JP2000140067A - Hermetically sealed hollow container, and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hermetically sealed hollow container wherein the carrying over of a chemical is eliminated, the cleaning property is excellent, and the strength is high, and which is suitable for the storage of a high purity chemical by forming a container main body and a lid body which is fitted on the opening of the main body of a specified modified polytetrafluoroethylene which cannot be worked from a molten state. SOLUTION: This hermetically sealed hollow container 10 for chemical storage is constituted of a container main body 11 wherein a chemical storage section 11a is formed by cutting the internal surface, and a lid body 12 which is fitted on the opening 11b of the container main body 11. In this case, the container main body 11 and the lid body 12 are respectively formed of modified polytetrafluoroethylene which cannot be worked from a molten state. The modified polytetrafluoroethylene is a copolymer at least containing 0.001-1 wt.% of a component unit which is derived from perfluorovinyl ether represented by the formula: CF2=CF-O-X, and a component unit which is derived from tetrafluoroethylene. Then, the container main body 11 and the lid body 12 are integrated by re-sintering together with fusing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ozone water producing apparatus used for storing various kinds of high-purity chemicals used in processes for processing semiconductor wafers, liquid crystal substrates, and the like, and for sterilization cleaning for medical use. The present invention relates to a sealed hollow container suitable for storing a chemical solution and a method for producing the same.

[0002]

2. Description of the Related Art Fluororesins have excellent chemical resistance, heat resistance and purity, and are therefore used as materials for high-purity chemical liquid storage containers used in semiconductor manufacturing processes and medical treatments. Fluorine resin cannot be melt-molded, and the raw material powder is compacted to form a preform, and this preform can be melt-molded with PTFE (polytetrafluoroethylene), which is formed by heating and firing at a temperature above the melting point. PFA (polytetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), ETFE (ethylene /
(Tetrafluoroethylene copolymer), PVDE (polyvinylidene fluoride) and the like.

[0003] In such a fluororesin, in terms of productivity, a molten resin (PF) which can be extruded and injection-molded.
A, FEP, etc.) are advantageous, but in terms of the above characteristics, P
Since it does not reach TFE, there is still a high demand for a container made of PTFE.

However, since PTFE cannot be injection-molded or the like as described above, it is impossible to integrally mold a sealed hollow container. When such a sealed hollow container is produced, it is fired from a preform. It is manufactured by joining a plurality of components.

FIG. 7 shows an example of a conventional sealed hollow container formed by joining a plurality of parts. The hermetically sealed hollow container 1 includes a container main body 2 having a chemical solution storage section 2a, and a lid 3 for closing an opening of the container main body 2, and is formed in a cylindrical shape. Reference numeral 4 denotes a hole for taking out a chemical solution to which a nozzle or the like is mounted later, or a hole for mounting a drain valve for discharging a chemical solution.

Here, the container main body 2 and the lid 3 are manufactured by firing the preformed body. To manufacture these preformed bodies, for example, as shown in FIG. A mold 6 is filled with PTFE powder 7 and then the powder 7 is compression molded. Thereafter, the obtained preformed body is housed in a furnace, and fired at a temperature equal to or higher than the melting point of PTFE (327 ° C.), for example, 360 to 380 ° C., to form the container body 2 and the lid 3. . And
These baked products are internally cut later, and then
The container main body 2 and the lid 3 are welded to form the sealed hollow container 1 before the nozzle or the drain is attached, as shown in FIG. Also, since PTFE has no self-fusing property,
The joining of the container body 2 and the lid 3 is performed by a PFA welding method using PFA having a fusion property with PTFE.

[0007]

The above-mentioned sealed hollow container 1 joined by PFA welding has the following problems.

That is, since the inner surface of the hermetically sealed hollow container 1 made of PTFE is cut after firing as described above, the inner surface is generally poor in smoothness.
Therefore, dust easily accumulates on the fine uneven surface, and the contact area with the chemical solution is increased. Therefore, there have been problems in terms of retention of particles, maintenance of cleanness, and cleanability.

Further, since the sealed hollow container 1 can be welded only from the outside, the strength of the welded portion 5 is
It is weaker than other parts. Therefore, in the sealed hollow container 1 which does not have sufficient strength to withstand use and further has the welded portion 5 subjected to only the outer welding, the chemical solution filled in the chemical solution storage portion 2a receives the chemical solution from the inside. The chemical solution easily penetrates into the gap between the welded portions 5, and if the chemical solution seeps into the gap between the welded portions 5, the chemical solution tends to remain even after repeated washing with pure water. Then, when replacing with another solution, the chemical solution is carried over, and there is a problem that this chemical solution mixes with a new chemical solution.

SUMMARY OF THE INVENTION In view of such circumstances, an object of the present invention is to provide a sealed hollow container which is excellent in cleaning properties without carrying over a chemical solution, has high strength, and is suitable for storing a chemical solution for high purity, and a method for producing the same. And

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a sealed hollow container for storing a chemical solution formed of a fluororesin having excellent heat resistance, permeability resistance, chemical resistance and cleanliness. The hermetically sealed hollow container includes a container main body in which a chemical solution storage portion is formed by cutting an inner surface, and a lid attached to an opening of the container main body, and the container main body and the lid are It is formed from a modified polytetrafluoroethylene that cannot be processed from a molten state, and the modified polytetrafluoroethylene is represented by the following formula [I]: CF ₂ ＣＦCF—O—X (I) Is a perfluoroalkyl group having 1 to 6 carbon atoms, a perfluoroalkoxyalkyl group having 4 to 9 carbon atoms, or a formula [II]:

[0012]

Embedded image

(In the formula [II], n represents 0 or 1.)
Represents a group represented by A copolymer comprising a component unit derived from a perfluorovinyl ether represented by｝ and a component unit derived from tetrafluoroethylene, wherein the copolymer is derived from a perfluorovinyl ether represented by the formula [I]. Is a modified polytetrafluoroethylene containing 0.001 to 1% by weight of a component unit, and the container body and the lid are refired together with fusion to be integrated. It is characterized by.

According to the present invention, it is possible to provide a hermetically sealed hollow container having no welded portion, thereby preventing the chemical solution from seeping and improving the purity. Further, the method for producing a sealed hollow container according to the present invention is characterized in that the modified PTFE according to claim 1 includes a preformed body corresponding to a container main body having a chemical solution storage part and a lid attached to an opening of the container main body. These preforms are formed and fired, and the formed body obtained by cutting the inner surface of the preformed body is welded using a fusion mold designed to have a size larger than the outer dimension of the formed body by 2 to 5%. It is characterized in that it is fused and subjected to refiring.

According to such a method, it has been found that the cut inner surface of the container body becomes smooth due to the properties of the modified PTFE. That is, when the conventional PTFE is used as a raw material, when refired, a lump is formed on a free surface which is not restrained by a mold, and is combined with the poor surface condition of the cut surface as described above. However, the state of the inner surface of the container in which the chemical is stored is further deteriorated. But,
It has been found that when the cut surface of the modified PTFE is refired, no remarkable massive projections are generated, fine irregularities on the cut surface are alleviated, the surface state is rather improved, and the surface is smoothed.

As a result, the inner surface on the liquid contact side can be formed smoothly, and the portion where particles easily accumulate can be reduced as much as possible. In addition, the dimensional accuracy could be improved. Therefore, according to the method of the present invention, it has become possible to provide a sealed hollow container suitable for storing a chemical solution used for manufacturing a liquid crystal semiconductor or medical treatment.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a sealed hollow container 10 according to one embodiment of the present invention. The sealed hollow container 10 includes a container body 1 having a storage section 11a for a chemical solution.
1 and a lid 12 attached to the opening 11b of the container body 11. Reference numeral 13 denotes a hole for mounting a nozzle, a drain, and the like used for taking in and out of the chemical solution.

The sealed hollow container 10 is made of modified PTFE (polytetrafluoroethylene) having excellent heat resistance, chemical resistance and cleanliness. In this case, the modified polytetrafluoroethylene has the following formula [I]: CF ₂ ＣＦCF—O—X... [I] In the formula [I], X is a perfluoro group having 1 to 6 carbon atoms. An alkyl group, a perfluoroalkoxyalkyl group having 4 to 9 carbon atoms, or a formula [II]:

[0019]

Embedded image

(In the formula [II], n represents 0 or 1.)
Represents a group represented by A copolymer comprising a component unit derived from a perfluorovinyl ether represented by｝ and a component unit derived from tetrafluoroethylene, wherein the copolymer is derived from a perfluorovinyl ether represented by the formula [I]. Is a modified polytetrafluoroethylene containing 0.001 to 1% by weight of a component unit.

The component units derived from the perfluorovinyl ether constituting the modified polytetrafluoroethylene include, for example, International Publication No. WO93 / 16126.
Component units derived from various types derived from the perfluorovinyl ether exemplified in the above item, among which perfluoro (propyl vinyl ether) unit and perfluoro (2-propoxypropyl vinyl ether)
Units are preferred.

The component units derived from such a perfluorovinyl ether are contained in the modified polytetrafluoroethylene in an amount of usually 0.001 to 1% by weight, preferably 0.03 to 0.20%, as described above. It is desirable that the content of the component unit [I] derived from perfluorovinyl ether and the component unit derived from tetrafluoroethylene be 100% by weight.
% By weight).

A filler may be appropriately added to the modified polytetrafluoroethylene. Examples of such a filler include glass fiber, graphite powder,
It may contain nickel powder and the like.

In order to form the above-mentioned sealed hollow container 10 by such modified PTFE, first, as shown in FIG. 2, a mold 15 having a desired shape of the container body 11 and the lid 12, 16 is uniformly filled with the raw material powder F, and is usually compressed at a pressure of 300 to 500 kg / cm ² , and the pressure is maintained for 0.5 to 10 minutes to form a block-shaped preform 17, 18 having a solid structure. Get. The obtained preform 1
7 and 18 are taken out from the respective molds 15 and 16. Then, the taken out preforms 17 and 18 are housed in a furnace 19, where the first firing is performed. At the time of sintering, in the furnace 19, the sintering temperature is raised at a constant speed, for example, to 355 ° C., and sintering is performed at that temperature until the sintering is completed uniformly over the whole, and the temperature of the furnace 19 is maintained at a constant speed. Cool down to room temperature to complete.

Thus, the compacts 17 'and 18' which have been first fired in the furnace 19 are once taken out of the furnace 19, and the inner surface, the holes 13 and the like are cut. As a result, the liquid medicine storage section 11a having an appropriate size is formed. On the other hand, a dedicated mold 20 for fusing the molded bodies 17 ′ and 18 ′ subjected to the primary firing to each other is prepared.
The molded bodies 17 ′ and 18 ′ are combined with each other in a posture that forms a sealed hollow container. Then, the mold 20 is again housed in the furnace 19, in which the molded bodies 17 ′ and 18 ′ made of modified PTFE are fused and refired, for example, under the following conditions. You.

Here, the conditions for fusion will be described. In addition, the following conditions are the outer shape 216mmφ x length 3
This is an example in the case of manufacturing a 70 mm hollow container and a lid having an outer shape of 216 mmφ.

First, a dedicated mold 20 is used for fusion. If a pressure necessary for fusion is applied without using the dedicated mold 20, the container body 11 'buckles and deforms as shown in FIG. 3, and a product having a desired shape cannot be obtained.
Therefore, a mold for restraining at least the outside is required. Also, if the dimensions of the mold 20 are made to match the external dimensions of the product, there is no escape area for the increase due to the thermal expansion at the time of fusion, and after cooling, as shown in FIG.
The container body 11 'will be deformed. Therefore,
The dimensions of the exclusive mold 20 are made 2 to 5% larger than the outer shape of the product, so that deformation during fusion can be prevented and proper dimensions can be obtained.

The conditions for setting the special mold 20 in the furnace 19 and then fusing in the furnace 19 are as shown in FIG.
As shown in FIG. That is, first, room temperature 25 ° C
And heated to 355 ° C., which is higher than the melting point of PTFE of 327 ° C., over a period of 5 hours, and kept at that state for 5 hours.
C). The pressure at this time is 50 gf / cm ² with respect to the fused area.

Under these conditions, the molded body 17 'of the primary fired container body 11 made of the modified PTFE and the molded body 18' of the primarily fired lid 12 are mutually fused as shown in FIG. Be worn.

The obtained sealed hollow container 10 was excellent in dimensional accuracy and could be formed into a desired shape. Also, in the sealed hollow container 10 made of modified PTFE manufactured in this way, since it is re-fired at the same time as the fusion, as shown in FIG. After performing the processing, the fine irregularities on the cut surface of the storage part 11a of the chemical solution on the inside are alleviated,
Smoothness was provided.

Therefore, the inner surface of the container body 11 is excellent in surface smoothness, and the surface is smooth even when contacted with a chemical solution, so that no chemical components, dust and the like remain on the surface, and the surface is clean. In addition to the excellent performance, the number of times of washing is reduced, and the cost can be reduced. Also,
Modified PTFE has excellent chemical resistance such as resistance to gas and chemical liquid permeation, and has little elution of impurities. Therefore, modified PTFE is extremely suitable as a liquid chemical storage container in liquid crystal, semiconductor, medical fields and the like.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example,
In the above embodiment, the two members, the container body 11 and the lid 12, are fused to each other, but the hollow container may be composed of two or more members, for example, three members.

[0033]

According to the present invention, there is no welded portion in the sealed hollow container by using the modified PTFE,
The mechanical strength could be increased. Further, since there is no welded portion, the chemical solution does not seep into the gap. Furthermore, since the inner surface of the cut chemical solution storage portion was refired, the inner surface smoothness could be obtained, and the number of minute gaps on the inner surface was reduced. Therefore,
The location where the chemical solution or the like permeated could be reduced as much as possible, whereby the carry-over of the chemical solution was eliminated and the cleaning property was improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a sealed hollow container according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a simplified method according to the invention.

FIG. 3 is a cross-sectional view showing a state of the container body when a pressure is applied without using a dedicated mold.

FIG. 4 is a cross-sectional view showing a state of the container body after cooling when using a mold whose dimensions match the product dimensions.

FIG. 5 is a graph showing conditions for refiring in the method according to the present invention.

FIG. 6A is a micrograph of the cut surface before re-firing, and FIG. 6B is a micrograph of the cut surface after re-firing.

FIG. 7 is a sectional view of a conventional sealed hollow container.

FIG. 8 is a cross-sectional view illustrating preforming.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Sealed hollow container 11 Container main body 11a Storage part 11b Opening 12 Lid 17,18 Preformed body 19 Furnace 20 Special mold

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) (C08F 214/26 216: 14) B29K 27:18 B29L 22:00 F term (Reference) 3E035 AA03 BA04 BC02 CA02 4F208 MA10 4F211 AA17J AG07 AH56 TA01 TC14 TH16 TN01 TN87 TQ01 4J100 AC26P AE38Q AE39Q BA02Q BB07Q BB13Q BB18Q BC58Q CA04 JA58

Claims (2)

[Claims] 1. A sealed hollow container for storing a chemical solution formed of a fluororesin having excellent heat resistance, permeability resistance, chemical resistance and cleanliness, wherein the sealed hollow container is obtained by cutting an inner surface. A container body having a chemical solution storage section formed therein, and a lid attached to an opening of the container body, wherein the container body and the lid are formed of modified polytetrafluoroethylene which cannot be processed from a molten state; The modified polytetrafluoroethylene is represented by the formula [I]: CF ₂ ＣＦCF—O—X... [I] In the formula [I], X is a perfluoroalkyl group having 1 to 6 carbon atoms, and 4 carbon atoms. Or a perfluoroalkoxyalkyl group represented by the formula [II]: (In the formula [II], n represents 0 or 1.) A copolymer comprising a component unit derived from a perfluorovinyl ether represented by｝ and a component unit derived from tetrafluoroethylene, wherein the copolymer is derived from a perfluorovinyl ether represented by the formula [I]. Is a modified polytetrafluoroethylene containing 0.001 to 1% by weight of a component unit, wherein the container body and the lid are refired together with fusion to be integrated. A sealed hollow container. 2. The modified PTFE of claim 1 forms a preform corresponding to a container body provided with a chemical solution storage portion and a lid attached to an opening of the container body, and preforms these preforms. The molded body obtained by firing the body and cutting the inner surface is fused using a fusion mold designed to have a size larger than the outer dimension of the molded body by 2 to 5%, and subjected to a refiring treatment. A method for producing a hermetically sealed hollow container.