JP5794110B2 - Gas separation membrane module - Google Patents

Description

  The present invention relates to a gas separation membrane module for mixed gas separation, in which yarn bundles composed of a large number of selectively permeable hollow fiber membranes are fixed integrally with a tube sheet obtained by curing a specific epoxy composition.

  A method of separating a mixed gas using a gas separation membrane having selective permeability has attracted attention. Examples of the gas separation membrane module used in this method include a plate and frame type, a tubular type, and a hollow fiber type. Among them, the hollow fiber type gas separation membrane module not only has the advantage that the membrane area per unit volume is the largest, but also is excellent in terms of pressure resistance and self-supporting properties, so it is industrially advantageous. It is widely used.

  In the hollow fiber type gas separation membrane module, at least one end of a yarn bundle composed of a number of hollow fiber membranes having selective permeability is integrally bound and fixed with a cured resin plate (tube plate) for casting. , And is housed in a casing having at least a mixed gas inlet, a permeate gas outlet, and a non-permeate gas outlet. In addition to the role of fixing the yarn bundle integrally, the tube sheet seals the hollow fiber and the hollow fiber and between the hollow fiber and the casing, thereby isolating the internal space and the external space of the hollow fiber membrane, It has a role of maintaining the airtightness between the internal space and the external space. In the hollow fiber type gas separation membrane module, when the airtightness by the tube plate is lost, suitable separation is not performed.

  In a gas separation method using a separation membrane, suitable gas separation may be achieved by supplying the gas mixture at a high temperature and high pressure. In that case, the tube sheet material is required to have high heat resistance and pressure resistance, and its glass transition temperature and heat distortion temperature must be at least several tens of degrees higher than the operating temperature of the gas separation membrane module.

  A thermosetting resin is generally used as a tube sheet material to achieve high heat resistance and pressure resistance. However, at the time of tube sheet molding, in order to complete the curing reaction of the thermosetting resin, the temperature is extremely high. It is processed. If a tube plate that does not complete the curing reaction is used, the curing reaction proceeds while the separation membrane module is operated at a high temperature, and the tube plate contracts, resulting in an insufficient sealing function between the tube plate and the casing. Because it becomes. Accordingly, the tube sheet material is also required to have heat resistance against a remarkably high temperature when the tube sheet is formed.

  As a gas separation membrane module that can be used for separation of a high-temperature and high-pressure mixed gas, Patent Document 1 discloses that a phenol novolac type epoxy resin is reacted with a liquid polybutadiene having a reactive functional group at its end. A hollow fiber element produced using the modified epoxy resin is described.

JP 62-74434 A

  However, the conventional tube sheet material has problems such as large shrinkage in curing at the time of tube sheet molding, cracking, and destruction of the tube sheet. Furthermore, when only pressure resistance and heat resistance are emphasized, the flexibility of the tube sheet material is poor.For example, when an impact is applied during operation, the tube sheet cracks or the tube sheet breaks. There was a problem such as. An object of the present invention is to provide a tube sheet of a gas separation membrane module that does not cause cracks while maintaining sufficient heat resistance and pressure resistance under high temperature and high pressure.

  The present invention relates to the following matters.

1. A yarn bundle comprising a number of hollow fiber membranes having gas separation performance;
A casing having a mixed gas inlet, a permeate gas outlet, and a non-permeate gas outlet, in which the hollow fiber bundle is disposed;
A tube plate for fixing at least one end of the hollow fiber bundle;
A gas separation membrane module comprising:
The tube sheet is
(A) a modified epoxy resin obtained by reacting a phenol novolac-type epoxy compound with (b) a butadiene-acrylonitrile copolymer having a terminal functional group capable of reacting with an epoxy group, and (c) a note containing a curing agent A gas separation membrane module formed of an epoxy cured product obtained by curing a mold resin composition.

  2. 2. The gas separation membrane module according to 1 above, wherein the casting resin composition further contains a curing accelerator.

  3. 3. The gas separation membrane module according to 1 or 2 above, wherein the functional group capable of reacting with the epoxy group is a carboxyl group.

  4). 4. The gas separation membrane module according to any one of 1 to 3, wherein the curing agent is an acid anhydride.

  5. 5. The gas separation membrane module according to any one of 2 to 4 above, wherein the curing accelerator is an imidazole compound.

  The tube sheet in the gas separation membrane module of the present invention is manufactured using a butadiene-acrylonitrile copolymer having a functional group capable of reacting with an epoxy group at its end, so that it is more flexible than a conventional tube sheet. Have. When the tube sheet is molded or when the gas separation membrane module is operated and exposed to high temperature and high pressure gas, the tube sheet does not crack, and adheres to the hollow fiber, and the tube sheet and the casing. There is no problem with the sealing function.

It is the schematic which shows an example of a gas separation membrane module. It is the schematic which shows the preparation methods of the tube sheet for mixed gas separation.

The epoxy cured product forming the tube sheet of the hollow fiber element of the present invention comprises at least (a) a phenol novolac type epoxy compound and (b) a butadiene-acrylonitrile copolymer having a functional group capable of reacting with an epoxy group at the terminal. A modified epoxy resin obtained by reaction, and (c) a cast resin composition containing a curing agent can be obtained by curing by heat treatment. Details will be described below.

<Modified epoxy resin>
The modified epoxy resin includes a phenol novolac type epoxy compound (hereinafter sometimes referred to as an epoxy compound (a)) and a butadiene / acrylonitrile copolymer having a functional group capable of reacting with an epoxy group at the terminal {hereinafter referred to as a compound ( b) may be obtained by reacting.

  The phenol novolac type epoxy compound (a) used in the present invention is a compound represented by the following general formula (a).

（式中、Ｒ”は、炭素数１〜３のアルキル基、または水素原子を表し、ｎは、０〜５００、好ましくは０〜２０の整数を表す。）

(In the formula, R ″ represents an alkyl group having 1 to 3 carbon atoms or a hydrogen atom, and n represents an integer of 0 to 500, preferably 0 to 20.)

  In the formula (a), R ″ is preferably a methyl group or a hydrogen atom. The epoxy compound (a) represented by the general formula (a) preferably has a molecular weight of 300 to 2,000, The equivalent is preferably 150 to 250. As the epoxy compound (a), jER152, jER154 manufactured by Mitsubishi Chemical Corporation, EPICLON-N740, N-770, N-775 manufactured by DIC Corporation, etc .; Examples thereof include YDPN-638 and YDCN-700 series manufactured by Kasei Co., Ltd .; DEN 438 manufactured by The Dow Chemical Company.

  In the butadiene / acrylonitrile copolymer {compound (b)} having a functional group capable of reacting with an epoxy group used in the present invention, as the functional group capable of reacting with an epoxy group, for example, a carboxyl group, an amino group, A hydroxyl group etc. are mentioned, A carboxyl group is especially preferable. By containing the compound (b), flexibility can be imparted to the formed tube sheet.

  As the butadiene / acrylonitrile copolymer having a functional group capable of reacting with an epoxy group at the terminal, for example, a carboxyl group-terminated butadiene / acrylonitrile copolymer (CTBN) represented by the following general formula (b) is preferable.

式（ｂ）中、ｍはブタジエンモノマーユニットの繰り返し数の合計を示し、ｎはアクリロニトリルモノマーユニットの繰り返し数の合計を示し、［ ］内の構造が２以上存在するとき、ｍ、ｎはそれぞれの単位の繰り返し数の総和を示し、ブロックとして存在してもランダムに存在していてもどちらでもよい。

In formula (b), m represents the total number of repeating butadiene monomer units, n represents the total number of repeating acrylonitrile monomer units, and when there are two or more structures in [], m and n are Indicates the total number of repeating units, and may be present as a block or randomly.

The molecular weight of CTBN represented by the general formula (b) is preferably 2000 to 4000. For example, it is preferable that 5 to 50% by weight of acrylonitrile monomer unit is contained in CTBN. Examples of commercially available products include Hyper ^TM CTBN 1300 × 8, CTBN 1300 × 13, and CTBN 1300 × 31 manufactured by Emerald Performance Materials.

  The modified epoxy resin is obtained by mixing and reacting the compound (b) so as to be preferably 5 to 50 parts by weight, more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the epoxy compound (a). . When a modified epoxy resin in which the content of each compound is within the above range is used, the formed tube sheet does not crack at high temperatures and pressures, and the glass transition temperature is greatly lowered and deformed. There is no problem. Further, other compounds may be mixed as long as the object of the present invention is not impaired. The reaction conditions for preparing the modified epoxy resin are not particularly limited, but the reaction temperature is preferably 100 to 200 ° C., and the reaction time is preferably 2 to 5 hours.

<Curing agent>
The curing agent used in the present invention is not particularly limited as long as it is an epoxy resin thermosetting agent, and examples thereof include amines, phenols, and acid anhydrides, and it is more preferable to use acid anhydrides. Examples of the acid anhydride include phthalic anhydride, pyromellitic dianhydride, methyl-5-norbornene-2,3-dicarboxylic acid anhydride (anhydrous methylnadic acid), benzophenone tetracarboxylic acid dianhydride, and the like. And methyl-5-norbornene-2,3-dicarboxylic acid anhydride is particularly preferred.

<Curing accelerator>
The casting resin composition used in the present invention may contain a curing accelerator if necessary, and examples of the curing accelerator include imidazole compounds. Examples of the imidazole compound include 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-benzyl-2-methyl. Examples include imidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and 2-ethyl-4-methylimidazole is particularly preferable.

<Epoxy cured product>
The epoxy cured product forming the tube sheet of the present invention may be described as a cast resin composition (hereinafter referred to as a cast resin composition) in which the modified epoxy resin, a curing agent, and, if necessary, a curing accelerator are mixed. ) Can be cured by heat treatment. The mixing ratio of the modified epoxy resin and the curing agent in the preparation of the casting resin composition depends on the number of epoxy functional groups of the modified epoxy resin and the number of functional groups of the curing agent, and also depends on the viscosity and the like of the casting resin composition. It can be adjusted as appropriate. In addition, a hardening accelerator becomes like this. Preferably it is 0-5 weight part with respect to 100 weight part of modified epoxy resins, More preferably, it is 0.1-3 weight part.

  In the heat treatment, for example, it is preferable to heat the casting resin composition to perform primary curing to such an extent that the casting resin composition loses fluidity, and then to post-cur the primary cured resin at a higher temperature. When post-curing, the casting resin composition is heated to a temperature equal to or higher than the final operation temperature of the module, for example, preferably 100 ° C. to 250 ° C., more preferably so that the tube sheet material does not change physical properties during module operation. Heat treatment is preferably performed at 120 ° C. or higher for 2 to 10 hours. Moreover, although primary limitation is not specifically limited, For example, Preferably it is less than 100 degreeC, More preferably, it is preferable to carry out for 2 to 24 hours at 50-85 degreeC. The primary-cured resin is preferably heated to a post-curing temperature at a temperature rising rate of 5 ° C./min or less without causing a problem of thermal runaway due to the reaction heat generated abruptly within the cast resin composition. A method for producing the tube sheet will be described later.

<Gas separation membrane module>
Next, the structure of the gas separation membrane module of the present invention will be described.

  As gas separation membrane modules constituted by hollow fiber membranes, so-called bore feed type and shell feed type are known. For example, in a bore feed type gas separation membrane module, as shown in FIG. 1 (A), a large number of hollow fiber membranes 14 (for example, hundreds to hundreds of thousands) are converged to form a hollow fiber bundle, The hollow fiber bundle is accommodated in a casing 15 having at least a mixed gas inlet 11, a permeate gas outlet 12, and a non-permeate gas outlet 13, and the hollow fiber membrane 14 is opened at both ends of the hollow fiber bundle. The tube plates 16a and 16b are configured to be fixed to the casing 15 so as to be in a state, and a gas is supplied from the mixed gas inlet 11 to the non-permeate gas discharge port 13 through the inside of the hollow fiber membrane 14 (non- The permeation side) is separated from the space (permeation side) that leads from the outside of the hollow fiber membrane 14 to the permeate gas outlet 12. The casing 15 is made of, for example, a metal material such as stainless steel, a plastic material, a fiber reinforced plastic material, and a ceramic material. In the shell-feed type gas separation membrane module, for example, as shown in FIG. 1 (B), a tube sheet is formed at one end of the hollow fiber bundle, and gas is supplied from the mixed gas inlet 11 and impervious. The non-permeate side space leading to the gas exhaust port 13 is outside the hollow fiber membrane 14, and the permeate side space leading to the permeate gas exhaust port 12 is configured inside the hollow fiber membrane 14.

  1A and 1B, the mixed gas supplied from the mixed gas inlet 11 of the gas separation membrane module flows through the hollow fiber membrane 14 while flowing in contact with the hollow fiber membrane 14 in the gas separation membrane module. The high permeation gas is preferentially permeated, and is separated into a gas containing a large amount of the high permeation gas (permeation gas) and a remaining gas not containing the high permeation gas (non-permeation gas). The permeated gas is discharged from the permeated gas outlet 12, and the non-permeated gas is discharged from the non-permeated gas outlet 13. Only one or both of the non-permeate gas and the permeate gas discharged from the gas separation membrane module are recovered depending on the application.

  As the hollow fiber used in the gas separation membrane, a large number of hollow fibers having a small thickness and a small diameter can be used even in a small apparatus, can increase the membrane area, increase the separation efficiency, and are economical and preferable. Examples of the hollow fiber include those having a film thickness of 10 to 500 μm and an outer diameter of 50 to 2000 μm, but are not particularly limited. Further, the gas separation membrane may be homogeneous, may be non-uniform such as a composite membrane or an asymmetric membrane, and may be microporous or nonporous.

  Examples of the gas separation membrane include those formed of polyimide, polyetherimide, polyamide, polyamideimide, polysulfone, polycarbonate, silicone resin, a polymer material such as a cellulose-based polymer, or a ceramic material such as zeolite. As a gas separation membrane formed of polyimide, for example, an aromatic polyimide hollow fiber separation membrane is preferable, and an aromatic polyimide asymmetric hollow fiber separation membrane is more preferable.

  Examples of the distribution form of the hollow fiber bundle include a parallel arrangement, a cross arrangement, a woven form, and a spiral form. Moreover, the hollow fiber bundle may be provided with a core tube at a substantially central portion, and a film may be wound around the outer peripheral portion of the hollow fiber bundle. Further, the hollow fiber bundle may have a cylindrical shape, a flat plate shape, a prismatic shape, or the like, and may be stored in the casing as it is, bent into a U shape, or wound in a spiral shape.

  The manufacturing method of the gas separation membrane module of this invention is demonstrated below.

  First, a method for converging a hollow fiber membrane as a hollow fiber bundle will be described.

  Examples of the method for converging the hollow fiber membranes so as to alternately intersect with each other at an angle of 5 to 30 degrees with respect to the axial direction include the following methods. 1 to 100 hollow fiber membranes are arranged in the core tube by a yarn distribution guide that reciprocates at a constant speed in the axial direction of the tubular object (core tube) that becomes the core. Rotate. For this reason, the hollow fiber membrane is not distributed in parallel with the shaft, but is distributed at an angle corresponding to the rotation of the core tube with respect to the axial direction. When the yarn distribution reaches one end, the hollow fiber membrane is fixed there, and the yarn distribution guide is pulled back in the opposite direction for further yarn distribution. Since the core tube continues to rotate in the same direction, the yarn is now distributed with an angle that is the same as the previous time but in the opposite direction with respect to the axial direction. When this process is repeated, the hollow fiber membranes to be distributed are alternately arranged on the hollow fiber membranes distributed at the opposite angle and converged into the hollow fiber bundle.

  Next, a method for forming a tube sheet in the present invention will be described. Examples of the method for forming the tube sheet include a centrifugal molding method and a static molding method. The static molding method is preferable because the apparatus is simple and productivity can be improved. Hereinafter, an example of the static molding method will be described.

  The hollow fiber bundle in which the hollow fiber membranes 24 having a predetermined length and the number are bundled by the above-described method or the like is stored in the casing 22 while the core tube is removed or the core tube is left in the substantially central portion of the bundle as it is. Thereafter, the hollow fiber bundle and the cylindrical casing 22 are held substantially vertically with the end portion facing down, and the hollow fiber bundle and the cylindrical casing 22 are placed at predetermined positions in the mold 21 for forming the tube sheet at the end portion. A schematic diagram of this state is shown in FIG.

  A predetermined amount of a casting resin composition for forming the tube plate 23 is injected into the mold 21. A schematic diagram of the state in which the casting resin composition is injected is shown in FIG. 2c. The method of injecting the casting resin composition is not particularly limited, but it is easy to uniformly inject the casting resin composition into the mold 21 and between the hollow fiber membranes 24 by injecting with a syringe from the lower part of the mold. Therefore, it is preferable. If the injection rate of the casting resin composition is too high, it will be difficult to uniformly inject the casting resin composition into the site to be filled. While the casting resin composition is injected into the mold 21, it is preferable to appropriately control the temperature of the mold 21. Similarly, it is preferable to control the temperature of the casting resin composition.

  From the viewpoint of moldability, the cast resin composition before curing is preferably liquid at the temperature at the time of resin injection.

  Although there is no restriction | limiting in particular about the viscosity of a casting resin composition, It is preferable that the viscosity in the temperature of 70-90 degreeC used normally at the time of resin injection | pouring is less than 120 poise, and it is especially preferable that it is less than 20 poise. Here, the viscosity of the resin composition is suitably measured using a rotational viscometer.

  When the viscosity at 70 to 90 ° C. of the casting resin composition is 120 poise or more, it takes a long time to inject the resin when molding the tube plate, and it is difficult for bubbles to be generated when the resin is injected, and further the resin enters between the hollow fiber membranes. Does not sufficiently permeate and voids are generated.

  After injecting the casting resin composition into the mold 21, the casting resin composition is primarily cured by maintaining the mold 21 and the hollow fiber bundle at a constant temperature, and the tube plate 23 is formed. The temperature at this time is less than 100 ° C., preferably 50 to 85 ° C. If the temperature at this stage is high, the curing reaction of the cast resin composition becomes violent, and the strength of the finally obtained tube sheet is affected, which is not preferable.

  After the casting resin composition is cured, post-curing is preferably performed by further heating the casting resin composition in terms of improving the durability and mechanical properties of the tube sheet. The temperature during post-curing is preferably 100 ° C to 250 ° C. When the post-curing temperature is lower than 100 ° C., the casting resin composition is not sufficiently cured, which is not preferable. Moreover, when the temperature at the time of post-curing is too high, the curing reaction of the cast resin composition becomes violent, which causes a problem in the strength of the tube sheet, which is not preferable. When post-curing the cast resin composition, it may be divided into a plurality of times and heated to different temperatures.

  After the post-curing of the casting resin composition, the tube sheet is cut and the hollow fiber membrane is opened at the end, so that the hollow fiber is held open at the end and the hollow fiber is fixed by the tube plate Element.

  Here, in the case where the tube sheet is formed at both ends of the hollow fiber bundle, after the tube sheet is formed at one end of the hollow fiber bundle by the above procedure, the tube sheet is formed by the same procedure at the other end. Is done by forming. After the tube sheet is formed at one end, it may be after the tube sheet is cut and the hollow fiber membrane is opened. In addition, after one end is placed in the mold, the casting resin composition is injected, after primary curing, before post-curing, a tube plate is formed on the other end, and the procedures after post-curing It is also suitable to carry out at both ends simultaneously.

  In the method for separating a mixed gas using the gas separation membrane module of the present invention, the mixed gas to be separated is not particularly limited as long as it is a mixture of two or more gases. The gas separation membrane module of the present invention includes, for example, separation of nitrogen-enriched gas and oxygen-enriched gas from air, separation of hydrogen gas from a mixed gas containing hydrogen gas, and water vapor from a mixed vapor of water vapor and organic vapor. It can be suitably used for separation (dehydration of organic vapor).

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to an Example.

<Example 1>
(Manufacture of casting resin composition)
100 parts by weight of polyglycidyl ether of phenol novolac and 10 parts by weight of a carboxyl group-terminated butadiene / acrylonitrile copolymer (molecular weight 3100) were mixed and heated at 150 ° C. for 3 to 4 hours to prepare a modified epoxy resin. 100 parts by weight of the prepared modified epoxy resin, 80 parts by weight of methyl-5-norbornene-2,3-dicarboxylic anhydride and 0.3 part by weight of 2-ethyl-4-methylimidazole are mixed and stirred. Thus, a casting resin composition was prepared.

(Evaluation of formability of tube sheet)
A bundle of 12,000 bundled polyimide hollow fiber membranes (length: 100 cm, outer diameter: 500 μm) was placed in a φ100 mm mold as shown in FIG. 2b. The cast resin composition prepared by the above-described method was substantially upright with the front end of the yarn bundle down, and was slowly poured into a mold kept at 70 ° C. The amount of the casting resin composition was controlled so that the thickness was about 90 mm. After the injection, primary curing was performed at 70 ° C. for 12 hours, followed by heating to 142 ° C. and post-curing for 4 hours to form a tube sheet. After curing, the hollow fiber element was removed from the casing and visually observed, and the tube sheet was further divided in half and the state of the central portion was also visually observed.

  As a result, no cracks were observed in the molded tube sheet.

11 Mixed gas inlet 12 Permeate gas outlet 13 Non-permeate gas outlet 14 Hollow fiber membrane 15 Casing 16a, 16b Tube plate 21 Mold 22 Casing 23 Tube plate 24 Hollow fiber membrane

Claims (1)

A yarn bundle comprising a number of hollow fiber membranes having gas separation performance;
A casing having a mixed gas inlet, a permeate gas outlet, and a non-permeate gas outlet, in which the hollow fiber bundle is disposed;
A tube plate for fixing at least one end of the hollow fiber bundle;
A gas separation membrane module comprising:
The tube sheet is
(A) a modified epoxy resin obtained by reacting a phenol novolac-type epoxy compound with (b) a butadiene-acrylonitrile copolymer having a functional group capable of reacting with an epoxy group at the end, and (c) a curing agent and (d ) A casting resin composition containing a curing accelerator is formed by a cured epoxy cured product ,
The (b) butadiene / acrylonitrile copolymer having a functional group capable of reacting with an epoxy group at its end is a carboxyl group-terminated butadiene / acrylonitrile copolymer represented by the following general formula (b):
(C) the curing agent is an acid anhydride,
(D) A gas separation membrane module in which the curing accelerator is an imidazole compound .

(In the formula, m represents the total number of repeating butadiene monomer units, n represents the total number of repeating acrylonitrile monomer units, and when there are two or more structures in [], m and n represent the respective units. Indicates the total number of repetitions, which may be present as a block or randomly.)

Images