JPS6353205B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel copolymers, and more particularly to novel copolymers of allyltri(alkyl or and phenyl)silanes and dienes having good selective permeability. It is often industrially necessary to enrich or separate a particular gas from a gas mixture. Examples include the production of oxygen-enriched air for combustion, medical, and wastewater treatment applications, the separation or recovery of helium from natural gas and other sources, and the separation of hydrogen from mixed gases in coal pyrolysis processes. 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. Furthermore, for example, an ABA type block copolymer of vinyltrimethylsilane (A) and a conjugated diene (B) is weak against mechanical stress and has insufficient film-forming ability. In order to solve these problems, the present inventors conducted extensive research and found that a copolymer based on allyltri(alkyl or phenyl)silane has the mechanical strength to withstand continuous use as a gas separation membrane. The present invention was achieved by discovering that this material has good selective permeability to gas mixtures. That is, the present invention provides (a) at least one repeating unit represented by the following formula (); [However, in the formula, R ₁ , R ₂ and R ₃ represent one 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) at least one repeating unit represented by the following formula (), [However, in the formula, R ₄ and R ₅ are the same or different and represent a hydrogen atom or a methyl group. ] and/or a repeating unit () represented by the following formula, [However, in the formula, R ₆ and R ₇ are the same or different and represent a hydrogen atom or a methyl group. ], the ratio of (a) and (b) is 5:95 to 95:5, and the intrinsic viscosity of the copolymer is
This is a novel copolymer consisting essentially of 1.0 to 3.0. In the repeating units () constituting the copolymer of the present invention, R ₁ , R ₂ , and R ₃ are the same or different alkyl groups having 1 to 10 carbon atoms, or substituted or unsubstituted phenyl groups to alkyl having 1 to 4 carbon atoms. Examples of alkyl groups include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, tert-butyl group, n-pentyl group, neopentyl group, n-hexyl group, n-octyl group,
Examples include n-decyl group. Among these, particularly preferred are straight chain or branched alkyl groups having 1 to 5 carbon atoms. Examples of monomers corresponding to the repeating unit () include allyltrimethylsilane, allyltriethylsilane, allyltri n-butylsilane, allyltri t-butylsilane, allyltri n-decylsilane, allyldimethyl n-propylsilane,
Examples include allyldimethyl t-butylsilane, allyldimethyl n-octylsilane, allyltriphenylsilane, allyldimethylphenylsilane, and allyldimethyltolylsilane. These monomers can be used alone or in combination of two or more. On the other hand, in the repeating unit () R ₄ , R ₅
are the same or different and are hydrogen atoms or methyl groups. In the repeating unit (), R ₆ and R ₇ are the same or different and are a hydrogen atom or a methyl group. The repeating units () and () can be obtained by polymerizing a conjugated diene, and examples of such dienes include butadiene, isobrene, and dimethylbutadiene. These dienes can be used alone or in combination of two or more. Copolymerization can be performed by changing the ratio of repeating units () and () and/or () in the copolymer of the present invention over a wide range, but it can withstand continuous use as a gas separation membrane. Has mechanical strength,
In order to achieve the objective of the present invention of providing a membrane material with good selective permeability to gas mixtures, the ratio of the repeating units ():() and/or () is from 5:95 to 95: 5, preferably 20:80 to 80:20. If the content of units () 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 is so poor that it cannot be put to practical use. Furthermore, the unit () is 95%
If it exceeds 100%, good gas selective permselectivity cannot be obtained. Advantageously, in the copolymer of the present invention, the sum of the repeating units () and the repeating units represented by () and/or () is 60 mol% or more, preferably 70 mol% or more based on the total repeating units. It is. The copolymer of the present invention has repeating units () and ()
In addition to and/or (), other components may be included, and the other components may be contained in either copolymerization or blending. Examples of other components include olefin polymers, diene polymers, vinyl polymers, allyl-methacrylic polymers, polyethers, polyesters, and polyamides. The viscosity of the copolymer is preferably 1.0 to 3.0 as an intrinsic viscosity measured using an Ostwald viscometer as a 0.5 g/100 c.c. cyclohexene solution at 25°C; The membrane is 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. The novel copolymer of the present invention comprises a monomer corresponding to the repeating unit (), a monomer corresponding to the repeating unit () and/or (),
For example, 10
It can be produced by polymerization at a temperature of ~120°C, preferably 20-100°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. The catalyst employed for producing the copolymer of the present invention may be any catalyst that can generally be used for polymerization of α-olefins, and a preferred example is the Ziegler-Natta catalyst. Such a Ziegler-Natta catalyst consists of a combination of a transition metal halide and a metal alkyl, and examples of transition metals include group a, group a,
Examples include transition metals of Group A, Group A, and Group A. 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 group metals. Examples of suitable metals are
Examples include Be, Al, Mg, Zn, etc. Alkylated products of Al, Zn, etc. are preferably used because of their high 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. Transition metal halides and metal alkyls have an atomic ratio of transition metal to metal other than transition metal of 1:1 or more.
10, particularly preferably in a ratio of 1:1 to 6. The copolymer 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, and is highly selective for oxygen enrichment from air. Application to the industrially useful process of air production is possible. The copolymer of the present invention is soluble in various solvents, such as halogen solvents and hydrocarbon solvents,
Various membrane forming methods can be selected, and its usefulness as a membrane material is extremely high. Examples of preferred solvents include halogen solvents such as chloroform, trichloroethylene, tetrachloroethylene, 1,2,3-trichloropropane, dichlorobenzene, and chloronaphthalene, and hydrocarbon solvents such as benzene, toluene, xylene, cyclohexene, tetralin, and decalin. can be mentioned. When the copolymer of the present invention is used as a separation membrane, the amount of permeation is inversely proportional to the thickness of the membrane. In order to obtain as much transmission as possible, it is desirable that the material be as thin as possible. For example, a preferable film thickness is 0.01 to 500μ. 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. Hereinafter, the present invention will be explained in detail with reference to Examples. Example 1 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 left standing in a constant temperature bath at -20°C for 140 hours to carry out polymerization. The obtained viscous polymer solution was diluted with toluene, thoroughly washed with INHCl and water in that order, and reprecipitated into methanol. These polymers were further purified by fractional precipitation. The results are shown in Table 1.

[Table] Example 2 The amounts of allyltrimethylsilane, styrene, isoprene, catalyst, and solvent shown in Table 2 were charged into a glass ampoule, and the ampoule was sealed under a nitrogen atmosphere. While shaking this sealed tube in an oil bath kept at 40℃,
When polymerization was carried out for a period of time, a viscous polymer solution was obtained. After diluting this solution with toluene, INHCl,
The residue was thoroughly washed with 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.
It was shown to. This polymer was dissolved in toluene to form a homogeneous solution from which a self-supporting membrane could be obtained by casting.

[Table] In order to further clarify the usefulness of the present invention, an ultra-thin film having a thickness of approximately 0.1 μm was formed from a solution prepared by dissolving the copolymer of the present invention, and its gas separation characteristics were measured. Example 3 A solution was prepared by dissolving 4 parts by weight of the polymer obtained in Example 1 in a solvent consisting of 93.12 parts by weight of cyclohexene and 2.88 parts by weight of cyclohexenyl hydroperoxide. This solution was maintained at 50°C and one drop was placed on the surface of the still water kept at 15°C through an opening having a cross-sectional area of about 2mm ² spaced about 10mm 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 solid membranes obtained by repeating the same operation is
It was ^240cm2 . The solid film thus formed on the water surface is pressed down below the water surface and closely supported on the porous polypropylene membrane, and by repeating this operation twice, the two solid films are placed heavily on the porous membrane. A mature composite membrane was obtained. The oxygen permeation rate of this composite membrane is 60×10 ^-4
cc(STP)/cm ² ·sec·cmHg, the permeability coefficient ratio of oxygen to nitrogen was 3.0.

Claims (1)

[Claims] 1 (a) At least one repeating unit represented by the following formula () [However, in the formula, R ₁ , R ₂ and R ₃ 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) at least one repeating unit represented by the following formula ( ) [However, in the formula, R ₄ and R ₅ are the same or different and represent a hydrogen atom or a methyl group. ] and/or a repeating unit () represented by the following formula, [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 5:95 ~
A novel copolymer having a ratio of 95:5 and an intrinsic viscosity of 1.0 to 3.0.