JP2003119617A - Minus ion generating porous acrylic fiber and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a minus ion generating porous acrylic fiber higher comprising a tourmaline composition with improved minus ion releasing function and having an amount of minus ion generated of practical level, useful as a material for various industries. SOLUTION: This minus ion generating porous acrylic fiber comprises the composition obtained by mixing tourmaline having <=3 μm average particle diameter with an electrical insulating substance having <=1 μm average particle diameter. The average particle diameter of the tourmaline is preferably >=0.1 μm and <=1 μm. The total content of the tourmaline and the electrical insulating substance is preferably 2-15 wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous acrylic fiber that generates negative ions and a method for producing the same.

[0002]

2. Description of the Related Art Negative ions are usually 0.5 to 1 nm
It is associated with water in small clusters on the ground and exists on the ground, especially in waterfalls and forests. Also, it can be artificially made with a corona discharge device or the like. However, negative ions are extremely reduced in places where many people gather, and for example, in a room full of cigarettes, the number of negative ions is extremely small, which is about one-thousandth of Takiguchi and about one-hundredth of the forest. on the other hand,
The effects of negative ions on the human body are the cerebral cortex,
It is said that most of them are good for the body, such as decreasing the amount of serotonin in blood, increasing the amount of oxygen and SOD enzyme in blood, and increasing the stress-suppressing hormone (cabbage).

Conventionally, tourmaline, which is also called tourmaline, has been known as a substance that releases negative ions.
Its negative ion emission function was weak and not practical.

Further, there has been proposed an electret fiber in which tourmaline kneaded into an acrylic fiber releases active electrons to give an activating effect to living cells (Japanese Patent Laid-Open No. 10-
183422). However, even if only tourmaline was kneaded into the acrylic fiber, the amount of negative ions generated was naturally small, and the utility as negative ion generating fibers was low.

On the other hand, since tourmaline alone has a small amount of negative ion emission, a negative ion generation temperature control body has been proposed which is used in combination with an exciter such as thorium stone to improve the generation efficiency of negative ions (Japanese Patent Laid-Open No. 2001-2001). -21
165). However, since a radioactive substance is used as the stimulant, and even if the product has a weak radiation dose, a large amount of the radioactive substance is handled at the time of manufacture, which poses a safety problem.

[0006]

In view of the above problems, the present inventors have earnestly studied to increase the negative ion generation efficiency of porous acrylic fibers, and as a result, have found that fine particles of tourmaline and fine particles of an electrically insulating substance are used. The present invention has been completed by finding that by uniformly kneading a composition obtained by mixing and with an acrylic polymer containing cellulose acetate, the amount of negative ions generated becomes extremely large.

That is, the object of the present invention is to produce a negative ion containing a tourmaline composition having an improved negative ion releasing function without using an exciter such as a radioactive substance and having a practical level of negative ion generation amount. It is an object to provide a porous acrylic fiber and a method for producing the same.

[0008]

SUMMARY OF THE INVENTION The gist of the present invention is that tourmaline having an average particle size of 3 μm or less and an average particle size of 1
A negative ion generating porous acrylic fiber comprising a composition obtained by mixing an electrically insulating substance having a size of not more than μm.

The average particle size of the tourmaline is preferably 0.1 μm or more and 1 μm or less. Further, the total content of the tourmaline and the electrically insulating substance is preferably 2 to 15% by weight.

Further, there are three methods for producing the negative ion generating porous acrylic fiber of the present invention. The first method, for a solvent solution of an acrylonitrile copolymer containing cellulose acetate and an acrylonitrile copolymer containing cellulose acetate, tourmaline in a solvent having the same composition as the solvent solution of the acrylonitrile copolymer containing cellulose acetate. It is characterized in that a mixed solution obtained by wet-grinding and dispersing and then adding and mixing fine particles of an electrically insulating substance is adjusted to a predetermined concentration and mixed, and the obtained solution is used as a stock solution for spinning. There is.

Next, the second method is to prepare tourmaline fine particles obtained by subjecting tourmaline to dry pulverization and classification with respect to a solvent solution of an acrylonitrile copolymer containing cellulose acetate and an acrylonitrile copolymer containing cellulose acetate. It is characterized in that a mixture obtained by adding and mixing fine particles of an electrically insulating substance was adjusted to a predetermined concentration and mixed, and the obtained solution was used as a stock solution for spinning.

The third method is to wet-mill tourmaline in water to a solvent solution of an acrylonitrile copolymer containing cellulose acetate and an acrylonitrile copolymer containing cellulose acetate, and then dry, crush and / or The mixture obtained by adding the fine particles of the electrically insulating substance to the fine particles of tourmaline obtained by re-grinding and mixing them was adjusted to a predetermined concentration and mixed, and the obtained solution was used as a stock solution for spinning. It has a feature.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The porous acrylic fiber in the present invention is obtained by spinning a copolymer of cellulose acetate and acrylonitrile and another monomer. The ratio is not particularly limited, but cellulose acetate / acrylonitrile / other monomer = 1 to 15% by weight / 65 to 99% by weight / 0 to 20% by weight is preferable. Examples of the other monomer include methyl acrylate, vinyl acetate, sodium allyl sulfonate, sodium methallyl sulfonate, sodium styrene sulfonate, and sodium acrylamido 2-methylpropane sulfonate, which may be used alone or You may use it in combination of 2 or more type.

The cellulose acetate used in the present invention is not particularly limited, but may be in a dimethylformamide solvent at 50 ° C.
The viscosity at 30% concentration in the above is preferably 30 to 150P. The cellulose acetate and the acrylic polymer are phase-separated in an organic solvent such as dimethylformamide, dimethylacetamide, and dimethylsulfoxide, and the cellulose acetate solution is spherically dispersed (island) in the acrylic polymer solution (sea). When this dope is spun through a spinneret, the cellulose acetate polymer is stretched in the fiber axis direction in a streak shape. At that time,
Voids are created at the interface between the cellulose acetate polymer, which is an island, and the acrylic polymer, which is the sea. When the fiber is stretched, the voids communicate with each other to form a porous acrylic fiber. Porous acrylic fibers typically have a surface area of 10 to 1 of the acrylic fiber.
Since it owns 00 times, the generation of static electricity due to friction increases proportionately.

The tourmaline used in the present invention may be one known in the prior art. That is, it is represented by the following general formula. NaX ₃ Al ₆ (BO ₃ ) ₃ Si ₆ O ₁₈ (OH) ₄ However, in the formula, X represents the same or different Mg, Fe, Li. Particularly preferable specific examples are as follows. _{(B) NaFe 3 Al 6 (BO 3} ) 3 Si 6 O 18 (OH) 4 ( _{ii) Na (Li, Al) 3} Al 6 (BO 3) 3 Si 6 O
₁₈ (OH) ₄ (C) NaMg ₃ Al ₆ (BO ₃ ) ₃ Si ₆ O ₁₈ (OH) _{4 In} addition, (a) above is a shawl, (B) is an elbaite,
(C) is sometimes called a drabite.

The average particle size of this tourmaline needs to be 3 μm or less, more preferably 0.1 to 1 μm, depending on the amount of anion release and the spinnability.
Is. If the average particle size of tourmaline exceeds 3 μm,
Not only the amount of negative ions released decreases, but also the filter cloth is clogged when the porous acrylic fiber is spun, or the spinneret hole is blocked, resulting in yarn breakage, which causes a decrease in operability. On the other hand, the smaller the average particle size of tourmaline, the larger the amount of released negative ions, but if it is smaller than 0.1 μm, the particles of tourmaline are likely to undergo secondary aggregation, and the amount of released negative ions also decreases. There is a tendency.

There are no particular restrictions on the method for adjusting the average particle size of tourmaline to an appropriate size, that is, 0.1 to 1 μm, but wet pulverization or dry pulverization using a general pulverizer is performed. Milling is preferred. Examples of the pulverizer include rolling mills such as rolling ball mills, rod mills and tube mills; stirring mills such as bead mills, sand mills and tower mills; vibration mills; jet mills; planetary mills;
A roller mill or the like can be used, but it is particularly preferable to use balls as a grinding medium because uniform fine particles can be easily obtained. That is, among the crushers, a rolling mill, a stirring mill, a vibration mill, and a planetary mill are applicable. Further, it is more preferable that a large mill container can be industrially used, and a rolling mill or a stirring mill is most suitable.

On the other hand, in the case of dry crushing, a tourmaline crushing agent, an optional crushing medium and an optional crushing aid may be charged into a crusher and crushed. In the case of wet crushing, a solvent is further added. Will be needed. Among the solvents, water may be mentioned in terms of ease of handling, but other solvents may also be used for the porous acrylic fiber. In particular, when wet pulverization is performed using a solvent used for porous acrylic fibers, the particle size distribution of tourmaline crushed organisms is relatively narrow, and the solution after crushing can be used as it is as a raw material for spinning porous acrylic fibers. Since it is possible, there is no need for a drying step or the like, which is preferable.

The electrically insulating substance used in the present invention is an inorganic substance that does not or hardly conducts electricity, and may be solid at room temperature. Examples thereof include, but are not limited to, talc, mica, tricalcium phosphate, and calcium pyrophosphate. The average particle size of the electrically insulating substance needs to be 1 μm or less due to the miscibility with tourmaline. If the average particle size exceeds 1 μm, it is not preferable because it leads to mixed spots with tourmaline.

When an electrically insulating substance is used in combination with tourmaline, the amount of released negative ions is remarkably improved. There are two possible reasons for this, but the details are not clear.
Firstly, it is considered that the electric insulating material disturbs the electric field generated by tourmaline, so that the charge balance in the electric field is lost and negative ions are emitted. Secondly, since there is an electrically insulating substance between the tourmaline particles, it is possible to prevent the secondary aggregation of the tourmaline particles, and the tourmaline can be allowed to remain in the porous acrylic fiber as it is.
It is considered that the decrease in the amount of released negative ions can be prevented. In addition, there is a secondary effect that the spinning operability is not deteriorated.

Further, in the present invention, the ratio of the tourmaline fine particles and the fine particles of the electrically insulating material is 10
With respect to 0 parts by weight, the latter is preferably 5 to 49 parts by weight,
It is preferably 10 to 20 parts by weight. The total content of tourmaline and the electrically insulating substance is preferably 2 to 15% by weight with respect to the porous acrylic fiber in the present invention. This is because the larger the content, the larger the amount of released negative ions, but the larger the content, the lower the operational stability during spinning and the lower the strength and elongation of the obtained yarn.

Next, since there are three methods for producing the negative ion generating porous acrylic fiber of the present invention, they will be described in order.

In the first method, first, tourmaline is wet-milled using a solvent having the same composition as the solvent solution of the acrylonitrile copolymer containing cellulose acetate. Then, the particles of the electrically insulating substance are added to the solvent solution in which the tourmaline particles are dispersed, and further mixed and stirred to obtain a mixed solution. Next, a solvent solution of an acrylonitrile copolymer containing cellulose acetate and an acrylonitrile copolymer containing cellulose acetate is mixed and stirred with the mixed solution so that tourmaline and the electrically insulating substance have a predetermined content. Adjust the concentration. Then, the obtained solution is used as an undiluted solution for spinning and fiberized by ordinary wet or dry spinning.

The solvent solution is preferably an organic solvent such as dimethylformamide, dimethylacetamide or dimethylsulfoxide. As the method of wet pulverization, the pulverizer described above may be used. The spun yarn can be obtained by a conventional method, that is, a spinning, drawing, washing, drying, oiling and crimping process.

Next, in the second method, first, tourmaline is dry pulverized. Then, after classifying the obtained tourmaline fine particles, the fine particles of the electrically insulating substance are added and further mixed and stirred to obtain a mixture. Next, a solvent solution of an acrylonitrile copolymer containing cellulose acetate and an acrylonitrile copolymer containing cellulose acetate is mixed and stirred with the mixture, and the concentration of tourmaline and the electrically insulating substance is adjusted to a predetermined content. Adjust. Then, the obtained solution is used as an undiluted solution for spinning and fiberized by ordinary wet or dry spinning.

As the dry pulverization method, the pulverizer described above may be used. Moreover, the classification method is not particularly limited, but classification using a general sieving machine or classifier may be used as long as predetermined fine particles of tourmaline can be obtained. As the classifier, there are wet and dry gravity classifiers, wet and dry centrifugal force classifiers, dry inertial force classifiers, etc., but especially when a dry classifier is used, a drying step etc. is required after classification. None preferred. If a wet classifier is used, it is preferable to use the solvent used for the porous acrylic fiber as the solvent. This is because it is only necessary to add fine particles of the electrically insulating substance to the solution after classification, and a drying step is not necessary.

In the third method, first, tourmaline is wet-milled with water. Then, the aqueous solution in which the tourmaline particles are dispersed is dried, and the obtained dried aggregate of tourmaline particles is crushed and / or re-ground, and then the particles of the electrically insulating substance are added, and further mixed and stirred. A mixture is obtained. Next, a solvent solution of an acrylonitrile copolymer containing cellulose acetate and an acrylonitrile copolymer containing cellulose acetate is mixed and stirred with the mixture, and the concentration of tourmaline and the electrically insulating substance is adjusted to a predetermined content. Adjust. Then, the obtained solution is used as an undiluted solution for spinning and fiberized by ordinary wet or dry spinning.

As the method of wet pulverization, the pulverizer described above may be used. The drying method is not particularly limited, and may be natural drying or drying using a general dryer as long as water can be separated. Examples of the dryer include a diffusion type, a hot air type, a vacuum type, a freezing type, and the like, and the hot air type is preferable in consideration of the facility simplicity, manufacturing cost, and the like. Further, as a method of crushing and / or re-grinding as required, a general crusher and / or a general crusher may be used, but in particular, a crusher such as a cage mill or an impact mill and / or a jet mill. It is preferred to use a mill grinder. The spun yarn can be obtained by a conventional method, that is, a spinning, drawing, washing, drying, oiling and crimping process.

[0029]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Negative ion measurement method (method A) The amount of negative ions is measured using an ion counter SC-50 (manufactured by Sigma Tech Co.). That is, the sample (nonwoven fabric) is placed in the box and 60 liters / minute of air is sucked from the opposite side of the box. The amount of negative ions is measured at the midpoint between the sample and the suction outlet for 5 minutes, the average value of the number of negative ions per 1 cc is calculated, and compared with the number of negative ions when the sample is absent to confirm the increased number.

Negative ion measurement method (method B) The amount of negative ions is measured using an ion tester KST-900 (Kobe Denpa Co., Ltd.). That is, the sample (nonwoven fabric) is gently rubbed with the skin for 30 seconds in an atmosphere of 60% ^{RH and} 20 ° C., measured with the device, and the average value of the number of negative ions per 1 cc is determined.

Method for evaluating spinning operability Filtration area 7 cm ² , filter cloth Gozamin, 5000 H *
Discharge rate 320cc / min using 0.06mmφ
Spinning was carried out for 1 hour at a winding speed of 10.5 m / min, and evaluation was made based on a pressure increase (filterability) on a filter cloth and a single yarn breakage condition (yarn breakage). a) Filterability A ... 0 or more and less than 0.1 O ... 0.1 or more and less than 0.5 B A ... 0.5 or more and less than 1.0 X ... 1.0 or more and less than 2.0 XX ... 2.0 or more ( Each value is a pressure rise value: kg / cm ² ) b) Thread break ◎ ... 0 or more and less than 3 ○ ... 3 or more and less than 6 △
… 6 or more and less than 12 ×… 12 or more and less than 20 XX… 20
Above (each number is the number of single yarn breaks)

· Method of measuring water absorption It was measured according to DIN-53814.

Examples 1 to 6 (first production method: wet grinding using a solvent solution) 100 kg of Shawl Tourmaline # 325 and 120 kg of 20 mmφ balls were placed in a rolling ball mill having a volume of 300 m ^3.
Then, 180 kg of a 10 mmφ ball and 150 kg of dimethylformamide were added and pulverized for 240 hours. The average particle size of the shawl tourmaline in the obtained stock solution was 0.8 μm. Further, 15 kg of tricalcium phosphate having an average particle diameter of 0.5 μm was added and mixed for another 5 hours. 50 kg of an acrylic dope (acrylonitrile / methyl acrylate / sodium methallyl sulfonate = 91/8/1 (wt%) acrylic polymer concentration 20% dimethylformamide solution) was added to the solution obtained by removing the balls by filtration.
A dimethylformamide solvent was added and the concentration was adjusted so that the total amount of shawl tourmaline and tricalcium phosphate would be a 20% solution.

This additive solution was added to a cellulose acetate polymer-containing acrylic dope (polymer concentration 25% dimethylformamide solution) containing cellulose acetate polymer in an amount of 3% by weight based on the acrylic polymer having the above composition at the ratio shown in Table 1. Then, it was spun into a 60% aqueous solution of dimethylformamide with a 0.06 mmφ spinner and solidified. After that, stretching, washing, drying, oiling, crimping,
A fiber of about 3.3 dtex was obtained through a heat setting step at 130 ° C. The fiber was applied to a card spinning machine / needle punch machine to prepare a non-woven fabric of 50 g / m ² , and negative ions were measured.

[0036]

[Table 1]

As is clear from the results shown in Table 1, the larger the total content of tourmaline and tribasic calcium phosphate, the larger the amount of negative ion increase, but the spinning operability tends to decrease.

Examples 7 to 10 and Comparative Example 1 (first production method: wet grinding using a solvent solution) Shawl tourmaline # 325 was ground with a rolling ball mill in the same manner as in Examples 1 to 6 to 0. Fine particles of 0.8 μm were obtained. After adding tribasic calcium phosphate having the respective average particle diameters shown in Table 2, the cellulose acetate polymer was mixed in the same manner as in Example 3 so that the total content of tourmaline and tribasic calcium phosphate was 5% by weight. Add to the contained acrylic dope,
The spinning was carried out in exactly the same manner as in Examples 1-6.

[0039]

[Table 2]

As is clear from Table 2, when the average particle size of the tricalcium phosphate is 1 μm or less, the amount of negative ions generated is high, and there is no problem in spinning operability. On the other hand, 1 μm
If it exceeds, the amount of negative ions generated will be slightly reduced, and there will be a problem in the spinnability. This causes mixed spots of tourmaline and tricalcium phosphate, and during spinning,
This is because the filter cloth tends to be clogged.

Comparative Examples 2 to 7 (First Production Method: Wet Grinding Using Solvent Solution) In the same manner as in Examples 1 to 6, Shoal Tourmaline # 325 was crushed with a rolling ball mill to obtain 0.8 μm fine particles. Got To this, without adding tricalcium phosphate as an electrically insulating substance, the same procedure as in Examples 1 to 6 was carried out in the same manner as in Examples 1 to 6 except that the acetic acid cellulose polymer-containing acrylic dope was added in the proportions shown in Table 3. Acrylic fiber was obtained.

[0042]

[Table 3]

As is clear from Table 3, it is found that with only shawl tourmaline, even if the content thereof is increased, the number of increase of negative ions is extremely small, and the spinning operability is remarkably reduced, which is not practical. . That is, if there is no electrically insulating substance such as tricalcium phosphate,
This is because secondary agglomeration also immediately occurs in the shawl tourmaline made into fine particles.

Examples 11 to 15 and Comparative Example 8 (second manufacturing method: dry crushing) Shoal tourmaline # 325 was dry crushed with a rolling ball mill and classified with a dry gravity classifier to obtain Table 4. 100 parts of fine particles having the respective average particle diameters shown were obtained. After that, 0.8μ
10 parts of synthetic mica of m was added and mixed with shawl tourmaline, and as in Examples 1 to 6, acrylic dope (acrylonitrile / methyl acrylate / sodium methallyl sulfonate = 91/8/1 (wt%) composition was used. 50 kg of a 20% acrylic polymer in dimethylformamide solution)
And a dimethylform solvent were added to obtain a 20 wt% tourmaline dimethylformamide solution. This was added to the above-mentioned acrylic dope containing cellulose acetate so that the total content of shawl tourmaline and synthetic mica was 5% by weight, and spinning was performed to obtain a tourmaline-containing porous acrylic fiber.

[0045]

[Table 4]

As is clear from Table 4, when the average particle size of tourmaline exceeds 3 μm, the spinning operability is remarkably reduced,
The amount of negative ions generated also decreases. On the other hand, the smaller the average particle size, the greater the amount of negative ions generated,
Spinning operability tended to decrease slightly.

Examples 16 to 21 Here, examples in which the amount of cellulose acetate is changed are shown. Shoal tourmaline # 325 was pulverized by a rolling ball mill in the same manner as in Examples 1 to 6 to obtain fine particles of 0.8 μm. After adding tribasic calcium phosphate or the like in the same manner as in Examples 1 to 6, the same procedure as in Example 3 was performed so that the total content of tourmaline and tribasic calcium phosphate was 5% by weight. Added to
The spinning was carried out in exactly the same manner as in Examples 1-6. However, the acryl dope containing cellulose acetate polymer used is
The amount of cellulose acetate polymer contained was changed at the ratios shown in Table 5. The amount of negative ions was measured by the B method.

[0048]

[Table 5]

As is clear from Table 5, as the amount of cellulose acetate polymer increases, the amount of negative ions generated by friction increases. However, if it exceeds 15%, the water absorption rate (porosity) becomes high, which is not preferable. Further, if the amount of cellulose acetate polymer is less than 2%, the increasing effect by friction is small.

Examples 22 to 23 Here, the first production method (wet grinding using a solvent solution)
Examples of the second manufacturing method (dry grinding) and the third manufacturing method (wet grinding with water) will be shown. When Elbaite Tourmaline # 325 is carried out in an organic solvent as in Examples 1-10, 16-21 and Comparative Examples 1-7 (Example 22), it is the same as Examples 11-15 and Comparative Example 8. And the one which was pulverized by a dry method (Example 23) and which was wet pulverized with water using a rolling ball mill, dried with hot air, and then crushed by a cage mill and passed through a jet mill (Example 2).
In 4), tourmaline was pulverized to have an average particle size of 0.7 μm, and 15 parts by weight of calcium pyrophosphate having an average particle size of 0.7 μm was mixed with tourmaline. Similarly, it was kneaded into a porous acrylic fiber so as to be 5% by weight. The spinning experiment was carried out for 8 hours in order to confirm the difference in the grinding method.

[0051]

[Table 6]

As is clear from Table 6, all of the results were good in the 8-hour spinning, but especially Example 16 pulverized in dimethylformamide was extremely good with no rise in spinneret pressure.

[0053]

As an effect of the present invention, the amount of negative ion generation of tourmaline is increased to a practical range by an extremely simple means of simply mixing an electrically insulating substance without using an exciting agent such as a radioactive substance. The fact that the negative ion generating porous acrylic fiber can be easily produced industrially is extremely large. Furthermore, since negative ions are also generated by friction and peeling, extremely high negative ions, which are higher than the tourmaline effect, are generated. Of course, the fiber can be used for construction bedding such as blankets, sheets, carpets and curtains, and clothing such as underwear and sweaters.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Chieko Iwamoto             4-1, Kanebocho, Hofu City, Yamaguchi Prefecture Kanebo Go             Fiber Co., Ltd. F term (reference) 4L035 AA04 BB03 BB06 BB11 BB17                       DD07 EE08 EE20 FF05 JJ01                       JJ05 JJ08 JJ09 KK01 KK05                       LB11

Claims (6)

[Claims] 1. A negative ion generating porous acrylic fiber comprising a composition prepared by mixing tourmaline having an average particle size of 3 μm or less and an electrically insulating substance having an average particle size of 1 μm or less. 2. The average particle size of the tourmaline is 0.1 μm.
The negative ion generating porous acrylic fiber according to claim 1, wherein the negative ion generating porous acrylic fiber is m or more and 1 μm or less. 3. The negative ion generating porous acrylic fiber according to claim 1 or 2, wherein the total content of the tourmaline and the electrically insulating substance is 2 to 15% by weight. 4. Wet tourmaline in a solvent solution having the same composition as the solvent solution of the acrylonitrile copolymer containing cellulose acetate and the acrylonitrile copolymer containing cellulose acetate. It is characterized in that a mixed solution obtained by pulverizing and dispersing and then adding and mixing fine particles of an electrically insulating substance is adjusted to a predetermined concentration and mixed, and the obtained solution is used as a spinning dope. Method for producing negative ion generating porous acrylic fiber. 5. Fine particles of an electrically insulating substance are added to fine particles of tourmaline obtained by dry pulverizing tourmaline after classification in a solvent solution of an acrylonitrile copolymer containing cellulose acetate and an acrylonitrile copolymer containing cellulose acetate. A method for producing a negative ion generating porous acrylic fiber, characterized in that the mixture obtained by additionally mixing is adjusted to a predetermined concentration and mixed, and the obtained solution is used as a stock solution for spinning. 6. A solvent solution of an acrylonitrile copolymer containing cellulose acetate and an acrylonitrile copolymer containing cellulose acetate is obtained by wet-milling tourmaline in water and then drying, crushing and / or re-milling. Negative ion generation characterized in that the mixture obtained by adding fine particles of an electrically insulating substance to fine particles of tourmaline was mixed and adjusted to a predetermined concentration, and the resulting solution was used as a stock solution for spinning. Method for producing porous acrylic fiber.