JP2006274464A - Sulfonated rayon fiber and method for producing the same, sheet for chemical filter, chemical filter and method for producing the same - Google Patents

Abstract

To solve the problem, a sulfonated rayon fiber having high ion exchange capacity and high fiber strength, a sheet for a chemical filter composed of rayon fiber and having a large ion exchange capacity, and composed of rayon fiber and basic gaseous contamination It is an object of the present invention to provide a chemical filter excellent in substance removal performance and a method for producing the same.
SOLUTION: A rayon fiber containing an aqueous sulfamic acid solution has a heating temperature of 70 to 150 ° C., and the product (t × h) of the heating temperature and the heating time is represented by the following formula (1):
−2.6 m + 200 ≦ t × h ≦ −80 m + 3000 (1)
(In formula (1), m represents the concentration (% by weight) of the aqueous sulfamic acid solution, t represents the heating temperature (° C.), and h represents the heating time (hours).) And the manufacturing method of the sulfonated rayon fiber characterized by having the heating reaction process and the acid treatment process which obtain sulfamic acid group introduction | transduction rayon fiber.
[Selection figure] None

Description

  The present invention relates to a sulfonated rayon fiber having a large ion exchange capacity, a production method thereof, a sheet for chemical filter, and a chemical filter.

  In the fields of semiconductor manufacturing and liquid crystal manufacturing, semiconductors and liquid crystals are manufactured in a clean room, and it is required to reduce basic gaseous pollutants in the clean room. The basic gaseous pollutant includes, for example, ammonia. In the exposure process at the time of manufacturing a semiconductor, ammonia causes deterioration of resolution at the time of exposure and fogging of the wafer surface. It is necessary to reduce the amount of ammonia. A chemical filter is then installed to remove the basic gaseous pollutant. At this time, the chemical filter is usually installed so as to be perpendicular to the direction of air to be treated.

  The chemical filter has a higher ion exchange capacity per unit area because the larger the ion exchange capacity per unit area or the higher the reaction rate, the better the initial removal performance and the sustainability of the removal performance. Is required. Moreover, since it installs so that it may become perpendicular | vertical with respect to the ventilation direction of to-be-processed air, high intensity | strength is requested | required. In addition, since the shape of the chemical filter differs depending on the application, the chemical filter must be able to be processed into various shapes. That is, an excellent moldability is required for a chemical filter sheet for producing the chemical filter.

  In order to produce a chemical filter or chemical filter sheet that satisfies these requirements, fibers having a high ion exchange capacity and high strength are required.

  As a resin having a large ion exchange capacity and a high reaction rate, for example, a sulfonated polystyrene resin is known.

  In addition, as a resin composition having a large ion exchange capacity, for example, Japanese Patent Application Laid-Open No. 2003-277626 of Patent Document 1 includes (a) an ester bond, an amide bond, an imide bond, a urethane bond, a carbonate bond, and a carbonate bond in the main chain. A thermoplastic resin having one or more types of bonds selected from ketone bonds, and (b) an aromatic thermoplastic resin having an ion exchange group introduced into the side chain and a main chain containing a linked structure via an aromatic ring A thermoplastic resin composition is disclosed.

JP 2003-277626 A (Claim 1)

  However, the sulfonated polystyrene resin is very brittle and has low strength when formed into fibers. Therefore, conventionally, reinforcing fibers have been put inside the fibers, or high strength resins and polymer alloys are used to increase the strength. However, there was still a problem that the strength of the fiber was low. Further, since the reinforcing fibers must be mixed, there is a problem that the ion exchange capacity per unit weight is lowered. Furthermore, since a complicated manufacturing method is required, there is a problem that the manufacturing cost is high.

  Further, if the electrical conductivity of the fiber used in the chemical filter is low, the fiber is easily charged, so that the fiber attracts particles such as metal powder in the manufacturing process, causing particle contamination of the chemical filter. Therefore, it is preferable that the electrical conductivity of the fiber is high. Moreover, since the ionic gaseous pollutants in the air to be treated are easily dissolved in water, it is preferable that the fibers constituting the chemical filter contain moisture in that the adsorption efficiency of the ionic gaseous pollutants is increased. . Therefore, it is preferable that the fibers used in the chemical filter have high ion exchange capacity, high conductivity, and easy water content during use.

Rayon fiber has a relatively high electrical conductivity of about 1 × 10 ⁷ Ω · g / cm ² and a molecular structure that easily contains moisture, so that it easily contains water in the air. Moreover, since the main chain is a cellulose, rayon fiber has high intensity | strength compared with a polystyrene resin. Therefore, if many sulfone groups can be introduced into the rayon fiber, a chemical filter with high performance can be manufactured.

  However, when the rayon fiber is sulfonated by the conventional sulfonating method, the rayon fiber is decomposed or deteriorated during the sulfonating, so that there is a problem that the sulfonated rayon fiber cannot be obtained.

  Accordingly, an object of the present invention is to provide a sulfonated rayon fiber having a high ion exchange capacity and high fiber strength, and a method for producing the same. Also, a chemical filter sheet composed of rayon fibers, having a high ion exchange capacity, high strength and excellent moldability, and a chemical filter composed of rayon fibers and excellent basic gas pollutant removal performance And a manufacturing method thereof.

  As a result of intensive studies to solve the above-described problems in the prior art, the present inventors have obtained a sulfamic acid aqueous solution-containing rayon fiber in which a specific concentration of a sulfamic acid aqueous solution is mixed with a rayon fiber at a specific ratio. As a result of heating reaction under specific conditions, the present inventors have found that a large amount of sulfamic acid groups are introduced on the surface of the thermoplastic resin without being decomposed, thereby completing the present invention.

  That is, the present invention (1) provides a sulfonated rayon fiber having an ion exchange capacity of 1 meq / g or more.

Further, in the present invention (2), the rayon fiber (a) has a sulfamic acid aqueous solution (b) having a sulfamic acid concentration of 1 to 40% by weight in a weight ratio of 1 to 20 ((b) / (a)). In the sulfamic acid aqueous solution-containing rayon fiber contained in, the heating temperature is 70 to 150 ° C., and the product (t × h) of the heating temperature and the heating time is represented by the following formula (1):
−2.6 m + 200 ≦ t × h ≦ −80 m + 3000 (1)
(In formula (1), m represents the concentration (wt%) of the aqueous sulfamic acid solution, t represents the heating temperature (° C.), and h represents the heating time (hour).)
To obtain a sulfamic acid group-introduced rayon fiber, a heating reaction step, and reacting the sulfamic acid group-introduced rayon fiber with an inorganic acid to obtain a sulfonated rayon fiber (A And a process for producing a sulfonated rayon fiber.

  Moreover, this invention (3) provides the sheet | seat for sulfonated chemical filters manufactured using the sulfonated rayon fiber of the said this invention (1).

  Moreover, this invention (4) provides the chemical filter obtained by shape | molding the sheet | seat for sulfonated chemical filters of the said invention (3).

In the present invention (5), the rayon fiber (a) has a sulfamic acid aqueous solution (b) having a sulfamic acid concentration of 1 to 40% by weight in a weight ratio of 1 to 20 ((b) / (a)). In the sulfamic acid aqueous solution-containing rayon fiber contained in, the heating temperature is 70 to 150 ° C., and the product (t × h) of the heating temperature and the heating time is represented by the following formula (1):
−2.6 m + 200 ≦ t × h ≦ −80 m + 3000 (1)
(In formula (1), m represents the concentration (wt%) of the aqueous sulfamic acid solution, t represents the heating temperature (° C.), and h represents the heating time (hour).)
To obtain a sulfamic acid group-introduced rayon fiber, a heating reaction step, and reacting the sulfamic acid group-introduced rayon fiber with an inorganic acid to obtain a sulfonated rayon fiber (A ), And forming the sulfonated rayon fiber to obtain a sulfonated chemical filter sheet, a chemical filter sheet manufacturing step (A), and forming the sulfonated chemical filter sheet to obtain a chemical filter. The manufacturing method of the chemical filter which has (A) is provided.

Further, in the present invention (6), the rayon fiber (a) has a sulfamic acid aqueous solution (b) having a sulfamic acid concentration of 1 to 40% by weight in a weight ratio of 1 to 20 ((b) / (a)). In the sulfamic acid aqueous solution-containing rayon fiber contained in, the heating temperature is 70 to 150 ° C., and the product (t × h) of the heating temperature and the heating time is represented by the following formula (1):
−2.6 m + 200 ≦ t × h ≦ −80 m + 3000 (1)
(In formula (1), m represents the concentration (wt%) of the aqueous sulfamic acid solution, t represents the heating temperature (° C.), and h represents the heating time (hour).)
Heat reaction step of obtaining sulfamic acid-introduced rayon fibers by heating under conditions that fall within the above range, and forming a sulfamic acid group-introduced rayon fiber to obtain a sulfamic acid group-introduced chemical filter sheet. A production step (B), molding the sulfamic acid group-introduced chemical filter sheet to obtain a chemical filter precursor, a molding step (B), and reacting the chemical filter precursor with an inorganic acid to obtain a chemical filter. The manufacturing method of the chemical filter which has an acid treatment process (B) is provided.

  The sulfonated rayon fiber of the present invention has a high ion exchange capacity and high fiber strength. Moreover, since the manufacturing method of the sulfonated rayon fiber of this invention can introduce | transduce many sulfone groups into a rayon fiber, it can manufacture the sulfonated rayon fiber with many ion exchange capacities. In addition, the chemical filter sheet of the present invention has a large ion exchange capacity, high strength, and excellent moldability, and the chemical filter of the present invention is excellent in the performance of removing basic gaseous contaminants. Further, the method for producing a chemical filter of the present invention includes a chemical filter in which many sulfone groups are introduced into the rayon fibers constituting the chemical filter, that is, a chemical filter constituted by rayon fibers and having a large ion exchange capacity. Can be manufactured.

  The rayon fiber (a) has the following formula (2):

As shown in Fig. 1, the cellulose is a fiber having a main chain, and the sulfonated rayon fiber of the present invention is a fiber in which a sulfonate group is introduced into cellulose. More specifically, cellulose is a polysaccharide in which β-D-glucopyranose is bonded to β-1,4-glycosides and is represented by (C ₆ H ₁₀ O ₅ ) _n . The basic unit C ₆ H ₁₀ O ₅ is represented by the following formula (3):

(Hereinafter also referred to as a basic structure (d)). The basic structure (d) has a hydroxyl group (—OH) at the 2-position, 3-position and 6-position carbon, and the sulfonated rayon fiber of the present invention has a 2-position, 3-position. And part of the hydroxyl group bonded to the 6-position carbon is sulfonated. Following formula (4):

Shows a structure in which the hydroxyl group of the 2-position carbon of the basic structure (d) is sulfonated, and as shown in the formula (4), the 2-position carbon has —OSO ₃ H A group is attached.

The rayon fiber has a number of hydroxyl groups in the fiber. In the sulfonated rayon fiber of the present invention, the sulfonated positions are the carbons at the 2-position, 3-position and 6-position in the fiber. Any of the hydroxyl groups bonded to may be used. In addition, the number of —OSO ₃ H groups introduced into each basic structure (d) constituting the sulfonated rayon fiber of the present invention may be 0 to 3.

  In a conventional sulfonation method, for example, a method using an aqueous sulfuric acid solution, carbon atoms in the fiber are sulfonated, and thus the resulting sulfonated fiber is represented by the following formula (5):

As shown in FIG. 2, the fiber is a fiber in which a sulfone group (—SO ₃ H) is introduced into a carbon atom in the fiber. On the other hand, as shown in the formula (4), the sulfonated rayon fiber of the present invention has a structure in which a hydroxyl group bonded to a carbon atom in the fiber is sulfonated, that is, —OSO ₃ is added to the carbon atom in the fiber. It has a structure in which an H group is bonded. Sulfonated rayon fiber of the present invention, confirmation of having -OSO 3 _H group can be carried out by IR analysis.

  The sulfonated rayon fiber of the present invention has a large number of sulfone groups on the surface and hardly contains any sulfone groups inside. That is, in the sulfonated rayon fiber, many sulfone groups are introduced on the surface of the rayon fiber. In addition, it can be confirmed by energy dispersive X-ray spectroscopy (EDX) of the cross section of the fiber that the sulfonated rayon fiber has almost no sulfone group inside. it can.

  The ion exchange capacity of the sulfonated rayon fiber is not less than 1 meq / g, preferably 1.5 to 5 meq / g, particularly preferably 2 to 4 meq / g.

  The average fiber diameter of the sulfonated rayon fiber is 0.01 to 100 μm, preferably 0.1 to 50 μm, particularly preferably 0.5 to 20 μm. If the average fiber diameter is less than 0.01 μm, the tensile strength tends to be low, and if it exceeds 100 μm, the surface area is small, so that the ion exchange capacity per unit weight tends to be small.

  Since the sulfonated rayon fiber has almost no sulfonate group inside the fiber, the strength of the fiber is high, and the sheet for chemical filter produced using the sulfonated rayon fiber is excellent in molding processability. .

  In the method for producing sulfonated rayon fiber of the present invention, an aqueous sulfamic acid solution (b) having a sulfamic acid concentration of 1 to 40% by weight is added to the rayon fiber (a) in a weight ratio of 1 to 20 (the rayon fiber (a The sulfamic acid aqueous solution-containing rayon fiber contained in the weight ratio ((b) / (a))) of the aqueous sulfamic acid solution (b) to) is heated to obtain a sulfamic acid group-introduced rayon fiber. And an acid treatment step (A) in which the sulfamic acid group-introduced rayon fiber is reacted with an inorganic acid to obtain a sulfonated rayon fiber.

Examples of the method for obtaining the sulfamic acid aqueous solution-containing rayon fiber include the following methods.
(I) First, the mixing ratio of the sulfamic acid aqueous solution (b) to the rayon fiber is larger than the content ratio of the aqueous sulfamic acid solution (b) in the aqueous sulfamic acid-containing rayon fiber, that is, the The aqueous sulfamic acid solution (b) is mixed in excess of the amount necessary for preparing the aqueous sulfamic acid-containing rayon fiber, and then the aqueous sulfamic acid solution is obtained from the mixture of the rayon fiber and the aqueous sulfamic acid solution (b). (B) is removed, and the rayon fiber (a) contains the aqueous sulfamic acid solution (b) in a weight ratio of 1 to 20 ((b) / (a)). How to get fiber.
(Ii) First, the mixing ratio of the sulfamic acid aqueous solution (b) to the rayon fiber is larger than the content ratio of the aqueous sulfamic acid solution (b) in the aqueous sulfamic acid-containing rayon fiber, that is, the The aqueous sulfamic acid solution (b) is mixed in excess of the amount necessary for preparing the sulfamic acid aqueous solution-containing rayon fiber, and then the mixture of the rayon fiber and the aqueous sulfamic acid solution (b) is added for 5 minutes or more. Preferably, a sulfamic acid adsorption step of maintaining at 5 to 60 ° C. for 5 minutes to 24 hours is performed, and then the aqueous sulfamic acid solution (b) is removed from the mixture of the rayon fiber and the aqueous sulfamic acid solution (b), The sulfaic acid containing the rayon fiber (a) and the aqueous sulfamic acid solution (b) in a weight ratio of 1 to 20 ((b) / (a)). Method of obtaining phosphate solution containing rayon fibers.

  The average fiber diameter of the rayon fiber is 0.01 to 100 μm, preferably 0.1 to 50 μm, particularly preferably 0.5 to 20 μm.

  Moreover, it is preferable that the rayon fiber is an opened fiber because the ion exchange capacity per unit weight of the sulfonated rayon fiber is increased. The opened rayon fiber can be obtained by stirring the rayon fiber in water or the aqueous sulfamic acid solution (b) using a stirrer or the like to untangle the rayon fibers. At this time, the rayon fiber is cut to a length of 1 to 20 mm, preferably 2 to 10 mm before stirring and stirring in water or the aqueous sulfamic acid solution (b) using a stirrer or the like. This is particularly preferable because the ion exchange capacity per unit weight of the sulfonated rayon fiber is increased. In addition, opening refers to releasing the entanglement between fibers.

  The sulfamic acid concentration of the aqueous sulfamic acid solution (b) is 1 to 40% by weight, preferably 2 to 30% by weight, particularly preferably 5 to 20% by weight. If the sulfamic acid concentration is less than 1% by weight, it is difficult to be converted to a sulfamic acid group, and if it exceeds 40% by weight, the rayon fiber is easily decomposed in the heating reaction step.

  In the method of (i) or (ii), when mixing the rayon fiber and the aqueous sulfamic acid solution (b), the mixing ratio of the rayon fiber and the aqueous sulfamic acid solution (b) is not particularly limited, A weight ratio (sulfamic acid aqueous solution (b) / rayon fiber (a)) of 2 to 200 is that the aqueous sulfamic acid solution (b) is easily dispersed uniformly in the sulfamic acid aqueous solution-containing rayon fiber. 5 to 100 is preferable and particularly preferable.

  The method of mixing the aqueous sulfamic acid solution (b) with the rayon fiber is not particularly limited. For example, a method of adding the rayon fiber little by little while stirring the aqueous sulfamic acid solution (b), Examples thereof include a method of impregnating the rayon fiber that has been added with the aqueous sulfamic acid solution (b).

  The method (ii) includes the sulfamic acid adsorption step. In the sulfamic acid adsorption step, the mixture of the rayon fiber and the aqueous sulfamic acid solution (b) is 5 to 60 ° C., preferably 10 to 50 ° C., particularly preferably 20 to 40 ° C. for 5 minutes or more, preferably 5 It is maintained for min-24 hr, particularly preferably 10 min-12 hr, more particularly preferably 30 min-4 hr. When the holding time and holding temperature during the holding are in the above-mentioned range, it is easily converted into a sulfamic acid group in the heating reaction step described later. When the holding time is longer than 24 hours or the holding temperature is higher than 60 ° C., the rayon fiber is likely to be deteriorated.

  By performing the sulfamic acid adsorption step, sulfamic acid is adsorbed on the surface of the rayon fiber, so that it is easily converted to a sulfamic acid group in the heating reaction step. Therefore, it is preferable to have the sulfamic acid adsorption step in that a sulfonated rayon fiber having a high ion exchange capacity can be obtained.

  The mixture of the rayon fiber and the aqueous sulfamic acid solution (b) may be maintained by standing the mixture, or while stirring or shaking the reaction vessel containing the mixture. There is no particular limitation. Among these, it is preferable to carry out stirring because the contact efficiency of the aqueous sulfamic acid solution (b) is increased and sulfamic acid is easily adsorbed.

  In the method (i), after mixing the rayon fiber and the aqueous sulfamic acid solution (b), in the method (ii), after the sulfamic acid adsorption step, the rayon fiber and the aqueous sulfamic acid solution (b) The aqueous sulfamic acid solution (b) is removed from the mixture, and the aqueous sulfamic acid solution (b) is added to the rayon fiber at a weight ratio ((b) / (a)) of 1 to 20, preferably 2 to 15. The rayon fiber containing the sulfamic acid aqueous solution is particularly preferably contained in a weight ratio of 3 to 10, in a weight ratio of 3 to 10. When the content of the aqueous sulfamic acid solution (b) is less than the range of the weight ratio, it is difficult to convert to a sulfamic acid group, and when the content of the aqueous sulfamic acid solution (b) is greater than the range of the weight ratio, Degradation of the rayon fiber occurs. The removal method is not particularly limited, and a known method such as suction filtration or centrifugation can be employed.

And the heating temperature of this rayon fiber containing sulfamic acid aqueous solution is 70-150 degreeC, and the product (txh) of a heating temperature and a heating time is following formula (1):
−2.6 m + 200 ≦ t × h ≦ −80 m + 3000 (1)
(In formula (1), m represents the concentration (% by weight) of the aqueous sulfamic acid solution (b), t represents the heating temperature (° C.), and h represents the heating time (hours).)
The sulfamic acid group is introduced into the rayon fiber to obtain a sulfamic acid group-introduced rayon fiber.

  The heating temperature (t) is 70 to 150 ° C, preferably 80 to 130 ° C. The product of the heating temperature and the heating time (t × h) is “(−2.6 m + 200) or more and (−80 m + 3000) or less”, that is, “−2.6 m + 200 ≦ t × h ≦ −80 m + 3000” (formula ( 1)), preferably “(−2.6 m + 250) or more and (−80 m + 2500) or less”, that is, “−2.6 m + 250 ≦ t × h ≦ −80 m + 2500”. When the heating temperature (t) is less than 70 ° C, sulfamic acid groups are hardly introduced, and when it exceeds 150 ° C, the rayon fiber is decomposed. Further, when the product (t × h) of the heating temperature and the heating time is less than the range of the formula (1), it is difficult to introduce a sulfamic acid group, and when the product exceeds the range of the formula (1), the rayon fiber Decomposition occurs.

  For example, when the concentration (m) of the aqueous sulfamic acid solution (b) is 10% by weight, the product of the heating temperature and the heating time (t × h) is “−2.6 × 10 + 200 ≦ t × h ≦ −80. × 10 + 3000 ”, that is,“ 174 ≦ t × h ≦ 2200 ”, so if the heating temperature is 100 ° C., the heating time must be 1.74 hours or more and 22 hours or less. . For example, when the concentration (m) of the aqueous sulfamic acid solution (b) is 15% by weight, the product of the heating temperature and the heating time (t × h) is “−2.6 × 15 + 200 ≦ t × h ≦ −80 × 15 + 3000 ”, that is,“ 161 ≦ t × h ≦ 1800 ”, so if the heating temperature is 80 ° C., the heating temperature is 2.01 hours or more and 22.5 hours or less. And shall be.

  The reaction for obtaining the sulfamic acid group-introduced rayon fiber from the rayon fiber in the heating reaction step is shown in the following reaction formula (6).

As shown in the reaction formula (6), the reaction between the rayon fiber (a) and the sulfamic acid (b) is a dehydration condensation reaction between the hydroxyl group and the sulfamic acid in the rayon fiber (a), and the rayon fiber (a hydroxyl group) (-OH) is sulfamic acid group ^_(-O-SO 3 - a reaction that is converted to a · _NH ^{4 +).} A sulfamic acid group-introduced rayon fiber (g) is produced by the reaction between the rayon fiber (a) and the sulfamic acid (b). In the reaction formula (6), the rayon fiber (a) is represented by its basic structure.

  Since the rayon fiber (a) has a number of hydroxyl groups in the fiber, a portion of the hydroxyl group in the rayon fiber (a) is reacted in the reaction of the rayon fiber (a) with sulfamic acid (b). The group is converted to a sulfamic acid group.

  Next, an acid treatment step (A) is performed in which the sulfamic acid group-introduced rayon fiber (g) is reacted with an inorganic acid to obtain a sulfonated rayon fiber.

  The reaction to obtain the sulfonated rayon fiber by reacting the sulfamic acid group-introduced rayon fiber and the inorganic acid in the acid treatment step (A) is shown in the following reaction formula (7).

As shown in Scheme (7), by the sulfamate group introducing rayon fibers (g) an inorganic acid is reacted, the sulphamic acid groups introduced rayon fibers (g) in the sulfamic acid group (-OSO ₃ ^- · NH ₄ ⁺⁾ is, -OSO ₃ H group (-OSO ₃ ^- is converted to · ^{H +).} The sulfonated rayon fiber (h) is obtained by the reaction of the sulfamic acid group-introduced rayon fiber (g) with an inorganic acid.

  The inorganic acid according to the acid treatment step (A) is not particularly limited, and examples thereof include sulfuric acid, hydrochloric acid, nitric acid and the like. Of these, sulfuric acid is preferred because of its high reaction efficiency.

  The amount of the inorganic acid according to the acid treatment step (A) may be equal to or greater than the number of moles of the sulfamic acid group in the sulfamic acid group-introduced rayon fiber (g). It is preferable that the amount of the inorganic acid is 20 mmol or more with respect to 1 g of rayon fiber (g) from the viewpoint of increasing reaction efficiency, and particularly preferably 50 to 200 mmol.

  The concentration of the inorganic acid in the acid treatment step (A) is 0.1 to 10% by weight, preferably 0.5 to 5% by weight. When the concentration of the inorganic acid is less than 0.1% by weight, the sulfamic acid group is hardly converted, and when it exceeds 10% by weight, the sulfonated rayon fiber is liable to deteriorate.

  In the acid treatment step (A), the reaction temperature for reacting the sulfamic acid group-introduced rayon fiber (g) with the inorganic acid is 5 to 80 ° C., preferably 10 to 40 ° C., and the reaction time. Is 1 minute to 1 hour, preferably 5 minutes to 0.5 hour. When the reaction temperature or the reaction time is less than the above range, the reaction between the sulfamic acid group-introduced rayon fiber (g) and the inorganic acid is difficult to occur, and when it exceeds the above range, the sulfonated rayon fiber is deteriorated. It becomes easy to do. The reaction between the sulfamic acid group-introduced rayon fiber (g) and the inorganic acid is carried out by immersing the sulfamic acid group-introduced rayon fiber (g) in the inorganic acid and bringing them into contact with each other.

  By performing the acid treatment step (A), the sulfonated rayon fiber can be obtained. After the acid treatment step (A), the inorganic acid remaining in the sulfonated rayon fiber is removed. Can be washed with water.

As described above, since the heating reaction step is performed under the specific conditions described above, a large amount of sulfamic acid groups can be introduced to the surface of the rayon fiber while keeping the decomposition of the rayon fiber low. According to the method for producing a sulfonated rayon fiber of the invention, a sulfonated rayon fiber having a high ion exchange capacity and a high fiber strength can be obtained. Specifically, in the method for producing a sulfonated rayon fiber of the present invention, the tensile strength (Y) of the rayon fiber after sulfonated is reduced with respect to the tensile strength (X) of the rayon fiber (a) before sulfonated as a raw material. The rate (Z) (value obtained by the following formula (8)) is 50% or less, preferably 40% or less, particularly preferably 30% or less. Sulfone is obtained by a conventional sulfonation method using rayon fiber as a raw material. The rate of decrease (Z) is small as compared to the case where the conversion is performed. In addition, since many of the sulfonated rayon fibers obtained by the conventional sulfonation method are very brittle fibers, they cannot be processed into a chemical filter sheet, and the reduction rate (Z) is 50% or less. Never become.
Z (%) = (X−Y) × 100 / X (8)
Moreover, the ion exchange capacity of the rayon fiber after sulfonation is 1 meq / g or more. That is, in the manufacturing method of the sulfonated rayon fiber of this invention, the sulfonated rayon fiber which has high ion exchange capacity can be manufactured, suppressing the fall rate of tensile strength low.

  The sulfonated rayon fiber obtained by the method for producing the sulfonated rayon fiber of the present invention has the same physical properties as the sulfonated rayon fiber of the present invention. Therefore, the method for producing the sulfonated rayon fiber of the present invention is as follows. It is suitably used for the production of the sulfonated rayon fiber of the present invention. Further, according to the method for producing a sulfonated rayon fiber of the present invention, a sulfonated rayon fiber having a high strength can be obtained without performing a technique such as inserting a reinforcing fiber inside the fiber or polymer alloying with a high-strength resin. Since rayon fibers can be obtained, rayon fibers having a large ion exchange capacity can be produced at low cost.

  The sheet | seat for sulfonated chemical filters of this invention is a woven fabric or a nonwoven fabric manufactured using the sulfonated rayon fiber of this invention. The method for producing the woven fabric or the nonwoven fabric is not particularly limited, and can be performed by a conventional method. In addition, the sulfonated rayon fiber can be used alone to make the woven fabric or the non-woven fabric. If necessary, the low-density polyethylene resin fiber, the high-density polyethylene resin fiber, and the organic binder may be added to the woven fabric. Alternatively, the woven fabric or the nonwoven fabric can be mixed by mixing the nonwoven fabric. That is, the sulfonated chemical filter sheet of the present invention is a chemical filter sheet in which sulfone groups are introduced into the rayon fibers constituting the chemical filter sheet.

The ion exchange capacity per unit area of the sulfonated chemical filter sheet is 0.01 to 16 equivalent / m ² , preferably 0.04 to 4.8 equivalent / m ² , and the sulfonated chemical filter sheet is used. Is usually 0.01 to 5 mm, and the weight per unit area of the sulfonated chemical filter sheet is usually 10 to 1000 g / m ² .

  Since the sulfonated chemical filter sheet is produced using the sulfonated rayon fiber of the present invention having a large ion exchange capacity, the ion exchange capacity per unit area is high, and the sulfonated chemical filter has almost no sulfonate groups inside the fiber. Since it is manufactured using the sulfonated rayon fiber of the present invention, it is excellent in moldability.

  The sulfonated chemical filter sheet may be used in the production of an air filter described later, or may be used as a material for wrapping the filter.

  The chemical filter of the present invention is obtained by molding the sulfonated chemical filter sheet of the present invention.

  Examples of the chemical filter include a chemical filter having a corrugated honeycomb structure, a pleated structure chemical filter, and the like. The chemical filter having the corrugated honeycomb structure is obtained by corrugating the sulfonated chemical filter sheet, and then alternately corrugating the sulfonated chemical filter sheet and the flat sulfonated chemical filter sheet. The pleated chemical filter is obtained by laminating the sulfonated chemical filter sheet, the pleated sulfonated chemical filter sheet, and the flat sulfonated chemical filter sheet. Can be stacked alternately.

  Since the chemical filter is a chemical filter obtained by molding the sheet for a sulfonated chemical filter of the present invention having a large ion exchange capacity per unit area, the performance of removing basic gaseous pollutants is high.

  The manufacturing method of the chemical filter of the first aspect of the present invention (hereinafter also referred to as the manufacturing method of the first aspect of the present invention) includes a heating reaction step, an acid treatment step (A), and a chemical filter sheet. It has a manufacturing process (A) and a molding process (A).

  The heating reaction step and the acid treatment step (A) according to the production method of the first aspect of the present invention are the same as the heating reaction step and the acid treatment step (A) according to the method for producing the sulfonated rayon fiber of the present invention. is there.

  In the chemical filter sheet manufacturing step (A) according to the manufacturing method of the first aspect of the present invention, the sulfonated rayon fiber obtained by performing the heating reaction step and the acid treatment step (A) is molded, and the sulfone This is a process for producing a woven or non-woven fabric of rayon fibers, that is, a sheet for a sulfonated chemical filter. The method for producing the woven fabric or the nonwoven fabric is not particularly limited, and can be performed by a conventional method. In addition, the sulfonated rayon fiber can be used alone to make the woven fabric or the non-woven fabric. If necessary, the low-density polyethylene resin fiber, the high-density polyethylene resin fiber, and the organic binder may be added to the woven fabric. Alternatively, the woven fabric or the nonwoven fabric can be mixed by mixing the nonwoven fabric.

  The sulfonated air filter sheet obtained by the air filter sheet manufacturing step (A) is the same as the sulfonated air filter sheet of the present invention.

  The forming step (A) according to the manufacturing method of the first aspect of the present invention is a step of forming a chemical filter by forming the sulfonated air filter sheet obtained by the air filter sheet manufacturing step (A). It is.

  In the forming step (A), the sulfonated air filter sheet is formed into, for example, a chemical filter having a corrugated honeycomb structure, a pleated structure chemical filter, or the like.

  The manufacturing method of the chemical filter of the second aspect of the present invention (hereinafter also referred to as the manufacturing method of the second aspect of the present invention) includes a heating reaction step, a chemical filter sheet manufacturing step (B), and molding. It has a process (B) and an acid treatment process (B).

  The heating reaction step according to the production method of the second aspect of the present invention is the same as the heating reaction step according to the method for producing the sulfonated rayon fiber of the present invention.

  In the chemical filter sheet manufacturing step (B) according to the manufacturing method of the second aspect of the present invention, the sulfamic acid group-introduced rayon fiber obtained in the heating reaction step is molded to manufacture a sulfamic acid group-introduced chemical filter sheet. It is a process to do.

  In the chemical filter sheet manufacturing step (B), the formed fiber is the sulfonated rayon fiber in the chemical filter sheet manufacturing step (A), whereas the chemical filter sheet manufacturing step (B) In the chemical filter sheet manufacturing step (A), the resulting sulfamic acid group-introduced rayon fiber is the sulfonated chemical filter sheet. The step (B) is the same as the chemical filter sheet manufacturing step (A) except that the sulfamic acid group-introduced chemical filter sheet is used.

  The sulfamic acid group-introduced chemical filter sheet is a chemical filter sheet in which sulfamic acid groups are introduced into rayon fibers constituting the chemical filter sheet.

  In the molding step (B) according to the production method of the second aspect of the present invention, the chemical filter precursor is obtained by molding the sulfamic acid group-introduced chemical filter sheet obtained by the chemical filter sheet production step (B). It is the process of obtaining.

  In the molding step (B), the chemical filter sheet to be molded is the sulfonated chemical filter sheet in the molding step (A), whereas in the molding step (B), the sulfamic acid group is formed. Except for being a chemical filter sheet in the molding step (A), the obtained chemical filter sheet is the chemical filter in the molding step (A), whereas the chemical filter precursor is obtained in the molding step (B). The same as in the forming step (A). That is, in the forming step (B), the sulfamic acid group-introduced chemical filter sheet is formed into a chemical filter structure.

  In the chemical filter precursor, sulfamic acid groups are introduced into the rayon fibers constituting the chemical filter precursor.

  The acid treatment step (B) according to the production method of the second aspect of the present invention is a step of obtaining a chemical filter by reacting the chemical filter precursor obtained in the molding step (B) with an inorganic acid.

  In the acid treatment step (B), what is reacted with the acid is the rayon fiber having sulfamic acid groups introduced in the acid treatment step (A), whereas in the acid treatment step (B), the chemical filter is used. In the acid treatment step (A), what is obtained is the sulfonated rayon fiber, whereas in the acid treatment step (B), the chemical filter is used except that it is the chemical filter. The same as in the acid treatment step (A).

By performing the acid treatment step (B), sulfamic acid groups (—O—SO ₃ ^— · NH ₄ ⁺ ) in the chemical filter precursor are converted to —OSO ₃ H groups (—O—SO ₃ ^—. H ⁺ ).

  Thus, according to the manufacturing method of the first aspect of the present invention or the manufacturing method of the second aspect of the present invention, a sulfone group is introduced into the rayon fibers that are formed of rayon fibers and that constitute the chemical filter. The chemical filter can be manufactured.

  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.

Example 1
(Production of sulfonated rayon fiber)
5 g of 1.7 dtex rayon fiber (tensile strength: 2.3 CN / dtex) was placed in 2 L of ion-exchanged water and stirred using a stirrer to open the fiber. Then, it filtered using the aspirator. This operation was repeated twice, and further washed with water and dried at 80 ° C. to obtain a spread fiber. The spread fiber was mixed with 200 g of a sulfamic acid aqueous solution having a sulfamic acid concentration of 5%, and kept at 25 ° C. for 1 hour with stirring. After holding for 1 hour, the sulfamic acid aqueous solution was removed by suction using an aspirator so that the weight ratio of the spread fiber to the sulfamic acid aqueous solution was 1: 4 to obtain a sulfamic acid aqueous solution-containing fiber. The sulfamic acid aqueous solution-containing fiber was put in a thermostat and heated and reacted at 80 ° C. for 4 hours. At this time, the product of the heating temperature and the heating time is within the range of the formula (1). The fiber obtained by the heating reaction was transferred onto a filter paper, and the aqueous sulfamic acid solution was removed while sucking. Next, the fiber on the filter paper was stirred in 2 L of ion-exchanged water, then transferred to the filter paper, and the water washing operation of removing moisture while sucking was performed twice. Subsequently, the fiber after the water washing operation was added to a 5% sulfuric acid aqueous solution, and acid treatment was performed at 25 ° C. for 30 minutes. The acid-treated fiber was transferred onto a filter paper and the sulfuric acid aqueous solution was removed while sucking. Next, the fiber on the filter paper was stirred in 2 L of ion-exchanged water, then transferred to the filter paper, and the water washing operation of removing moisture while sucking was repeated until the pH of the filtrate reached 4 or higher. . The obtained fiber was dried at 110 ° C. to obtain a sulfonated rayon fiber.

(Measurement of physical properties of sulfonated rayon fiber)
1. Measurement of tensile strength When conducted according to JIS L 1013, the tensile strength of the sulfonated rayon fiber was 1.6 CN / dtex. At this time, the rate of decrease in tensile strength before and after sulfonation was 30% ((2.3-1.6) × 100 / 2.3).
2. Measurement of ion exchange capacity Next, the obtained sulfonated rayon fiber was collected and its dry weight was measured to be 3.044 g. Next, the collected fiber was added to 1100 ml of a 0.1N sodium hydroxide aqueous solution (specific gravity 1.004), and a neutralization reaction was performed for 2 hours with stirring. The aqueous solution after the neutralization reaction was filtered, and 50.00 ml of the obtained filtrate was neutralized with a 0.1N aqueous hydrochloric acid solution (specific gravity 1.005). The amount of aqueous hydrochloric acid required for the neutralization titration was 11.79 ml, and the ion exchange capacity of the sulfonated rayon fiber was calculated to be 2.51 meq / g.

(Manufacture of chemical filters)
A sulfonated rayon fiber was produced in the same manner as described above, and a nonwoven fabric was produced using this. First, 9 g of the sulfonated rayon fiber and 1 g of low density polyethylene fiber (average fiber diameter: 1.5 dtex) were added to 10 L of ion-exchanged water and stirred for 10 minutes with a stirrer. Next, filter paper was laid on a filter having a diameter of 150 mm, and gently filtered while pouring the mixed liquid into the filter to obtain a sheet-like filtrate. This filtrate was dried with a dryer at 100 ° C. and then hot-pressed at 130 ° C. to obtain a sheet-like molded body having a thickness of 0.2 mm. The basis weight (weight per unit area) of the obtained sheet-like material was about 130 g / m ² on average.

(Chemical filter performance evaluation test)
Using the obtained sheet-like material, the ammonia removal rate was measured under the following test conditions. The ammonia removal rate immediately after the start of the test was 98.4%, and the removal rate after 6 hours was 91.2%.
・ Composition of aeration gas: air containing 240 μg / m ^{3 of} ammonia ・ Temperature and humidity of aeration gas: 23 ° C., 50% RH
-Gas to be removed: Ammonia-Ventilation air speed: 0.5 m / s
・ Chemical filter installation direction: Direction perpendicular to the direction of air flow

(Comparative Example 1)
When 5 g of 1.7 dtex rayon fiber used in Example 1 was added to 200 g of 5% sulfuric acid aqueous solution and stirred at 80 ° C. for 1 hour, the fiber deteriorated brown, and when washed with water, the fiber was Ripped finely. Next, when the solution was poured into water, only a blocky resin was obtained, and a fibrous product was not obtained.

(Comparative Example 2)
(Manufacture of sulfonated rayon fiber)
When the sulfamic acid aqueous solution-containing fiber is put into a thermostat and subjected to a heating reaction, the same method as in Example 1 except that the heating reaction is performed at 80 ° C. for 48 hours instead of the heating reaction at 80 ° C. for 1 hour. As a result, only a black powder was obtained, but a fibrous one was not obtained. At this time, the product of the heating temperature and the heating time is out of the range of the formula (1).

Claims (7)

  A sulfonated rayon fiber having an ion exchange capacity of 1 meq / g or more. A sulfamic acid aqueous solution containing a sulfamic acid aqueous solution (b) having a sulfamic acid concentration of 1 to 40% by weight in a rayon fiber (a) at a weight ratio ((b) / (a)) of 1 to 20 The rayon fiber has a heating temperature of 70 to 150 ° C., and the product (t × h) of the heating temperature and the heating time is represented by the following formula (1):
−2.6 m + 200 ≦ t × h ≦ −80 m + 3000 (1)
(In formula (1), m represents the concentration (wt%) of the aqueous sulfamic acid solution, t represents the heating temperature (° C.), and h represents the heating time (hour).)
To obtain a sulfamic acid group-introduced rayon fiber, a heating reaction step, and reacting the sulfamic acid group-introduced rayon fiber with an inorganic acid to obtain a sulfonated rayon fiber (A And a method for producing a sulfonated rayon fiber.   Before the heating reaction step, the rayon fiber is mixed with the aqueous sulfamic acid solution, and then the mixture of the rayon fiber and the aqueous sulfamic acid solution is maintained at 5 to 60 ° C. for 5 minutes or more. The method for producing a sulfonated rayon fiber according to claim 2, comprising:   A sulfonated chemical filter sheet produced using the sulfonated rayon fiber according to claim 1.   A chemical filter obtained by molding the sulfonated chemical filter sheet according to claim 4. A sulfamic acid aqueous solution containing a sulfamic acid aqueous solution (b) having a sulfamic acid concentration of 1 to 40% by weight in a rayon fiber (a) at a weight ratio ((b) / (a)) of 1 to 20 The rayon fiber has a heating temperature of 70 to 150 ° C., and the product (t × h) of the heating temperature and the heating time is represented by the following formula (1):
−2.6 m + 200 ≦ t × h ≦ −80 m + 3000 (1)
(In formula (1), m represents the concentration (wt%) of the aqueous sulfamic acid solution, t represents the heating temperature (° C.), and h represents the heating time (hour).)
To obtain a sulfamic acid group-introduced rayon fiber, a heating reaction step, and reacting the sulfamic acid group-introduced rayon fiber with an inorganic acid to obtain a sulfonated rayon fiber (A ), And forming the sulfonated rayon fiber to obtain a sulfonated chemical filter sheet, a chemical filter sheet manufacturing step (A), and forming the sulfonated chemical filter sheet to obtain a chemical filter. (A) and the manufacturing method of the chemical filter characterized by the above-mentioned. A sulfamic acid aqueous solution containing a sulfamic acid aqueous solution (b) having a sulfamic acid concentration of 1 to 40% by weight in a rayon fiber (a) at a weight ratio ((b) / (a)) of 1 to 20 The rayon fiber has a heating temperature of 70 to 150 ° C., and the product (t × h) of the heating temperature and the heating time is represented by the following formula (1):
−2.6 m + 200 ≦ t × h ≦ −80 m + 3000 (1)
(In formula (1), m represents the concentration (wt%) of the aqueous sulfamic acid solution, t represents the heating temperature (° C.), and h represents the heating time (hour).)
Heat reaction step of obtaining sulfamic acid group-introduced rayon fiber by heating under the conditions in the above range, and molding the sulfamic acid group-introduced rayon fiber to obtain a sulfamic acid group-introduced chemical filter sheet for chemical filter A sheet manufacturing process (B), a sheet for a chemical filter having a sulfamic acid group-introduced chemical filter, and a chemical filter precursor are obtained. A molding process (B), the chemical filter precursor and an inorganic acid are reacted, and a chemical filter is obtained. A method for producing a chemical filter, comprising: an acid treatment step (B).