JPS60175505A - Preparation of gas separation composite membrane - Google Patents

Abstract

PURPOSE:To prepare a composite membrane reduced in the generation of a pinhole and excellent in gas separation capacity, by coating a porous support with a solution of polyorganosiloxane having an amino group in a non-aqueous solvent and, thereafter, performing the crosslinking reaction of said polyorganosiloxane with a multifunctional reagent having reactivity with the amino group. CONSTITUTION:A solution prepared by dissolving polyorganosiloxane having an amino group in an org. solvent having no compatitility with water such as polymer solution prepared by dissolving amino modified silcone oil in hexane is applied to a porous support such as a polysulfone microporous membrane. Subsequently, a crosslinking agent solution prepared by dissolving a polyfunctional reagent having reactivity with the amino group of polyorganosiloxane in an org. solvent compatible with the solvent of the polymer solution, for example, a solution of trimedinic chloride in hexane is applied to the coated support to obtain a composite membrane wherein an amido crosslinked polysiloxane layer is closely adhered to the support.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a method for producing a composite membrane for gas separation.
The present invention relates to a method for producing a composite membrane having a structure provided with an active layer mainly composed of a crosslinked polyorganosiloxane polymer having 1f ability.

[Prior art]

Conventionally, methods for producing composite membranes for gas separation include: (1) coating a polymer solution on a support and then removing the solvent by drying; (2) coating a porous support with chlorine containing dimethyl silicone monomer and a crosslinking agent; A method of heating and crosslinking after immersion in a polyorganosiloxane-based solvent solution (see Japanese Patent Application Laid-open No. 54-82380); A method of adhering to a porous support (for example, U.S. Pat. No. 3,874,986); A method of attaching the above to a porous support and then heating and crosslinking it (
JP-A-58-92430), etc.

However, these methods make the active layer very thin (
Since it is painted on, defects are likely to occur due to scratches on the porous support or foreign matter. In addition, due to the formation of crosslinked polymers in the pores of the porous support, the amount of gas permeation is reduced9, the durability and pressure resistance of the composite membrane are low, and furthermore, the complexity of equipment and operations when performing water surface casting, etc. These drawbacks exist, and none of them are necessarily satisfactory in terms of production methods for industrially obtaining highly durable composite membranes.

The present invention relates to a method for producing an amino-modified polysiloxane crosslinked membrane disclosed in JP-A-57-105203 and other publications. Conventionally, when producing such a crosslinked membrane, for example, JP-A-57-105203 discloses a method in which a water or alcohol solution of amino-modified polysiloxane and a cross-linking agent is coated on a porous support and dried; A method is described in which a film is formed on a support by an interfacial sheathing method using a water or alcohol solution of siloxane and a solution of a crosslinking agent in a non-aqueous solvent. However, it has been found that the conventional method is not always satisfactory because it is difficult to ensure stable gas separation performance due to the occurrence of pinballs and the like.

[Object of the present invention]

The present inventors have conducted intensive studies on a method for manufacturing a composite membrane that is industrially easy to manufacture, has no defects with good reproducibility, and has excellent gas separation performance (particularly oxygen enrichment performance), and has developed the present invention. Reached. That is, according to the present invention, it is possible to provide a manufacturing method that stably supplies a composite membrane having excellent gas separation performance with extremely few occurrences of pinholes and the like.

[Configuration of the present invention]

In order to achieve the above object, the present invention applies a water-immiscible organic solvent solution containing at least 0.1% of polyorganosiloxane having an amino group onto a porous support, and then , an organic solvent miscible with the organic solvent,
A gas that is characterized by applying a crosslinking agent solution in which a multifunctional reagent that is reactive with amino groups and capable of condensation or addition to generate new bonds is applied to proceed with a crosslinking reaction. The present invention relates to a method for manufacturing a composite membrane for separation.

In the present invention, the porous support is a layer that does not substantially have separation performance, and is used to give strength to a thin film that does have separation performance. It is preferable to use a support having a structure in which the other surface has fine pores that gradually become larger, and the size of the GaIII pores is about 100 to 1000 A on one surface.

The microporous support described above is a Millipore filter (VSWP).
) and Toyo Roshi (U.K.I.O.), but typically "Office of Saline Water Research and Development [1st Progress Report] No. 3
59 (1968). Its materials include polis, ruhonya, cellulose acetate,
Homopolymers or blends of cellulose nitrate and polyvinyl chloride are usually used. For example, a solution of polysulfone in dimethylformamide (DMF) is cast to a certain thickness onto a tightly woven Tetoron cloth or non-woven cloth. Sodium dodecyl sulfate 0.5% by weight and DMF
2! By wet coagulation in an aqueous solution containing I [%], a porous support having most of its surface having fine pores with a diameter of several hundred angstroms or less can be obtained.

Note that during film formation, such a porous support is preferably in a water-containing state to such an extent that no water droplets appear on the surface of the support. This prevents the water-immiscible organic solvent solution, which is mainly composed of polyorganosiloxane having amino groups, from entering the pores of the porous support during film formation. This seems to prevent the reduction in gas permeation of the composite membrane due to the formation of crosslinked polymers.

In the present invention, a polymer mainly composed of polyorganosiloxane having amino groups is used as a polyfunctional reagent that is reactive with amino groups and can be condensed or added to form new bonds. It is important to form a three-dimensional network structure by causing a crosslinking reaction. This imparts durability to the composite membrane.

The polyfunctional reagent used here usually reacts immediately with amino groups at room temperature to generate a crosslinked structure, so it forms a homogeneous solution with a polymer whose main component is polyorganosiloxane, which already has amino groups. It is not possible.

The polyorganosiloxane containing amino groups in the present invention is an organic polymer having at least two or more amino groups in the molecule and containing at least 30% or more of organosiloxane segments. Here, the organosiloxane segment is one in which a substituted or unsubstituted alkyl or aryl group having 1 to 12 carbon atoms is bonded to a silicon atom, and an h atom group such as methyl, ethyl, t-butyl, phenyl, or cyclohexyl is bonded. are preferred, and dimethylsiloxane, phenylmethylsiloxane, xane, t-butylmethylsiloxane, cyclohexylmethylsiloxane and the like are particularly preferred. The general formula is shown as formula (1).

Here, R, R' are substituted or unsubstituted carbon atoms
~12 alkyl or aryl groups.

Here, regarding the method of introducing an amine group, it is common to copolymerize a monomer having an amino group with an organosiloxane, but the amino group can also be introduced by a polymer reaction. For example, bisaminopropyltetramethyldisiloxane, which has an amino group and can be easily copolymerized with an organosiloxane, reacts as shown in formula (2) to give an organosiloxane having an amino group.

Further, dialkoxyalkylaminoprobylsilane is copolymerized with dialkyldialkoxysilane as shown in formula (3) to give an amino group-containing polyorganosiloxane.

In addition, the polymer obtained by formula (3) can easily be used to form copolymers with various polymers or seven polymers by utilizing the reactivity of the terminal alkoxy-silicon bond. You can also.

In addition, as a method for introducing amino groups through a polymer reaction, a commonly used method is to introduce a halogen group into the main chain and/or side chain in advance, and then introduce the amino group by reaction with an amine, etc. It is.

Utilizing such a reaction, in order to further improve pressure resistance and gas selectivity, the organosiloxane segment and other segments such as styrene, carbonate, urethane, and fluorine-containing monomers are combined to improve film formability and separation performance. , copolymerization can also be carried out within a range that does not adversely affect the permeation rate and the like. Furthermore, in order to further improve pressure resistance and gas selectivity, the polymer solution prepared by dissolving a polyorganosiloxane having an amino group as a main component in a water-immiscible organic solvent system has the above-mentioned properties. It is also possible to dissolve various organic polymers other than polyorganosiloxane having an amino group within the range that does not adversely affect film forming properties, separation performance, permeation rate, etc.

Crosslinking agents used to crosslink polyorganosiloxanes having amine groups include functional groups such as acid chlorides, acid anhydrides, isocyanates, thioisocyanates, sulfonyl chlorides, epoxies, aldehydes, or active halogens in the molecule. Examples include compounds with two or more. Among these, acid chlorides and isocyanate compounds are preferred, with isophthaloyl chloride, terephthaloyl chloride, trimesoyl chloride, fumaroyl chloride, tolylene-2,4-diisocyanate, diphenylmethane-4,4'-diisocyanate and the like being particularly preferred.

In the present invention, an organic solvent that is immiscible with water is one that dissolves at least 0.1% by weight or more without dissolving the porous support used or reacting with the polyorganosiloxane containing amino groups, and Those having adequate volatility under operating conditions are used.

Such solvents include hydrocarbon solvents such as hexane, heptane, Schiff [1 hexane, isopentane, etc., fluoro solvents such as trichlorotrifluoroethane and tetrachlorodifluoroethane, and mixtures of these with each other or other solvents. Various types can be used, and it is desirable to select an appropriate one in consideration of the solubility of the polymer used, operating conditions, etc. The optimum concentration of polyorganosiloxane having amino groups in this solution varies depending on the polymer, crosslinking agent, and solvent, and is best determined experimentally, but in general, a concentration of about 0.1 to 2% by weight is recommended. Gives good results.

Furthermore, the solvent for the crosslinking agent is preferably a solvent for the polymer solution that does not react with the crosslinking agent (hydrocarbon solvent, fluorosolvent, etc.), but it does not have to have the same components as the polymer solution. The optimal 11 degrees of crosslinking agent in this solution is the polymer,
Since it varies depending on the crosslinking agent and solvent, it is best to determine it experimentally, but generally a concentration of about 0.05 to 3% by weight gives good results.

In the present invention, an active layer mainly composed of a crosslinked polyorganosiloxane polymer is formed on a porous support layer by coating a solution mainly composed of the polyorganosiloxane having amino groups on the porous support layer. After that, a crosslinking agent solution is poured over it, spread for a certain period of time, and then the solvent is dried. There are no particular limitations on the method of uniformly applying the polymer solution containing polyorganosiloxane having an amino group as a main component onto the porous support, but the method may include immersing the porous support in the polymer solution. The polymer solution can then be drawn up and drained, or the polymer solution can be poured through an appropriately shaped injection port onto a porous support that is moving at a constant speed using a winding roller, etc. Conventional methods can also be applied. Next, air drying (forced drying may be performed if necessary) until no polymer solution is observed on the surface of the support.

), the crosslinking agent is uniformly spread over the support for a certain period of time (several seconds to 3 minutes) to allow the crosslinking reaction to proceed. The method of contacting the crosslinking agent solution onto the support is not particularly limited, but it is preferable to follow the method of applying the polymer solution described above.

Thereafter, the liquid is drained, and if necessary, forced drying is performed in an LFF1 oven or a hot air circulation dryer. Generally, 30 seconds to 3 minutes at 50 to 150°C is good.

[Effects of the present invention]

According to the present invention, a composite membrane with few defects such as pinholes and excellent gas separation performance (particularly oxygen enrichment performance) can be obtained industrially very easily and with good stability.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 Production of polysulfone microporous membrane.

A casting solution containing 15 parts by weight of polysulfone and 85 parts by weight of dimethylformamide was prepared.

Spread this casting solution on a dry, scratch-free glass plate for 210 minutes.
It was cast to a thickness of μm. Immediately thereafter, the cast membrane was quickly and quietly placed into water together with the glass plate at a uniform speed. Although the polysulfone microporous membrane soon peeled off from the glass plate, it was kept in a 10f7m water tank, and then taken out, thoroughly washed with tap water, and then stored in distilled water. It is known that the polysulfone microporous membrane obtained in this way has micropores on the side that was in contact with the air during casting, and relatively large pores on the side that was in contact with the glass plate. ing.

Furthermore, this microporous polysulfone membrane was taken out of distilled water during film formation, and water droplets on the surface of the microporous polysulfone membrane were removed by a compressed nitrogen stream.

Next, amine-modified silicone oil (modified silicone oil 5F8417 manufactured by Toray Silicone Co., Ltd., amino base 0.5
A polymer solution was prepared by dissolving 1 part by weight (% by weight) in 99 parts by weight of n-hexane.

In addition, 3 parts by weight of trimesic acid chloride was added to 97 m parts of n
- A solution was made in hexane. After pouring the polymer solution uniformly onto the polysulfone porous MW material membrane prepared in advance, the membrane was held vertically, the liquid was drained, and the membrane was air-dried for 30 seconds. A solution of trimesic acid chloride was uniformly poured onto the membrane for 30 seconds, and then the membrane was turned vertically to drain the liquid. This was air-dried for 3 minutes and then hot-air dried for 5 minutes to obtain a composite membrane having an amide crosslinked polysiloxane layer in close contact with the support.

A disk-shaped test piece with a diameter of 5 cm was cut out from the composite membrane thus obtained, fixed in a measurement cell, and pure oxygen and pure nitrogen were permeated at a temperature of 25°C and an external pressure of lki/cnf. When oxygen enrichment performance was calculated from speed, QO2 (oxygen permeation rate) was 0, 82 m'/n+'hr
atll, tx (Qo2/Q82') was 2.0.

Example 2 A 1 mm portion of amino-modified silicone oil (modified silicone oil 5F8417 manufactured by Toray Silicone Co., Ltd.) and a screw (
A solution was prepared by uniformly dissolving 0.5 parts of tetramethyl (aminopropyl)tetramethyldisiloxane in 98.5 parts by weight of n-hexane. In addition, a solution was prepared by dissolving trimesic acid chloride o and im in 99.9 parts by weight of n-hexane.

Using these materials, a composite II having an amide crosslinked polysiloxane layer formed by a crosslinking reaction on the crotch of a polysulfone porous base material prepared in advance in the same manner as in Example 1 was obtained.

The oxygen enrichment performance of the composite membrane thus obtained was measured in the same manner as in Example 1, and the QO2 was 2.2yn'
/ln211ratm, aha 2.0 Tea Tsuta.

Example 3 1 part by weight of amine-modified silicone oil (modified silicone A-il 5F8417 manufactured by Toray Silicone Co., Ltd.) was added to 99 wt.
A solution was prepared by dissolving 100% of the compound in trinororotrichloroethane. In addition, 0.1 mm part of fumaric acid chloride was added to 99
．． A solution was prepared in 9 parts by weight of trifluoro-1-lichloroethane.

Using these materials, a composite membrane having an amide crosslinked polysiloxane layer formed by a crosslinking reaction on a polysulfone porous base membrane prepared in advance in the same manner as in Example 1 was prepared. It's I.

When the MIA enrichment performance of the composite membrane thus obtained was measured in the same manner as in Example 1, it was found that QO2 = 0.95t
n''/TII2hratm, α-2,l.

Example 4 A solution was prepared by dissolving 1 part by weight of amino-modified silicone oil (silicone oil 5F8417 manufactured by Toray Silicone Co., Ltd.) in 99% n-hexane. A solution was also prepared by dissolving 0.5 parts by weight of diphenylmethane-4,4'-diisocyanate in 99.5 parts by weight of n-hexane.

Using these, a composite membrane having a urea crosslinked polysiloxane layer formed by a crosslinking reaction on the crotch of a polysulfone porous substrate prepared in advance in the same manner as in Example 1 was obtained.

When the oxygen enrichment performance of the composite membrane thus obtained was measured in the same manner as in Example 1, QO2 = 3.25 m'
/yn”hratm, a=2.0 Tea Tsuta.

Example 5 A solution was prepared by dissolving 1 mm part of amino-modified silicone oil (modified silicone oil 5F8417 manufactured by Toray Silicone Co., Ltd.) in 99 parts by weight of trifluorotric ethane. Also, 0.5 m of hexamethylene diisocyanate
A solution was prepared by dissolving 1 part of ff in 99.5 parts by weight of n-hexane.

Using these materials, a composite membrane having a urea crosslinked polysiloxane layer formed by a crosslinking reaction on a polysulfone porous nag prepared in advance in the same manner as in Example 1 was obtained.

The oxygen enrichment performance of the composite membrane thus obtained was measured in the same manner as in Example 1. QO2 = 0, 5yn'/
11'11ratm, α-2,2.

Example 6 1 part by weight of amine-modified silicone oil (modified silicone oil 5F8417 manufactured by Toray Silicone Co., Ltd.) and 0.05 part by weight of bis(aminopropyl)tetramethyldisiloxane were uniformly dissolved in 98.95 parts by weight of n-hexane. A solution was prepared. In addition, 0.1 inch of cyanuric chloride was added to the hanging part.
A solution was prepared in 9.9 parts by weight of n-hexane.

Using these, a composite membrane having a siameroamide crosslinked polysiloxane layer formed by a crosslinking reaction on the crotch of a polysulfone porous substrate prepared in advance in the same manner as in Example 1 was obtained.

When the oxygen enrichment performance of the composite membrane thus obtained was measured in the same manner as in Example 1, it was found that QO2 = 4.5TIl
'/W12hratll, U=1, 7TatTC6 Example 7 Amino-modified silicone oil (Modified silicone oil 5F8417 manufactured by Toray Silicone Co., Ltd.), type 1 can part and screws (
aminopropyl)tetramethyldisiloxane 0.051
A solution was prepared by uniformly dissolving 31 parts in 98.95 parts by weight of n-hexane. Further, a solution was prepared by dissolving 0.1 part by weight of a triisocyanate compound (IPDI-71890, manufactured by +1jils, West Germany) in 99.9 parts by weight of n-hexane.

Using these materials, a composite membrane having a urea crosslinked polysiloxane layer formed by crosslinking reaction on a polysulfone porous base membrane prepared in advance in the same manner as in Example 1 was obtained.

The oxygen enrichment performance of the composite membrane thus obtained was measured in the same manner as in Example 1, and it was found that QO2 = 3.6 Tll.
'/Tl12haratII, a=2.2.

Example 8 3-aminopropylmethyljethoxysilane 0°955
g and dimethyl 1-xysilane 11.4 (] and water 25
While stirring 1 and 1 at 70°C, 41L was reacted and hydrolyzed. Next, the oil layer was separated by liquid separation, and then 5
The mixture was placed under a vacuum of mm1-IQ and heated to a bath height of 110 DEG C. while distilling off the alcohol produced, and the remaining silicone hexamer and oligomer were distilled off to obtain an amino-modified siloxane oil.

This oil was soluble in methanol, n-bequinone, trifluorotrichloroethane, and the like.

A polymer solution was prepared by dissolving 1 iJffi part of the above amine-modified silicone oil in 99 weight units of trifluorotrichloroethane. Further, a solution was prepared by dissolving 1 part by weight of fumaric acid chloride in 1 part of 99 mff of trichloroethane. Using these materials, a composite membrane having an amide crosslinked polysiloxane layer formed by crosslinking reaction on a polysulfone porous base membrane prepared in advance in the same manner as in Example 1 was obtained.

When the oxygen enrichment performance of the composite membrane thus obtained was measured, it was found that QO2=0.92 and α-1°90.

Comparative Example 1 A polymer solution was prepared by dissolving the amine-modified silicone oil 1 Toyobu synthesized in Example 8 in 99 parts by weight of methanol. Further, a solution was prepared by dissolving 1 part by weight of fumaric acid chloride in 99 parts by weight of n-hexane. Using these, a membrane was formed on a polysulfone porous base material prepared in advance in the same manner as in Example 1 to obtain a composite membrane.

When the oxygen enrichment performance of this membrane was measured, it was found to be Q　O.

=2.0. α=0.97.

Patent applicant Higashi Shikikai Co., Ltd.

Claims (1)

[Claims] (1) A solution of an organic solvent immiscible with water containing at least 0.1% of a polyorganosiloxane having an amino group is applied onto a porous support, and then a solution of an organic solvent immiscible with water is applied. A crosslinking agent solution prepared by dissolving a polyfunctional reagent that is reactive with the amino groups of the polyorganosiloxane and capable of condensation or addition to form new bonds is applied to an organic solvent to perform crosslinking. A method for producing a composite membrane for gas separation, characterized by allowing a reaction to proceed.