JPS6143082B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water removal filter formed by compression molding a fiber aggregate containing specific water-swellable fibers into a hollow cylindrical shape, and a method for manufacturing the same. In recent years, highly water-swellable and water-insoluble polymers (hydrogel) are being applied to a wide range of fields such as diapers, sanitary products, soil improvement materials, and soft contact lenses. On the other hand, there is a strong demand to reuse or extend the lifespan of liquids that are not miscible with water, such as organic solvents and lubricating oils, by removing water from them. For example, granular materials of inorganic salts such as silica gel and zeolite are used in some cases for this purpose. However, although it is possible to remove some water with such inorganic salts, their water removal ability is extremely low, and furthermore, such inorganic salts have the inherent defect that they are mixed into purified liquids to some extent, and therefore cannot be used. , its field of use had to be restricted. In addition, some attempts have been made to use fibers such as natural pulp that have some degree of hygroscopicity or water absorption, but these have extremely low water removal ability and are of little practical use. Therefore, the present inventors focused on the instantaneous large water absorption capacity or water retention capacity of the water-swellable polymer (hydrogel), and investigated the possibility of using such hydrogel as a water removal material for liquids. . However, when using hydrogels in particulate form,
Although it has excellent water absorption performance, it has been found that it has the disadvantage that it swells instantaneously and causes clogging, making it necessary to stop water removal treatment in an extremely short period of time. Therefore, in order to improve such clogging, we tried using a hydrogel with a fibrous form.
Although it is possible to extend the water removal treatment time to some extent compared to granular hydrogels, it is still not possible to overcome the problem of clogging due to swelling and settling of the fibers, and the water absorption performance cannot be fully demonstrated. Ta. Therefore, the inventors of the present invention proposed the following patent application:
As proposed in the specification of No. 15786, a single water-swellable fiber having a multiphase structure of a hydrogel outer layer and an AN polymer and/or other polymer inner layer, or a combination of this fiber and other fibers. It has been found that by using a mixed product, water removal treatment can be carried out for a long time without fibers becoming sag, and the water absorbing performance of the hydrogel can be fully demonstrated. Under such circumstances, the present inventors, based on such knowledge, conducted intensive studies to provide a new hollow cylindrical filter as a water removal material for liquids using the above-mentioned specific fibrous hydrogel. It is composed of an outer layer made of a polymer and an inner layer made of an acrylonitrile (AN) polymer and/or other polymer, and in which at least a portion of the carboxyl group is an acid type carboxyl group (-COOH). A fiber aggregate containing latent water-swellable fibers containing ~4.0 mmol/g bond is compression molded into a hollow cylindrical shape, and then neutralized and dried in a non-swollen state to form a support such as a middle cylinder or an adhesive. A hollow cylindrical filter is obtained that is easy to install, replace, and handle without the need for water removal, etc., and the filter can perform water removal treatment for a long time without problems such as fiber settling or clogging. The present invention was achieved by discovering that it is possible to fully utilize the water absorbing performance of . That is, the main object of the present invention is to provide a novel water removal filter having excellent water removal ability and a method for manufacturing the same. The purpose of the present invention is to prevent the water removal agent from being mixed into the purified liquid, which is the case when using granular inorganic salts, etc., and to enable long-term use without causing fiber fatigue or clogging. Another object of the present invention is to provide a water removal filter that is easy to handle such as installation and replacement.Another object of the present invention is that fiber aggregates in various forms can be used as a raw material, and that fiber aggregates of any density can be used. A hollow cylindrical water removal filter,
The object of the present invention is to provide an industrially advantageous manufacturing method that does not require a middle cylinder or an adhesive. Further objects of the present invention will become apparent from the detailed description of the invention provided below. The water removal filter according to the present invention for achieving the above-mentioned object of the present invention is composed of an outer layer made of a hydrophilic crosslinked polymer and an inner layer made of an AN polymer and/or other polymer, Furthermore, the fiber aggregate containing water-swellable fibers containing 0.1 to 4.0 mmol/g of salt-type carboxyl groups (-COOX; X is an alkali metal or ammonium) is compression-molded into a hollow cylindrical shape, Further, such a water removal filter is composed of an outer layer made of a hydrophilic crosslinked polymer and an inner layer made of an AN polymer and/or other polymer, and furthermore, at least a portion of the water removal filter has an acid type carboxyl group (-COOH ) is advantageously obtained by compression molding a fiber aggregate containing potentially water-swellable fibers containing 0.1 to 4.0 mmol/g of bonded carboxyl groups into a hollow cylindrical shape, and then neutralizing and drying in a non-swollen state. can be manufactured. Here, the water-swellable fiber according to the present invention is a hydrogel layer that exhibits water absorption and swelling performance, and an AN-based polymer and/or that shares fiber physical properties such as strength and elongation.
or has a multilayer structure with other polymer layers, and has a salt type carboxyl group (-COOX: X is an alkali metal or ammonium) in the fiber of 0.1 to 4.0 m
mol/g, preferably 0.2 to 3.5 mmol/g, more preferably 0.2 to 2.0 mmol/g, is a general term for fibers containing bonds. If the amount of the salt-type carboxyl group is out of the range recommended for the present invention, it is undesirable in terms of water swelling performance, physical properties, flexibility, etc. of the fiber. Also,
The degree of water swelling of such fibers is preferably within the range of 2 to 300 c.c./g, more preferably 3 to 200 c.c./g. Furthermore, the proportion of the hydrogel layer should be appropriately set in consideration of water swelling performance and fiber physical properties, and it is difficult to define it unambiguously, but it is approximately 55% based on the total volume of the fiber when dry. %
Below, it is more preferably within the range of 5 to 40%. Note that the ammonium constituting the salt-type carboxyl group does not only refer to ammonium ions in which hydrogen ions are trapped in ammonia, but also includes ions in which hydrogen ions are trapped in amines. It goes without saying that such salt-type carboxyl groups do not need to be 100% salt-type, and acid-type carboxyl groups may coexist as long as fibers having a predetermined degree of water swelling can be obtained. The above-mentioned AN-based polymer is a general term for polymers containing 30% by weight or more, preferably 50% or more of AN, and is an AN homopolymer or a polymer containing AN and at least 1% by weight.
copolymers with other ethylenically unsaturated compounds of the species,
Alternatively, graft polymers of AN and other polymers such as starch, polyvinyl alcohol, etc. can be mentioned, but as long as the above AN content is satisfied, AN
It is also possible to use a mixed polymer of this polymer and other polymers such as polyvinyl chloride, polyamide, polyolefin, polystyrene, polyvinyl alcohol, cellulose, etc. Regarding the hydrogel formation method, as long as a hydrogel layer can be introduced into at least a part of the outer layer of the fiber, there are no restrictions and the method can be adopted. A hydrogel layer having the desired water swelling performance can be created by only using a hydrolysis treatment process without using fibers or special spun fibers such as sheath-core composite fibers as a starting material or performing any crosslinking treatment in advance. As an industrially advantageous method for producing the introduced multilayer fiber, for example, the following means can be suitably employed. That is, the method described in JP-A-53-80493, in which AN-based fibers or fiber aggregates containing AN-based fibers are treated with a highly concentrated alkali metal hydroxide aqueous solution of 6.0 mol/1000 g or more; or
Examples include the method described in Japanese Patent Application No. 1983-47974 in which a low-concentration alkali metal hydroxide aqueous solution coexisting with an electrolyte salt such as sodium chloride, mirabilite, or sodium nitrate at a concentration of 0.5 mol/1000 g or more is applied. be able to. In addition, the latent water-swellable fiber containing bonded carboxyl groups, at least a portion of which is an acid-type carboxyl group (-COOH), according to the present invention, is a general term for fibers that can be made into the above-mentioned water-swellable fibers by neutralization treatment. The latent water-swellable fibers can be advantageously prepared by acid-treating the water-swellable fibers at a desired pH to convert a desired amount of salt-type carboxyl groups into acid-type fibers. It is also possible to directly produce fibers into which acid-type carboxyl groups have been introduced by hydrolyzing the fibers with acid. The acid treatment method includes, for example, a method in which water-swellable fibers are immersed in a water bath adjusted to a pH of 5.5 or less, more preferably 5.0 or less. In addition, by using latent water-swellable fibers in which at least 50 mol%, more preferably 75 mol% or more of the total carboxyl groups are acid type carboxyl groups, various processes such as moldability, dehydration, drying, etc. can be improved industrially. This is desirable because it can be carried out with great advantage. Furthermore, the above-mentioned water-swellable fibers or fiber aggregates containing latent water-swellable fibers refer to single water-swellable fibers or latent water-swellable fibers or mixtures of these fibers and other fibers, In addition, the forms of such fiber aggregates include short fibers, long fibers, webs, threads,
Examples include knitted fabrics and nonwoven fabrics. Among these, it is preferable to use short fibers in the form of opened fibers, as this allows the production of a homogeneous compression molded product, and the use of short fibers with crimping ability makes it easier to use water removal filters. This is desirable because it can significantly improve problems such as fiber settling and clogging, which can significantly extend the life of the filter. Other fibers that may be mixed if desired include natural fibers such as cotton and wool; recycled or semi-synthetic fibers such as rayon, kyupra, and acetate; polyvinyl alcohol-based, polyvinyl chloride-based, polyamide-based, polyester-based, and polyacrylonitrile. The mixing ratio of such other fibers depends on the water removal performance required of the water removal filter finally obtained, the degree of water swelling of water swelling fibers, moldability, etc. Although it can be set as appropriate and cannot be defined uniquely, it is generally used at a ratio of 95% by weight or less. In addition, the degree of water swelling of the fiber aggregate constituting the finally obtained water removal filter can be set appropriately depending on the type of liquid to be treated, the moisture content, the viscosity, etc., and it is difficult to define it unambiguously. However, it is generally 1 to 200c.c./g, more preferably 2 to 100c.c./g.
It is desirable to set it within the range of cc/g. Furthermore, the shape and packing density of the final water removal filter cannot be unambiguously defined as they need to be changed depending on the type of liquid to be treated, moisture content, viscosity, etc., but the diameter of the cylinder The ratio of height to height is generally 1:0.5 to 10, and the packing density is approximately 0.1 to 0.6 g/cm ² , more preferably 0.15 to 0.4.
It is desirable that it be within the range of g/cm ³ . Note that the term "hollow cylindrical shape" as used in the present invention not only refers to a so-called hollow cylindrical shape, but also includes shapes such as a hollow truncated cone shape in some cases. Next, a method for forming the hollow cylindrical water removal filter will be described. First, the fiber aggregate containing the latent water-swellable fibers is preferably 100% or less, more preferably 50%.
Dehydrate until the moisture content is below. If such dehydration is insufficient, subsequent drying becomes difficult, which is undesirable, but after filling a fiber aggregate that has not been dehydrated in advance into a molding machine, suction dehydration, etc. is performed until the desired moisture content is reached. It can also be applied. Next, a predetermined amount of the fiber aggregate, preferably dehydrated to 100% or less, is charged into a molding machine equipped with a fluid inlet and an outlet, and compression molded. Note that the packing density and form of the finally obtained water removal filter can be adjusted as desired by adjusting the amount of fibers charged and the compression conditions. The fiber aggregate compression-molded as described above is then neutralized and dried in a non-swelled state while being compressed without being removed from the molding machine. This neutralization process converts the carboxyl groups from acid type to salt type, and the fibers significantly swell upon water absorption, making drying very difficult. Molding alone is insufficient to bond fibers together and fix the shape of the filter.
Neutralize while compressed without removing it from the molding machine.
It is desirable to perform a drying process. Further, such neutralization and drying treatments can be employed without any limitations as long as they can be carried out in a non-swelling state. Ammonia, Examples include a method of neutralizing by contacting with a gas such as a lower amine. Note that water-miscible and non-swelling solvents include methanol,
Examples include lower alcohols such as ethanol and isopropanol, acetone, methyl ethyl ketone, dioxane, dimethyl sulfoxide, and dimethyl formamide, but it is preferable to use a solvent with a low boiling point because subsequent drying is easy, and it is also non-swelling. As long as the properties are maintained, it is preferable to use these solvents mixed with water (for example, 30% or less) because the neutralization time can be shortened.
Furthermore, it is needless to say that it is not necessary to convert the entire amount of carboxyl groups into the salt form by such neutralization treatment, and it is also possible for acid type carboxyl groups to coexist. The water removal filter obtained in this way not only exhibits outstanding water removal ability, but also eliminates the mixing of water removal material into purified liquids and can be used for long periods of time without fibers becoming sagging or clogging. It has excellent characteristics that have not been seen before in terms of ease of use, ease of handling, such as equipment and removal. In addition, by adopting the manufacturing method according to the present invention, it is possible to form any shape and fill it without using a middle tube, adhesive, etc., and without the difficulties of dehydration, drying, etc. peculiar to water-swellable fibers. has a density,
Moreover, a water removal filter having the above-mentioned excellent properties can be manufactured with industrial advantage. The water removal filter according to the present invention can be suitably used as a water removal material for liquids mixed with water, and with the advent of such a filter, it has become possible to regenerate and reuse liquids that were previously discarded. The significance of this path being opened is great. In addition, such liquids are a general term for liquids that are liquid under water removal treatment conditions and undergo phase separation from water (even if some mutual dissolution occurs, phase separation is sufficient), such as petroleum ether. , pentane, hexane,
Petroleum hydrocarbons such as heptane and petroleum benzine;
Alicyclic saturated hydrocarbons such as cyclohexane and cyclooctane; aliphatic unsaturated hydrocarbons such as 1-octene and cyclohexene; benzene, toluene,
Aromatic hydrocarbons such as xylene and styrene; Halogenated aliphatic hydrocarbons such as tetrachlorethylene, methylene chloride, chloroform, and carbon tetrachloride; Spindle oil, refrigeration oil, dynamo oil, turbine oil, machine oil, cylinder oil , marine engine oil, gear oil, cutting oil, hydraulic oil, compressor oil, and other lubricating oils. In order to further facilitate understanding of the present invention, Examples are described below, but the gist of the present invention is not limited in any way by the description of these Examples.
It should be noted that all percentages and parts described in the Examples are based on weight unless otherwise specified. The degree of water swelling, the amount of carboxyl groups, and the volume ratio of the outer layer of the hydrogel described in the Examples were measured or calculated by the following methods. (1) Water swelling degree (cc/g) Immerse the sample in pure water, keep it at 25℃ for 24 hours, wrap it in a nylon filter cloth (200 mesh), and put it in a centrifugal dehydrator (3G x 30 minutes, except for G. gravitational acceleration)
water between the fibers is removed. The weight of the sample thus prepared is measured (W _1g ). Next, the sample is dried in a vacuum dryer at 80° C. until it reaches a constant weight, and the weight is measured (W _2g ). From the above measurement results, it was calculated using the following formula. Therefore, the actual water swelling degree is a numerical value indicating how many times the weight of the fiber can absorb and retain water. (Water swelling degree) = W ₁ - W ₂ / W ₁ (2) Amount of carboxyl groups (mmol/g) Approximately 1 g of a sufficiently dried sample was accurately weighed (Xg), and 200 ml of water was added to it, and 50 ml of water was added to it. A 1N aqueous hydrochloric acid solution was added while heating to 0.degree. C. to adjust the pH to 2, and then a titration curve was determined using a 0.1N aqueous sodium hydroxide solution according to a conventional method. The amount of caustic soda aqueous solution consumed by carboxyl groups (Ycc) was determined from the titration curve. From the above measurement results, it was calculated using the following formula. Amount of carboxyl group=0.1Y/X Note that when polyvalent cations are included, it is necessary to determine the amount of these cations by a conventional method and correct the above formula. In addition, when determining the amount of acid-type carboxyl groups, use 1N hydrochloric acid aqueous solution in advance to determine the pH value.
2. Titration was carried out without preparation. (3) Volume ratio of the outer layer of the hydrogel (V: %) 20 water-swollen samples were magnified 100 to 1000 times (Z
The average value (l ₁ mm) of the diameter of the core (the layer within the AN polymer and/or other polymers) was calculated using the following formula. V={1-(1000l ₁ /Zl) ² }×100 where l: Diameter of treated AN-based fiber (μ) Example 1 Opened two-component bonded AN-based composite fiber (Japan Exlan Kogyo Co., Ltd. Co., Ltd., single fiber fineness: 6 ^d , fiber length: 5 mm) was uniformly sprayed with 30% caustic soda aqueous solution to make it adhere to 20%, and then placed in an autoclave and heated in saturated steam at 105°C for 5 minutes. . The obtained fiber (1) did not dissolve in water, and when it was squeezed in a water-swollen state, the AN polymer core remained, and only the outer layer of the treated fiber was hydrogelized (hydrogel). Volume ratio of outer layer part V = 5
%) was confirmed. In addition, the fiber (1) is 0.4m
Contains mol/g of -COONa group, 7.0cc/g
It had a degree of water swelling of . Disperse this fiber (1) in water and adjust the pH of the water with nitric acid.
After acid treatment at a pH of 3.5, it was dehydrated using a centrifugal dehydrator until the moisture content reached 20%. Note that 90 mol% of the carboxyl groups in this fiber were converted to acid form. The fibers obtained in this way were placed in a molding machine with a packing density of 0.18 g/ ^cm3 , an inner diameter of 32 mm, and an outer diameter of 180 mm.
mm, height 150 mm, and then neutralized by introducing methanol/water (=80/20) mixed solvent containing 0.1% caustic soda into the molding machine. /20) Washed with a mixed solvent and then dried by introducing hot air at 60°C. The filter () prepared in this way was installed in a water remover, and turbine oil (white cloudy state) mixed with 0.3% water was supplied into the water remover at a rate of 1000 ml/min. A water removal treatment operation was carried out for 10 hours in which the treated oil was passed from the outer surface of the filter toward the inner surface to take out the refined oil. During this period of operation, no pressure increase due to clogging occurred, and the operating conditions were good, and the refined oil was clear, confirming that water removal was complete. In addition, when the filter was observed after use, no fibers were found to be sagging or deformed at all. On the other hand, water-swellable fibers (-
COONa group: 8.7 mmol/g, water swelling degree: 334 c.c./g)
However, it was extremely sticky and extremely brittle.
It could not be molded into a filter. Example 2 The AN-based composite fiber described in Example 1, a single-component AN-based fiber with mechanical crimping (AN = 90%, single fiber fineness: 6 ^d , fiber length: 5 mm, Cn = 9.0 pieces/25 mm, Ci=
10.0%) and the single component without crimp
A 10% caustic soda aqueous solution containing 20% Glauber's salt was uniformly sprayed on each AN fiber to make it adhere to 30%, and then heated in an autoclave with saturated steam at 115°C for 4 minutes to form water-swellable fibers. 2 to 4) were prepared. In addition, all of these fibers have V=5%
After the acid treatment, about 90 mol% of the carboxyl groups in the fibers were converted to the acid type. Three types of water removal filters (~) were prepared from these three types of fibers (2 to 4) according to the formulation described in Example 1.
and these three types of water removal filters (~
) and the water removal filter () produced in Example 1, and the water removal treatment operation was carried out in the same manner as described in Example 1. The results are shown in Table 1.

[Table] From the results in Table 1, the filter of the present invention has excellent water removal ability, and especially the water removal filter (~
It is clearly understood that the performance of ) is particularly excellent. For comparison, the water removal ability of kraft pulp was measured in the same manner as above, and the performance was extremely poor, with the amount of oil that could be treated being 250 and the amount of water removed being 610 g. Example 3 The AN-based composite fiber described in Example 1 (however, 2.5 ^d ×
10 mm) was hydrolyzed (115°C x 7 minutes) according to the recipe described in Example 1 to obtain 1.4 mmol/g of -
Fibers (5, V=12%) containing COONa groups and having a water swelling degree of 43 c.c./g were prepared. This fiber (5) 20% and polyester fiber (3 ^d × 10
After opening and mixing 80% of the fibers (mm), a water removal filter (V; however, the packing density
0.2 g/cm ³ ) was prepared, water removal treatment was performed in the same manner as described in Example 1 (however, the oil supply rate was 500 ml/min), and its water removal ability was measured. The amount of oil that could be treated was 620, It had excellent performance with a water removal amount of 1410g.

Claims (1)

[Scope of Claims] 1. Consisting of an outer layer made of a hydrophilic crosslinked polymer and an inner layer made of an acrylonitrile polymer and/or other polymer, the salt-type carboxyl group (-COOX: X is an alkali metal A water removal filter comprising a fiber assembly containing water-swellable fibers containing 0.1 to 4.0 mmol/g of bonded ammonium or ammonium) and compression molded into a hollow cylindrical shape. 2. The water removal filter according to claim 1, wherein the water swelling degree of the water swelling fiber is 2 to 300 c.c./g. 3 The carboxyl group, which is composed of an outer layer made of a hydrophilic crosslinked polymer and an inner layer made of an acrylonitrile polymer and/or other polymer, and in which at least a portion is an acid type carboxyl group (-COOH), is 0.1 A method for producing a water removal filter, which comprises compression molding a fiber aggregate containing latent water-swollen fibers containing ~4.0 mmol/g bond into a hollow cylindrical shape, and then neutralizing and drying in a non-swollen state. 4. The production method according to claim 3, wherein at least 50 mol% is an acid type carboxyl group. 5. The manufacturing method according to claim 3, which uses a fiber aggregate with a moisture content of 100% or less.