JPS5881404A - Degassing or defoaming method - Google Patents

Abstract

PURPOSE:To suppress the foaming of a liquid effectively without providing a special means to a pressure reduced vacuum system, by sucking the liquid having a gas dissolved or contained therein through a porous membrane. CONSTITUTION:In order to remove a gas dissolved in a liquid or to remove foam therein, the aforementioned gas or foam is removed by passing the liquid through a porous membrane under reduced pressure. The porous membrane to be used has capacity for suppressing the foam generated in degassing the liquid and is made of a high molecular film having a fine pore with an average pore size of 1mum or less comprising a material such as polyethylene, polypropylene, PVC, polyester, polycarbonate, polyamide, cellulose acetate or a fluoro resin and, in use thereof, a metal porous plate is used as a reinforcing material. By this method, it is unnecessary to sadvantageous from a standpoint of an installation and energy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing dissolved gases and/or bubbles from a liquid under reduced pressure.

Conventionally, various methods have been attempted to remove dissolved gases and bubbles under reduced pressure. For example, in the viscose rayon industry, an instant defoaming machine (dualerator) is used to remove the bubbles contained in the viscose when spinning the raw viscose solution. Defoaming is performed by letting the dripping flow down the wall.Also, as an example of the deaeration method, photocurable resins are exposed to air for a long period of time and their sensitivity decreases due to dissolved oxygen in the resin ("photosensitive resins"). In order to restore the sensitivity of this resin, it is necessary to deoxidize it under a high vacuum (Cm). When defoaming or degassing, it is necessary to take measures to suppress bubbles as a large amount of bubbles will be generated. Therefore, as a measure to suppress bubbles, in the case of bistooth rayon, a large space and a wet wall structure in the deaerator are provided, and in the case of photocurable resin, We have purchased means to eliminate foaming by stirring, etc.
-39777).

The inventors of the present invention have arrived at the present invention as a result of extensive research into a method that can effectively suppress bubbles without providing any special means in the reduced-pressure vacuum system.

That is, the present invention provides degassing and/or defoaming in which the gas or bubbles are vented and removed through a porous membrane under reduced pressure in order to remove gas dissolved in the liquid and/or bubbles in the liquid. It's a method.

The porous membrane that can be used in the present invention has the function of suppressing bubbles that are generated and rises during degassing of the liquid port, and the porous membrane is rattanned to allow the liquid to penetrate. is not suitable. The average pore diameter of the porous membrane is 1 g (micron)
The following is preferable, and the more preferable range is 0.5 μ to 9.05 J. Pores with a fine pore diameter of less than O,OSμ are not preferable because the drop in liquid pressure during depressurization is small, requiring a long time for degassing and defoaming. Further, in the case of cast films that are not porous, such as unstretched polypropylene, the vacuum degassing method cannot be applied. Both so-called membrane filters and depth filters can be used.

Next, the porous membrane of the present invention can be made of various polymer films. Specifically, polyethylene, polypropylene, polyvinyl chloride, polyester,
Polycarbonate.

Examples include polyamide, cellulose, cellulose acetate, fluororesin, etc. A fluororesin-based polymer film is most preferred because of its foam-inhibiting effect.

The porous membrane itself used in the present invention has considerably low mechanical strength due to its porosity, and therefore cannot withstand pressure at all during depressurization. Therefore, a reinforcing material is required to support this porous membrane. The reinforcing material may be any material as long as it is porous and has high mechanical strength. Perforated metal plates (so-called punching plates) with many holes larger than the pore diameter of the porous membrane, sintered metal plates, and wire mesh.

Examples of reinforcing materials include screens made of fiber materials, screens for cloth, and screens made of these materials in combination.

In the present invention, a porous membrane reinforced with a reinforcing material can be placed so as to cover the surface of the liquid, or can be provided at a position above the liquid surface. In either case, it is placed between the liquid surface and the Makabe type gas suction means so as to be in contact with the liquid surface or not in contact with the vicinity of the liquid surface. When the pressure is reduced to remove dissolved gases and bubbles from a liquid, bubbles form near the liquid surface, but their growth is suppressed by the porous membrane. Therefore, the gas that is degassed and degassed from the liquid must pass through the porous membrane.
It is necessary to prevent gas from being sucked out from around the porous membrane.

For this purpose, it is preferable to seal the periphery of the porous membrane.

According to the present invention, there is no need to install a wetted wall or stirring means as in the prior art, and the foam suppressing effect can be achieved simply by providing a simple porous membrane. Therefore, it is advantageous both in terms of equipment and energy.

5-Next, the present invention will be described in a second embodiment with respect to the regeneration of a photocurable resin, but the present invention is not limited to this in any way.

The photocurable resin used in the examples was diethylene 9 coat.
1.5.90 parts of 7i-ruic acid, 1.160 parts of 7i-luic acid.

320 parts of trimellitic anhydride and 730 parts of adipic acid were stirred and reacted at 100 to 120°C for 30 minutes under a nitrogen atmosphere, and the temperature was further raised to 200°C and reacted for 5 hours.
An unsaturated polyester having an acid value of 140 was obtained. Then, 6 parts of methacrylamide was added to 65 parts of this unsaturated polyester.

Tetraethylene glycol dimeta, 10 parts of acrylate, 9 parts of 2-7 setoxylated methyl meth 7 acrylate, 10 parts of diallylisophtha V-), 1 part of benzoin methyl ether, mel, captobenzoxazole & 041i1 and N-2) lodge phenylamine Add 2 parts a0 to 6
It was prepared by stirring at 0°C for 30 minutes. [
However, all of the above parts indicate weight.] The sensitivity of the photocurable resin is determined by...Ration 6- On the support with the pasting adhesive layer, apply the curable resin to a thickness of 0.71EII. Apply layers. Then, on the opposite side from the support, place 9 pieces of negative film on which an independent point with a diameter of 160μ is drawn.
The negative was placed in close contact with the resin layer through a polyethylene terephthalate cover film, and an ultraviolet fluorescent lamp (SOW) was irradiated through this negative for 6 minutes, the liquid resin in the unexposed areas was removed with dilute alkaline water WI solution, and the film was developed. The shoulder shape of the independent point (the ratio of the diameter LK of the independent point relief base to the diameter l of the top part L/R) was evaluated.

In this case, a larger value indicates higher visibility.

Examples 1-3. Comparative Examples 1 to 4 Liquid photocurable resin 250I with reduced photocurable properties (Comparative Example 1) was placed in a separable flask for 5009, and bubbles were added by stirring to promote degassing. Next, various porous membranes whose upper and lower surfaces were reinforced with 100-mesh wire mesh were placed near the opposite sides of the separable flask, and the periphery was brought into close contact with the flask. Furthermore, place a separable cover on top of it, and clamp the flask and cover in several places at the same time to prevent gas from leaking or infiltrating between the flask, the reinforcing material, the porous membrane, the reinforcing wire mesh, and the cover. It was then completely airtight using grease. When the pressure is reduced using a vacuum pump from the opening of the separable cover, the resin in the flask foams.

A co-electric current occurred and the bubbles reached the surface of the porous membrane. The gas in the resin is removed through the pores of this membrane, but the oily resin is trapped in this membrane, resulting in foam suppression. It depends on the decompression speed and the type of membrane, but if it is fast, an oil rotary vacuum pump with a displacement of 1 ooJ/m will generate electricity and reach the membrane within 1 minute after decompression, and the level of this bubble will decrease in a few minutes, and it will last for 1 hour. At this point, almost no bubbles disappeared, and the degassing and defoaming were completed. In Examples 1 to 3, degassing was performed under reduced pressure for 1 to 3 hours at a vacuum degree of 2 to 3 wmHI.

Table 1 shows the sensitivity change due to resin regeneration when the average pore diameter of the porous membrane and the material were changed.

In addition, a case in which a porous membrane with a foam suppressing effect is not used is also listed as Comparative Example 2, and a case in which a cast film is used (
Comparative Examples 3 to 4) are also listed in the same table.

In the case of Comparative Example 2, which was subjected to regeneration treatment without using a porous membrane in Table 1, the bubbles rose intermittently, and the vacuum pump could not be operated continuously, and while watching the bubbles rise, the bubbles occasionally rose. I spent a lot of time playing it for two reasons. However, compared to these, it can be seen that in Examples 1 to 3, the sensitivity was recovered to 9- in a short period of time and regenerated. Moreover, no liquid was seen seeping into the reaction zone of the membrane.

Historically, it has been found that in the case of fluororesin-based membranes, it is possible to use the membrane repeatedly.

10-

Claims (1)

[Claims] 1) When removing dissolved gas or bubbles from a housing containing dissolved gas or bubbles under reduced pressure using a gas suction means, the difference between the liquid level and the axillary gas evacuation means A degassing or defoaming method characterized by placing a porous membrane in between and sucking and removing gas through the porous membrane. 2) The degassing or defoaming method according to claim 1, which comprises providing a porous membrane having an average pore diameter of 1 micron or less. 3) The degassing or defoaming method according to claim 1 or 2, wherein the porous membrane is made of a fluorine-based resin.