JPH0155658B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides for mixed fluids, especially mixed gases,
The present invention relates to a method for producing an ultra-thin polymer membrane having permselectivity.

Configuration of conventional examples and their problems In recent years, there has been remarkable progress in separation technology using membranes, and some of them have actually been put into practical use on an industrial scale. However, what has been put into practical use is liquid-liquid separation or liquid-solid separation, such as seawater desalination, factory waste treatment, food concentration, etc., and gas-gas separation, that is, two or more types of separation. The separation of mixed gases has hardly been put to practical use.

The reason why membrane separation of gases cannot be easily put into practical use is that the permselectivity is relatively low.In other words, there is no membrane that selectively passes a specific gas and hardly allows other gases to pass through. In order to obtain gas, it is necessary to adopt a multi-stage method in which membrane separation is repeated several times, which results in the equipment being too large, and the amount of permeation is small, making it impossible to produce large amounts of gas. be. However, from the point of view of selective permselectivity, there are many fields in which the final use of gas does not necessarily require high purity. For example, in the case of oxygen, high purity oxygen is not necessarily required for use in blast furnace ventilation, combustion assistance, petroleum protein processing, wastewater treatment, and medical use such as exhalation. Not only that,
High-purity oxygen often has disadvantages such as damage to the furnace, risk of fire, and blindness in premature infants. Conventionally, as a method for obtaining oxygen-enriched air for use in the above-mentioned applications, high-purity oxygen has been produced using an air separation device (air liquefaction method) and then mixed with air to achieve the desired oxygen concentration.

However, in such methods, high-purity oxygen is generally contained in a pressure vessel, so there are risks in handling the pressure vessel, the need for a pressure regulator to keep the mixed gas concentration constant, and the complexity of its operation. There are many problems. Therefore, as a method for obtaining oxygen-enriched air of low or intermediate purity, air separation using membrane separation is easier and more economical as it allows oxygen-enriched air to be obtained directly from air in the atmosphere. It is also advantageous.

Conventionally, two methods are known as methods for producing oxygen-enriched air by membrane separation. One is a method using hollow fibers such as polyethylene, polystyrene, or polyethylene terephthalate.
(Refer to JP-A-49-10192 and JP-A-49-81298.) The other is organopolysiloxane.
There is a method using an ultra-thin film such as a polycarbonate copolymer (see US Pat. No. 3,980,456 and US Pat. No. 3,874,986). Although the method using hollow fibers increases the membrane area per unit area and increases the amount of permeation, it is still too large and simple to obtain a practical amount of permeation. On the other hand, ultra-thin membranes increase the amount of permeation by utilizing the fact that the amount of permeation is inversely proportional to the membrane thickness, and the thinner the membrane thickness, the more compact the separation device becomes possible. This is based on the fact that when gas passes through a homogeneous membrane, the amount is generally expressed as:

F: Permeation flow rate (cm ³ /sec); Gas permeability coefficient (cm ³・cm/cm ²・sec・cmHg) △P: Pressure difference (cmHg) A: Membrane area (cm ² ) L: Membrane thickness (cm) In the above equation, A and ΔP depend on the external equipment required for gas separation and have certain limits. Alternatively, since it is constant depending on the material, in order to increase the permeation flow rate F, it is necessary to ultimately make the film thickness as large as possible and the film thickness L as thin as possible. One of the ultra-thin films known to date is a film made of an organopolysiloxane-polycarbonate copolymer. The film thickness of this copolymer is
It is about 0.1μ, and the oxygen permeability coefficient of the material itself is ~10 ^-8 (cc・cm/cm ²・sec・cmHg),
Although it has a good oxygen separation coefficient (P _O2 /P _N2 ) of 2.0 to 2.4, it has poor chemical resistance and there is a risk of deterioration due to contaminated air or oil from oil-filled pumps or compressors used for depressurization and pressurization. , deterioration due to hydrolysis is also considered, which poses a practical problem. An even bigger problem is that in order to produce an ultra-thin film of this organopolydimethylsiloxane-polycarbonate copolymer, it is necessary to use 1,2,3-trichloropropane, trichloroethylene, chloroform, etc., which have a higher specific gravity than water, as a solvent for this polymer. When this polymer solution is dropped onto the water surface to obtain an ultra-thin film, a portion of the polymer solution settles below the water surface and cannot spread sufficiently on its own, making it difficult to use for practical purposes. It is difficult to easily produce such a uniform thin film. Other methods for producing ultra-thin films include JP-A-56-166232 and JP-A-Sho.
There is one shown in No. 56-92925. These methods involve adding compounds such as alcohols with hydrophilic groups to a cyclohexene solution of hydrophobic polymers such as polyolefins and diene polymers, or adding a mixture mainly composed of partially oxidized cyclohexene to a solution of hydrophobic polymers such as polyolefins and diene polymers in cyclohexene. By using it as a solvent for the polymer, it was devised so that it would spread spontaneously and uniformly on the water surface. However, although these methods are effective for polyolefin and diene polymers, they have the disadvantage that they cannot be applied to other polymers.

Purpose of the Invention The present invention has been made in order to solve the above-mentioned conventional problems, and mainly uses a polymer material that has a large gas permeation rate and a separation function with excellent selectivity. The purpose of the present invention is to provide a method for manufacturing a uniform ultra-thin film.

Structure of the Invention In order to achieve this object, the present invention uses a silicone-based surfactant in a hydrophobic solution of a polymer for thin film production, which has been difficult to spread on the water surface, is non-uniform, and is difficult to form into a thin film. By adding 1 to 10% by weight of the polymer, it is possible to spread the polymer, make it uniform, and make it an ultra-thin film.

Hydrophobic solvents in this invention include benzene, toluene, xylene, chlorobenzene, ethyl acetate, methyl acetate, chloroform, methylene chloride, chloroethane, chloropropane, and the like. In addition, as silicone-based surfactants, JP-A-56
Copolymers of polyhydroxystyrene and terminally reactive polydimethylsiloxane shown in -26506, copolymers of phenolic resin and terminally reactive polydimethylsiloxane shown in JP-A No. 56-24019, and other silicones. By adding a surfactant as the main component, a very good ultra-thin film was obtained.

DESCRIPTION OF EXAMPLES The present invention will be described in more detail below by giving examples mainly based on experiments conducted so far, but the examples are for illustrating the present invention and are not limited thereto. It's not a thing.

<Comparative Example 1> Polyphenylene oxide (PPO) having a weight average molecular weight of approximately 100,000 was dissolved in toluene to prepare a 2% by weight solution. Using this solution, we investigated forming an ultra-thin film on the water surface using the Langmiur method, but with this solution composition, PPO did not diffuse uniformly on the water surface and it was not possible to form a thin film.

<Example 1> When 1 c.c. of a 10wt% benzene solution of a copolymer of polyhydroxystyrene and polydimethylsiloxane shown in JP-A-56-26506 was added to the solution shown in Comparative Example 1, PPO was uniformly diffused on the water surface, giving a uniform ultra-thin film over an area of 50 cm x 50 cm. The volume of the droplet at this time was 0.05 cc, and the weight of PPO contained in the droplet was 2.09×10 ⁻³ g. From this, if the specific gravity of PPO is 1.0 and the film thickness is calculated, it will be approximately 0.1μ, and the copolymer of polyhydroxystyrene and polydimethylsiloxane will be
It has been found to be a very effective additive in producing ultra-thin films.

<Example 2> Polybutadiene was dissolved in benzene to form a 2% by weight solution, and as in Comparative Example 1, attempts were made to form an ultra-thin film on the water surface, but the results were not good. Therefore, when a benzene solution of a copolymer of polyhydroxystyrene and polydimethylsiloxane was added in the same manner as in Example 1, this time it immediately spread on the water surface, resulting in a uniform ultra-thin film. The membrane thus obtained was coated with porous polypropylene (Dyuragart 2400).
Polyplastic Co., Ltd.) was deposited on the film and its properties were measured. As a result, the film thickness was about 0.1 μ and the separation coefficient (P _O2 /P _N2 ) was 4.0.

<Example 3> Silicone system containing polyhydroxystyrene
The HS copolymer was made into a 2% by weight solution of benzene and then diffused onto the water surface, but it took a considerable amount of time to diffuse, and the spread was small and non-uniform. Therefore, as in Example 1,
4 wt% benzene solution of PHS-PDMS copolymer
Approximately 10% was added and diffused on the water surface under the same conditions. The droplets spread rapidly and a uniform ultra-thin film was obtained. The film thickness is approximately 0.1μ, and the separation coefficient (P _O2 /
P _N2 ) was 2.1.

<Example 4> Similar to Example 3, this time a study was conducted on a silicone-based HS copolymer containing novolak as the polymer. Again, 4% by weight of PHS-PDMS
By adding a benzene solution, it was possible to produce a uniform ultra-thin film. The film thickness was approximately 0.2μ, and the separation coefficient (P _O2 /P _N2 ) was 2.2.

<Example 5> Similar to Example 1, as a polymer for thin film production.
PPO was used to prepare a 2% by weight solution in toluene.
Toray Silicone SH3748 (trade name) was used as a surfactant, and about 1 ml of this was added to 100 ml of the above polymer solution. At this time, the spread on the water surface was very good as in Example 2. 0.05cc, spreads approximately 60cm square, equivalent film thickness is
It was 0.08μ.

<Example 6> As in Example 1, as a polymer for thin film production,
chemical formula is Using polyurethane (w≒60,000) shown in
This was made into a 2% by weight benzene solution. When no surfactant was added, a uniform thin film was not formed on the water surface as in the case of PPO, but Toray Silicone SH3530 (trade name) was used as a surfactant, and it was added to 100 ml of polymer solution. As a result, the spreading on the water surface was significantly improved, and a uniform ultra-thin film was formed over an area of about 50 cm ² . The equivalent film thickness was approximately 0.05μ.

In Examples 1 to 6, typical polymers for producing ultra-thin films are mainly used, and appropriate silicone surfactants are selected accordingly. Therefore, although it cannot be said that the explanations so far have covered everything, the surfactant used in the present invention has a high affinity for all polymer solutions, and the condensation shown here It can be easily inferred that similar effects can be obtained with materials other than molds, vinyl-based polymers, and silicone-based polymers.

Effects of the Invention As explained above, the present invention facilitates the formation of ultra-thin polymer films by adding 1 to 20% of a surfactant containing organosiloxane as a main component to a polymer solution in a hydrophobic solvent. It is possible to manufacture uniformly. In particular, unlike conventional methods, this method can be applied to all hydrophobic polymers, and in this case, there is no need to change the solvent for each polymer, making it suitable for producing ultra-thin polymer films. This is a very effective means.

Claims (1)

[Claims] 1. A mixture of a surfactant containing organosiloxane as a main component and a non-aqueous organic solvent is used as a solvent, and a solution of a polymer dissolved therein is diffused on the water surface,
A method for producing an ultra-thin film, comprising forming an ultra-thin film of the polymer on the water surface. 2. The method for producing an ultra-thin film according to claim 1, wherein the surfactant contains silicone as a main component. 3. The surfactant is a silicone copolymer synthesized from polyhydroxystyrene and terminal-reactive polydimethylsiloxane.
A method for producing an ultra-thin film as described in Section 1. 4. The method for producing an ultra-thin film according to claim 1, wherein the surfactant is a silicone copolymer synthesized from a phenolic resin and a terminally reactive polydimethylsiloxane. 5 Claims in which the nonaqueous organic solvent is at least one selected from the group consisting of benzene, toluene, xylene, chlorobenzene, ethyl acetate, methyl acetate, chloroform, methylene chloride, chloroethane, chloropropane, and carbon tetrachloride. 2. The method for producing an ultra-thin film according to item 1. 6. The method for producing an ultra-thin film according to claim 1, wherein the polymer is at least one selected from the group consisting of condensation polymers, polyurethanes, polyolefins, diene polymers, and silicone copolymers. 7 The condensation type polymer has the general formula: (However, m is an integer of 1 or 2, X is a hydrogen atom,
Selected from the group consisting of methyl group, ethyl group, halogen atom, sulfonic acid group, and nitro group. ) The method for producing an ultra-thin film according to claim 6, which is a polyphenylene ether represented by: 8 Polyurethane has the general formula: (However, R ₁ is −CH ₂ −CH ₂ −, (−CH ₂ −) ₃ , (−
CH ₂ −) ₄ , (−CH ₂ −) ₅ , (−CH ₂ −) ₆ ,
[Formula] [Formula] R ₂ is selected from the group consisting of [Formula] [Formula] [Formula] [Formula] [Formula] −CH ₂ −CH ₂ −, (− CH ₂ −) ₃ . ) The method for producing an ultra-thin film according to claim 6, which is a polyurethane represented by: 9. Production of an ultra-thin film according to claim 6, wherein the polyolefin and diene polymer are at least one selected from the group consisting of polybutene, polypentene, polymethylpentene, polyhexene, polymethylhexene, polybutadiene, and polyisoprene. Method. 10. The method for producing an ultra-thin film according to claim 6, wherein the silicone copolymer is a block copolymer or a graft copolymer with polyorganosiloxane.