials show a reduced flexibility and are liable to generate particles due to mechanical abrasion. Moreover, it is a typical problem encountered in the art that for example sulfuric acid is too aggressive against presently used sealing materials so that a suitable sealing property is not achieved.

Although materials containing copolymers of ethylene and α-olefins are known, their use has been in resin mixtures to give improved insulating layers for flame retardant cables, as it is disclosed in the U.S. Patent No. 5,707,732. Also, elastomer compositions containing ethylene/α-olefin copolymers are proposed for food packings (e.g. WO 98/05731).

In view of the foregoing, it is an object of the present invention to provide an improved container, an improved gasket and an improved method of storing.

SUMMARY OF THE INVENTION

In one aspect, the invention is embodied by a container for containing a high-purity etchant which comprises a vessel, the vessel having a sealable opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer.

In another aspect the invention is embodied by a method of storing an etchant in a vessel comprising a vessel opening and a closing member wherein a gasket made of a polymer material comprising an ethylene/octene-copolymer is positioned between said vessel opening and said closing member to seal the etchant within said vessel.

In another aspect the invention is embodied by a gasket for sealing a high-purity etchant which comprises a polymer material, the polymer material comprising an ethylene/octene-copolymer for sealing against a high-purity etchant.

Preferred embodiments of the container, the gasket and the method, respectively, are set forth in the dependent claims.

According to the above the present invention provides a container for containing a high-purity etchant, said container comprising a vessel having a sealable opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene- copolymer.

Examples of a container according to the present invention are containers made from various materials like plastics, rubbers, metals, alloys, glass, ceramics or any other material suitable for the use and/or the substance to be contained therein. Container, as used herein, may refer to a vessel with no sealing member or capping member. Alternatively, container, as used herein, may refer to a container apparatus comprising a vessel and one or more of a sealing member, such as a gasket, and a capping member, such as a plug cap or stopper.

Ethylene/octene-copolymers are a comparably inexpensive raw material; accordingly the costs arising from the use of the present sealing material can be significantly reduced, thereby reducing the price of the container itself, as well.

In a particular embodiment, said container may be designated for containing or actually contain sulfuric acid because the gasket according to the present invention is especially resistant to sulfuric acid. That is, even if highly concentrated sulfuric acid, e.g. one having a concentration of equal to or larger than about 95 wt.-%, is contained, almost no degradation of the employed gasket like yellowing or other indications of chemical or physical degradation occurs.

Similarly, remarkable advantageously tight sealing is obtained even if the etchant to be contained or contained and maintained in the container is, for example, hydrochloric acid (HC1) , hydrofluoric acid (HF) , ammonia solution, acetic acid, nitric acid, ammonium fluoride, hydrogen peroxide, isopropanol or a base such as, for example, potassium hydroxide or sodium hydroxide. The gasket in accordance with the present invention is especially useful to densely, i.e. tightly and securely, seal containers containing an acid, e.g. the acids among those compounds explicitly mentioned above. Generally, an etchant according to the present invention is a chemical compound or mixture having a pH different from 7.0, i.e. a compound which is chemically not neutral in terms of acids and bases. In the present invention, the hardness of the polymer material is especially important to achieve a sufficient sealing property. In this regard the Shore A-hardness of said polymer material is preferably in the range of about 72 to about 92, wherein a range of about 82 to about 92 is more preferred.

Further, even better sealing properties result if the density of the aforementioned polymer material falls within the preferred range of about 0.87 to about 0.91 g/cm³, a range of about 0.88 to about 0.90 g/cm³ being more preferred. The density of the used polymer material can be adjusted by suitably selecting the comonomer content of the ethylene/octene copolymer.

Moreover, a varying amount of comonomer leads to a change in the melting point of the polymer material. For maintaining the desired sealing properties under various environmental conditions, especially during storage of the sealed container, the melting point of said polymer material is preferably in the range of about 60 to about 98 °C, more preferably in the range of about 72 to about 98 °C. While the above density and melting point can be selected independently, it leads to even more improved sealing properties when the density and the melting point are simultaneously controlled within the aforementioned preferred respective ranges.

For a container according to the present invention it is desired that all parts thereof are etchant-resistant, accordingly the gasket should likewise be etchant- resistant. Such a resistance is usually evaluated by the yellowing characteristics of the employed materials. In this regard it is preferred in the present invention that if a gasket having the form of a ring with a thickness of about 3 to 5 mm and a diameter of about 60 mm is tested, said gasket reveals an Apha-number of smaller than about 10.

In order to further enhance the impact properties of the gasket as used according to the present invention, it is preferable that the elastomer further comprises at least one further polymer selected from the group of linear or branched polyalkylenes. In this regard, the use of polyethylene, polypropylene or a mixture thereof as said polyalkylene leads to enhanced sealing qualities, with minimal chemical and mechanical degradation.

However, the best results as to impact and sealing properties in common are obtained if the present polymer material further comprises modified polyethylene in a content of up to 50 wt.-% based on the total weight of the gasket. Here, it is especially preferred that said polyethylene is LDPE or HDPE or a mixture thereof, to reliably achieve the above mentioned improved characteristics .

Since the container of the present invention is for containing high-purity etchants, especially those used in the semi-conductor industry, it is important that extremely few contaminations are eluted by the contained chemical substance from the container materials. Although it usually exhibits a comparably small surface area, it is found that the typically employed gasket contributes to the total contamination of the contained etchant in an extent of up to 20 to 30%. Thus, according to the present invention, it is preferred that the used gasket is etchant-resistant so that less than 48 ppt Al, less than 134 ppt Ca, less than 26 ppt Cu, less than 219 ppt Fe, less than 7 ppt K, less than 57 ppt Mg, less than 542 ppt Na, less than 64 ppt Ti, less than 13 ppt Zn, less than 3 ppb chloride, less than 10 ppb sulfate, or less than 5 ppb nitrate are eluted from said gasket by a contained etchant over 3 months at 25°C.

It is more preferred that the gasket is etchant-resistant so that less than 48 ppt Al, less than 196 ppt Ca, less than 26 ppt Cu, less than 219 ppt Fe, less than 7 ppt K, less than 57 ppt Mg, less than 454 ppt Na, less than 51 ppt Ti, less than 13 ppt Zn, less than 3 ppb chloride, less than 7 ppb sulfate, or less than 1 ppb nitrate are eluted from said gasket by a contained etchant over 14 days at 25°C.

It is still more preferred that said gasket is etchant- resistant so that less than 28 ppt Al, less than 184 ppt Ca, less than 26 ppt Cu, less than 219 ppt Fe, less than 7 ppt K, ' less than 54 ppt Mg, less than 384 ppt Na, less than 26 ppt Ti, less than 12 ppt Zn, less than 2 ppb chloride, less than 3 ppb sulfate, or less than 1 ppb nitrate are eluted from said gasket by a contained etchant over 24 hours at 25°C.

However, it is even more preferred that two or more of the above conditions are fulfilled in order to obtain even better purity characteristics. From the same viewpoint it is especially preferred that all of the above limits apply at the same time. Further, these limits apply for example for a gasket having a weight of 2.5 g, while 1 kg etchant is used and said gasket has the form of a ring with a thickness of about 3 to about 5 mm and a diameter of about 60 mm.

However, it is to be understood that the above preferred boundary values are not limited in that they only apply at room temperature, i.e. at 25 °C, but they also hold good for a preferred temperature range of -20 to 40°C.

Further, the present invention provides a gasket made from a polymer material comprising an ethylene/octene-copolymer for sealing against a high-purity etchant.

The present invention is also directed to the use of a gasket made from a polymer material comprising an ethylene/octene-copolymer for sealing a container for containing a high-purity etchant, wherein said gasket is used for sealing an opening of said container. Here, the same preferred embodiments of the container, the polymer material and its parameters, the contained etchant and so on as given above for the container according to the present invention are also preferred for this use. Further, by these respective preferred embodiments the same advantages as discussed above can be achieved for the use according to the present invention.

In the present invention, the polymer material is preferably molded into a gasket having the form of a profile ring or an O-ring.

DETAILED DESCRIPTION OF THE INVENTION

In the following, several examples are given for the different aspects of the invention and for the purpose of illustration only, which demonstrate the superior sealing properties of the present gasket comprised by the present container and hence the denseness and other advantages of the container itself. It can also be understood that the use of a gasket according to the present invention leads to particular improved sealing properties and advantageous effects in terms of etchant-resistance, such as chemical degradation, mechanical degradation and the like.

Example 1 (chemical resistance)

From a commercially available polymer material containing ethylene/1-octene copolymer (Engage®, manufactured by DuPont Dow) several profile rings and so-called 0-rings were prepared by ink-jet molding, which can be used as a gasket. To assess the chemical resistance of the resulting rings they were treated individually with sulfuric acid (95-97%), HC1 (37%), HF (50%), ammonia solution (30%), acetic acid (99%), nitric acid (70%), ammonium fluoride, hydrogen peroxide and isopropanol, respectively.

As a result, none of the treated samples revealed a material degradation or swelling. Moreover, the color of the used rings did not change upon applying any of the aforementioned chemicals to the molded rings. Thus, the rings usable as seals according to the present invention are chemically resistant to etchants, especially to those employed in this example. It is to be noted in this regard that the ethylene/octene-comonomer content of the copolymer used has no influence on the chemical stability.

Comparative Example 1

In a similar way to Example 1 a low-density polyethylene type elastomer modified with ethylene/butylene-copolymer was treated with sulfuric acid. However, in this case a remarkable change in color was observed, i.e. the sealing material showed insufficient resistance to sulfuric acid used as an exemplary etchant.

Example 2

With a series of gaskets made from various elastomer mixtures storage tests were performed for the same chemical compounds as used in Example 1, wherein storage temperatures of 20 °C, 40 °C and 65 °C, respectively, were applied. It was determined that gaskets made from a material having a melting point in the temperature range of 60-98 °C showed a superior sealing property in view of the stored etchants, with even better results obtained from gaskets made from a raw material having a melting point in the temperature range of 72-98 °C. Example 3 (hardness)

The hardness is a further indicator for the sealing performance, since the softer and more elastic a respective sealing member is, the more it becomes possible for the sealing member to provide adequate sealing in the case of an occasional unevenness on the surfaces (container surfaces) that might otherwise prevent adequate sealing. This is of special importance in the case of e.g. unevenly blown casks (surfaces to be sealed), cans and IBC- containers, which are combined with precisely ejection- molded sealing parts. In the present case, a Shore-hardness is usually in the range of 72 and 92 from the viewpoint of an appropriate elasticity to smooth out any unevenness. However, even better results are achieved in this regard if the Shore-hardness of the gasket is at least 82, more preferably from 82 to 92, especially for ejection-molded articles (seal-in-seal containers) .

Example 4 (purity)

In the present invention, the polymer material from which the gasket is made can advantageously be used for semiconductor-packaging in which high-purity chemicals for electronics are stored. For such packings it is of special importance that an extremely low ionic contamination occurs, since such a contamination affects the quality of said chemicals for electronics in an unfavorable manner, as has already been discussed above. Accordingly, said polymer material has been tested in practical use for said contamination, the respective ion concentrations being measured by usual methods well known in the art. Firstly, the respective rings as obtained in Example 1 were used as gaskets to seal conventional 200L-containers with suitable plugs. By using a sealing material according to the present invention very low contamination levels of at most 100 ppt can be achieved. This result provides a considerable improvement in comparison with known etchant sealing members, made of, e.g., Viton® or EPDM which result in contamination levels of above 10 ppb.

Secondly, further tests on the ionic contamination were performed by static extraction experiments, which were conducted at room temperature, i.e. at 25°C. However, similar results are obtainable in a temperature range of -20 to +40°C.

Although in practical use the surface area of the gasket which is actually in contact with the etchant is usually far smaller than the entire surface area of gasket, the following experiments have been made under the provision that the whole gasket surface area. These experiments therefore resemble a worst-case-scenario, which is to be tested to give the limits of achievable contamination ratios.

Example 4a:

In a first experiment a profile ring was made from natural POE type 8402 (Engage®), the weight of said ring being 2.5 g while said ring further had a thickness of 3 to 5 mm and a diameter of 60 mm. This profile ring was then immersed into 1000 g hydrofluoric acid (49%, XLSI) for 24 hours. As a testing vessel a IL PE-flask was used. Thereafter the respective ion concentrations as given in Table 1 below were measured. The ring was rinsed with purified water and immersed into hydrofluoric acid (49%, XLSI) again. After 14 - J days and 3 months, respectively, the same ionic concentrations as above were measured again, the results also being shown in Table 1.

Table 1

As demonstrated by the results achieved and set forth in Table 1 above, no significant increase in either metallic or anionic contaminations occurs even after 3 months. It is thus understood that the gaskets of the present invention are superior in sealing acid-containing containers.

Example 4b :

The same experiment as in Example 4a was repeated except for 2.5 g of a POE-granulate made from POE type 8411 (Engage®) being used as the sample to be tested instead of the profile ring. The respective results are shown below in Table 2.

Table 2

As demonstrated by the results achieved and set forth in Table 2, no significant increase in either metallic or anionic contaminations occurs even after 3 months of contact.

Example 4c:

The same experiment as in Example 4b was repeated except for 1000 g ammonia solution (28-30%, XLSI) being employed instead of hydrofluoric acid. The results of this example are shown below in Table 3.

Table 3

As demonstrated by the results achieved and set forth in Table 3 above no significant increase in either metallic or anionic contaminations occurs even after 3 months. It is thus understood that the gaskets of the present invention are also superior in sealing base-containing containers.

It should be mentioned that the slightly increased sodium contents as measured in examples 4b and 4c are most probably due to measurement errors, as it is often the case in analytics when the sodium concentration is measured, too. This phenomenon, however, is well known to the skilled chemist and does not constitute a disadvantageous result. In fact, even these slightly increased sodium contents still indicate a superior purity of the etchant used in the tests.

Example 5 (particles)

Usually, particles are generated upon screwing a plug into a respective opening when placing a gasket between the plug and the opening, said particles originating from the employed gasket. It was thus examined which particle concentrations in the stored liquid are encountered if a container according to the present invention is used. As in the examples above, 200L-containers were sealed using a gasket of the present invention. Here, usual measurement setups were used to obtain respective values of the particle concentration. Several experiments were performed in which a typical particle concentration was 2 particles per 200L-container (0.01 μ/mL) , and at most only 10 particles per 200L-container (0.2 μ/mL). It was thus confirmed that the gaskets of the present invention exhibit almost no abrasion upon screwing so that the particle contamination in the sealed container is drastically reduced. Example 6 (density)

Sealed containers as described in Example 4 above were subjected to a hydraulic pressure test. In this test an increasing hydraulic pressure was applied until the respective container burst. In each case the container was found to withstand a pressure of 3.3 bar which indicates a strong sealing property.

Example 7 (safty)

Drop test were conducted on sealed containers as described in Example 4, wherein at a temperature of 18 °C no gasket failure occurred up to a drop height of 1.9 m. It was thus confirmed that a high safety is achieved by the present invention.

Claims

Claims :

1. A container for containing a high-purity etchant comprising: an opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer.

2. A container according to claim 1, further comprising an etchant in the container.

3. A container according to claim 2, wherein the etchant is sulfuric acid.

4. A container according to claim 3, wherein said sulfuric acid has a concentration of equal to or larger than 95 wt.-%.

5. A container according to any preceding claim, wherein the Shore A-hardness of said polymer material is in the range of 72 to 92.

6. A container according to any preceding claim, wherein the density of said polymer material is in the range of

0.87 to 0.91 g/cm³.

7. A container according to any preceding claim, wherein the melting point of said polymer material is in the range of 60 to 98°C.

8. A container according to any preceding claim, wherein the gasket has the form of a ring, the ring having a thickness of 3 to 5 mm and a diameter of 60 mm, and has an Apha-number of smaller than 10.

9. A container according to any preceding claim, wherein said gasket further comprises modified polyethylene in a content of up to 50 wt.-% based on the total weight of the gasket.

10. A container according to claim 9, wherein said polyethylene is LDPE or HDPE or a mixture thereof.

11. Container according to any preceding claim, wherein said gasket is etchant-resistant so that less than 48 ppt Al, less than 234 ppt Ca, less than 26 ppt Cu, less than 219 ppt Fe, less than 7 ppt K, less than 57 ppt Mg, less than 542 ppt Na, less than 64 ppt Ti, less than 13 ppt Zn, less than 3 ppb chloride, less than 10 ppb sulfate, or less than 5 ppb nitrate are eluted from said gasket by a contained etchant over 3 months at 25°C.

12. Container according to any preceding claim, wherein said gasket is etchant-resistant so that less than 48 ppt Al, less than 196 ppt Ca, less than 26 ppt Cu, less than 219 ppt Fe, less than 7 ppt K, less than 57 ppt Mg, less than 454 ppt Na, I less than 51 ppt Ti, less than 13 ppt Zn, less than 3 ppb chloride, less than 7 ppb sulfate, or less than 1 ppb nitrate are eluted from said gasket by a contained etchant over 14 days at 25°C.

13. Container according to any preceding claim, wherein said gasket is etchant-resistant so that less than 28 ppt Al, less than 184 ppt Ca, less than 26 ppt Cu, less than 219 ppt Fe, less than 7 ppt K, less than 54 ppt Mg, less than 384 ppt Na, less than 26 ppt Ti, less than 12 ppt Zn, less than 2 ppb chloride, less than 3 ppb sulfate, or less than 1 ppb nitrate are eluted from said gasket by a contained etchant over 24 hours at 25°C.

14. A container according to any one of claims 11-13, wherein the weight of the gasket is 2.5 g and 1 kg etchant is used and wherein said gasket has the form of a ring, the ring having a thickness of 3 to 5 mm and a diameter of 60 mm.

15. A container according to any of claims 1, 2 and 5-14, wherein said etchant is hydrochloric acid, hydrofluoric acid, ammonia solution, acetic acid, nitric acid, ammonium fluoride, hydrogen peroxide or isopropanol.

16. A method of storing an etchant in a container comprising an opening and a closing member wherein a gasket made of a polymer material comprising an ethylene/octene- copolymer is positioned between said opening and said closing member to seal the etchant within said container.

17. A method according to claim 16, further comprising the steps of: providing an- etchant in the container; placing the gasket at the opening and placing a cap serving as said closing member upon the opening, wherein the gasket seals the etchant within the closed container.

18. A method according to claim 16 or 17, wherein said etchant is sulfuric acid.

19. A method according to claim 18, wherein said sulfuric acid has a concentration of equal to or larger than 95 wt.-%.

20. A method according to any one of claims 16-19, wherein the Shore A-hardness of said polymer material is in the range of 72 to 92. v

21. A method according to any one of claims 16-20, wherein the density of said polymer material is in the range of 0.87 to 0.91 g/cm³.

22. A method according to any one of claims 16-21, wherein the melting point of said polymer material is in the range of 60 to 98°C.

23. A method according to any one of claims 16-22, -wherein the gasket has the form of a ring, the ring having a. thickness of 3 to 5 mm and a diameter of 60 mm, and has an Apha-number of smaller than 10.

24. A method according to any one of claims 16-23, wherein said gasket further comprises modified polyethylene in a content of up to 50 wt.-% based on the total weight of the gasket.

25. A method according to claim 24, wherein said polyethylene is LDPE or HDPE or a mixture thereof.

26. A method according to any one of claims 16-25, wherein said gasket is etchant-resistant so that less than 48 ppt Al, less than 134 ppt Ca, less than 26 ppt Cu, less than 219 ppt Fe, less than 7 ppt K, less than 57 ppt Mg, less than 542 ppt Na, less than 64 ppt Ti, less than 13 ppt Zn, less than 3 ppb chloride, less than 10 ppb sulfate, or less than 5 ppb nitrate are eluted from said gasket by a contained etchant over 3 months at 25°C.

27. A method according to any one of claims 16-26, wherein said gasket is etchant-resistant so that less than 48 ppt Al, less than 196 ppt Ca, less than 26 ppt Cu, less than 219 ppt Fe, less than 7 ppt K, less than 57 ppt Mg, less than 454 ppt Na, less than 51 ppt Ti, less than 13 ppt Zn, less than 3 ppb chloride, less than 7 ppb sulfate, or less than 1 ppb nitrate are eluted from said gasket by a contained etchant over 14 days at 25°C.

28. A method according to any one of claims 16-27, wherein said gasket is etchant-resistant so that less than 28 ppt Al, less than 184 ppt Ca, less than 26 ppt Cu, less than 219 ppt Fe, less than 7 ppt K, less than 54 ppt Mg, less than 384 ppt Na, less than 26 ppt Ti, less than 12 ppt Zn, less than 2 ppb chloride, less than 3 ppb sulfate, or less than 1 ppb nitrate are eluted from said gasket by a contained etchant over 24 hours at 25°C.

29. A method according to any one of claims 26-28, wherein the weight of the gasket is 2.5 g and 1 kg etchant is used, and wherein said gasket has the form of a ring, the ring having a thickness of 3 to 5 mm and a diameter of 60 mm.

30. A method according to any one of claims 16, 17 and 20- 29, wherein said etchant is hydrochloric acid, hydrofluoric acid, ammonia solution, acetic acid, nitric acid, ammonium fluoride, hydrogen peroxide or isopropanol.

31. A gasket for sealing a high-purity etchant comprising a polymer material, the polymer material comprising an ethylene/octene-copolymer for sealing against a high-purity etchant.

32. A gasket for sealing a high-purity etchant according to claim 31, wherein the etchant is sulfuric acid having a concentration of equal to or larger than 95 wt.-%.

33. A gasket for sealing a high-purity etchant according to claim 31 or 32, wherein the Shore A-hardness of said polymer material is in the range of 72 to 92.

34. A gasket for sealing a high-purity etchant according to any one of claims 31-33, wherein the density of said polymer material is in the range of 0.87 to 0.91 g/cm³.

35. A gasket for sealing a high-purity etchant according to any one of claims 31-34, wherein the melting point of said polymer material is in the range of 60 to 98 °C.

36. A gasket for sealing a high-purity etchant according to any one of claims 31-35, wherein said gasket has the form of a ring, the ring having a thickness of 3 to 5 mm and a diameter of 60 mm

37. A gasket for sealing a high-purity etchant according to any one of claims 31-36, wherein said gasket has an Apha- number of smaller than 10.

38. A gasket for sealing a high-purity etchant according to any one of claims 31-37, wherein said gasket further comprises modified polyethylene in a content of up to 50 wt.-% based on the total weight of the gasket.

39. A gasket for sealing a high-purity etchant according to claim 38, wherein said polyethylene is LDPE or HDPE or a mixture thereof.

40. A container for containing a high-purity etchant comprising: a vessel, the vessel having an opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer.

41. A container for containing a high-purity sulfuric acid comprising: a vessel, the vessel having an opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer.

42. A container according to claim 41, wherein said sulfuric acid has a concentration of equal to or larger than 95 wt.-%.

43. A container for containing a high-purity etchant comprising: a vessel, the vessel having an opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer and the Shore A- hardness of said polymer material is in the range of 72 to 92.

44. A container for containing a high-purity etchant comprising: a vessel, the vessel having an opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer and the density of said polymer material is in the range of 0.87 to 0.91 g/cm³.

45. A container for containing a high-purity etchant comprising: a vessel, the vessel having an opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer and the melting point of said polymer material is in the range of 60 to 98°C.

46. A container for containing a high-purity etchant comprising: a vessel, the vessel having an opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer, and wherein said gasket, when formed to a ring having a thickness of 3 to 5 mm and a diameter of 60 mm, has an Apha-nu ber of smaller 10.

47. A container for containing a high-purity etchant comprising: a vessel, the vessel having an opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer and further comprises modified polyethylene in a content of up to 50 wt.-% based on the total weight of the gasket.

48. A container according to claim 47, wherein said polyethylene is LDPE or HDPE or a mixture thereof.

49. A container for containing a high-purity etchant comprising: a vessel, the vessel having an opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer, said gasket being etchant-resistant so that less than 48 ppt Al, less than 234 ppt Ca, less than 26 ppt Cu, less than 219 ppt Fe, less than 7 ppt K, less than 57 ppt Mg, less than 542 ppt Na, less than 64 ppt Ti, less than 13 ppt Zn, less than 3 ppb chloride, less than 10 ppb sulfate, or less than 5 ppb nitrate are eluted from said gasket by a contained etchant over 3 months at 25°C.

50. A container according to claim 49, wherein the weight of the gasket is 2.5 g and 1 kg etchant. is used and wherein said gasket has the form of a ring, the ring having a thickness of 3 to 5 mm and a diameter of 60 mm.

51. A container for containing a high-purity etchant comprising: a vessel, the vessel having an opening and a gasket for sealing said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer. wherein said etchant is selected from the group consisting of hydrochloric acid, hydrofluoric acid, ammonia solution, acetic acid, nitric acid, ammonium fluoride, hydrogen peroxide, isopropanol, potassium hydroxide and sodium hydroxide.

52. A container for containing a high-purity etchant comprising: a vessel, the vessel having an opening and a gasket for sealing- said opening, wherein said gasket is made from a polymer material comprising an ethylene/octene-copolymer. wherein said etchant is selected from the group consisting of hydrochloric acid, hydrofluoric acid, ammonia solution, acetic acid, nitric acid, ammonium fluoride, hydrogen peroxide, isopropanol and a base.

53. A method of storing an etchant in a container, comprising: providing a container, the container having an opening; providing a closing member; providing a gasket, the gasket is an ethylene/octene- copolymer, wherein the gasket may be positioned between the opening of the container and the closing member to seal an etchant within the container.

54. A method according to claim 53, further comprising the steps of: providing an etchant in the container; placing the gasket at the opening of the container and placing a cap serving as said closing member upon the container opening, wherein the gasket seals the etchant within the capped vessel.