Bubbler tube and bubbler

Abstract

To provide a bubbler tube that allows a bubbler to be excellent in chemical resistance and heat resistance and have a high degree of freedom in installation.SOLUTION: A bubbler tube includes: a first tube, at least part thereof being a porous structure, including a polytetrafluoroethylene; and a second tube having a non-porous structure and including a fluorine resin. The second tube has one end connected to one end of the first tube.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a bubbler tube and a bubbler. [Background technology]

[0002] In semiconductor manufacturing processes, etc., gas injection devices, so-called bubblers, are used to prevent chemical liquids from stagnating and to eliminate temperature variations. Bubblers used for these purposes are required to have excellent chemical resistance and heat resistance. Therefore, bubblers made of fluororesin, which have excellent chemical resistance and heat resistance, are commercially available.

[0003] Many known bubblers have a cylindrical, spherical, or flat shape that is inflexible, resulting in a problem of limited installation flexibility. When the bubbler is designed with the location of use in mind, installation flexibility is often not a major issue. However, when rearranging the bubbler, for example, in a case where the bubbler is to be rearranged to an unexpected location, or when it is discovered that the stirring efficiency is poor only after use and a change in installation location is required, bubblers having the above-mentioned shapes tend to be subject to space constraints. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-331980 [Patent Document 2] Japanese Patent Application Publication No. 61-66730 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a bubbler tube that has excellent chemical resistance and heat resistance and can realize a bubbler with a high degree of freedom in installation, and a bubbler equipped with the bubbler tube. [Means for solving the problem]

[0006] According to a first aspect of the present invention, there is provided a bubbler tube. The bubbler tube includes a first tube having at least a portion of a porous structure and containing polytetrafluoroethylene, and a second tube having a non-porous structure and containing a fluororesin. One end of the second tube is connected to one end of the first tube. A portion of the outer circumferential surface of the first tube faces a portion of the inner circumferential surface of the second tube. An intermediate layer is further included between the outer circumferential surface of the first tube and the inner circumferential surface of the second tube. The wall thickness of the first tube is within a range of 0.1 mm to 5.0 mm.

[0007] According to a second aspect of the present invention, there is provided a bubbler, comprising the bubbler tube according to the first aspect and a gas supply means, the gas supply means being connected to the other end of the second tube. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a bubbler tube that has excellent chemical resistance and heat resistance and can realize a bubbler with a high degree of freedom in installation, and a bubbler equipped with the bubbler tube. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view schematically showing an example of a bubbler tube according to an embodiment. [Figure 2] FIG. 10 is a cross-sectional view schematically showing a state in which a bubbler tube according to a reference example is connected to a gas supply means. [Figure 3] FIG. 2 is a cross-sectional view schematically showing a state in which a bubbler tube according to an embodiment is connected to a gas supply means. [Figure 4] FIG. 10 is a cross-sectional view schematically showing another example of a bubbler tube according to an embodiment. [Figure 5] FIG. 10 is a cross-sectional view schematically showing another example of a bubbler tube according to an embodiment. [Figure 6] FIG. 3 is a perspective view schematically showing an example of a third tube that can be included in the bubbler tube according to the embodiment. [Figure 7]7 is a cross-sectional view of the third tube shown in FIG. 6 taken along line XII-XII. [Figure 8] FIG. 10 is a diagram illustrating an example of a bubbler according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes the embodiments with reference to the drawings as appropriate. Note that common components throughout the embodiments are designated by the same reference numerals, and redundant explanations will be omitted. The drawings are schematic diagrams for explaining and facilitating understanding of the embodiments, and the shapes, dimensions, ratios, etc. may differ from those of actual devices. However, these can be appropriately modified in design, taking into consideration the following explanation and known techniques.

[0011] (First embodiment) A bubbler tube according to an embodiment includes a first tube having at least a partial porous structure. The porous structure of the first tube is a structure resulting from the property of polytetrafluoroethylene (PTFE), which does not exhibit thermal fluidity. That is, the porous structure of the first tube is a microstructure consisting of nodes and fibrils made of PTFE. When a tube with a solid structure containing PTFE is uniaxially stretched, fibrils are pulled out from the nodes roughly along the stretching direction. Nodes refer to regions where the polymer fibers are not stretched and the PTFE material is aggregated. Fibrils refer to polymer fibers present between the nodes and oriented along the stretching direction.

[0012] Numerous through-holes (communicating holes) are formed between the nodes, between the fibrils, and between the nodes and the fibrils. At least a portion of the wall surface of the first tube has a porous structure with such a microstructure, and the portion having the porous structure has the function of allowing only particles larger than the through-holes to pass through and preventing the passage of particles smaller than the through-holes. Therefore, for example, by immersing the portion of the first tube having the porous structure in a chemical solution and injecting a gas into the inner circumferential surface of the first tube, the gas can be supplied into the chemical solution through the porous structure while preventing the chemical solution from entering the first tube.

[0013] The first tube has a cylindrical tube shape and is therefore flexible. Therefore, it can be easily inserted and placed in narrow or complicated spaces, and the first tube can also be easily moved within a stirring vessel filled with a chemical solution or the like. Another advantage is that it can be bent to fit the required installation shape. In other words, the bubbler tube including the first tube offers a high degree of freedom in installation. Furthermore, the first tube contains PTFE, which provides excellent chemical resistance and heat resistance.

[0014] Hereinafter, a bubbler tube according to an embodiment will be described with reference to the drawings, in which: Fig. 1 is a cross-sectional view schematically showing an example of a bubbler tube.

[0015] The bubbler tube 10 includes a first tube 11 and a second tube 12. The bubbler tube 10 shown in Fig. 1 further includes a fluororesin-containing cap 16 at the end of the first tube 11, but the fluororesin-containing cap 16 can be omitted depending on the application of the bubbler tube 10. In Fig. 1, the symbol C indicates the center line of the bubbler tube 10.

[0016] At least a portion of the first tube 11 has a porous structure and contains polytetrafluoroethylene. The first tube 11 may be made of polytetrafluoroethylene. The first tube 11 is a tube that extends from one end 110 to the other end 111. The first tube 11 has an inner circumferential surface 11a and an outer circumferential surface 11b. The first tube 11 is, for example, a cylindrical tube having a predetermined inner diameter and outer diameter.

[0017] The porous structure portion included in the first tube 11 may occupy, for example, 50% or more by volume of the first tube 11, 80% or more by volume, or even 100% by volume. In the present specification and claims, the porous structure refers to a portion having a porosity of 5% or more. The upper limit of the porosity is, for example, 80%. The porosity is preferably within the range of 10% to 40%.

[0018] The first tube containing PTFE can also be used as a bubbling section for, for example, chemicals used in semiconductor manufacturing, such as resist, developer, organic solvent, strong acid, and strong alkali. In the bubbler tube 10 shown in FIG. 1, the portion of the first tube 11 where its outer circumferential surface 11b is exposed can function as the bubbling section 30. The bubbling section 30 is a portion where at least a portion of the outer circumferential surface has a porous structure. The bubbling section 30 is, for example, a portion that is immersed in a chemical or the like. Portions other than the bubbling section 30 may also be immersed in a chemical or the like.

[0019] When the first tube is immersed in a chemical solution or the like and gas is injected, there is no problem if the entire part consisting of the porous structure is immersed in the chemical solution or the like. However, if part of the porous structure is not immersed in the chemical solution or the like and is exposed to the atmosphere, there is a problem in that some of the gas supplied into the first tube will be released (leaked) into the atmosphere through this exposed part.

[0020] FIG. 2 is a cross-sectional view schematically illustrating a state in which a bubbler tube 50 according to a reference example is connected to a gas supply means. The bubbler tube 50 shown in FIG. 2 is composed of only a first tube 11 having a porous structure entirely. A fitting 60 is directly connected to the end of the first tube 11. The fitting 60 includes, for example, a socket 61 and a plug 62. The end of the fitting 60 on the plug 62 side is connected to a gas supply means (not shown). The socket 61 included in the fitting 60 can be attached to, for example, a portion of the first tube 11 having a porous structure. Here, as an example, a case in which the entire first tube 11 has a porous structure is shown, but as described above, it is sufficient that at least a portion of the first tube 11 has a porous structure.

[0021] When the bubbler tube 50 according to the reference example shown in FIG. 2 is immersed in a chemical solution or the like, for example, a portion 15 of the wall surface of the first tube 11, typically located near the socket 61 of the fitting 60, is not immersed in the chemical solution or the like. The reason for this is that, for example, the chemical resistance of the fitting 60 is poorer than that of the first tube 11, and therefore the fitting 60 may be corroded by the chemical solution or the like. In this case, since the entire first tube 11 having a porous structure is not immersed in the chemical solution or the like, some of the gas injected into the first tube 11 through the fitting 60 from the gas supply means may leak from portion 15 to the outside of the first tube 11 through the porous structure.

[0022] Meanwhile, FIG. 3 is a cross-sectional view schematically illustrating a state in which a bubbler tube 10 according to an embodiment is connected to a gas supply means. In the bubbler tube 10 shown in FIG. 3, one end 120 of a second tube 12 having a non-porous structure is connected to one end 110 of a first tube 11 via a fused portion 122. In the bubbler tube 10, a fitting 60 is connected to the other end 121 of the second tube 12. The fitting 60 includes, for example, a socket 61 and a plug 62. The end of the fitting 60 on the plug 62 side can be connected to a gas supply means (not shown). The bubbler tube 10 shown in FIG. 3 may or may not include the fitting 60. A known fitting 60 can be used as the fitting 60.

[0023] The second tube 12 has a non-porous structure (solid structure). Therefore, even if the entire bubbling section 30 of the first tube 11, in which the outer circumferential surface 11b is exposed, is immersed in a chemical solution or the like, the fitting 60 does not come into contact with the chemical solution or the like. Furthermore, gas supplied into the bubbler tube 10 through the fitting 60 does not leak from the wall surface of the second tube 12, which has a non-porous structure. Therefore, with the bubbler tube 10 shown in FIG. 3, gas can be injected into the chemical solution or the like from the bubbling section 30 while preventing the gas supplied into the bubbler tube 10 from the fitting 60 side from leaking into the atmosphere.

[0024] In addition, because the second tube 12 does not have a porous structure, the other end 121 of the second tube 12 can be easily fitted with various commonly used devices such as flanges and nuts, as well as the fitting 60. Therefore, the installation cost of the bubbler tube according to the embodiment is low. If such processing were directly performed on a tube with a porous structure, additional processing would be required to prevent gas leakage or to reinforce the mechanical strength of the tube, which could increase costs.

[0025] (1st tube) The inner diameter of the first tube 11 is not particularly limited, but is, for example, in the range of 0.5 mm to 30 mm. The outer diameter of the first tube 11 is not particularly limited, but is, for example, in the range of 0.7 mm to 40 mm. The wall thickness of the first tube 11 is, for example, in the range of 0.1 mm to 5.0 mm. The wall thickness of the first tube 11 is defined as the radial distance from the inner circumferential surface 11a of the first tube 11 to the nearest outer circumferential surface 11b.

[0026] The inner and outer diameters of the tube can be measured using pin gauges or calipers with an accuracy of 1 / 1000 mm.

[0027] If the wall of the first tube 11 is excessively thick, the first tube 11 may become less flexible.

[0028] The apparent specific gravity of the first tube 11 alone is, for example, in the range of 0.10 to 2.0. The apparent specific gravity of the first tube 11 alone may be in the range of 0.11 to 1.87. The apparent specific gravity of the first tube 11 is desirably greater than the specific gravity of the chemical solution or the like in which the first tube 11 is immersed. In this case, even if bubbling is performed while the first tube 11 is immersed in the chemical solution or the like, the first tube 11 can be prevented from floating up. That is, a decrease in stirring efficiency due to bubbling can be suppressed. In this case, since it is not necessary to fix the first tube 11 externally, the degree of freedom in installing the bubbler tube according to the embodiment can be increased. The specific gravity of the first tube 11 can be measured by specific gravity measurement using an underwater displacement method. Note that, when the bubbling unit 30 is composed of the first tube 11 alone, the apparent specific gravity of the first tube 11 can be the apparent specific gravity of the bubbling unit 30.

[0029] The length of the first tube 11 is not particularly limited, but is, for example, in the range of 0.1 m to 5.0 m. The length of the first tube 11 refers to the length from one end 110 to the other end 111. If the length of the first tube 11 is excessively long, the gas pressure near the other end 111 of the first tube 11 will be significantly lower than near the one end 110 of the first tube 11 that is closer to the gas inlet, which is undesirable. This tendency is particularly pronounced when the entire first tube 11 has a porous structure.

[0030] One way to suppress an increase in pressure loss near the other end 111 of the first tube 11 is to shorten the length of the first tube 11. Alternatively, as in a second modified example described below, when a third tube including many solid structures is provided on the inner diameter side of the first tube 11, the increase in pressure loss can be suppressed.

[0031] The other end 111 of the first tube 11 may be one end 100 of the bubbler tube 10 .

[0032] (2nd tube) The second tube 12 has a non-porous structure and contains a fluororesin. The second tube may be made of a fluororesin. The second tube 12 is a tube that extends from one end 120 to the other end 121. The second tube 12 has an inner circumferential surface 12a and an outer circumferential surface 12b. The second tube 12 is, for example, a cylindrical tube having a predetermined inner diameter and outer diameter.

[0033] The non-porous structure portion of the second tube 12 may, for example, account for 50% or more by volume of the second tube 12, 80% or more by volume, or even 100% by volume. In the present specification and claims, the term "non-porous structure" refers to a portion having a porosity of less than 5%. The lower limit of the porosity is not particularly limited and may be 0%.

[0034] The inner diameter of the second tube 12 is not particularly limited, but is, for example, in the range of 0.7 mm to 40 mm. The outer diameter of the second tube 12 is not particularly limited, but is, for example, in the range of 1.3 mm to 50 mm. The inner diameter of the second tube 12 is preferably larger than the outer diameter of the first tube 11.

[0035] The wall thickness of the second tube 12 is, for example, in the range of 0.3 mm to 5.0 mm. The wall thickness of the second tube 12 is defined as the radial distance from the inner circumferential surface 12a of the second tube 12 to the nearest outer circumferential surface 12b.

[0036] The length of the second tube 12 is not particularly limited, but is within the range of 0.1 m to 5.0 m, for example.

[0037] One end 120 of the second tube 12 is connected to one end 110 of the first tube 11. For example, at one end 110 of the first tube 11 and one end 120 of the second tube 12, a portion of the outer circumferential surface 11b of the first tube 11 faces, for example, a portion of the inner circumferential surface 12a of the second tube 12. The connection between one end 120 of the second tube 12 and one end 110 of the first tube 11 is achieved by fusion-bonding the one end 120 of the second tube 12 to the outer circumferential surface 11b of the first tube 11 with the one end 120 of the second tube 12 covering the one end 110 of the first tube 11, as shown in FIG. 1 . That is, the one end 120 of the second tube 12 is fusion-bonded to the outer circumferential surface 11b of the first tube 11 via a fusion portion 122.

[0038] It is preferable that one end 120 of the second tube 12 is not butted against one end 110 of the first tube 11. The fused portion 122 may be a portion where the second tube 12 itself is melted, or may be a portion containing a separately prepared melt-flowable fluororesin.

[0039] The fluororesin contained in the second tube 12 may be at least one selected from the group consisting of polytetrafluoroethylene (PTFE), modified PTFE, perfluoroalkoxyalkane (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), perfluoroethylenepropene copolymer (FEP), and polyvinylidene fluoride (PVDF). From the viewpoints of excellent chemical resistance and heat resistance as well as exhibiting an anchoring effect to the first tube 11, the fluororesin contained in the second tube 12 is preferably PFA.

[0040] The fused portion 122 may contain at least one melt-flowable fluororesin selected from the group consisting of PFA, ETFE, FEP, and PVDF.

[0041] The other end 121 of the second tube 12 may be the other end 101 of the bubbler tube 10 .

[0042] The total length of the bubbler tube 10 is determined from the other end 111 of the first tube 11 to the other end 121 of the second tube 12. The total length of the bubbler tube 10 is not particularly limited, but is within a range of 0.2 m to 10 m, for example. The bubbling section 30 described above may be the portion of the total length of the bubbler tube 10 where the outer circumferential surface 11b of the first tube 11 is exposed. The length of the bubbling section 30 is not particularly limited, but is within a range of 0.1 m to 5.0 m, for example.

[0043] (Fluororesin-containing cap) 1 can suppress the release of gas that may be released to the outside of the bubbler tube 10 from the other end 111 of the first tube 11. In other words, the fluororesin-containing cap 16 can seal the other end 111 of the first tube 11. The size and shape of the fluororesin-containing cap 16 are not particularly limited. Although not shown, the other end 111 of the first tube 11 may be sealed by ultrasonic welding with the edges of the tubes overlapping each other, instead of being provided with the fluororesin-containing cap 16.

[0044] The fluororesin contained in the fluororesin-containing cap 16 is not particularly limited, but may be, for example, a melt-flowable fluororesin. As the melt-flowable fluororesin, for example, the types described above for the fused portion 122 can be used.

[0045] (First Modification) The bubbler tube according to the embodiment may further include an intermediate layer 14. Fig. 4 is a cross-sectional view schematically showing an example in which the bubbler tube 10 further includes an intermediate layer 14. The intermediate layer 14 may also be called a spacer.

[0046] The bubbler tube 10 shown in Fig. 4 includes an intermediate layer 14 fused to both the inner circumferential surface 12a of the second tube 12 and the outer circumferential surface 11b of the first tube 11, between them. The intermediate layer 14 may be formed, for example, on at least a portion of the area where the inner circumferential surface 12a of the second tube 12 and the outer circumferential surface 11b of the first tube 11 face each other. A portion of the intermediate layer 14 may also be formed on an area where the inner circumferential surface 12a of the second tube 12 and the outer circumferential surface 11b of the first tube 11 do not face each other. The intermediate layer 14 has, for example, a cylindrical shape that covers the outer circumferential surface 11b of the first tube 11.

[0047] The intermediate layer 14 contains, for example, a melt-flowable fluororesin. The melt-flowable fluororesin contained in the intermediate layer 14 may be, for example, at least one melt-flowable fluororesin selected from the group consisting of PFA, ETFE, FEP, and PVDF.

[0048] The thickness of the intermediate layer 14 is not particularly limited, but is, for example, in the range of 0.005 mm to 5.0 mm. When the outer diameter of the first tube 11 is small and the inner diameter of the second tube 12 is large, it is effective to fill the gap between the first tube 11 and the second tube 12 by forming an intermediate layer 14 with a relatively large thickness. This can prevent wrinkles and other defects from forming at the joint between the first tube 11 and the second tube 12. Therefore, when used as a bubbler, gas leakage at the joint and intrusion of chemicals and the like into the tube can be prevented. On the other hand, when the outer diameter of the first tube 11 is large and the inner diameter of the second tube 12 is small, it is possible to fill the gap between the first tube 11 and the second tube 12 with an intermediate layer 14 with a relatively small thickness.

[0049] The presence of the intermediate layer 14 strengthens the bond between the first tube 11 and the second tube 12. Therefore, even when the bubbler tube 10 is used in an installation method that increases the bending radius of the bubbler tube 10, gas leakage from the bonded portion between the first tube 11 and the second tube 12 can be suppressed.

[0050] (Second Modification) The bubbler tube according to the embodiment may further include a third tube. Fig. 5 is a cross-sectional view schematically showing an example of a bubbler tube 10 further including a third tube 13. First, an example of the third tube will be described with reference to Figs. 6 and 7. Fig. 6 is a perspective view schematically showing an example of the third tube 13. Fig. 7 is a schematic cross-sectional view taken along line XII-XII in Fig. 6.

[0051] The third tube 13 is a tube at least partially having a non-porous structure (solid structure). The entire third tube 13 may have a non-porous structure. However, the third tube 13 has at least one through-hole 132. The third tube 13 is a tube extending from one end 130 to the other end 131. The third tube 13 has an inner circumferential surface 13a and an outer circumferential surface 13b. The third tube 13 is, for example, a cylindrical tube having a predetermined inner diameter and outer diameter.

[0052] The non-porous structure portion included in the third tube 13 may, for example, occupy 50% by volume or more, 80% by volume or more, or even 100% by volume of the third tube 13. However, this does not include the volume of the hollow portion formed by the through holes 132. In other words, the above volume percentages are applied to the solid portion of the third tube 13 other than the through holes 132.

[0053] The wall thickness of the third tube 13 is, for example, in the range of 0.1 mm to 5.0 mm. The wall thickness of the third tube 13 is defined as the radial distance from the inner circumferential surface 13a of the third tube 13 to the nearest outer circumferential surface 13b. If the wall of the third tube 13 is excessively thick, the tube may lack flexibility. In order for the third tube 13 to have excellent flexibility, the wall thickness of the third tube 13 is preferably in the range of 0.5 mm to 1.5 mm.

[0054] The third tube 13 preferably has two or more through holes 132. The through holes 132 are holes that penetrate the wall surface of the third tube 13. That is, the through holes 132 are holes that penetrate from the inner circumferential surface 13a to the outer circumferential surface 13b. The two or more through holes 132 are preferably arranged along the longitudinal direction of the third tube 13, that is, the direction from one end 130 to the other end 131. The two or more through holes 132 do not have to be arranged along one direction.

[0055] The size of the through-hole 132 is not particularly limited, but the diameter of the hole is within the range of 0.1 mm to 5.0 mm, for example.

[0056] When there are two or more through holes 132, the arrangement interval (distance between the centers of the holes) is not particularly limited and is, for example, in the range of 10 mm to 500 mm. The two or more through holes 132 may be arranged at a constant interval, or may be arranged at any interval. For example, the interval between two adjacent through holes 132 provided at a certain position may be different from the interval between two adjacent through holes 132 provided at a different position.

[0057] The resin constituting the third tube 13 is not limited to fluororesin, and various thermoplastic resins and thermosetting resins can be used. From the viewpoint of chemical resistance and heat resistance, it is preferable that the third tube 13 contains a fluororesin. Examples of the fluororesin contained in the third tube 13 include at least one selected from the group consisting of polytetrafluoroethylene (PTFE), modified polytetrafluoroethylene, perfluoroalkoxyalkane (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), perfluoroethylenepropene copolymer (FEP), and polyvinylidene fluoride (PVDF).

[0058] Next, the bubbler tube 10 including the above-mentioned third tube 13 will be described with reference to Fig. 5. The bubbler tube 10 shown in Fig. 5 has the same configuration as the bubbler tube 10 shown in Fig. 4, except that it further includes the third tube 13.

[0059] The third tube 13 is disposed on the inner diameter side of the first tube 11. Therefore, the outer diameter of the third tube 13 may be smaller than the inner diameter of the first tube 11. At least a portion of the outer peripheral surface 13b of the third tube 13 is fused to the inner peripheral surface 11a of the first tube 11 via a fusion layer 20. A tube having a two-layer structure of the third tube 13 and the first tube 11 can also be called a composite tube.

[0060] The wall thicknesses of the first and third tubes in the composite tube can be measured by observing the cross section of the composite tube with a scanning electron microscope (SEM). Specifically, at least five cross sections of the tube to be measured are prepared, and the wall thicknesses are determined by calculating the simple average of the measured values ​​for each cross section.

[0061] 5, as an example, the fusion layer 20a fuses the vicinity of one end 110 of the first tube 11 to the vicinity of one end 130 of the third tube 13. The fusion layer 20b fuses the vicinity of the other end 111 of the first tube 11 to the vicinity of the other end 131 of the third tube 13.

[0062] The fusion layers 20a and 20b are each provided in an annular shape on the outer circumferential surface 13b of the third tube 13.

[0063] The bonding layer 20 includes, for example, a melt-flowable fluororesin. Examples of the melt-flowable fluororesin include at least one selected from the group consisting of perfluoroalkoxyalkane (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), perfluoroethylenepropene copolymer (FEP), and polyvinylidene fluoride (PVDF).

[0064] At least a portion of the outer circumferential surface 11b of the first tube 11 faces the inner circumferential surface 12a of the second tube 12 via the intermediate layer 14. Therefore, the outer diameter of the first tube 11 may be smaller than the inner diameter of the second tube 12.

[0065] Of the entire length of the bubbler tube 10, in the composite tube formed by laminating the first tube 11 and the third tube 13, the portion where the outer surface 11b of the first tube 11 is exposed can function as a bubbling section 30.

[0066] The apparent specific gravity of the bubbling section 30 in the composite tube may be in the range of 0.10 to 2.0, or may be in the range of 0.11 to 1.87. The apparent specific gravity of the bubbling section 30 is preferably larger than the specific gravity of, for example, the chemical solution in which the bubbling section 30 is immersed. In this case, even if bubbling is performed while the bubbling section 30 is immersed in the chemical solution, the bubbling section 30 can be prevented from floating up. The apparent specific gravity of the bubbling section 30 can be measured by specific gravity measurement using the underwater displacement method.

[0067] The other end 111 of the first tube 11 and the other end 131 of the third tube 13 may be one end 100 of the bubbler tube 10. The other end 121 of the second tube 12 may be the other end 101 of the bubbler tube 10. The overall length of the bubbler tube 10 is defined, for example, from the other end 111 of the first tube 11 to the other end 121 of the second tube 12.

[0068] As shown in FIG. 5, when the third tube 13 is disposed on the inner diameter side of the first tube 11, an increase in pressure loss of gas flowing in from the other end 121 of the second tube 12 can be suppressed even if the first tube 11 is long. Specifically, for example, gas flowing into the bubbler tube 10 from the other end 121 of the second tube 12 passes mainly through the third tube 13 to reach the one end 100 of the bubbler tube 10. Although the third tube 13 has at least one through-hole 132, its inner circumferential surface 13a is configured, for example, with a non-solid structure. Therefore, pressure loss can be reduced compared to when gas flows directly through the first tube 11, which has a porous structure.

[0069] The gas flowing through the third tube 13 passes from the inner circumferential surface 13a of the third tube 13 through the through holes 132, passes between the outer circumferential surface 13b of the third tube 13 and the inner circumferential surface 11a of the first tube 11, and further passes through the porous structure portion of the first tube 11 before being released to the outside of the first tube 11. The provision of the third tube 13 makes it possible to release the gas relatively uniformly from the entire outer circumferential surface 11b of the first tube 11.

[0070] (Manufacturing method) An example of a method for manufacturing a bubbler tube according to the embodiment will be described below. The first tube can be produced, for example, by uniaxially stretching a PTFE tube having a non-porous structure (solid structure). The PTFE tube having a solid structure that serves as a precursor of the first tube can be, for example, an extrusion-molded product. An example of extrusion molding is described below.

[0071] The raw materials for extrusion molded products can be PTFE fine powder and an extrusion aid such as a lubricant. By mixing PTFE fine powder with an extrusion aid such as a lubricant, a paste-like mixture can be obtained. By extruding the mixture containing PTFE fine powder into a tubular shape, a tubular extrusion molded product can be obtained.

[0072] Examples of extrusion aids include commonly used solvent naphtha (e.g., registered trademark: Isoper E, manufactured by Exxon Chemical Co.), white oil, and liquid paraffin having 6 to 12 carbon atoms (e.g., registered trademark: Cactus Normal Paraffin N-10, manufactured by Japan Energy Corporation).

[0073] The mixture obtained by mixing the PTFE fine powder and the extrusion aid may be aged before being subjected to extrusion molding. The aged mixture may also be compressed to produce a compression-molded body (billet). Compression removes air from the PTFE fine powder, improving the uniformity of the extrusion-molded product. The shape of the compression-molded body is not particularly limited, but may be, for example, cylindrical.

[0074] Next, the PTFE tube manufactured as the first tube precursor is uniaxially stretched. Uniaxial stretching pulls polymer fibers from the polymer material contained in the first tube precursor and stretches them in the stretching direction. This allows the formation of a microstructure containing nodes and fibrils.

[0075] The specific gravity or porosity of the first tube can be adjusted by adjusting the stretching ratio during uniaxial stretching. A first tube with a low specific gravity can be formed by increasing the stretching ratio during uniaxial stretching. A first tube with a high specific gravity can be formed by decreasing the stretching ratio during uniaxial stretching. For example, if the stretching ratio during uniaxial stretching is set to 2 times, a first tube with a porosity of approximately 50% can be produced. The stretching ratio can be adjusted appropriately depending on the target specific gravity, and is, for example, within the range of 1.2 times to 6 times. It can be adjusted appropriately depending on the target specific gravity.

[0076] Next, the unsintered first tube is dried and sintered. Drying is carried out, for example, in a drying oven. By drying at a temperature above the boiling point of the petroleum-based extrusion aid used earlier, the aid can be volatilized. Next, the dried tube is heated and sintered at a temperature above the melting point of PTFE, for example, at a temperature above 330°C. In this way, the first tube can be produced.

[0077] The second tube having a non-porous structure is made of, for example, the above-mentioned fluororesin, and can be made by a known molding method such as extrusion molding or injection molding.

[0078] The inner and outer diameters of the first tube and the second tube can be designed and manufactured to desired values. As described above, for example, the inner diameter of the second tube is made larger than the outer diameter of the first tube.

[0079] One end of the fabricated first tube is inserted into one end of the second tube, and the two tubes are heat-treated at a temperature equal to or higher than the melting point of the fluororesin that makes up the second tube, thereby fusing the one end of the second tube to the outer circumferential surface of the first tube. This allows the fabrication of the bubbler tube 10 having the fused portion 122, as described with reference to FIG. 1, for example.

[0080] Furthermore, when manufacturing the bubbler tube 10 further including the intermediate layer 14 described with reference to FIG. 4, it can be manufactured, for example, as follows.

[0081] After the first tube is produced, a dispersion containing fluororesin particles is prepared to form the intermediate layer 14. As the fluororesin particles, it is preferable to use the above-mentioned melt-flowable fluororesin particles.

[0082] The dispersion contains a dispersion medium and a melt-flowable fluororesin powder in the dispersion medium. The melt-flowable fluororesin powder may be a material commonly used in methods for forming resin tubes by coating, such as dip coating. For example, the dispersion is an aqueous dispersion in which a melt-flowable fluororesin powder is dispersed in an aqueous dispersion medium by emulsion polymerization.

[0083] The dispersion medium may be, for example, water. The composition of the dispersion is not particularly limited, and for example, a dispersion or suspension having a composition commonly used in techniques such as dip coating may be used. The dispersion may or may not further contain a filler or additive, etc., different from the melt-flowable fluororesin powder.

[0084] The prepared dispersion is applied to a portion of the outer circumferential surface of the first tube to form a coating film. Next, one end of the first tube is inserted into one end of the second tube, and at least a portion of the coating film is covered with the inner circumferential surface of the second tube. The joint between the first tube and the second tube is then subjected to heat treatment. In this way, an intermediate layer can be formed on at least a portion of the area where the outer circumferential surface of the first tube and the inner circumferential surface of the second tube face each other.

[0085] The bubbler tube 10 further including the third tube, which has been described with reference to FIG. 5, can be produced, for example, by the following method.

[0086] First, a third tube is prepared. The third tube can be prepared by drilling desired through holes in a resin tube having a non-porous structure, which is prepared by a known molding method such as extrusion molding or injection molding. When multiple through holes are provided in the third tube, these through holes may or may not be aligned in one direction.

[0087] Next, the prepared third tube is combined with the first tube. Specifically, first, a dispersion containing melt-flowable fluororesin particles is applied to the outer peripheral surface of the third tube near one end and the other end of the third tube. The dispersion may be any of those described above. The third tube is then inserted into the inner diameter side (inner peripheral surface side) of the first tube, and these are subjected to heat treatment, whereby the fluororesin particles contained in the coating melt and form a fusion layer. In this way, a composite tube having a two-layer structure of the third tube 13 and the first tube 11 can be prepared.

[0088] Next, the second tube is joined to the outer surface of the first tube combined with the third tube in the same manner as described above, thereby producing a bubbler tube further comprising the third tube.

[0089] The bubbler tube according to the embodiment may employ either one of the first and second modified examples, or may employ both of them. Also, it is not necessary to employ both the first and second modified examples.

[0090] (Second embodiment) According to the second embodiment, a bubbler is provided that includes the bubbler tube according to the first embodiment and a gas supply means. The gas supply means is connected to the other end of the second tube included in the bubbler tube according to the first embodiment. Although not shown, the bubbler may include two gas supply means. That is, the bubbler tube may be provided with a gas supply means at one end and another end.

[0091] The type of gas supply means is not particularly limited. The gas supply means may be a conventionally known device. The gas supply means is, for example, a device that can release a gaseous material at a constant supply amount per unit time. The gaseous material can be supplied from the device through a gas supply pipe into the bubbler tube according to the first embodiment.

[0092] The type of gas to be supplied can be changed appropriately depending on the purpose of the bubbler, but is, for example, at least one selected from the group consisting of air, nitrogen, ozone gas, ammonia, and the like.

[0093] Fig. 8 is a diagram schematically illustrating an example of a bubbler according to an embodiment. In the bubbler shown in Fig. 8, a gas supply means 40 is connected to the other end of a second tube 12 provided in a bubbler tube via a gas supply pipe 41. A device such as a one-touch joint can be installed at the connection between the other end of the second tube 12 and the gas supply pipe 41, if necessary.

[0094] The first tube 11 included in the bubbler tube is immersed in the liquid material 43 stored in the container 42. In this state, by supplying gas from the gas supply means 40 into the bubbler tube, the gas can be diffused into the liquid material 43 through the wall surface of the first tube 11, which has a porous structure. In other words, bubbling can be performed.

[0095] The type of liquid material can be changed appropriately depending on the purpose of the bubbler, but may be, for example, a resist used in semiconductor manufacturing, a developer, an organic solvent, various aqueous solutions, a strong acid, a strong alkali, etc. An example of various aqueous solutions is a sodium hypochlorite aqueous solution.

[0096] The apparent specific gravity of the bubbling portion, i.e., the portion of the entire length of the bubbler tube where the outer peripheral surface of the first tube 11 is exposed, is preferably greater than that of the liquid material 43. In this case, it is possible to prevent the bubbling portion from floating up to near the liquid surface and reducing the efficiency of stirring the liquid material by bubbling.

[0097] The bubbler according to the second embodiment includes the bubbler tube according to the first embodiment. For example, the bubbling section formed by the first tube 11 has a tubular shape, which makes it easy to bend it to fit the installation shape and to move it within the liquid material 43 stored in the container 42. That is, according to the second embodiment, a bubbler is provided which has excellent chemical resistance and heat resistance, and also has a high degree of freedom in installation.

[0098] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention. [Explanation of symbols]

[0099] 10...bubbler tube, 11...first tube, 11a...inner surface, 11b...outer surface, 12...second tube, 12a...inner surface, 12b...outer surface, 13...third tube, 13a...inner surface, 13b...outer surface, 14...intermediate layer, 16...fluororesin-containing cap, 20...fused layer, 30...bubbling portion, 40...gas supply means, 41...gas supply pipe, 42...container, 43...liquid material, 60...joint, 61...socket, 62...plug, 122...fused portion, 132...through hole.

Claims

1. a first tube having at least a portion of a porous structure and containing polytetrafluoroethylene; a second tube having a non-porous structure and containing a fluororesin; One end of the second tube is connected to one end of the first tube, a part of an outer circumferential surface of the first tube faces a part of an inner circumferential surface of the second tube; an intermediate layer interposed between the outer circumferential surface of the first tube and the inner circumferential surface of the second tube; The wall thickness of the first tube is in the range of 0.1 mm to 5.0 mm.

2. a third tube having an inner circumferential surface and an outer circumferential surface; the first tube covers at least a part of the outer circumferential surface of the third tube, and an inner circumferential surface of the first tube is fused to the outer circumferential surface of the third tube via a fusion layer at the one end and the other end of the first tube; the third tube has a plurality of through holes that penetrate from the inner circumferential surface to the outer circumferential surface and are arranged in a direction from one end of the third tube to the other end, 2. The bubbler tube according to claim 1, wherein the wall thickness of the third tube is in the range of 0.1 mm to 5.0 mm.

3. a bubbling portion, which is a portion of the entire length of the bubbler tube defined from the other end of the first tube to the other end of the second tube, where the outer peripheral surface of the first tube is exposed; 3. The bubbler tube according to claim 1, wherein the apparent specific gravity of the bubbling portion is in the range of 0.10 to 2.

0.

4. 3. The bubbler tube according to claim 1, wherein the length of the first tube is in the range of 0.1 m to 5.0 m.

5. Further provided with a fluororesin-containing cap, 3. The bubbler tube according to claim 1, wherein the other end of the first tube is sealed with the fluororesin-containing cap.

6. The bubbler tube according to claim 1 or 2; a gas supply means; The gas supply means is a bubbler connected to the other end of the second tube.

7. 1. A bubbler for bubbling a liquid material, comprising: a bubbling portion, which is a portion of the entire length of the bubbler tube defined from the other end of the first tube to the other end of the second tube, where the outer peripheral surface of the first tube is exposed; The bubbler according to claim 6 , wherein the apparent specific gravity of the bubbling portion is greater than the specific gravity of the liquid material.

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