JPS63100905A - Permselective membrane formed with novel copolymer - Google Patents

Abstract

PURPOSE:To prepare a membrane with a mechanical strength durable for continuous use and with a good permselectively for a gas mixture by providing a copolymer constituted with specific allyltri(alkyl or phenyl)silane and diene group. CONSTITUTION:A membrane is formed from a copolymer with the ratio of 5:95-95:5 of repeating units I:II and/or III and with an intrinsic viscosity of 1.0-3.0 (R1, R2 and R3 in formula I show same or different alkyl with 1-10 carbon atoms, or phenyl, substituted or not substituted with alkyl with 1-4 carbon atoms. R4 and R5 in formula II show same or different hydrogen atom or methyl. R6 and R7 in formula III show same or different hydrogen atom or methyl). Said copolymer can be prepared, for instance, by polymerizing a monomer corresponding to the repeating unit I and a monomer corresponding to the repeating unit II and/or III together with regular alpha-olefin polymerization catalyst at 10-120 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to selectively permeable membranes formed from novel copolymers of allyltri(alkyl or phenyl)silanes and dienes.

It is often industrially necessary to enrich or separate specific gases from gas mixtures. production of oxygen-enriched air for applications such as combustion, medical, and wastewater treatment;
Examples include separation or recovery of helium from natural gas and other sources, and separation of hydrogen from mixed gas in coal pyrolysis.

Conventionally, many attempts have already been made to separate gases using membranes made of synthetic polymers. However, membranes made of these synthetic polymers are not suitable for practical use because they do not have sufficient gas permeability and selectivity, or have insufficient mechanical strength.

For example, Japanese Patent Publication No. 47-51715 discloses a technique for separating gas mixtures using a membrane made of polyvinyltrimethylsilane. It is known that silicon-containing carbon chain polymers such as polyvinyltrimethylsilane exhibit selective permselectivity for various gas mixtures. However, thin films of polyvinyltrimethylsilane are relatively fragile, and it is difficult to manufacture extremely thin films that can provide a practically sufficient amount of permeation. Further, for example, an ABA type block copolymer of vinyltrimethylsilane (A) and conjugated diene (B) is weak against mechanical stress and has insufficient film-forming ability.

・In order to solve these problems, the present inventors have conducted extensive research and found that a membrane made of a copolymer of allyltrialkyl (or phenyl) silane and dienes has been developed as a selectively permeable membrane that can be used continuously. The present invention was achieved based on the discovery that the material has excellent selective permeability to gas mixtures.

That is, the present invention provides (a) at least one repeating unit (I) represented by the following formula, and (b) at least one repeating unit (ff) represented by the following formula, -(-CH, -C÷ ...(II)-R
5 CI+□ and/or repeating unit (I[I
), and the ratio of (a) and (b) is 5=
95-95:5, and the intrinsic viscosity of the copolymer is 1.0-95:5.
The selectively permeable membrane is formed from a copolymer consisting essentially of 3.0.

In the repeating unit (I) constituting the copolymer of the present invention, R+, Rz, Ih are the same or different alkyl groups having 1 to 10 carbon atoms or alkyl substituted or unsubstituted phenol groups having 1 to 4 carbon atoms; Examples of the alkyl group include methyl group, ethyl group, n-propyl group, 1so-propyl group, n-butyl group, tert-
Butyl group, n-pentyl group.

Neopentyl group, n-hexyl group, n-octyl group, n
-decyl group and the like. Among these, particularly preferred are straight chain or branched alkyl groups having 1 to 5 carbon atoms.

Examples of the seven polymers corresponding to the repeating unit (I) include allyltrimethylsilane, allyltriethylsilane,
Allyltri n-butylsilane, allyltri n-butylsilane, allyltri n-decylsilane, allyldimethyl n
-Propylsilane.

Allyltridimethyl also monobutylsilane, allyltridimethyl n-octylsilane, allyltriphenylsilane,
Examples include allyldimethylphenylsilane and allyldimethyltolylsilane. These monomers can be used alone or in combination of two or more.

On the other hand, in the repeating unit (n), R4 and Rs are the same or different and are a hydrogen atom or a methyl group.

In the repeating unit (III), R6 and R7 are the same or different and are a hydrogen atom or a methyl group.

The repeating units (II) and (I[I) can be obtained by polymerizing a conjugated diene, and examples of such dienes include butadiene, isoprene, and dimethylbutadiene. These dienes are one or two types.
More than one species can be used in combination.

In the repeating unit (IV), R6 is a hydrogen atom or a methyl group. Examples of the monomer corresponding to the repeating unit (IV) include styrene and α-methylstyrene. One or two of these monomers
Seeds can be used in combination.

Repeating unit (I) in the copolymer used in the present invention
Although it is possible to copolymerize by changing the ratio of (II) and/or (If) over a wide range, it has the mechanical strength to withstand continuous use as a selectively permeable membrane, and has a high resistance to gas mixtures. In order to achieve the object of the present invention of providing a membrane material having good selective permeability, the ratio of the repeating units (I):(II) and/or (III) is 5:5:
Range of 95-95:5, preferably 20:80-8
A range of 0:20 is desirable. Unit (I)
If it is less than 5%, the resulting copolymer becomes crystalline, resulting in poor solubility in solvents, resulting in problems in film formation, and the strength of the resulting film decreases (unable to be put to practical use. If (I) exceeds 95%, good gas selective permselectivity cannot be obtained.

The copolymer used in the present invention is the repeating unit (I
) and (n) and/or (I [I) is advantageously at least 60 mol %, preferably at least 70 mol %, based on all repeat units.

The copolymer used in the present invention may contain other components in addition to repeating units (I), (It), and/or (III), and the form in which the other components are contained may be either a copolymer or a blend. You can. Examples of other components include olefin polymers, diene polymers, vinyl polymers, allyl-methacrylic polymers, polyethers, polyesters, and polyamides.

The viscosity of the copolymer is 0.5 g/100 c at 25°C.
It is desirable that the intrinsic viscosity of the cyclohexene solution of c is 1.0 to 3.0 as measured using an Ostwald viscometer, and if it is less than 1.0, the film will be brittle and cannot be put to practical use. When it is larger than 3.0, the fluidity of the solution deteriorates, making it difficult to form a film.

This copolymer comprises a monomer corresponding to the repeating unit (I) and the repeating unit (II) and/or (III).
For example, a monomer corresponding to
It can be produced by polymerization at a temperature of 100°C. At temperatures lower than 10'C, the polymerization rate is slow and economically disadvantageous. On the other hand, temperatures exceeding 120°C are not preferred because the catalyst activity tends to decrease.

Therefore, any catalyst that can be generally used for the polymerization of α-olefins may be used, and a preferable example is Zieg
ler-Natta catalyst may be mentioned. Kayouna Zi
Examples of the Egler-Natta catalyst include a combination of a halogenated transition metal and a metal alkyl; examples of transition metals include the IVa group, Va group, and the A group.

Examples include transition metals of group ①a and group ②a. Examples of suitable transition metals include Ti, Zr, V, Cr.
.

These include Mo, W, Mn, Fe, etc. Among these, halides such as Ti and V are particularly preferred because of their high activity. Examples of metal alkyl include metals of group 1 and group 2. Examples of suitable metals are Be, Al.

Examples include Mg and Zn. Alkylated products such as AI and Zn are preferably used because of their catalytic activity. The quantitative ratio of the catalyst consisting of a transition metal halide and a metal alkyl greatly influences the polymerization rate and conversion rate.

The transition metal halide and metal alkyl have an atomic ratio of transition metal to metal other than transition metal of 1:1 to 10, particularly 1:
It is preferable to use a ratio of 1 to 6.

The membrane of the present invention exhibits high selectivity for various gas mixture components; for example, a membrane made of allyltrimethylsilane/isoprene copolymer has a high oxygen-nitrogen separation ability;
Application to the industrially advantageous process of producing oxygen-enriched air from air is possible.

This copolymer can be used in various solvents, such as halogenated solvents,
It is soluble in hydrocarbon solvents, etc., and various film forming methods can be selected. Examples of preferable solvents include chloroform, trichloroethylene, tetrachloroethylene, 1,2.3-
) Lichloropropane.

Halogens such as dichlorobenzene and chloronaphthalene?
Examples include hydrocarbon solvents such as e solvent, benzene, toluene, xylene, cyclohexene, tetralin, and decalin.

Since the amount of permeation in the selectively permeable membrane of the present invention is inversely proportional to the thickness of the membrane, the inherent permselectivity is not substantially impaired;
As long as it has the strength to withstand continuous use as a separation membrane, it is desirable that it be as thin as possible in order to obtain a high permeation rate.

For example, a preferable film thickness is 0.01 to 500 μm. Membrane forms include hollow fiber membranes, flat membranes, asymmetric membranes, and composite membranes supported on porous supports obtained by various methods such as phase separation, extraction, and stretching. The film thickness is selected.

Reference Example 1 for Production of Copolymer Allyltrimethylsilane, isoprene, catalyst, and solvent in the amounts shown in Table 1 were charged into a glass ampoule and sealed under a nitrogen atmosphere. This sealed tube was heated to 140°C in a thermostatic oven at -20°C.
Polymerization was carried out by standing for a period of time.

The resulting viscous polymer solution was diluted with toluene and IN
It was thoroughly washed with IIcL and water in that order, and reprecipitated into methanol. These polymers were further purified by fractional precipitation.

Show the results to the table worker.

Example 1 Allyltrimethylsilane, styrene, in the amounts shown in Table 2
Charge isoprene, catalyst, and solvent into a glass ampoule,
It was melt-sealed under a nitrogen atmosphere. Polymerization was carried out for 90 hours while shaking this sealed tube in an oil bath kept at 40°C, and a viscous polymer solution was obtained.

This solution was diluted with toluene, washed thoroughly with IN MCI and water, and precipitated into methanol.

The obtained polymer was further purified by fractional precipitation.

The polymer composition and properties of the obtained polymer are shown in Table 2 below. This polymer is dissolved in toluene to form a homogeneous solution,
A self-supporting membrane could be obtained by casting from this solution.

Example 2 A solution was prepared by dissolving 4 parts by weight of the polymer obtained in Reference Example 1 in a solvent consisting of 93.12 parts by weight of cyclohexene and 2.88 parts by weight of cyclohexymonylhydroperoxide.

This solution was maintained at 50°C, and one drop was placed on the surface of still water maintained at 15"C through an opening having a cross-sectional area of approximately 2 spindles, spaced approximately 10 mm above the surface. .

The dropped droplets immediately spread on the water surface, forming a circular solid film centered approximately at the droplet position.

The average membrane area of the solid membrane obtained by repeating the same operation was 240
It was Ω2.

The solid film thus formed on the water surface is pressed down below the water surface and closely supported on the polypropylene porous film, and by repeating this operation twice, a composite of two solid films superimposed on the porous film is formed. A membrane was obtained. The oxygen permeation rate of this composite membrane is 60 × 10-'cc (STP)/c
m"-see-cm)Ig, the permeability coefficient ratio of oxygen to nitrogen was 3.0.

Claims (1)

[Claims] 1. (a) A repeating unit (I) represented by at least one of the following formulas ▲There are mathematical formulas, chemical formulas, tables, etc.▼... (I) [However, R_1, R_2, R_3 in the formula represent the same or different alkyl groups having 1 to 10 carbon atoms or substituted or unsubstituted phenyl groups with alkyl having 1 to 4 carbon atoms. ] and (b) a repeating unit (II) represented by at least one of the following formulas ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(II) [However, in the formula, R_4 and R_5 are the same or different, and are hydrogen atoms. Or indicates a methyl group. ] and/or a repeating unit (III) represented by the following formula ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(III) [However, in the formula, R_6 and R_7 are the same or different and represent a hydrogen atom or a methyl group. . ] Consists of a repeating unit with (a) and (b) in a ratio of 5:9
5 to 95:5, and the intrinsic viscosity of the copolymer is 1.0 to 3.
．． A selectively permeable membrane formed from a copolymer consisting essentially of 0.