JP4879861B2 - Charcoal-containing fiber and method for producing the same - Google Patents

Description

  The present invention relates to a charcoal-containing fiber excellent in VOC adsorption such as toluene and a method for producing the same.

Charcoal can be mixed with compound materials such as synthetic resin or mixed with paper slurry such as pulp for papermaking to give charcoal moisture absorption and deodorization properties to products. Generally done.
As such a conventional technique, a method for producing a functional regenerated cellulose composition using activated carbon fine particles adsorbed with an organic solvent satisfying specific conditions (see Patent Document 1), charcoal powder obtained by finely pulverizing charcoal is dispersed in fibers. There are charcoal-containing fibers (see Patent Document 2).
However, in the technique of Patent Document 1, an organic solvent is essential, and there is a problem in that the organic solvent causes fiber formation. In the charcoal-containing fiber in which charcoal powder obtained by simply pulverizing charcoal is dispersed as in the technique of Patent Document 2, the performance exhibited by the fiber may be inferior to the performance of charcoal alone. . This is because the porous structure of charcoal is covered with synthetic resin or the like as a fiber raw material.

Therefore, various charcoal-containing fibers for solving the above problems have been proposed. Specifically, for example, by incorporating a large number of fine particles formed by pulverizing Bincho charcoal, which is irregular in shape with irregularities, into the matrix of rayon fibers, instead of a smooth spherical surface, Bincho charcoal A deodorant rayon fiber (see Patent Document 3) is known in which fine particles are exposed on the fiber surface so that the porous structure is not covered with a synthetic resin as a fiber raw material. Moreover, the surface area of the charcoal in a fiber is increased by employ | adopting the structure that charcoal powder with an average particle diameter of 0.01-1.0 micrometer is carry | supported by rayon fiber, and 1-60 mass% of charcoal powder is contained. A charcoal-carrying fiber (see Patent Document 4) that devises this is also known.
Japanese Examined Patent Publication No. 6-99595 JP 2000-290826 A JP 2001-98412 A JP 2001-262431 A

Regarding the fibers described in Patent Document 3 and Patent Document 4, the inventors have made additional trials and found that charcoal performances (gas adsorption, negative ion effect, electromagnetic wave shielding, greenhouse effect by far infrared rays, humidity control, etc.) (Effect) is a good fiber with almost no hindrance, but among the gas adsorption properties, the adsorption properties of VOC (Volatile Organic Compound) are poor or unstable. I found that there was still room for improvement.
Therefore, the problem to be solved by the present invention is to provide a charcoal-containing fiber excellent in VOC adsorption and a method for producing the same.

  The present inventors have intensively studied to solve the above problems. In the process, even if the techniques described in Patent Document 3 and Patent Document 4 are used, sufficient VOC adsorption ability is not stably exhibited because coarse particles may fall off from the fibers. It was found that this was because it was not suppressed. That is, even in the prior art, the charcoal powder having a small particle size is firmly supported in the fiber and hardly falls off, but the coarse particle is easily dropped from the fiber, and further, the particle size is large, so it has fallen off. Even if the number of coarse particles is small, the volume will drop off greatly, and the absolute value of the amount of charcoal powder in the fiber will decrease, resulting in a sufficient amount of charcoal to adsorb VOC. It was found that the powder was not secured in the fiber. And even if any of the average particle size and the maximum particle size is large, it is not possible to prevent charcoal powder such as charcoal from falling off from the fiber, and therefore, even if it is a charcoal-containing fiber excellent in initial performance It was found that the stability over time was low and the expected performance could not be exhibited gradually.

Based on such knowledge, in order to stably exhibit sufficient VOC adsorption ability over time, charcoal powder in the fiber is excellent in VOC adsorption ability, and most of it is ensured in the fiber. The present inventors have found that the average particle size and the maximum particle size of charcoal powder and the ratio to the cellulose content can be devised, and have confirmed that to complete the present invention. In addition, when the charcoal is charcoal, by devising the average particle size and the maximum particle size, the powder of charcoal is prevented from falling off the fiber, not only the stability over time of the charcoal-containing fiber is improved, It has also been found that the initial adsorption performance for VOC is significantly increased.
That is, the charcoal-containing fiber according to the present invention is a rayon fiber containing charcoal powder, and the charcoal powder has an average particle size of 1.2 μm or less and a maximum particle size of 2.2 μm or less. 80% or more of the particles are particles having a particle diameter of 1 μm or less, and the ratio to the cellulose content is 15% by mass or more.

In a preferred first embodiment of the charcoal-containing fiber according to the present invention, the charcoal is charcoal, and the charcoal powder has an average particle size of 0.65 μm or less.
In a second preferred embodiment of the charcoal-containing fiber according to the present invention, the charcoal is activated carbon.
In the method for producing charcoal-containing fibers according to the present invention, a charcoal powder having an average particle size of 1.2 μm or less and a maximum particle size of 2.2 μm or less is dispersed in water to obtain a 5 to 25 mass% aqueous dispersion. The aqueous dispersion and viscose are mixed so that the ratio of the charcoal powder to the cellulose content is 15% by mass or more, and the mixture is spun.

  ADVANTAGE OF THE INVENTION According to this invention, the various characteristics which charcoal has are exhibited favorably, and the charcoal containing fiber which is excellent also in VOC adsorptivity, and its manufacturing method can be provided.

Hereinafter, the charcoal-containing fiber and the method for producing the same according to the present invention will be described in detail. However, the scope of the present invention is not limited to these descriptions, and other than the following examples, the scope of the present invention is not impaired. Changes can be made as appropriate.
[Charcoal]
The raw materials and production methods are not particularly limited as long as they can exhibit various functions of charcoal such as gas adsorption, moisture absorption / desorption, deodorization, antistatic property, and ion exchange function, but charcoal (particularly described later) Activated charcoal obtained by the production method) and activated carbon are preferred.
By pulverizing the charcoal into a fine powder, the surface area is increased, the adsorption function and the like are further increased, and the support for the rayon fibers is facilitated.

  The charcoal powder needs to have an average particle size of 1.2 μm or less. When the average particle diameter exceeds 1.2 μm, charcoal powder falls off the fibers. On the other hand, the smaller the average particle size, the larger the surface area per unit mass and the various functions based on the surface properties are improved. Specifically, for example, the average particle diameter of the charcoal powder is preferably 0.65 μm or less. In particular, when using charcoal, the VOC adsorption ability is significantly improved when the average particle size of the powder is 0.65 μm or less. However, when the average particle size of the charcoal powder is small, it is advantageous in that the specific surface area is improved. However, when the charcoal powder is dispersed in water as described later, the concentration of the aqueous dispersion is considerably reduced. Otherwise, sufficient fluidity cannot be obtained, and it may be difficult to add and mix this aqueous dispersion into the viscose. Therefore, the thickness is preferably 0.2 μm or more. An average particle diameter of 0.3 to 0.6 μm is particularly preferable.

When the activated charcoal is used, the activated charcoal and further the activated charcoal powder obtained by pulverizing the activated charcoal include a low temperature carbonized portion and a high temperature carbonized portion. It is preferable that each activated charcoal powder has a low temperature carbonized portion and a high temperature carbonized portion, but even if the activated charcoal powder composed of the low temperature carbonized portion and the activated charcoal powder composed of the high temperature carbonized portion are uniformly dispersed. Good.
The charcoal powder has a maximum particle size of 2.2 μm or less, preferably 2.0 μm or less. If the maximum particle diameter exceeds 2.2 μm, the powder of charcoal will drop off from the fiber after the spinning step described later, and sufficient VOC adsorption capacity cannot be obtained. The proportion of the particle size of 2.0 μm or less is preferably 90% or more, more preferably 95% or more, and particularly preferably 100%. As the proportion of the particle size of 2.0 μm or less decreases, it becomes difficult to obtain charcoal powder having a maximum particle size of 2.2 μm or less.

The proportion of the particle size of 1.0 μm or less is more preferably 80% or more, further preferably 90% or more, particularly preferably 95% or more, and most preferably 100%. When the proportion of the particle size of 1.0 μm or less is 80% or more, even if it is contained in the fiber, it is difficult to cause dropout from the fiber or a decrease in fiber strength, so that a large amount of charcoal powder is contained in the fiber. As a result, various performances of the charcoal powder can be exhibited more remarkably.
For the pulverizing apparatus and the pulverizing conditions, basically, ordinary charcoal powder manufacturing technology can be applied. As the pulverizer, a dry pulverizer such as a jet mill, a wet pulverizer such as a tron mill, or a swirl vortex pulverizer is used. A swirling vortex crusher is a device that obtains a finely pulverized material by repeating impact crushing and grinding in a swirling vortex generated by a rotating rotor, etc. Therefore, there is an advantage that foreign matters such as metal are hardly mixed in the pulverized product. In the present invention, a method of first pulverizing to some extent by a dry pulverizer and then finely pulverizing by a wet pulverizer is particularly preferable. By pulverization in the first stage, that is, dry pulverization, for example, the average particle diameter is pulverized to 6 μm or less, and coarse particles are removed in advance, so that the second stage pulverization, that is, wet pulverization. The grinding efficiency is improved. In the wet pulverization stage, since coarse particles are not present, the powder is pulverized very efficiently and uniformly, and a charcoal powder with less unevenness is obtained on the surface. In addition, in wet grinding, water as a dispersion medium and charcoal powder as a dispersoid are sufficiently in contact with each other, so both are used well, so as it is used as an aqueous dispersion, and added to viscose as described later, It is preferable because charcoal powder is stably present in the viscose and also in the rayon fiber after fiberization. In this case, it is preferable to add a dispersant at the stage of wet grinding. The aqueous dispersion and the dispersant will be described in detail later.

<Charcoal>
Charcoal is a solid product mainly composed of carbon obtained by carbonizing wood, and examples thereof include activated charcoal and bincho charcoal. Among them, it is preferable to use activated charcoal described in detail below.
(Activated charcoal)
Activated charcoal is charcoal that is physically and chemically activated by appropriately setting the raw materials of charcoal, carbonization conditions, and the like, and the functions such as gas adsorption described above are remarkably improved. The activated charcoal manufacturing method includes a low-temperature carbonization step in which wood chips are carbonized by heat treatment at 450 to 550 ° C., followed by a low-temperature carbonization step, and carbide of wood chips at 800 to 900 ° C., preferably 3 to 60 minutes. More preferably, it includes a high-temperature carbonization step in which heat treatment is further performed for 5 to 15 minutes to further carbonize, and an activation step in which water is brought into contact with the carbide at the end of the high-temperature carbonization step.

The wood chip is a piece of wood or chip. As raw wood for wood chips, mainly coniferous materials such as cedar, Himalayan cedar and red pine are used, and red pine is particularly preferable. It is possible to use thin wood and waste materials that are difficult to use as wood products and inexpensive. Wood chip products that are industrially produced in large quantities can also be used as raw materials for pulp production and board building materials.
The shape and size of the wood chip are not particularly limited, but when the passing diameter of the wood chip is measured, the maximum diameter is preferably 10 to 60 mm. Wood chips that are too large are difficult to carbonize sufficiently, and wood chips that are too small are difficult to handle and have poor production yields.
In the low-temperature carbonization step, basically, an ordinary charcoal production apparatus and production process conditions may be employed. The temperature of heat processing is set to 450-550 degreeC. The heat treatment time may be such that the entire wood chip is sufficiently carbonized, and usually varies depending on the conditions of the wood chip or the manufacturing apparatus, but usually takes 100 to 120 hours.

The heat treatment atmosphere is performed in a state where the inflow of air is blocked. It can be treated with wood chips covered with fir shells and sawdust.
In the high-temperature carbonization step, basically, a normal charcoal production apparatus and production treatment conditions are adopted, the heat treatment temperature is 800 to 900 ° C., the heat treatment time is preferably 3 to 60 minutes, more preferably 5 to 15 minutes. Set to. In the high-temperature carbonization step, only a portion near the surface of the wood chip carbide that has been low-temperature carbonized in the previous step is high-temperature carbonized, and the low-temperature carbonization portion is left in the central portion of the wood chip carbide.
The ratio of the high temperature carbonization part and the low temperature carbonization part contained in the activated charcoal obtained is adjusted by processing time. If the treatment time is too short or too long, the respective characteristics of the high temperature carbonized portion and the low temperature carbonized portion cannot be sufficiently exhibited. It is preferable that the wood chip carbide that has been carbonized at low temperature is carbonized as it is by increasing the heat treatment temperature in the same apparatus as the low-temperature carbonization step. The heat treatment atmosphere is in a state where oxygen is supplied.

When water is brought into contact with the carbide that has been heat-treated in the high-temperature carbonization process, the carbide is rapidly cooled and extinguished. At that time, activation is performed by chemical and physical action of water such that fine pores having a complicated shape are formed in the carbide, or the surface of the carbide is modified to improve the adsorption ability.
Although water may be in a liquid state, it usually comes into contact with the carbide in a water vapor state. The specific treatment apparatus and treatment conditions of the activation step may be the same as the contact treatment with water that is performed in a known activated carbon production technique. However, the contact of water with the carbide in the activation process for obtaining activated charcoal is different from so-called steam activation performed in the activated carbon production technology. That is, in steam activation in activated carbon production, impurities or part of carbon remaining or adsorbed in the primary coal is gasified and removed by reacting raw carbon called primary coal with water vapor at around 1000 ° C. It has a large internal surface area and is clearly different from the action of water on the carbides in the above-mentioned activated carbon production (chemical and physical action of water by rapid cooling of the carbides).

Activated charcoal has a porous structure with a large number of micropores inside, and has a physical adsorption action due to the micropores, and the surface of the micropores is chemically or physically activated to provide high adsorption. Demonstrate the ability. This will be specifically described below in comparison with Bincho charcoal.
When activated charcoal and Bincho charcoal were analyzed by the electron spin resonance method, a singlet signal was detected in the activated charcoal, and no signal was detected in Bincho charcoal. And the g value of the signal detected in the said activated charcoal was 2.00, and was a value close | similar to a free electron. This suggests that the signal is caused by unpaired electrons derived from dangling bonds of carbon that are not bonded to hydrogen. On the other hand, when activated charcoal and Bincho charcoal were analyzed by X-ray diffraction, activated charcoal obtained only a wide peak peculiar to amorphous. A sharp peak due to crystallinity was also obtained, indicating that activated charcoal was amorphous and Bincho charcoal was amorphous and crystalline.

If the charcoal is amorphous, there will be many defects in the carbon bonds, and as a result, there will be free electron-like unpaired electrons, resulting in reactivity with other substances. Since activated charcoal has many amorphous parts, it is presumed that the activated charcoal exhibits better adsorption ability than Bincho charcoal.
As a result of analysis by X-ray photoelectron spectroscopy, the atomic composition of activated carbon is 89.1% carbon and 10.9% oxygen, and a hydroxyl group (—OH), carboxyl group or ester group ( -COOR: R is presumed to have H or an alkyl group. In addition, the activated charcoal was dispersed in water and examined for the presence or absence of radicals. As a result, radicals were not generated.Unpaired electrons in the activated charcoal contributed to the improvement of adsorption capacity, It can be seen that there is no reactivity enough to react to generate radicals. From these experimental facts, the functional group on the activated charcoal surface that causes adsorptive properties is not a highly reactive free radical such as a peroxide radical, but a carbon atom having an unpaired electron (organic radical ) And carbon, and it is presumed to be a hydroxyl group or oxygen atom having an unpaired electron.

As can be seen from the above production method, activated charcoal does not require the use of additives or activation treatment agents other than wood chips as raw materials.
Activated charcoal is excellent in adsorptive capacity, and is excellent in moisture absorption / desorption, deodorization, mildew resistance, far-infrared radiation, conductivity, electromagnetic wave absorption, ion adjustment function, and the like. The activated charcoal adsorbing ability has a large rising speed when it comes into contact with the adsorbing substance. Moreover, since it has the effect | action which decomposes | disassembles an adsorbent substance, it can prevent that an adsorbent substance clogs into the micropore of activated charcoal, and adsorbability falls, and can exhibit stable adsorbability over a long period of time. The activated charcoal contains a mixture of a low temperature carbonized portion carbonized in the low temperature carbonization step and a high temperature carbonized portion further carbonized in the high temperature carbonization step. Usually, there is a low-temperature carbonized portion on the center side and a high-temperature carbonized portion on the outer peripheral side.

The low-temperature carbonized portion has excellent adsorptivity to relatively high molecular weight compounds such as acetic acid and ammonia. The high-temperature carbonized portion is excellent in adsorptivity to relatively low molecular weight compounds such as formaldehyde, acetaldehyde, and ethylene. The activated charcoal can synergistically exhibit the functions and roles of the low temperature carbonized portion and the high temperature carbonized portion.
<Activated carbon>
Activated carbon is a carbonaceous substance that exhibits a strong adsorbing ability for gases or solutes in a solution, and is obtained by activating charcoal or the like. Examples of the activation method include steam activation, chemical activation, and other methods, and steam activation is particularly preferable.

As a raw material of activated carbon, known raw materials such as charcoal, fruit charcoal, coal, pitch coke can be used. In particular, activated carbon made from charcoal derived from charcoal has a large specific surface area and has excellent VOC adsorption characteristics. Is preferable.
The steam activation is performed through steam at a raw material such as charcoal at 1000 to 1200 ° C., for example.
The chemical activation is performed, for example, by drying a raw material such as charcoal and pulverizing it, immersing it in a solution of zinc chloride, phosphoric acid, sulfurous acid, alkali, etc., followed by firing and carbonization. Impurities may be washed and removed.

Other methods include, for example, heating a raw material such as charcoal in air, carbon dioxide or chlorine gas to oxidize a part of the raw material, a method in which the charcoal is ignited under reduced pressure, or a red hot charcoal in water. And soaking in nitric acid.
[Manufacture of charcoal-containing fibers]
When producing a carbon-containing fibers according to the present invention, described above, an average particle diameter of 1.2μm or less, the maximum particle diameter of Ri der less 2.2 .mu.m, and particle 80% or more of the following particle size 1μm with powder der Ru charcoal, said a satisfies charcoal powder and viscose are mixed and dispersed, and spinning the mixture.
First, charcoal powder satisfying the above conditions is dispersed in viscose, which is a raw material for rayon fibers. Viscose is a solution containing cellulose, and one manufactured through a normal viscose manufacturing process is used. Viscose and charcoal powder are mixed with stirring to prepare charcoal powder-dispersed viscose. The charcoal powder can be dispersed at any stage of the viscose production process, but it is preferably performed immediately before the viscose that has undergone the sulfidation process or the aging process enters the spinning process.

  It is preferable to preliminarily disperse charcoal powder in water to obtain a 5 to 25% by mass aqueous dispersion, which is added to the viscose. As described above, when wet pulverizing charcoal, the aqueous dispersion after wet pulverization may be used as it is, or further diluted with water. If the amount exceeds 25% by mass, the dispersion has thixotropy and may lose fluidity when allowed to stand, so that it is difficult to continuously add and mix into viscose. If it is less than 5% by mass, the viscosity becomes too low when added to and mixed with the viscose, and the spinnability of the viscose after the addition and mixing of the aqueous dispersion is lowered, and during the regeneration during viscose regeneration There is a risk that the yarn will be cut and fiberization will be difficult. Moreover, when using charcoal, the fiber which can be obtained by adding 5-25 mass% aqueous dispersion to viscose has wrinkles on the fiber surface, and the surface area increases, thereby improving VOC adsorption. I found out that Preferably it is 7-22 mass%, More preferably, it is 8-16 mass%, Most preferably, it is 9-12 mass%. The charcoal-containing fiber obtained by spinning a 9-12 mass% aqueous dispersion added and mixed with viscose has large wrinkles on the fiber surface, forms deep grooves, and significantly improves VOC adsorption. I understood that.

  The dispersion is performed so that the ratio of the charcoal powder to the cellulose content is 15% by mass or more. It is preferable that it is 50 mass% or less. If the said ratio is less than 15 mass%, VOC adsorptivity will not fully be exhibited. On the other hand, if it exceeds 50% by mass, the spinnability may deteriorate, the charcoal powder may easily fall off from the obtained rayon fiber, and the properties such as the strength and elongation of the rayon fiber may decrease. . When using charcoal, it is preferable that the said ratio is 40 mass% or less. More preferably, it is 20-38 mass%, More preferably, it is 25-35 mass%. When using activated carbon, it is preferable that the said ratio is 50 mass% or less. More preferably, it is 17-45 mass%, More preferably, it is 20-43 mass%.

In addition, since the charcoal powder according to the present invention has a small particle size and easily aggregates, it is preferable to add a dispersant. As the dispersant, an anionic surfactant is effective and is not particularly limited, and examples thereof include polystyrene sulfonate sodium salt. Although it does not specifically limit as addition amount of the said dispersing agent, For example, it can be set as the ratio of 2-10 mass% with respect to a dispersion liquid.
Next, the viscose in which the charcoal powder is dispersed is spun to obtain rayon fibers containing the charcoal powder. The spinning process includes a cellulose regeneration process and a coagulation process.
The produced charcoal-containing fiber is in a state where charcoal powder is supported inside a porous structure unique to rayon fiber. Charcoal powder is firmly captured in the rayon fiber and is not easily removed. In addition, unlike general synthetic fibers, rayon fibers are formed by regenerating cellulose contained in viscose into its original fiber state, so that the fine porous structure of charcoal powder is high. It will not be filled with molecules. Various treatments in the process of producing viscose and rayon fibers do not change the chemical properties of the surface of the charcoal powder, so that the chemical function of the surface of the charcoal powder is not impaired.

The spun carbon-containing fiber is turned into a product through drawing, cutting, drying and other processing steps as necessary. The fiber diameter of the carbon-containing fiber is about 5 to 50 μm. The charcoal-containing fibers can be provided either in the form of short fibers (staples) cut to a certain length or in the form of long fibers (filaments) of virtually infinite length. The fiber length of the short fiber can be appropriately set depending on the purpose of use and the required performance, but usually a fiber length of about 130 mm or less is used.
〔Use applications〕
Charcoal-containing fibers can be used to produce various products alone or in combination with other materials.

Charcoal-containing cotton can be obtained by accumulating charcoal-containing fibers. Charcoal-containing yarn can be produced from charcoal-containing fibers or charcoal-containing cotton. The charcoal-containing yarn can be blended with other fibers in addition to the charcoal-containing fiber alone. For example, the strength and durability of the charcoal-containing yarn can be improved by combining synthetic fibers that are superior in strength and durability compared to rayon fibers. Usually, when charcoal-containing fibers exhibiting black are combined with fibers having other colors such as white, charcoal-containing yarns other than black can be obtained. The charcoal-containing yarn can be used for sewing or embroidery of various fabric products.
A woven fabric can be produced using charcoal-containing yarn. As a yarn constituting the knitted fabric, a charcoal-containing yarn and a normal fiber yarn can be combined. A nonwoven fabric in which charcoal-containing fibers are accumulated can be produced. Charcoal-containing paper can be obtained by adding charcoal-containing fibers to a part of the paper-making raw material. The fiber-containing synthetic resin product in which the charcoal-containing fibers are blended can be obtained by mixing the charcoal-containing fibers with the synthetic resin. Charcoal-containing fibers can be included in cement, gypsum and other building materials.

  Examples of specific products manufactured using charcoal-containing fibers or materials containing charcoal-containing fibers include agricultural and horticultural sheets, mat materials, and heat insulating sheets. Excellent removal of nonpolar VOCs because of its excellent VOC adsorption properties, and especially good adsorption properties for nonpolar VOCs such as toluene, which are very difficult to adsorb in other charcoal-containing products. Can be used for Moreover, since the charcoal-containing fiber according to the present invention can exhibit not only the VOC adsorptivity but also the performance normally exhibited by charcoal, it can be used as a humidity control material for construction, industrial use, and agricultural use. . Since it has excellent deodorizing properties, it can also be used in deodorizing sheets. It can also be used for freshness-keeping sheets such as vegetables, fruits and cut flowers, and molded products for keeping freshness. It can also be used as a molded product for preventing electrification (static electricity). Because of its excellent electromagnetic shielding properties, it can be used as an electromagnetic shielding material used to prevent malfunctions in electronic devices, prevent interference with televisions, radios, etc., and prevent electromagnetic waves from being emitted from mobile phones. You can also use it. It can be used for various clothing, bedding and household items.

Hereinafter, the method for producing the charcoal-containing fiber of the present invention will be described more specifically by way of examples, but the present invention is not limited to these.
Measurement methods and evaluation methods in Examples and Comparative Examples are shown below.
<Measurement of particle size of charcoal>
Each aqueous dispersion after wet pulverization in each of Examples and Comparative Examples described later (however, when wet pulverization is not performed, dry pulverized charcoal powder is dispersed in water) The particle diameter of each charcoal particle contained in each aqueous dispersion was measured by passing it through a refined particle size distribution measuring instrument LA-920.

<Measurement of fiber properties>
In accordance with JIS L 1015, the fineness, dry strength, wet strength, dry elongation, and wet elongation were measured. <Measurement of the number of particles of charcoal powder in the fiber>
The fibers to be measured were bundled, inserted into a 1 mmφ slit, and then cut along the slit surface with a razor blade. This cut surface was observed with a microscope, and the number of particles present per 20 arbitrary fibers and having a particle diameter of 1.0 μm or more or exceeding 2.2 μm was counted.
<Measurement of VOC adsorption>
3.0 g of a measurement sample was placed in a 5 liter Tedlar bag, and 3 liters of a measurement target gas adjusted to a predetermined concentration was injected, and the change in gas concentration over time was measured with a detector tube.

<Dropping test>
After collecting 20 g of the fiber to be measured and passing it through a 500 mmφ semi-random card (manufactured by Yamato Kiko Co., Ltd.) three times, in the same manner as in the VOC adsorptivity measurement method, toluene having an initial concentration of 40 ppm is used as a symmetric gas, The VOC adsorptivity was measured by measuring the toluene concentration after 24 hours. In addition, in the same manner as the measurement of the number of particles of charcoal powder in the fiber described above, the same cross-section is observed and compared with the microscope for the fibers before and after passing through the semi-random card, and the charcoal powder is removed. The presence or absence was observed.
-Examples using charcoal, comparative examples-
[Example 1]
<Manufacture of activated charcoal>
Red pine wood was chipped (maximum span diameter 10-50 mm, thickness 3-5 mm) to obtain a charcoal material.

The carbon material was placed in a 100 m ³ flat kiln and carbonized at 500 ° C. for about 140 hours (low temperature carbonization step).
After completion of the low temperature carbonization step, oxygen was rapidly given by stirring the charcoal of the entire kiln, and then the temperature was raised to 850 ° C. and sufficiently refined over 40 minutes (high temperature carbonization step).
After completion of the high temperature carbonization step, water was applied to extinguish the fire. Activation was performed by this treatment, and activated charcoal was obtained (activation step). The activated charcoal thus obtained had a high tissue binding density and was hard. The carbon ratio was 85% or more.
<Manufacture of charcoal-containing fibers>
The activated charcoal obtained by the above operation was dry pulverized using a dry pulverizer (manufactured by Seishin Co., Ltd.) to a level of 1 to 60 μm. The dry-pulverized charcoal powder and naphthalenesulfonic acid / formalin condensate soda (trade name “Demol T”, manufactured by Kao Corporation) are dispersed in water so that the charcoal powder concentration is 20% by mass. Was subjected to a wet pulverization treatment for 2 hours using a wet pulverizer (manufactured by Mitsui Mining Co., Ltd.) to obtain an aqueous dispersion used for the production of the following charcoal-containing fibers.

Apart from the aqueous dispersion, rayon fiber raw pulp was immersed in caustic soda of about 18%, and alkali cellulose was obtained by pressing and grinding. Next, alkali cellulose was aged and carbon disulfide was reacted to obtain cellulose xanthate. Further, cellulose xanthate was dissolved with diluted caustic soda to obtain viscose. The proportions of cellulose, sodium hydroxide and carbon disulfide used to obtain viscose were 8.5% by mass of cellulose, 5.7% by mass of sodium hydroxide and 2.7% by mass of carbon disulfide.
Immediately before spinning the viscose, the aqueous dispersion obtained in the above step is added quantitatively and continuously using an injection pump so that the ratio of charcoal powder to cellulose content is 33.3 mass%. Then, viscose and activated charcoal powder were mixed uniformly. Viscose blended with activated charcoal powder was fiberized by a two-bath tension spinning method. At this time, spinning was performed from a spinneret having a nozzle diameter of 0.09 mm and a hole number of 4000 at a spinning speed of 50 m / min, and sent to a coagulation / regeneration bath. As the coagulation / regeneration bath, a Mueller bath (50 ° C.) having a composition of sulfuric acid: 100 g / liter, zinc sulfate: 15 g / liter, sodium sulfate: 350 g / liter was used.

A viscose rayon yarn obtained by fiberizing viscose was cut into 51 mm and subjected to hot water treatment, water flow treatment, and water washing treatment in order, and scoured. After scouring, excess water was removed from the fiber with a compression roller and then dried at 60 ° C. for 7 hours to obtain fiber A.
[Example 2]
Fiber B was obtained in the same manner as in Example 1, except that the aqueous dispersion was added to the viscose so that the ratio of charcoal powder to the cellulose content was 25.0% by mass.
Example 3
Fiber C was obtained in the same manner as in Example 1 except that the aqueous dispersion was added to the viscose so that the ratio of the charcoal powder to the cellulose content was 17.6% by mass.

Example 4
A fiber D was obtained in the same manner as in Example 1 except that the concentration of the charcoal powder in the aqueous dispersion added to the viscose was 10.0% by mass. The obtained fiber D had many large and deep wrinkles as compared with other fibers.
Example 5
As an aqueous dispersion to be added to the viscose, charcoal powder and naphthalenesulfonic acid / formalin condensate soda are dispersed in water so that the concentration of charcoal powder becomes 10% by mass, and then wet mill (Dyno Mill KDL- Fiber E was obtained in the same manner as in Example 1 except that PILOT (manufactured by Shinmaru Enterprises Co., Ltd.) was used and the wet mill was passed 6 times at a flow rate of 20 liters / minute. . The obtained fiber E, like the fiber D, had many large and deep wrinkles as compared with other fibers.

Example 6
As an aqueous dispersion to be added to the viscose, charcoal powder and naphthalenesulfonic acid / formalin condensate soda are dispersed in water so that the concentration of charcoal powder becomes 18% by mass, and then wet mill (Dyno Mill KDL- The fiber F was obtained in the same manner as in Example 1 except that a PILOT (manufactured by Shinmaru Enterprises Co., Ltd.) was used and the wet mill was passed three times at a flow rate of 20 liters / minute. .
[Comparative Example 1]
As an aqueous dispersion to be added to the viscose, the wet pulverization operation was changed in the same manner as in Example 6, and this charcoal powder and naphthalenesulfonic acid / formalin condensate soda had a charcoal powder concentration of 10% by mass. Thus, Example 1 and the point which used what was disperse | distributed to water, and the point which performed the aqueous dispersion addition to viscose so that the ratio of the charcoal powder with respect to a cellulose content might be 10.0 mass%. Similarly, fiber G was obtained.

[Comparative Example 2]
As a water dispersion to be added to the viscose, a wet pulverizer (Dyno Mill KDL-PILOT, manufactured by Shinmaru Enterprises Co., Ltd.) was used, and the liquid was passed through the wet pulverizer once at a flow rate of 20 liters / minute. In the same manner as in Example 1, except that this charcoal powder and naphthalenesulfonic acid / formalin condensate soda were dispersed in water so that the charcoal powder concentration was 18% by mass. Fiber H was obtained.
[Comparative Example 3]
As the aqueous dispersion added to the viscose, charcoal powder pulverized using a swirl vortex crusher and this charcoal powder and naphthalenesulfonic acid / formalin condensate soda were used, and the charcoal powder concentration was 18% by mass. A fiber I was obtained in the same manner as in Example 1 except that a material dispersed in water was used.

[Comparative Example 4]
As the aqueous dispersion added to the viscose, charcoal powder that is dry-grinded but not wet-milled is used, and this charcoal powder and naphthalenesulfonic acid / formalin condensate soda have a charcoal powder concentration of 25% by mass. A fiber J was obtained in the same manner as in Example 1 except that a material dispersed in water was used.
[Comparative Example 5]
Without adding anything, fiber K was obtained by simply spinning viscose in the same manner as in Example 1.

[Performance of each fiber]
<Evaluation of fiber properties>
About each fiber AK concerning each Example and a comparative example, the fiber physical property was measured according to the above-mentioned measuring method. Regarding the fineness, each fiber was 5.6 dtex. The results of other fiber properties are shown in Table 1 together with the particle diameter of charcoal powder contained in each fiber, the number of charcoal particles in the fiber, the concentration of the aqueous dispersion used, and the content of charcoal powder in the fiber.
<Evaluation of VOC adsorption>
Next, about each fiber AK, according to the above-mentioned measuring method, toluene adsorptivity (initial performance), the presence or absence of the drop-off in the drop-off test, and the toluene adsorbability after the drop-off test were measured. The results are also shown in Table 1.

  Furthermore, in order to see the VOC adsorption performance other than toluene, only the fiber spinning conditions in Example 1 were changed to obtain a fiber L having a fineness of 1.7 dtex. Further, only the fiber spinning conditions in Example 2 were changed to obtain a fiber M having a fineness of 1.7 dtex. Using these fibers L and M and the fiber K according to Comparative Example 4, the adsorptivity of formaldehyde was also measured. The results are shown in Table 2.

<Evaluation of blended felt>
Using the fiber L, a mixed cotton felt made of charcoal-containing fibers and other fiber materials was prepared by a conventional method, and acetaldehyde adsorptivity was evaluated. About the blended cotton in a table | surface, the used fiber and the blended cotton ratio are as follows.
Blended cotton X: Kanekalon / fiber L / rayon = 50/30/20
Blended Y: Kanekalon / Fiber L / Rayon = 60/30/10
Blended cotton Z: Kanekalon / fiber L = 70/30
The results are shown in Table 3.

<Repeated adsorptive evaluation>
Using the fibers L and M, the repeated adsorptivity of the fibers was evaluated. Specifically, the adsorptivity of acetaldehyde and formaldehyde was repeatedly measured as follows according to the measurement method described above. That is, after measuring the adsorptivity, a series of operations of repeatedly drying the sun from 9:00 to 16:00 and measuring the adsorptivity again was repeated. The results are shown in Table 4.

[Discussion]
(1) Looking at Table 1, each of the fibers A to F according to the examples had 0 particles before the fiberization because the number of particles having a particle diameter exceeding 2.2 μm included in the fiber cross section was zero. It has been demonstrated that not only the diameter was 2.2 μm or less, but even after fiberization, the maximum particle diameter did not exceed 2.2 μm due to secondary particle formation.
(2) From Table 1, it was found that any of the fibers A to F in the examples had a fiber capacity that the fibers could withstand practically.
(3) Moreover, it can also be seen from Table 1 that each of the fibers A to F of the example exhibits better toluene adsorptivity than the fibers G, I, and J of the comparative example. In particular, it can be seen that the fibers D and E according to Examples 4 and 5 having an aqueous dispersion concentration of 10.0% by mass and a large number of large and deep wrinkles have extremely excellent adsorptivity.

  (4) On the other hand, in the fiber G concerning the comparative example 1 whose ratio of the charcoal powder with respect to the cellulose content in a fiber is 10.0 mass%, toluene adsorption ability is remarkably inferior to each fiber AF concerning an Example. I found out. Moreover, when the maximum particle diameter of charcoal powder is within the range of the present invention but the average particle diameter is outside the range of the present invention and the fiber H according to Comparative Example 2 is used, each of the toluene adsorption capacities according to the examples. It was found to be significantly inferior to fibers A to F. This is probably because the average particle diameter of the charcoal powder is as large as 1.31 μm, so that coarse particles dropped out of the fiber until the fiber H was obtained. Also from the drop-off test, it can be seen that the charcoal powder tends to drop off from the fiber I, and the toluene adsorbability is further lowered due to this drop-out.

(5) Although the average particle size of the charcoal powder is within the range of the present invention, when the fiber I according to Comparative Example 3 whose maximum particle size is out of the range of the present invention is seen, toluene adsorption capacity is applied to the example. It was found to be significantly inferior to each fiber A-F. This is probably because the maximum particle diameter of the charcoal powder is as large as 2.5 μm, so that coarse particles dropped out of the fiber until the fiber I was obtained. Also from the drop-off test, it can be seen that the charcoal powder tends to drop off from the fiber I, and the toluene adsorbability is further lowered due to this drop-out.
(6) The average particle diameter of charcoal powder is 2.62 μm, and the maximum particle diameter is 12 μm. The fiber J according to Comparative Example 4 has a smaller surface area than other fibers, so toluene adsorption is also performed. It was remarkably inferior to each of the fibers A to F according to the examples. Further, in the dropout test, it was found that a large amount of dropout was observed and the toluene adsorption performance was also lowered.

(7) From Table 2, it can be seen that the charcoal-containing fiber according to the present invention is excellent in adsorptivity not only for toluene but also for other VOCs such as acetaldehyde. From Table 3, it can be seen that even if the charcoal-containing fiber according to the present invention is used in combination with other fibers, the VOC adsorptivity is excellent.
(8) From Table 4, it was found that even if the charcoal-containing fiber according to the present invention was repeatedly used over a plurality of times, excellent VOC adsorptivity was exhibited.
-Examples using activated carbon, comparative examples-
Example 7
Coconut shell-derived activated carbon (Futamura Chemical Co., Ltd.) was pulverized using a tornado mill and further pulverized with a jet mill (dry pulverization). The activated carbon powder after dry pulverization and sodium phthalene sulfonic acid / formalin condensate soda (trade name “Demol T”, manufactured by Kao Corporation) are dispersed in water so that the concentration of the activated carbon powder is 20% by mass. Was subjected to wet pulverization for 2 hours using a wet pulverizer (manufactured by Mitsui Mining Co., Ltd.) to obtain an aqueous dispersion for use in the production of the following activated carbon-containing fibers.

Apart from the aqueous dispersion, rayon fiber raw pulp was immersed in caustic soda of about 18%, and alkali cellulose was obtained by pressing and grinding. Next, alkali cellulose was aged and carbon disulfide was reacted to obtain cellulose xanthate. Further, cellulose xanthate was dissolved with diluted caustic soda to obtain viscose. The proportions of cellulose, sodium hydroxide, and carbon disulfide used to obtain viscose were 8.5% by mass of cellulose, 5.7% by mass of sodium hydroxide, and 2.8% by mass of carbon disulfide.
Immediately before spinning viscose, the aqueous dispersion obtained in the above step is added quantitatively and continuously using an injection pump so that the ratio of the activated carbon powder to the cellulose content is 33.3 mass%. Then, the viscose and the activated carbon powder were uniformly mixed. Viscose blended with activated carbon powder was fiberized by a two-bath tension spinning method. At this time, spinning was performed from a spinneret having a nozzle diameter of 0.09 mm and a hole number of 4000 at a spinning speed of 50 m / min, and sent to a coagulation / regeneration bath. As the coagulation / regeneration bath, a Mueller bath (50 ° C.) having a composition of sulfuric acid: 100 g / liter, zinc sulfate: 15 g / liter, sodium sulfate: 350 g / liter was used.

A viscose rayon yarn obtained by fiberizing viscose was cut into 51 mm and subjected to hot water treatment, water flow treatment, and water washing treatment in order, and scoured. After scouring, excess water was removed from the fiber with a compression roller, and then dried at 60 ° C. for 7 hours to obtain fiber A2 according to Example 7.
Example 8
A fiber B2 according to Example 8 is obtained in the same manner as in Example 7, except that the aqueous dispersion is added to the viscose so that the ratio of the activated carbon powder to the cellulose content is 25.0% by mass. It was.

Example 9
A fiber C2 according to Example 9 is obtained in the same manner as in Example 7 except that the addition of the aqueous dispersion to the viscose is performed so that the ratio of the activated carbon powder to the cellulose content is 17.6% by mass. It was.
Example 10
A fiber D2 according to Example 10 was obtained in the same manner as in Example 7 except that the concentration of the activated carbon powder in the aqueous dispersion added to the viscose was 10.0% by mass.
Example 11
As an aqueous dispersion to be added to the viscose, activated carbon powder and naphthalenesulfonic acid / formalin condensate soda are dispersed in water so that the concentration of the activated carbon powder becomes 10% by mass, and then wet mill (Dyno Mill KDL- Example 11 is the same as Example 7 except that PILOT (manufactured by Shinmaru Enterprises Co., Ltd.) was used and the wet mill was passed 10 times at a flow rate of 20 liters / minute. Fiber E2 was obtained.

Example 12
A fiber F2 according to Example 12 is obtained in the same manner as in Example 11 except that the aqueous dispersion is added to the viscose so that the ratio of the activated carbon powder to the cellulose content is 17.6% by mass. It was.
Example 13
Activated carbon made from Akamatsu is used as the activated carbon, and activated carbon powder and naphthalene sulfonic acid / formalin condensate soda are dispersed in water as an aqueous dispersion to be added to the viscose so that the concentration of the activated carbon powder is 18% by mass. Then, using the wet pulverizer (Dyno Mill KDL-PILOT, manufactured by Shinmaru Enterprises Co., Ltd.), except that the sample was passed through the wet pulverizer 15 times at a flow rate of 20 liters / min. In the same manner as in Example 7, a fiber G2 according to Example 13 was obtained.

Example 14
Activated carbon made from Akamatsu is used as the activated carbon, and activated carbon powder and naphthalene sulfonic acid / formalin condensate soda are dispersed in water as an aqueous dispersion to be added to the viscose so that the concentration of the activated carbon powder is 18% by mass. After that, using a wet pulverizer (Dyno Mill KDL-PILOT, manufactured by Shinmaru Enterprises Co., Ltd.), using a pulverizer that has been passed through the wet pulverizer 15 times at a flow rate of 20 liters / minute, to viscose A fiber H2 according to Example 14 was obtained in the same manner as in Example 7, except that the aqueous dispersion was added so that the ratio of the activated carbon powder to the cellulose content was 50.0% by mass.

Example 15
Activated carbon made from Akamatsu is used as the activated carbon, and activated carbon powder and naphthalene sulfonic acid / formalin condensate soda are dispersed in water as an aqueous dispersion to be added to the viscose so that the concentration of the activated carbon powder is 18% by mass. After that, using a wet pulverizer (Dyno Mill KDL-PILOT, manufactured by Shinmaru Enterprises Co., Ltd.), using a pulverizer that has been passed through the wet pulverizer 20 times at a flow rate of 20 liters / minute, to viscose A fiber I2 according to Example 15 was obtained in the same manner as in Example 7, except that the aqueous dispersion was added so that the ratio of the activated carbon powder to the cellulose content was 42.9% by mass.

Example 16
Activated carbon made from Akamatsu is used as the activated carbon, and activated carbon powder and naphthalene sulfonic acid / formalin condensate soda are dispersed in water as an aqueous dispersion to be added to the viscose so that the concentration of the activated carbon powder is 18% by mass. After that, using a wet pulverizer (Dyno Mill KDL-PILOT, manufactured by Shinmaru Enterprises Co., Ltd.), using a material that was passed through the wet pulverizer 8 times at a flow rate of 20 liters / minute, to viscose A fiber J2 according to Example 16 was obtained in the same manner as in Example 7, except that the aqueous dispersion was added so that the ratio of the activated carbon powder to the cellulose content was 42.9% by mass.

[Comparative Example 6]
As an aqueous dispersion to be added to the viscose, activated carbon powder and naphthalenesulfonic acid / formalin condensate soda are dispersed in water so that the concentration of the activated carbon powder becomes 10% by mass, and then wet mill (Dyno Mill KDL- PILOT (manufactured by Shinmaru Enterprises Co., Ltd.) using activated pulverized water for 10 minutes at a flow rate of 20 liters / minute, and addition of water dispersion to viscose activated carbon powder for cellulose The fiber K2 concerning the comparative example 6 was obtained like Example 7 except having performed so that the ratio might be 10.0 mass%.
[Comparative Example 7]
As an aqueous dispersion to be added to the viscose, activated carbon powder and naphthalenesulfonic acid / formalin condensate soda are dispersed in water so that the activated carbon powder has a concentration of 18% by mass, and then wet mill (Dyno Mill KDL- Comparative Example 7 was performed in the same manner as Example 7 except that PILOT (manufactured by Shinmaru Enterprises Co., Ltd.) was used and a wet pulverizer was passed 15 times at a flow rate of 20 liters / minute. Fiber L2 was obtained.

[Comparative Example 8]
As an aqueous dispersion to be added to the viscose, activated carbon powder and naphthalenesulfonic acid / formalin condensate soda are dispersed in water so that the activated carbon powder has a concentration of 18% by mass, and then wet mill (Dyno Mill KDL- Comparative example 8 is applied in the same manner as in Example 7 except that a PILOT (manufactured by Shinmaru Enterprises Co., Ltd.) is used and a wet pulverizer is passed three times at a flow rate of 20 liters / minute. Fiber M2 was obtained.
[Performance of each fiber]
<Evaluation of fiber properties>
About each fiber A2-M2 concerning each Example and a comparative example, the fiber physical property was measured according to the above-mentioned measuring method. The results of the fiber physical properties of each fiber are shown in Table 5 together with the particle diameter of the activated carbon powder contained in each fiber, the number of activated carbon particles in the fiber, the concentration of the aqueous dispersion used, and the content ratio of the activated carbon powder in the fiber. .

<Evaluation of VOC adsorption>
Next, about each fiber A2-M2, according to the above-mentioned measuring method, toluene adsorptivity (initial performance), the presence or absence of dropout in the dropout test, and the toluene adsorptivity after the dropout test were measured. The results are also shown in Table 5.

[Discussion]
(1) Looking at Table 5, each of the fibers A2 to J2 according to the example had 0 particles with a particle diameter exceeding 2.2 μm included in the fiber cross section. It has been demonstrated that not only the diameter was 2.2 μm or less, but even after fiberization, the maximum particle diameter did not exceed 2.2 μm due to secondary particle formation.
(2) From Table 5, it was found that any of the fibers A2 to J2 of the examples had a fiber capacity that the fibers could withstand practically.
(3) Moreover, from Table 5, in the fiber K2 concerning the comparative example 5 whose ratio of the activated carbon powder with respect to the cellulose content in a fiber is 10.0 mass%, toluene adsorption capacity is from each fiber A2-J2 concerning an Example. Was found to be significantly inferior.

  (4) The average particle size of the activated carbon powder is within the range of the present invention, but the maximum particle size is outside the range of the present invention, the fiber L2 according to Comparative Example 6, and the maximum particle size of the activated carbon powder is the present invention. Although the average particle diameter is outside the range of the present invention, the fiber M2 according to Comparative Example 7 is compared with the fiber A2 according to Example 7 manufactured under substantially the same conditions except for the conditions related to the particle diameter. Then, although it is not a remarkable difference as the difference seen between the Example and the comparative example in the above-mentioned activated charcoal, it turns out that fiber L2 and fiber M2 are still inferior to initial performance rather than fiber A2. . Further, it was found that these fibers L2 and fibers M2 were frequently dropped in the dropout test, and the toluene adsorption performance was also lowered. Therefore, in order to obtain an activated carbon-containing fiber having a VOC adsorption performance that is stable over time by preventing dropout, both the average particle size and the maximum particle size of the activated carbon powder must satisfy the conditions of the present invention. I understood.

  The charcoal-containing fiber and the method for producing the charcoal according to the present invention can be suitably used as, for example, various performances possessed by charcoal, in particular, various clothing items, bedding products, and household items that are also excellent in VOC adsorption.

Claims (10)

In the rayon fiber containing charcoal powder, the charcoal powder has an average particle size of 1.2 μm or less, a maximum particle size of 2.2 μm or less, and 80% or more of which has a particle size of 1 μm or less. A charcoal-containing fiber that is particles and has a VOC adsorptivity that is 15% by mass or more with respect to the cellulose content.   The charcoal-containing fiber according to claim 1, wherein a ratio of the charcoal powder to a cellulose content is 50% by mass or less.   The charcoal-containing fiber according to claim 1, wherein a ratio of the charcoal powder to a cellulose content is 38% by mass or less. The charcoal-containing fiber according to any one of claims 1 to 3 , wherein an average particle size of the charcoal powder is 0.2 µm or more. The charcoal-containing fiber according to any one of claims 1 to 4 , wherein a maximum particle size of the charcoal powder is 2.0 µm or less.   The charcoal-containing fiber according to any one of claims 1 to 5, wherein the charcoal is charcoal, and an average particle diameter of the powder is 0.65 µm or less.   The charcoal-containing fiber according to claim 6, wherein the charcoal is activated charcoal.   The charcoal-containing fiber according to any one of claims 1 to 5, wherein the charcoal is activated carbon. Average particle diameter of 1.2μm or less, the maximum particle diameter of Ri der less 2.2 .mu.m, and 5 to 25 mass flour Oh Ru charcoal 80% or more of the following particle diameter 1μm dispersed in water The aqueous dispersion and viscose are mixed so that the ratio of the charcoal powder to the cellulose content is 15% by mass or more, and the mixture is spun. The manufacturing method of the charcoal containing fiber in any one of to.   The method for producing charcoal-containing fibers according to claim 9, wherein the charcoal powder is obtained by dry-pulverizing charcoal and then wet-pulverizing the charcoal.