JPH04305236A - Production of gas permeable composite film - Google Patents

Abstract

PURPOSE:To produce the film having gas permeability and gas separability highly resistant to a change with lapse of time by polymerizing an organosiloxane monomer or its oligomer in plasma and laminating the film thereof on a thin film consisting of poly-substd. acetylene having a specific constitutional formula. CONSTITUTION:The polymerized film obtd. by polymerizing the organosiloxane monomer or its oligomer in the plasma is laminated on the thin film 5 consisting of the poly-substd. acetylene expressed by the formula (R is 1 to 4C alkyl group), by which the gas permeable composite film is produced. After the polymer film 5 is mounted on a holder 4, the pressure in a chamber is once reduced to a vacuum and in succession, the vapor of the organosiloxane monomer or its oligomer is introduced therein and is regulated to an arbitrary specified pressure. The plasma is thereafter generated by electrodes 3 to form the organosiloxane plasma polymer film on the surface of the polymer film 5. The thickness of the plasma polymer film is regulated by the plasma generation time of this time.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a gas permeable composite membrane.

0002

2. Description of the Related Art In the separation and purification of gases, methods using gas-permeable polymer membranes are attracting attention for reasons such as energy saving. Oxygen-enriched air separated from air and produced using this type of polymer membrane is expected to save energy by improving combustion efficiency, reduce harmful substances emitted due to its complete combustibility, and be used for raising animals and plants. There is.

[0003] From the viewpoint of such uses, the performances that this type of polymer membrane should have are: (1) high gas permeability;
○2 High gas separability (ratio of permeability between the gas to be separated and the gas that does not require separation). Especially when considering the intended use, high gas permeability is strongly desired. A polysubstituted acetylene represented by the structural formula shown by Chemical Formula 2 is cited as a material that most satisfies such performance.

0004

[Case 2]

[0005] This material is soluble in a specific organic solvent, and can be easily formed into a thin film from a solution by a casting method. The membrane produced in this manner has much better gas permeability than ordinary polymer films (eg, polydimethylsiloxane), and its gas permeability coefficient is more than an order of magnitude higher.

However, the gas permeability of this polymer film decreases over time, and after a long period of time, the gas permeability decreases to the same level or lower than that of a normal polymer film. Put it away.

[0007]

[Problems to be Solved by the Invention] The present invention aims to produce a gas permeable membrane using a polymer membrane made of polysubstituted acetylene that exhibits excellent gas permeability and gas separation performance over time. purpose.

[0008]

[Means for Solving the Problems] The present invention is characterized in that a plasma polymerized film obtained by polymerizing an organosiloxane monomer or its oligomer in plasma is laminated on a thin film made of polysubstituted acetylene. .

[0009]

[Operation] Polysubstituted acetylene is a product obtained by polymerizing disubstituted acetylene whose structural formula is represented by the following chemical formula 3.

0010

[Chemical formula 3]

[0011] The polymer is TaCl5, NbCl5, Ta
Group V transition metal catalysts such as Br5 and NbBr5 and solvents such as aromatic hydrocarbons (benzene, toluene, xylene, etc.), alicyclic hydrocarbons (cyclohexane, etc.), halogenated hydrocarbons (carbon tetrachloride, trichloroethylene, etc.) is obtained by heating at 30 to 100°C in an inert gas.

The obtained polymer can be made into a thin film by a conventional method. i.e. aromatic hydrocarbons (benzene,
It can be made into a thin film by dissolving it in a solvent such as toluene, xylene, etc.), alicyclic hydrocarbons (cyclohexane, etc.), or halogenated hydrocarbons (carbon tetrachloride, trichloroethylene, etc.) and casting this solution.

The substrate for casting at this time may be a glass plate with a smooth surface, a metal plate, a polymer plate insoluble in solvents (Teflon, etc.), or a liquid plane (water, an appropriate aqueous solution, a substrate in which the solvent and polymer are insoluble). (organic liquids, etc.) are used. This type of polymer film is obtained by spreading the solution on the substrate, evaporating it, and then peeling off the formed film.

In this case, the film thickness can be adjusted by the type of base used, the concentration of the solution, or the number of layers (overcoating). In addition, ready-made porous films can also be used as supports for mechanical strength reinforcement.

[0015] The thus formed polymer film is subjected to a plasma polymerization apparatus to form a plasma polymerized film of organosiloxane monomer or its oligomer on its surface. As a plasma polymerization apparatus, for example, one shown in FIG. 1 can be used. In FIG. 1, 1 is a vacuum chamber, 2 is a gas inlet through which organosiloxane monomer or oligomer gas is introduced at a constant flow rate;
3 is an electrode for plasma generation, 4 is a holder, and 5 is a vacuum exhaust port. A polymer film 5 is attached to and supported on the surface of the holder 4.

As described above, the polymer film is placed in the holder 4.
After attaching it to the
-5 torr), followed by organosiloxane monomers (e.g. hexamethyldisiloxane, dimethoxydimethylsilane, diethoxydimethylsilane, etc.)
Alternatively, the vapor of the oligomer is introduced and adjusted to an arbitrary constant pressure. After that, plasma is generated by the electrode 3,
An organosiloxane plasma polymerized film is formed on the surface of the polymer film 5. In some cases, a carrier gas such as argon or helium may be used.

The thickness of the organosiloxane plasma polymerized film can be adjusted by changing the plasma generation time at this time. However, the thickness of the organosiloxane plasma polymerized film at this time may be sufficient to cover the surface of the polymer film, and the film thickness is also preferably about 50 Å to 2000 Å. If it becomes thicker than this, the gas permeability deteriorates as a whole, which is not preferable.

In the manner described above, a laminated composite film of a polysubstituted acetylene film and an organosiloxane plasma polymerized film is formed.

[0019]

[Example] Example 1 1-(trimethylsilyl)-1
= Propyne (Aldrich) 1g, TaCl5 0.
A viscous polymer gel was obtained by reacting at 80° C. for 24 hours in a nitrogen atmosphere using 06 g of toluene and 10 cc of toluene. This polymer gel was diluted with toluene and then dropped into a large amount of methanol to precipitate the polymer. The obtained polymer was filtered and dried, and then redissolved in 100 cc of toluene to obtain a polymer solution. The obtained solution was spread on a Teflon plate, and after evaporating the solvent at room temperature, it was peeled off from the Teflon plate to obtain a 20 μm thick polymer film.

The obtained polymer film was placed in the plasma polymerization apparatus shown in FIG. 1, and the pressure was reduced to 1×10 −6 torr, and then vaporized hexamethyldisiloxane was heated outside to 0.00%.
It was introduced at a flow rate of 1 cc/min, and immediately a high frequency of 13.56 MHz, 30 W was introduced between the electrodes for plasma generation to generate plasma. After generating plasma for 1 minute, the composite membrane was taken out. The thickness of the obtained hexamethyldisiloxane plasma polymerized film was 1000 Å.

Example 2 A polymer membrane prepared in the same manner as in Example 1 was spread on the water surface, and after evaporating the solvent at room temperature, it was scooped up with a porous support (Duraguard #2400, Polyplastics) to form a composite membrane. And so. The above operation was repeated to obtain a polymer film having a surface thickness of 0.2 μm. Subsequently, under the same conditions as in Example 1, a hexamethyldisiloxane plasma polymerized film was formed on the surface polymer film to obtain a composite film.

Comparative Example A 20 μm thick polymer film prepared in the same manner as in Example 1 was used as it was without any further treatment.

[0023] Regarding the membranes of each of the above examples, the permeation amount of oxygen and nitrogen was measured using a gas permeability measuring device using a vacuum method at 35°C. Initial values of oxygen permeability coefficient (Po2), oxygen/nitrogen permeability coefficient ratio (separation performance α) of each example, and 10O
The values after the passage of days are shown in Table 1 below, and the characteristics over time are shown in Figure 2.
Shown below.

[0024] The unit of oxygen permeability coefficient (Po2) is c
m3(STP)・cm/cm2・sec・cmHg. It is.

[0025]

[Table 1]

As is clear from the results shown in Table 1 and FIG. 2, the polymer composite membranes of Examples 1 and 2 had better gas permeability (initial performance) than the polysubstituted acetylene membrane of Comparative Example. Although the separation performance is reduced by the amount of lamination of the organosiloxane plasma polymerized membrane, the separation performance is improved and stable characteristics are maintained over a long period of time, so both the permeability and separation performance after the passage of time are better than those of the comparative example. It turns out that it exhibits good properties. It has been confirmed that similar results were obtained when organosiloxane oligomers were used.

[0027]

Effects of the Invention As detailed above, according to the present invention, in obtaining a gas permeable membrane using polysubstituted acetylene as a material, this type of gas permeable membrane exhibits a more stable gas permeation performance over a long period of time than that obtained by conventional methods. This has the effect of making it possible to produce a sexual membrane.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a plasma polymerization apparatus used in an example method of the present invention.

FIG. 2 is a characteristic diagram showing changes in oxygen permeability coefficient with respect to elapsed days of a composite membrane obtained by the present invention.

[Explanation of symbols]

1 Vacuum chamber 2 Gas inlet 3. Electrode for plasma generation 4 Board holder 5 Substrate (polymer film)

Claims (1)

[Claims] [Claim 1] A plasma-polymerized film obtained by polymerizing an organosiloxane monomer or its oligomer in plasma is laminated on a thin film made of polysubstituted acetylene whose structural formula is represented by [Chemical formula 1] A method for producing a gas permeable composite membrane, characterized by: