JPS63134031A - Hollow yarn type composite membrane - Google Patents

Abstract

PURPOSE:To efficiently separate oxygen-enriched air from the atmosphere by providing an ultrathin separation functional layer consisting essentially of polymethylpentene on a hollow yarn carrier layer, and further laminating a polysiloxane layer thereon to form the title composite membrane. CONSTITUTION:The selective transmission composite membrane consisting of an ultrathin separation functional layer consisting essentially of polymethylpentene is provided on a hollow yarn carrier layer by a solvent coating method, and a polysiloxane layer is further laminated thereon to form a hollow yarn type composite membrane. Vitreous porous material, sintered metal, ceramics, cellulose esters, etc., are used for the carrier, and the pore diameter is generally controlled to about 50-10,000Angstrom . A polymer consisting essentially of polymethylpentene is used as the coating material constituting the ultrathin separation functional membrane, and poly-4-methylpentene-1 or poly-3-methylpentene is used as the polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field to which the invention pertains) The present invention relates to a gas component Il! Regarding. More specifically, the present invention relates to a gas separation membrane in which polymethylpentene is coated on the inner or outer surface of a porous hollow fiber.

(Prior Art) A method for manufacturing a thin film for gas separation has been proposed up to now, for example, in US Pat. No. 4,192,842.

Typical manufacturing methods that have been known include a water surface spreading method, an interfacial polymerization method, and a coating method in which a porous body is coated with a polymer solution. As for the shape, a flat membrane type and a hollow fiber type, which has a larger membrane area per unit volume than the flat membrane type, are known. Among the methods known as the water surface spreading method, there is a method in which a gas separation material such as polymethylpentene is uniformly spread on the water surface and placed on a flat membrane support such as polysulfone. Compared to methods such as interfacial polymerization that form membranes through chemical reactions, this method is relatively easy to create gas separation membranes in that it does not require any organic synthesis operations to combine two components at an interface. Although it is possible, since it is developed on the water surface, the shape is limited to a flat membrane type, and there are some difficulties in improving the shape.

In addition, interfacial polymerization is a well-known method in which a gas separation membrane made of polyurea with high gas permeability and high gas selectivity is made by impregnating a support with an amine or the like and combining it with an isocyanate or the like at the interface. ing. According to this method, it is possible to form a membrane in the shape of a hollow fiber, but the chemical reaction must be carried out at the interface, and therefore the membrane forming operation is difficult in that the reactants must be combined at the interface. tend to be relatively complex. Furthermore, the coating method is a method in which a gas separation material is dissolved in an organic solvent, spread on a support, and the solvent is removed.Although the operation is simple, it is difficult to uniformly and thinly coat the material.

To date, it has not been possible to create a hollow fiber type gas separation membrane with high selectivity and permeability.

(Problem to be solved by the present invention) In terms of the shape of the gas separation membrane, a hollow fiber type membrane with a larger membrane area per unit volume is better than a flat membrane type, provided that it has the same characteristics. It can be made lighter and more compact. Therefore, a hollow fiber type separation membrane is more desirable in terms of shape. However, at present, hollow fiber separation membranes are at the stage where membranes are created inside the hollow fibers using methods such as interfacial polymerization. Although this has been achieved, what is more desirable is a coating method that is easier to operate than interfacial polymerization methods, and that allows the gas separation material to be uniformly applied not only to the inside of the hollow fiber but also to the outside. thin,
A method is to be invented which allows coating onto a support.

In view of this situation, the present invention was arrived at as a result of intensive study on a method for coating hollow fibers.

(Structure of the Invention) That is, the present invention is a hollow fiber composite membrane in which a polymethylpentene layer is formed on the inner or outer surface of a porous hollow fiber, and a polysiloxane layer is further formed on the polymethylpentene layer.

In the present invention, the porous membrane is a layer that supports the 1 ul 1 minute I11 functional layer and does not itself have selective separation ability. Porous supports include glassy porous materials, sintered metals, ceramics, cellulose esters, polystyrene, polyvinyl butyral, polyvinyl chloride, polyesters, polyacrylonitrile, polyamides, etc., but polysulfone is particularly excellent among these supports. It has excellent performance.

The pore size is generally about 50 to 10,000, preferably 1
The pore size is preferably between 0 and 1,000 pores, but is not limited to this, and depending on the final membrane application, the pore size can vary between 50 and 10,000 pores. Further, the film thickness is preferably 5μ7yL to 5M, preferably 10t1m to 1μL, but is not limited thereto.

The support can be of either symmetrical or asymmetrical construction, but asymmetrical construction is more preferred.

Further, the shape of the hollow fiber type support is not limited, but one having an inner diameter of 500 to 1000 μm is usually used.

The gas separation membrane material, or coating material, constituting the ultra-thin separation functional layer is a polymer mainly composed of polymethylpentene.

The structure is poly-4-methylpentene-1゜poly-3
-Methylpentene.

Also preferably used are copolymers in which a portion of the monomer, for example, 40 mol % or less, preferably 20 mol % or less, particularly preferably 10 mol % or less, is replaced with α-olefin or diene monomer. Hexeno is an α-olefin. Diene monomers such as octene, decene, and dodecene include butadiene and isoprene. As a solvent for polymethylpentene, a hydrocarbon or halogenated hydrocarbon, preferably a boiling point of 50 to 200°C, more preferably a boiling point of 70 to 160°C, is used. Specific examples of solvents include cyclohexene,
Hydrocarbons such as cyclohexane, methylcyclohexane, ethylcyclohexane, toluene, xylene, benzene, cumene, trichloroethane.

Suitable examples include halogenated hydrocarbons such as tetrachloroethane, trichloroethylene, trichloropropane, chlorobenzene, and dichlorobenzene. The thickness is 0.01 to 10 μm, preferably 0.03 to 5 μm.
A μm one is better. Various methods can be used to apply the polymer solution, such as dipping, spray coating, and liquid feeding.

The concentration of non-polymer is preferably 30-0.01% by weight, preferably 10-0.1% by weight. As a silicon compound, even if polymethylpentene does not have a high gas selectivity, it is sufficient as long as it has appropriate permeability, and it can be cured to repair extremely slight partial defects that may occur during the film forming process. Any chemical compound may be used. Furthermore, in terms of hardening speed, from the viewpoint of durability as a separation membrane, it is preferable to use one that has mechanical strength and does not easily flow out or move, and preferably one that easily undergoes high polymerization or one that has a crosslinked structure. Specifically, a curable organosiloxane is preferably used. Such a curable organosiloxane has a halogen atom, a hydroxyl group, an alkoxy group, a hydrogen group, and/or a vinyl group at the terminal or side chain, and has a main chain structure of +5i- 0-)n. (R and R' are various groups having 1 to 8 carbon atoms, preferably methyl, ethyl, propyl, phenyl, or naphthyl, and n is 3 to 10QO, preferably 10 to
It is an integer of 500. ) Furthermore, a silane compound or siloxane compound having two or more functional groups is added as a crosslinking agent. Specific examples of the functional group include acetoxy, ketoxime, silazane amide, aminoxy, hydrogen, vinyl, and alkoxy. Further, in the curing reaction, the presence of a microcatalyst such as a metal alkoxide such as a tin-based, titanium-based, zinc-based, or platinum-based metal alkoxide is effective.

Solvents that dissolve silicon compounds include hydrocarbons and alcohols that do not dissolve the separation membrane; specific examples include hexane,
Octane, heptane, cyclohexane, benzene, toluene, xylene, methanol.

These include ethanol, n-propertool, and butanol (n-, iso-, tertiary). Further, the concentration can be arbitrarily used within the range of solubility. This polysiloxane layer not only has the effect of filling defects in the polymethylpentene layer, but also has positive effects such as preventing the adhesion of dirt, increasing mechanical strength, and improving heat resistance.

Since most of the pores on the surface of the porous support are filled with polymethylpentene, the polysiloxane layer provides the above-mentioned effect with a small amount, and there is almost no decrease in permeability.

One example of manufacturing the membrane of the present invention is to flow polymethylpentene dissolved in an organic solvent inside a porous hollow fiber at a constant rate using a pump or the like, and then to flow nitrogen gas inside the hollow fiber at a constant rate. An example of this method is to flow at a high speed to remove the organic solvent, then flow the silicon compound dissolved in the organic solvent inside the hollow fiber to the inside of the hollow fiber, and then flow nitrogen gas to the inside of the hollow fiber again to remove the organic solvent. Of course, the method is not limited to this, and a film can also be formed on the outside of the porous hollow fibers by sequentially immersing them in a polymethylpentene solution and a silicon compound solution.

(Effects) The membrane of the present invention is mainly used for gas separation. In particular, it can be preferably used for producing oxygen-enriched air (eg, 30 to 45% oxygen content) from the atmosphere.

The present invention will be described in detail below with reference to Examples, but the present invention is not limited to the Examples in any way.

Example 1 0.5 parts by weight of polymethylpentene was added to 99% of cyclohexane.
．． It was dissolved in 5 parts by weight. This solution was pumped inside a well-dried polysulfone hollow fiber. The flow velocity is 2m
/min, and the temperature was room temperature. Part 10.5. It was dried by blowing with N2 for 1 minute at a flow rate of Q/min. Thereafter, a solution prepared by dissolving 0.5 parts by weight of curable silicone in 99.5 parts by weight of hexane was passed through the inside of the hollow fiber for a short period of time.
It was dried by blowing with N2 for 1 minute at a flow rate of 1 minute.

The oxygen permeation rate of this hollow fiber is 2.0 to 2.5x 1O-
5cc (STP)/cj-sec-aahT near V),
M Basic? The ratio of fh overrate to nitrogen permeation rate (selectivity) was 4.2-4.4.

Example 2 0.5 parts by weight of polymethylpentene and 299 parts of cyclohexane
．． It was dissolved in 5 parts by weight. This solution was pumped inside polysulfone hollow fibers impregnated with ethylene glycol. The flow rate was 2te/min, and the temperature was air temperature. Then 0,5. It was blown with N2 for 1 minute at a flow rate of u/min, washed with water and dried. Thereafter, a solution prepared by dissolving 0.5 parts by weight of hardened silicon in 99.5 parts by weight of hexane was passed through the inside of the hollow fiber for a short time, and dried by blowing with N2 for 1 minute at a flow rate of 0.5 polish/min.

The oxygen permeation rate of this hollow fiber is 1.1~1.5X 10"
CC(STP)/C1-5ec-atrhT: Yes Ratio of oxygen permeation rate to nitrogen permeation rate (selectivity) is 3.6~
It was 4.4.

Comparative Example 1 0.5 parts by weight of polymethylpentene was added to 99% of cyclohexane.
．． This solution was pumped inside a well-dried polysulfone hollow fiber.

The flow rate was 2-/min and the temperature was room temperature. then 0.5
．． It was dried by blowing with N2 for 1 minute at a flow rate of Q/min. The amount of gas permeation through this hollow fiber is 10 to 20 times that of Example 1,
Furthermore, the oxygen concentration was 21.2%, making it impossible to obtain oxygen-enriched air.

Comparative Example 2 0.5 parts by weight of polymethylpentene was added to 99% of cyclohexane.
．． This solution was pumped inside polysulfone hollow fibers impregnated with ethylene glycol. The flow rate was 2 d/min and the temperature was room temperature. Thereafter, it was dried by blowing with N2 for 1 minute at a flow rate of 0.5 J1/min. The gas permeability of the hollow fibers was 10 to 20 times that of Example 2, and the oxygen concentration was 21.2%, making it impossible to obtain oxygen-enriched air.

Claims (1)

[Claims] A permselective composite membrane consisting of a hollow fiber support layer and an ultra-thin separation function layer mainly made of polymethylpentene formed on the support layer by a solution coating method, further comprising a polysiloxane layer on the separation function layer. A hollow fiber-like composite membrane characterized in that it consists of a structure formed by forming a hollow fiber.