JPH0423574B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a fluid separation molded body useful for separating a mixture of gas and liquid, and particularly useful for concentrating and separating oxygen from a gas mixture such as air. The present invention relates to a molded body for fluid separation.

[Prior Art] Conventionally, in order to separate oxygen from air or to concentrate oxygen in the air, a cryogenic separation method is generally used, in which the air is liquefied and then evaporated to take advantage of the difference in boiling point of each component. It is being However, this method
This method has disadvantages in that it requires large-scale equipment, consumes a large amount of energy, and is economically disadvantageous.
On the other hand, a method using a gas separation membrane is known as a method that uses a simple device and consumes less energy.

[Problems to be Solved by the Invention] However, in the past, oxygen separation or concentration using a method using a gas separation membrane has hardly been used. This is because gas separation membranes must have a large oxygen permeability coefficient, a large oxygen-to-nitrogen permeability coefficient ratio, and a sufficiently high mechanical strength that allows for good film-forming properties. However, there is no known gas separation membrane that satisfies these requirements at the same time. For example, a typical conventional gas separation membrane made of silicone rubber is known, but this membrane has an oxygen permeability coefficient of 3.
Although it has a large value of ~5×10 ^-8 cm ³ (STP) cm/cm ² • sec cmHg, it has the drawbacks of a low oxygen to nitrogen permeability coefficient ratio of about 2 and a weak mechanical strength. In addition, while ethylcellulose membranes are known to have excellent film formability and mechanical strength among cellulose derivative membranes, their permeability coefficient is 1.5×10 ^-9
It has the disadvantage of being small at cm ³ (STP) cm/cm ² sec cmHg.

[Means for Solving the Problems] The present invention solves the problems of the above-mentioned prior art by solving the general formula () [In the formula, R ¹ , R ² and R ³ may be the same or different and are a hydrocarbon group having 1 to 6 carbon atoms.] A triorganosilyl group represented by the following formula is present as a substituent in the side chain. The present invention provides a molded article for fluid separation having a separation layer made of at least one polymer selected from polysaccharides, polysaccharide derivatives, polyvinyl alcohol, and polyvinyl alcohol derivatives.

The polysaccharides, polysaccharide derivatives, polyvinyl alcohol, and polyvinyl alcohol derivatives used as raw materials for the triorganosilyl group-containing polymer used in the present invention can all be introduced with triorganosilyl groups to form silyl ether bonds. It is a polymer containing hydroxyl groups.

Examples of polysaccharides include cellulose,
Examples of the polysaccharide derivatives include starch, pullulan, chitosan, etc., and examples of polysaccharide derivatives include partially etherified and partially esterified polysaccharides. In particular, cellulose derivatives include, for example, alkylcelluloses such as methylcellulose, ethylcellulose, and propylcellulose; hydroxyalkylcelluloses such as hydroxyethylcellulose and hydroxypropylcellulose; ester derivatives of cellulose such as cellulose acetate and cellulose nitrate; and these two.
Mention may be made of mixtures of more than one species.

In addition, as polyvinyl alcohol derivatives,
For example, ethylene-vinyl alcohol copolymer,
Examples include partially saponified polyvinyl acetate.

Among the raw material polymers exemplified above, particularly preferred are cellulose and cellulose derivatives.

Examples of the hydrocarbon group having 1 to 6 carbon atoms in the triorganosilyl group of general formula () in the side chain of the polymer used in the present invention include linear or branched alkyl groups, such as methyl and ethyl. , propyl, isopropyl, butyl, tert-
Butyl, pentyl, hexyl, etc.; cycloalkyl groups, such as cyclopentyl, cyclohexyl, etc.;
Straight-chain or branched alkenyl groups, such as vinyl, allyl, isopropenyl, 1-butenyl, 1
-pentenyl, 1-hexenyl, etc.; and aryl groups, such as phenyl, among others, preferable hydrocarbon groups include the above-exemplified alkyl groups, especially methyl,
Examples include ethyl and propyl. In addition,
Phenyl and the like have the advantage of improving the heat resistance of the molded product. When these hydrocarbon groups have 7 or more carbon atoms, if the hydrocarbon groups are linear, the plasticity of the polymer becomes too high and the mechanical strength of the obtained molded product decreases. If it is branched or cyclic, the hydrocarbon group becomes too bulky and it becomes difficult to introduce an effective amount into the polymer.

Specific examples of the triorganosilyl group of general formula () having such a hydrocarbon group include trimethylsilyl group, triethylsilyl group, tripropylsilyl group, dimethylpropylsilyl group, butyldimethylsilyl group, dimethylpentylsilyl group, Examples include a cyclohexyldimethylsilyl group, a dimethylphenylsilyl group, and a methyldiphenylsilyl group.

The triorganosilyl group of general formula () is preferably contained in the polymer used in an average amount of 30% by weight or more, particularly 50% by weight or more. When the content of triorganosilyl groups is less than 30% by weight on average,
The permeability coefficient of the obtained molded body does not increase sufficiently.

As a method for producing the polymer used in the present invention by introducing the triorganosilyl group of the general formula () into a raw material polymer such as a polysaccharide, it is possible to use a silylating agent that corresponds to the required triorganosilyl group. can. For example, a method using a triorganochlorosilane-pyridine system and a method using a triorganosilylacetamide-N-methylpyrrolidone system, which are known as polymer silylation methods, can be used. In addition, a method using a triorganohalogenosilane-imidazole catalyst system, a method using a triorganosilyl perchlorate, and the like, which are known as alcohol silylation methods, can also be used. For example, when using triorganochlorosilane and 2 equivalents of imidazole as a catalyst, add the triorganochlorosilane and imidazole to a DMF solution of the polymer and stir for several hours at room temperature to introduce the triorganosilyl group into the polymer. can do.

In addition, when triorganosilane is used as a silylating agent, it is converted to triorganosilyl perchlorate with triphenylmethyl perchlorate, and this is activated with pyridine.
Further, a triorganosilyl group can be introduced into the polymer by dissolving it in acetonitrile and dropping it dropwise into a dimethylformamide solution of the polymer, and stirring at room temperature for several minutes to about an hour.

In addition, as a method for producing trialkylsilyl cellulose derivatives, US Patent No. 2532622, 3418312
It is also possible to use the methods disclosed in Nos., No. 3418313, and No. 4390692.

The produced polymer contains chloroform, THF,
It can be purified by dissolving it in a good solvent such as benzene, toluene, xylene, or carbon tetrachloride, and then pouring it into an alcohol, which is a poor solvent, to precipitate it.

The triorganosilyl group-containing polymer obtained as described above is usually used in the production of the molded article for fluid separation of the present invention as a polymer solution using an appropriate solvent. Examples of suitable solvents include benzene, toluene, xylene, carbon tetrachloride, chloroform, and tetrahydrofuran, and various additives such as antioxidants and plasticizers may be added as necessary. The polymer concentration of the polymer solution is usually approximately 0.1 to 20% by weight, but is not particularly limited and is appropriately selected depending on the required film thickness and film forming method.

Examples of the form of the molded product of the present invention include a normal flat membrane, a hollow type, etc., a homogeneous molded product consisting essentially only of the polymer, and a heterogeneous molded product that is a composite with a base material. It can be manufactured as a body. That is, the polymer solution can be formed into a flat film by casting it on a smooth plate and removing the solvent, or it can be formed into a hollow fiber by discharging it from a double nozzle and performing dry or wet spinning. A homogeneous molded body can also be obtained in the case of . Further, a heterogeneous molded body can be produced by applying the polymer solution to a porous flat membrane substrate, porous hollow fiber substrate, or porous hollow tube substrate and removing the solvent. The molded article for fluid separation of the present invention thus obtained has substantially no pores and has a dense separation layer with excellent fluid permeability and separation properties.

Materials for the porous base material used when producing the molded product of the present invention as a heterogeneous molded product include, for example, polysulfones, styrene-containing copolymers such as acrylonitrile-styrene copolymers, polycarbonates, cellulose derivatives, polyamides, etc. kind,
Polyimides, polyethers, polyesters, vinyl polymers, acetylene polymers, etc.
Further examples include copolymers and mixed polymers thereof. A known method can be used to produce a hollow fiber base material using these polymers. For example, the process of dissolving the polymer in a suitable solvent and preparing a uniform dope solution by filtration and defoaming, the process of extruding the dope solution through an annular double nozzle, the process of partially evaporating the solvent of the discharged dope, It can be produced by a step of introducing into a poor solvent or non-solvent and coagulating it, and a step of drying and heat-treating the obtained wet hollow fiber. Further, porosity can be imparted by mixing an inorganic substance.

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

Example 1 10 g (0.061 mol) of cellulose was dispersed in 90 g of dry N-methylpyrrolidone, and 24.8 g (0.122 mol) of N,O-bistrimethylsilylacetamide was added, heated, and stirred at 150° C. for 5 hours.
After cooling, the reaction solution was poured into methanol to precipitate a polymer, which was collected by filtration.

The obtained polymer was redissolved in 200 ml of toluene, and foreign matter was removed using a filter with a pore size of 10 μm.
The purified polymer solution was poured into methanol to precipitate, filtered off, air dried, and then vacuum dried at 60°C.

The resulting polymer was oxidized in a Teflon crucible, and the degree of substitution of trimethylsilyl groups was determined from ash content measurement. The degree of substitution is 1
It was 2.8 (55% by weight in the polymer) per glucose unit. Furthermore, absorption by trimethylsilyl groups was also observed in the infrared absorption spectrum.

Further, a 3% toluene solution of this polymer was coated on a glass flat plate using a blade, air-dried, and further vacuum-dried at 80° C. for 2 hours to obtain a film with a thickness of 35 μm.

The gas permeability and mechanical strength of the obtained membrane were measured. The gas permeability coefficient was measured using a gas permeation tester model K-315-N-02 manufactured by Rika Seiki Kogyo Co., Ltd. Further, the tensile strength was measured using Autograph DSS-10TS manufactured by Shimadzu Corporation.

The oxygen gas permeability coefficient is 1.08×10 ^-8 cm ³ (STP).
cm/ ^cm2・sec・cmHg, which is 51000 for cellulose
It was twice as hot. The permeability coefficient ratio between oxygen and nitrogen was 3. In addition, the mechanical strength is tensile strength of 500Kg/cm ³ ,
It showed an elongation rate of 15% and a strength almost equivalent to that of ethyl cellulose.

Example 2 1.5 g (0.009 mol) of cellulose was added to dry pyridine.
10 g (0.066 mol) of tert-butyldimethylchlorosilane was added thereto, and the mixture was stirred at 160° C. for 10 hours. Thereafter, the solution was poured into methanol to precipitate the polymer.

The resulting polymer had a degree of substitution of tert-butyldimethylsilyl groups of 1.06 per glucose unit.
(43% by weight in the polymer). This polymer was casted from a 3% toluene solution and thoroughly dried to obtain a 20 μm thick film.

The gas permeability and mechanical strength of the obtained membrane were measured in the same manner as in Example 1.

The oxygen gas permeability coefficient is 5.34×10 ^-9 cm ³ (STP).
cm/ ^cm2・sec・cmHg, which is 25000 for cellulose
It was twice as hot. The permeability coefficient ratio between oxygen and nitrogen was 3.4. Further, the tensile strength was 550 Kg/cm ³ and the elongation rate was 7%.

Example 3 6 g of ethyl cellulose (48% ethoxylation rate)
was dissolved in 40 g of dry dimethylformamide, 2.2 g (0.003 mol) of imidazole was added thereto, and 3.2 g (0.016 mol) of triethylbromosilane was added dropwise with stirring at room temperature. The solution, which had been stirred for 2 hours, was poured into methanol to precipitate the polymer.

The resulting polymer had a triethylsilyl group substitution degree of 0.33 per glucose unit (in the polymer).
14% by weight), and was casted from a toluene solution and thoroughly dried to obtain a film with a thickness of 16 μm.

The gas permeability and mechanical strength of the obtained membrane were measured in the same manner as in Example 1.

The oxygen gas permeability coefficient is 2.62×10 ^-9 cm ³ (STP).
cm/cm ² ·sec·cmHg, which was twice that of ethyl cellulose. The permeability coefficient ratio of oxygen and nitrogen was 3.1. In addition, the tensile strength is 570Kg/ ^cm3 , and the elongation rate is
It was 20%.

Example 4 A solution was obtained by dissolving 2 g of hydroxypropyl cellulose (71% hydroxypropoxylation rate) in a mixed solvent consisting of 20 g of dry dimethylformamide and 20 g of toluene, and separately adding 35 g of tert-butyldimethylsilyl perchlorate and pyridine.
A solution prepared from 1.3 g and 15 g of acetonitrile was stirred while being added dropwise to the hydroxypropyl cellulose solution at room temperature. The solution that had been stirred for 1 hour was poured into a 1:1 mixed solvent of water and methanol to precipitate the polymer.

The obtained polymer had a degree of substitution of tert-butyldimethylsilyl group per glucose unit,
1.94 (38% by weight in the polymer), casted from toluene solution and dried well to a thickness of 20 μm.
A film was obtained.

The gas permeability and mechanical strength of the obtained membrane were measured in the same manner as in Example 1.

The oxygen gas permeability coefficient is 1.32×10 ^-9 cm ³ (STP).
cm/cm ² ·sec·cmHg, which was 80 times that of hydroxypropyl cellulose. The permeability coefficient ratio of oxygen and nitrogen was 3.6. Also, the tensile strength is 110Kg/cm ³ ,
A flexible membrane with an elongation rate of 80% was obtained.

Example 5 10 g (0.062 mol) of pullulan was dissolved in 100 ml of dry dimethylformamide, 30.3 g (0.446 mol) of imidazole and 30.5 g (0.223 mol) of dimethylpropylchlorosilane were added, and the mixture was heated at 50°C.
Stirred for 24 hours. The reaction solution was poured into methanol to precipitate a polymer.

The obtained polymer had a degree of substitution of dimethylpropylsilyl groups of 2.5 per glucose unit (61% by weight in the polymer), and was casted from a 5% toluene solution to obtain a film with a thickness of 30 μm.

The gas permeability of the obtained membrane was measured. Oxygen gas permeability is 4.55×10 ^-9 cm ³ (STP)・cm/cm ²・sec・
cmHg, which was 25,000 times higher than pullulan. The permeability coefficient ratio of oxygen and nitrogen was 3.0.

Example 6 5 g (0.114 mol) of polyvinyl alcohol is dispersed in 100 g of dry N-methylpyrrolidone, and further 23.2 g of N,O-bistrimethylsilylacetamide is dispersed in 100 g of dry N-methylpyrrolidone.
g (0.114 mol) was added. The solution stirred at 150°C for 3 hours was poured into methanol to precipitate the polymer.

The resulting polymer had a trimethylsilyl group substitution degree of 0.86 per unit (58% by weight in the polymer).
A 5% toluene solution was casted on a Teflon plate to obtain a 90 μm thick film.

The gas permeability of the obtained membrane was measured. The oxygen gas permeability is 3.6×10 ^-9 cm ³ (STP)・cm/cm ²・sec・
cmHg, 4000 times higher than polyvinyl alcohol. The permeability coefficient ratio of oxygen and nitrogen was 3.5.

Example 7 2.5 g (0.016 mol) of cellulose was added to dry pyridine.
14.7 g (0.086 mol) of dimethylphenylchlorosilane was added thereto, and the mixture was stirred at 160° C. for 10 hours. Thereafter, the reaction solution was poured into methanol to precipitate the polymer.

The obtained polymer had a degree of substitution of dimethylphenylsilyl groups of 2.93 per glucose unit (71% by weight in the polymer), and was casted from a toluene solution and dried to obtain a film with a thickness of 43 μm.

When the gas permeability of the obtained membrane was measured, the oxygen gas permeability coefficient was 2.39×10 ^-10 cm ³ (STP)
cm/cm ² ·sec·cmHg, and the ratio of oxygen to nitrogen permeability coefficients was 4.0.

[Effects of the Invention] The molded article for fluid separation of the present invention has a gas permeability coefficient tens to tens of thousands of times larger than that of gas separation membranes made of non-organosilylated polymers such as polysaccharides and polyvinyl alcohol. Since it has excellent permeability, for example, the permeability coefficient ratio between oxygen and nitrogen is as large as 3 or more, it is useful as a separation membrane for mixed gases, especially oxygen separation membranes for air and the like. In addition, the molded article for fluid separation of the present invention has the following properties in terms of film formability and mechanical strength:
It is as good as the non-organosilylated polymer film mentioned above, and therefore has the advantage of being easy to form into a thin film and having high durability.

Furthermore, since the molded article for fluid separation of the present invention has good heat resistance, it is also useful for recovering hydrogen gas in chemical plants exposed to high temperatures.

As described above, the fluid separation molded article of the present invention has excellent performance required for gas separation membranes, and is useful for separating and concentrating specific components from gas mixtures, as well as for liquid mixtures such as water and alcohol. It is also expected to be used for separation purposes.

Claims (1)

[Claims] 1. General formula: [In the formula, R ¹ , R ² and R ³ may be the same or different and are hydrocarbon groups having 1 to 6 carbon atoms] Having a triorganosilyl group shown as a substituent in the side chain, A molded article for fluid separation having a separation layer made of at least one polymer selected from polysaccharides, polysaccharide derivatives, polyvinyl alcohol, and polyvinyl alcohol derivatives.