JPH0532162Y2 - - Google Patents

Description

[Detailed explanation of the invention] ``Purpose of the invention'' The present invention relates to the invention of a deaeration tube, which is designed to increase the amount of ventilation (deaeration amount) for the tube for removing gas contained in various liquids. It is an object of the present invention to provide a deaeration tube which can obtain a high temperature and maintain high liquid pressure resistance and perform efficient deaeration.

Industrial applications Degassing mechanism for ultrapure water for LSI cleaning, aqueous solvent resin film raw materials, liquid chromatography aqueous solvent liquid, etc.

BACKGROUND OF THE INVENTION Various methods have been used to deaerate liquids in cases where air or other gases are undesirably mixed in. That is, for example, deaerators are used for ultrapure water for LSI cleaning, aqueous solvent resin film raw materials, liquid chromatography aqueous solvent liquid, etc. to separate and remove the gases contained therein. Porous tubes of polytetrafluoroethylene are commonly used for this purpose.

Problems to be solved by the invention The conventional porous tube made of polytetrafluoroethylene described above has excellent chemical resistance and has a favorable deaeration effect, but when the aeration rate is increased, the water pressure resistance becomes low. On the other hand, if this water pressure resistance is to be maintained at a high level, the amount of ventilation will inevitably be low. That is, these relationships are as shown in Fig. 4. For example, if the ventilation rate is 5 × 10 ^-2 cc/cm ² .
When increasing from sec to 10×10 ^-2 cc/cm ²・sec, the liquid pressure (water pressure) resistance decreases from approximately 0.9Kg/cm ² to 0.3Kg/cm ² .
Generally required such as tube
Conventionally available polytetrafluoroethylene porous tubes do not have a pressure resistance of 0.8 Kg/cm ² , have high liquid pressure, and cannot perform efficient deaeration treatment with a large amount of ventilation.

Therefore, the only way to increase the amount of deaeration with conventional deaeration tubes is to increase the surface area by making the tube longer, or to increase the number of tubes, but the former increases the internal resistance of the liquid. It is necessary to increase the pressure, and the latter leads to an increase in the size of the equipment, which inevitably results in disadvantageous equipment and operation. In other words, the high precision of various industries today has made it impossible to ignore the presence of gas in the liquid, and the gas in the LSI cleaning water is
Gases in resin raw materials can adhere to surfaces and interfere with post-processing, and gases in resin raw materials can cause pinholes during film molding and other processes, so it is strongly recommended that deaeration be carried out efficiently in as compact equipment as possible. Despite requests, we are unable to respond appropriately to such requests.

"Structure of the invention" Means for solving the problem It has an inner tube and an outer tube made of flexible polytetrafluoroethylene tube, and between these inner and outer tubes, an average pore diameter of 0.2 to 0.8 is made of polytetrafluoroethylene. A degassing tube characterized in that a tubular body formed of a planar stretched porous film having a pore diameter smaller than the average pore diameter of the inner and outer tubes in μm is inserted.

Function By interposing between the inner and outer tubes a tubular body formed of a planar stretched porous film made of polytetrafluoroethylene and having an average pore diameter of 0.2 to 0.8 μm and smaller than the average pore diameter of the inner and outer tubes. The tubular body plays a main role in the degassing action, that is, its microporous structure and thin layer property due to planar stretching, together with the water repellency of the material itself, ensure appropriate air permeability and effectively prevent water permeation. Furthermore, such a planar stretched structure has preferable strength, and a structure with a high porosity has excellent water pressure resistance, allowing efficient degassing.

The inner and outer tubes located on the inner and outer sides of the tubular body allow the tubular body to be appropriately thinned and ensure efficient deaeration as described above.

Since each tube and the tubular body are both made of polytetrafluoroethylene, each member is compatible with each other, and has excellent properties such as heat resistance and chemical resistance. The relatively large porosity of the body allows the entire degassing tube to maintain flexibility and allow for the design of flexible degassing equipment that can be bent at will.

EXAMPLE To explain a specific embodiment of the present invention as shown in the attached drawings, a polytetrafluoroethylene porous tube is also used in the present invention, and as shown in FIG. A tube is used as the inner tube 1 and the outer tube 3, and a tubular body 2 made of a planar stretched polytetrafluoroethylene porous film 4 is interposed between the tubes 1 and 3.

In order to obtain the tubular body 2, as shown in FIG. It can be easily manufactured by attaching the tube 3 to the outer surface of the tube 3 and then covering the outside thereof with the tube 3.

The porous film 4 described above is obtained by flatly rolling and stretching a polytetrafluoroethylene film material to form a porous structure, that is, a countless number of fine fibers are formed in a spider web shape between a large number of micro nodules. It is generally known that polytetrafluoroethylene can be made porous with high precision through planar stretching, and its fine fiber structure and resin itself Combined with its water repellency, it allows ventilation but does not allow liquid (particularly water) to pass through. Therefore, in the present invention, the tubular body 2 made of such a film 4 plays the main role in degassing. It is. For this reason, the pore size of the porous structure is important; in other words, since it is a film, its thickness should be at least a fraction of that of a tube, such as 30 to 100 μm, to increase the amount of ventilation. Although it is important to achieve this thickness and can be easily formed by stretching etc. under such conditions, the diameter of the pores formed between the above-mentioned fine fibers is 0.2.
It should be about 0.8 μm. In other words, if the pore size exceeds 0.8 μm, sufficient liquid pressure resistance cannot be obtained.
For example, under water pressure conditions of 1.0 Kg/cm ² or more, some water will permeate, making it impossible to obtain an effective deaeration effect. On the other hand, the pore diameter
When the thickness is less than 0.2 μm, there is a tendency that proper air permeability cannot be obtained.

As an example, the average pore size is 0.2 to 1 μm and the film thickness is
The relationship between the water pressure resistance value and the air permeability of a polytetrafluoroethylene film with a diameter of 65 μm and a porosity of 85% is shown in Figure 3. When the water pressure resistance is 1.0 Kg/cm ² , the air permeability is 10 c.c./cm 2 . Ensuring sufficient cm ² sec, water pressure resistance 0.5
Kg/cm ² can sufficiently obtain 30 c.c./cm ² sec.

As mentioned above, since the main body of the degassing function is the tubular body 2 made of the porous film 4 made of planar stretching of polytetrafluoroethylene, the functions of the inner tube 1 and the outer tube 3 are Even though the polytetrafluoroethylene porous body is the same, its technical characteristics are different from those of the conventional degassing tube, and the tubular body 2
serves as a support or protector for Therefore, the pore size,
The thickness etc. are determined in this sense, and the pore diameter is larger than the pore diameter of the planar stretched porous film 4 (therefore, the pore diameter of the planar stretched porous film is larger than that of the tubes 1 and 3).
(smaller than the pore diameter). Note that the film 4
The tubes 1 and 3 made of polytetrafluoroethylene can be used to prevent stains and scratches on the tubular body 2 due to
In particular, elution must be taken into account in degassing tubes for liquid chromatography, and porous tubes made of polytetrafluoroethylene as described above are effective in this respect as well.

Some manufacturing examples according to the present invention will be described below.

Manufacturing example 1 On the outside of the inner tube 1 made of polytetrafluoroethylene, which has an outer diameter of 7.2 mm, an inner diameter of 6.0 mm, a porosity of 50%, and a pore diameter of 3.5 μm, a thickness of 50 μm, a porosity of 85%,
A tubular body 2 made of a planar stretched polytetrafluoroethylene film with a pore diameter of 0.45 μm is coated, and an outer tube 3 having an outer diameter of 10.0 mm, an inner diameter of 8.0 mm, and the same porosity and pore diameter as the inner tube 1 is provided on the outside thereof. A product according to the present invention was obtained by covering the product.

An aqueous solution at 25℃ is placed inside the tube of this invention.
When the air flows in at a pressure of 1.5Kg/cm ² and the outside of the tube is degassed with a vacuum of 70cmHg, the amount of air passing through the tubular body 2 and exiting outside is 8.0×
10 ^-2 cc/cm ²・sec, and the water inside tube 1
However, effective deaeration treatment can be performed without leaking out from the tubular body 2, and the equipment can be made more compact.

Manufacturing example 2 Inner tube 1 made of polytetrafluoroethylene with an outer diameter of 7.2 mm, an inner diameter of 6.0 mm, a porosity of 70%, and a pore diameter of 1.0 μm, a thickness of 50 μm, a porosity of 85%,
A tubular body 2 made of polytetrafluoroethylene porous film with a pore diameter of 0.8 μm is polymerized, and a polytetrafluoroethylene tube 3 with an outer diameter of 10.0 mm, an inner diameter of 8.0 mm, a porosity of 70%, and a pore diameter of 1.0 μm is placed on the outside of the tubular body 2. The product of the present invention was obtained by masking.

When this product is degassed under the same conditions as in Production Example 1, the amount that can be degassed is 5.0 ×
10 ^-2 cc/cm ² ·sec, and as in Production Example 1, no internal water leaked out.

``Effect of the invention'' The invention as explained above can provide a high-performance deaeration tube with high liquid pressure resistance and high air permeability, which is necessary for high precision in various industries. This invention is industrially very effective because it allows the degassing treatment of the treatment liquid to be carried out in a small mechanism with high efficiency and at low cost.

[Brief explanation of the drawing]

The drawings show the technical contents of the present invention, and Fig. 1 is a cross-sectional view of a tube according to the invention, Fig. 2 is a perspective view of a tubular body made of the polytetrafluoroethylene porous film, and Fig. 3 is a cross-sectional view of a tube according to the invention. A chart showing the relationship between water pressure resistance and air permeability for one example of this polytetrafluoroethylene porous film. Figure 4 is a chart showing the relationship between water pressure resistance and air flow rate for a conventional polytetrafluoroethylene porous tube. It is. In FIGS. 1 and 2, 1 is an inner tube made of a porous tube, 2 is a tubular body, 3 is an outer tube made of a porous tube, 4 is a polytetrafluoroethylene porous film forming the tubular body, and 5 is a porous tube made of a porous tube. This shows the fused part.

Claims (1)

[Scope of utility model registration request] It has an inner tube and an outer tube made of flexible polytetrafluoroethylene tubes, and the average pore size of polytetrafluoroethylene between these inner and outer tubes is 0.2 to 0.8 μm, which is smaller than the average pore size of the inner and outer tubes. A degassing tube characterized in that a tubular body formed of a planar stretched porous film is inserted therein.