JP3504096B2 - Spinning solution for tin oxide fiber and method for producing tin oxide fiber - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tin oxide fiber and a method for producing a tin oxide fiber spinning solution used for producing the same.

[0002]

2. Description of the Related Art Tin oxide has excellent chemical resistance and heat resistance,
Moreover, it is an excellent material capable of controlling conductivity in a wide range and is used for various purposes. Recently, research is also progressing as a third-order nonlinear optical material.

In a gas sensor, it has been strongly desired to provide tin oxide in a fiber shape from the viewpoint of improving sensitivity and response speed. Further, carbon fibers and the like have been added for the purpose of imparting conductivity to polymer materials,
When carbon is used, there are problems that the material itself cannot be brightened because it is black and that it is very light and easily scatters. For this reason, it has been practiced to add powders of metal fibers and metal oxides. Although metal fibers have high conductivity, they have the drawback that their surface is oxidized or corroded over a long period of time to lower their conductivity. In addition, the conductivity of conventional metal oxide powders is not as high as that of metal fibers, so in order to impart conductivity to polymer materials, a relatively large amount must be added, and the physical properties inherent in polymer materials deteriorate. There was a drawback that caused it. Even tin oxide, which has excellent chemical resistance and heat resistance, has been attempted to be added in the form of powder that imparts conductivity. By the way, it is known that the effect of imparting conductivity increases as the aspect ratio of the conductivity imparting material increases. For this reason, it has been required to make tin oxide having conductivity into a fiber.

However, it has been difficult to manufacture fibers by the conventional solid-phase reaction method. Therefore, JP-A-60-5997, JP-A-60-161337, and JP-A-60-158199 propose methods for producing tin oxide fibers by a melt precipitation method. However, since these methods require a high temperature of 1000 ° C. or more and a reaction time of many days, it is possible to produce a very small amount on a laboratory scale, but it has not been industrially produced yet. . Moreover, the shape of the obtained tin oxide fiber is 1 μm or less in diameter and 3 in length.
When it is used as a composite material, there is a problem that its function cannot be sufficiently exerted and its application is limited because the aspect ratio is small when it is less than or equal to mm and the cross section is often rectangular. Furthermore, since the major axis is too small, it is difficult to produce a paper-like material. Further, in order to enhance the reproducibility of physical properties such as conductivity of the obtained composite material, it is important to control the shape and size of the tin oxide whiskers to be added with good reproducibility. However, since it is actually difficult to control the shape of tin oxide whiskers, if the fiber diameter and length of the added tin oxide were to be made uniform, it was only possible to classify what was accidentally produced. Therefore, the whiskers produced by such an inefficient method are extremely expensive and practically unusable.

The present inventors have found that when a solution containing a tin compound and an alcohol as a main component is used, the spinnability is surprisingly exhibited. By spinning and heating the solution, it is easily oxidized at a very low cost. It was found that a tin fiber can be obtained, and it has already been proposed (JP-A-4-35287, JP-A-5-35287).
-117906, JP-A-5-179512).

[0006]

The above method is an industrially excellent method, but there has been a demand for an efficient production method using a spinning solution for tin oxide fiber, which is further excellent in spinnability.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have succeeded in solving the above problems by simply using metallic tin without using expensive tin compounds such as tin halide. It was found that a tin oxide fiber spinning solution having excellent properties was obtained, and that tin oxide fiber was obtained by spinning the spinning solution and subjecting it to heat treatment, and completed the present invention.

That is, the present invention is a method for producing a tin oxide fiber spinning solution, which comprises dissolving metal tin in an organic solvent in the presence of hydrogen halide, and then concentrating the solution.

Another invention is characterized in that when metal tin is dissolved in an organic solvent in the presence of hydrogen halide, air or oxygen is blown into the liquid phase to dissolve the metal tin and then the metal tin is concentrated. It is a method for producing a spinning solution for tin oxide fiber.

Still another invention is a method for producing tin oxide fibers, characterized in that the spinning solution for tin oxide fibers obtained by the above-mentioned production method is spun and then heat-treated.

Next, the present invention will be described more specifically.

The shape of metallic tin used in the present invention is not particularly limited, and may be plate-like, rod-like, sheet-like, granular, powder-like, sand-like,
Examples thereof include flower-like ones, and from the viewpoint of easy dissolution, granular, powdery, and sandy ones are preferable. The higher the purity, the better, but it may be appropriately determined depending on the use of the tin oxide fiber. Generally, it is not particularly limited as long as it does not affect the production method and does not affect the specific resistance and mechanical strength described later, but when the obtained tin oxide fiber is used as a material for a lead storage battery, Metal tin that does not contain an element that causes a side reaction other than the reaction is preferable. For example, when the battery is a lead storage battery, metal tin that does not contain impurities such as hydrogen and oxygen overvoltage, such as iron and nickel, is preferable.

As a solvent for dissolving the metal tin,
It is not particularly limited as long as it dissolves metal tin in the presence of hydrogen halide described below, but generally alcohol,
Examples thereof include organic solvents such as acetone and mixed solutions of these organic solvents and water.

The alcohol represented by the general formula ROH is R
Is an unsubstituted alkyl group such as methyl group, ethyl group, propyl group, butyl group, octyl group, 2-methoxyethyl group, 2
-Ethoxyethyl group, 2-hydroxyethyl group, 1-methoxy-2-propyl group, methoxyethoxyethyl group,
Examples thereof include substituted alkyl groups such as 2-phenylethyl group and phenylmethyl group, unsubstituted alkenyl groups such as allyl group, and substituted alkenyl groups such as 2-methyl-2-propenyl group and 3-methyl-3-butenyl group.

Specific examples of the substituent in the above-mentioned substituted alkyl group, substituted alkenyl group or substituted aryl group include alkoxy groups such as methoxy group and ethoxy group, hydroxyl group, phenyl group and the like which are found in the above-mentioned specific examples of R. In addition to the aryl group, the alkyl group such as a methyl group and an ethyl group, a halogen atom such as an amino group, a cyano group, a Cl atom, a Br atom, an I atom and an F atom.

Specific examples of these alcohols include methyl alcohol, ethyl alcohol, propyl alcohol,
Butyl alcohol, octyl alcohol, 2-methoxyethanol, 2-ethoxyethanol, ethylene glycol, 1-methoxy-2-propyl alcohol, methoxyethoxyethanol, 2-phenylethyl alcohol, benzyl alcohol, allyl alcohol, 2-methyl-2-propene-1. -Ol, 3-methyl-3-butene-1-ol and the like. In particular, methyl alcohol and ethyl alcohol are preferable because they have high solubility of metallic tin. The above alcohols are usually used alone, but a mixture of two or more kinds of alcohols can be used in order to control the reactivity with metal tin, the solubility, or the like.

When a mixed solvent of the above organic solvent and water is used, the amount of water is preferably 4.0 or less, more preferably 3.5 or less in terms of molar ratio with respect to metal tin.

The mixing ratio of the metal tin and the solvent is not particularly limited as long as the metal tin and the solvent are uniformly dissolved in the solvent. However, if the proportion of metallic tin is too low, it does not show spinnability, so it needs to be concentrated considerably, and the solvent is wasted. Further, if the amount of metallic tin is too high, it may take a long time for dissolution or precipitation may occur, whereby a uniform spinning solution may not be obtained. Therefore, the mixing ratio varies depending on the type of the solvent, but generally, the mixing ratio of metallic tin to the solvent is preferably 0.01 to 0.5 in terms of molar ratio. After mixing in this ratio to form a transparent and uniform solution, a solvent such as alcohol is further evaporated and concentrated to obtain a tin oxide fiber spinning solution having a desired viscosity.

Metal tin is simply added to the solvent and stirred.
Even if it is attempted to dissolve it, it may take a long time, or it may hardly dissolve. Therefore, it is necessary to allow hydrogen halide to exist when the metal tin is dissolved. The method for allowing hydrogen halide to exist is not particularly limited. It is possible to employ a method in which hydrogen halide is previously blown and dissolved in a solvent such as alcohol, or a method in which metallic tin is dissolved while blowing hydrogen halide. The method of blowing hydrogen halide is not particularly limited, but it is preferable to make fine bubbles to increase the area of contact with the solvent and blow it to the bottom of the organic solvent in the container to prolong the contact time. As hydrogen halide,
Examples thereof include hydrogen chloride, hydrogen bromide, hydrogen fluoride and the like, with hydrogen chloride being preferred from the viewpoint of price and ease of handling.

The amount of hydrogen halide to be blown is such that the amount of dissolved hydrogen halide is the atomic ratio [X / (Sn + M)] (wherein X, Sn, and M are halogen, tin, and It represents the number of atoms of Group V element of the periodic table, and M can be zero}, and it is preferable to control so as to be 0.6 to 2.0, and more preferably 0.6 to 2.0.
It is 1.5. The larger the atomic ratio [X / (Sn + M)] is, the more easily the metallic tin is dissolved, but if it is too large, the gel fiber obtained by spinning the obtained tin oxide fiber spinning solution has high hygroscopicity and is difficult to dry. . Further, if it is less than the above range, it may take a long time to dissolve the metal tin, and precipitation may occur depending on the mixing ratio of the metal tin and the solution.

The method of measuring the number of each atom for obtaining the above [X / (Sn + M)] ratio is not particularly limited, and a known method can be adopted. As a specific example, the method for measuring the amount of halogen includes ion chromatography, and when the halogen is chlorine, silver nitrate titration and the like can be mentioned. As the method for measuring tin and the group V element of the periodic table described later, plasma emission analysis and the like Can be mentioned.

In the present invention, it is more effective to blow oxygen or air into the liquid phase when the metallic tin is dissolved. JP-A-58-185436 proposes blowing air when dissolving stannous chloride. This is said to be effective for preventing the resulting solution from becoming cloudy over a long period of time and for dissolving stannous chloride in a short time. However, the problem in the present invention is how to dissolve metallic tin rather than stannous chloride. As a result of various studies, the present inventors have found that when oxygen or air is present in the solvent, metallic tin dissolves in a short time. The reason for this cannot be fully explained by the present inventors, but since metallic tin is a metal having a high hydrogen overvoltage, the remaining electrons generated when metallic tin changes from 0-valent to 2-valent or 4-valent, It is also presumed that the reaction that water receives and becomes hydrogen is difficult to proceed on metallic tin. In this case, it is considered that the metal tin is difficult to dissolve because electrons are not consumed. It may also be related to the fact that the solvent is mainly composed of an organic solvent. Therefore, if oxygen is present in the solution, it is presumed that the oxygen is more likely to dissolve because the reaction of consuming the electrons generated when the metal tin is dissolved is likely to occur.

The method of absorbing oxygen or air in the solvent is not particularly limited, but a method of forming the solvent in the form of droplets or a liquid film and dispersing it in oxygen or air to absorb it, or a liquid phase containing oxygen or air in the solvent It is possible to use a method in which the solvent is blown in to be dispersed and absorbed, but the latter method is preferable because metallic tin is contained in the solvent.
The method and apparatus for blowing oxygen or air into the liquid phase composed of the solvent are not particularly limited, and known ones can be adopted, but they are blown into the bottom of the liquid phase in the container by forming fine bubbles to increase the area in contact with the solvent. It is preferable to lengthen the contact time because the dissolution operation time can be shortened. To specifically exemplify these methods, a method in which oxygen or air filled in a cylinder is blown into a solvent in the form of small bubbles through a tube having a glass filter at the tip can be used in the laboratory. Industrially, a bubble column, a bubble stirring tank or the like can be used.

The amount of oxygen or air blown in varies greatly depending on the amount of metal tin to be dissolved and the amount of solvent, and therefore cannot be uniquely determined, but usually the volume ratio to the solvent is 1 / 2-1 / 1 / min. A rule of thumb is to run 200. Further, the blowing operation is generally performed continuously before and after the metallic tin is put into the solvent until the metallic tin is completely dissolved, but it may be intermittently performed while observing the dissolved state. .

In the present invention, in order to carry out spinning stably and to enhance the mechanical strength and stability of the obtained fiber, silicon, aluminum, germanium,
Titanium, zirconium, magnesium, boron (hereinafter,
(Although sometimes collectively referred to as the second element) alkoxide,
A soluble metal compound such as a halide, an oxychloride, a nitrate, a sulfate, or a phosphate (hereinafter sometimes referred to as a soluble metal compound) may be added to the tin oxide fiber spinning solution. If the acetate salt is also soluble, it can be used.

The amount of the soluble metal compound added is determined by spinning,
The oxide of the second element in the final form produced by the heat treatment may be calculated and determined in advance so that the composition ratio falls within the above range. Usually, the calculated value from the used raw material molar ratio agrees with the molar ratio of the oxide of the second element in the tin oxide fiber.

Examples of the soluble metal compound of silicon include silicon alkoxide and silicon halide. As the silicon alkoxide, the general formula Si (OR
Silicon alkoxides represented by _A ) ₄ , R _B Si (OR _A ) ₃ and R _B R _C Si (OR _A ) ₂ are used. Where R
_A , R _B , and R _C are each a linear or branched alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group; and a direct group such as an ethenyl group, a propenyl group, a butenyl group, and a pentenyl group. A chain or branched alkenyl group; an aryl group such as a phenyl group is shown. Specific examples of silicon alkoxides include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, phenyltrimethoxysilane, propyltrimethoxysilane, and n-butyltrimethoxy. Silane, isobutyltrimethoxysilane, n-hexyltrimethoxysilane, n-octadecyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, amyltriethoxysilane, phenyltriethoxysilane,
n-octyltriethoxysilane, n-octadecyltriethoxysilane, n-dodecyltriethoxysilane,
Methyltributoxysilane, ethyltributoxysilane, ethyltripropoxysilane, vinyltriethoxysilane, allyltriethoxysilane, diphenyldimethoxysilane, dimethyldiethoxysilane, vinylmethyldiethoxysilane, diethyldimethoxysilane, ethylmethyldiethoxysilane, etc. Is mentioned. Examples of silicon halides include SiCl ₄ , SiHCl ₃ , and SiH ₂ Cl ₂ .

Examples of soluble metal compounds of aluminum include AlCl ₃ , AlCl ₃ .6H ₂ O and AlB.
_{r 3, AlBr 3 · 6H 2} O, AlI 3, AlI 3 · 6H
_{2 O, Al (NO 3)} 3 · 9H 2 O, Al (NO 3) 3 · 6H
Examples include aluminum alkoxides such as ₂ O and aluminum isopropoxide.

Examples of the soluble metal compound of germanium include germanium alkoxides such as GeCl ₄ , GeBr ₂ , GeBr ₄ , and tetraethoxygermanium, and the soluble metal compound of titanium includes TiC.
l ₄ , TiCl ₃ , TiCl ₂ , TiBr ₄ , TiBr ₄ ·
6H ₂ O, TiF ₄ , titanium alkoxides such as tetraisopropoxy titanium, and the like. Soluble metal compounds _{Jirukonimu, ZrCl 4, Zr (NO 3} ) 4 · 5
_{H 2 O, ZrOCl 2 · 8H} 2 O, ZrOI 2 · 8H 2 O,
Zirconium alkoxides such as tetrabutoxy zirconium may be mentioned, and as the soluble metal compound of magnesium, MgCl ₂ .6H ₂ O, MgBr ₂ .6H ₂ O, Mg
(NO ₃ ) ₂ · nH ₂ O, magnesium alkoxide and the like can be mentioned. H ₂ is a soluble metal compound of boron.
Examples thereof include boron alkoxides such as B ₄ O ₇ , H ₃ BO ₃ , HBF ₄ , BBr ₂ , and trimethoxyboron.

When a halide is used as the soluble metal compound, it must be adjusted in consideration of the halogen derived from the soluble metal compound as the halogen of [X / (Sn + M)].

The soluble metal compound does not have to be the compound from the beginning, but may be the compound in the solution in the initial stage. For example, in the case of aluminum halide, metal aluminum may be added to the solution and hydrogen halide may be blown into the solution to partially halogenate it.

When the soluble metal compound is a zirconium compound, the tetragonal crystal or cubic crystal of zirconium oxide formed in the tin oxide fiber is stabilized or meta-stabilized to increase the strength and oxygen ion conductivity. In order to contain calcium oxide, alkaline earth oxides such as magnesium oxide, yttrium oxide, cerium oxide, neodymium oxide, samarium oxide, gadolinium oxide, europium oxide, and rare earth oxides such as scandium oxide, these elements are used as raw materials. Soluble raw materials such as alkoxides, chlorides, oxychlorides, nitrates, sulfates, or acetates can be used.

By adding the soluble metal compound to the tin oxide fiber spinning solution, it is possible to spin a fiber having a large major axis relatively stably even in a high humidity atmosphere. Further, the gel fiber immediately after spinning is less likely to be softened and crumbled, which makes the handling very easy. Furthermore, the mechanical strength and stability of the finally obtained fiber are improved.

Although tin oxide exists in either an amorphous or crystalline form depending on the heat treatment temperature, the crystalline form is preferable in order to obtain a highly conductive one. Further, the soluble metal compound becomes an oxide of the second element by the heat treatment described later. It is presumed that tin oxide exists as a solid solution of a part of the oxide of the second element, and most of it is contained in the form of a mixture. In the case of solid solution, the second element substitutes for a tin atom in tin oxide or penetrates into the crystal structure of tin oxide and exists, but in this case also, it is expressed here as being contained only in the form of an oxide. Sometimes. In addition, even when it exists in the form of a mixture without solid solution, the second element,
Most of the materials that are heat-treated in an atmosphere containing oxygen are oxides, but some may be contained without being oxidized.

The components of the oxides of the second element such as silica, aluminum oxide, zirconium oxide, magnesium oxide and boron oxide are mostly in the form of a mixture in tin oxide, except for a very small amount which forms a solid solution in tin oxide. It is presumed that they exist dispersedly in. In the case of germanium oxide and titanium oxide, the range of solid solution becomes wider. Also, about 16 to about 82 mol%, or about 12 to about 86 mol%.
When titanium oxide (the range is slightly different depending on the reporter) was added, spinodal decomposition separated tin oxide-rich solid solution and titanium oxide-rich solid solution, and both phases were complexed with a microstructure. Presumed to exist. As a result, besides improving the mechanical strength,
It is promising as a novel fibrous capacitor material and a semiconductor material such as a gas sensor element.

The oxides of the above-mentioned second elements may be contained individually, or a plurality of them may be contained at the same time. The content of the component is not particularly limited and may be appropriately determined according to the purpose. Particularly when it is desired to increase the tensile strength and the like, it is effective to contain a large amount of the component. Usually, tin oxide is 20 to 98 mol%, and the oxide of the second element is 2 to 80 mol%. The composition ratio of the oxide of the second element in the tin oxide fiber can be confirmed by chemical analysis or X-ray fluorescence analysis, but it usually does not differ greatly from that calculated by theoretical calculation from the raw material ratio. When the raw material ratio is clear, it can be calculated from the raw material ratio.

In the present invention, a soluble polymer compound may be added to the tin oxide fiber spinning solution in order to enable high-speed spinning. As such a high molecular compound, any soluble high molecular compound can be used without any limitation. Specific examples include celluloses such as ethyl cellulose, cellulose acetate, cellulose nitrate, cellulose propionate, cellulose triacetate, acetyl butyl cellulose and hydroxyl propyl cellulose, polyvinyl butyral, polymethylene oxide, polyethylene oxide, polypropylene oxide, polyacetic acid. Vinyl etc. are mentioned. The addition amount of these soluble polymer compounds is 0.0 with respect to the metal tin.
1 to 20% by weight is preferable. If the amount of the soluble polymer compound added is less than 0.01% by weight, a sufficient effect cannot be obtained. On the other hand, if the amount exceeds 20% by weight, the effect is not only saturated, but also when the spun gel fiber is heat-treated, the amount of carbon and carbon dioxide gas generated increases and it is difficult to remove it. Porosity is generated, which is not preferable.

In the present invention, in order to obtain a tin oxide fiber having high conductivity, a soluble group V compound (hereinafter referred to as a group V compound) of the periodic table is contained in the spinning solution for tin oxide fiber, if necessary. Can be made. The Group V compound is finally converted into an oxide by the heat treatment described later and is dissolved as a solid solution in tin oxide or exists as a mixture.

Examples of the Group V compound include compounds of Group V elements such as vanadium compounds, niobium compounds, tantalum compounds, antimony compounds, and bismuth compounds. These compounds need to be soluble in an organic solvent such as alcohol, but when the above-mentioned hydrogen halide is dissolved in the solution, even a simple substance such as antimony may be dissolved. Such a simple substance can also be used.

Specifically, as the vanadium compound, V
Br ₃ , VCl ₂ , VCl ₃ , VCl ₄ , VOBr ₂ , VO
Br ₃ , VOCl ₃ , VF ₃ , VF ₄ , VF ₅ , VI ₃ 6H ₂
Examples of the niobium compound include NbCl ₅ , NbBr ₅ , NbF ₅ , and NbOC.
l ₃ , alkoxides of niobium, tantalum compounds such as TaBr ₅ , TaCl ₅ and tantalum alkoxides, and antimony compounds such as SbCl ₃ and SbC.
Examples include l ₅ , SbBr ₃ , antimony oxychloride, or antimony alkoxide, and examples of the bismuth compound include BiCl ₃ , BiI ₃ , and bismuth alkoxide.

The mixing ratio of the Group V compound is determined based on the calculated amount of the Group V element oxide in the tin oxide fiber in consideration of the desired conductivity.

When a halide is used as the Group V compound, the halogen derived from the Group V element must be taken into consideration as the halogen of [X / (Sn + M)] described above.

The method of dissolving the metal tin, hydrogen halide, the soluble metal compound, the soluble polymer compound, the soluble group V compound and the solvent such as alcohol is not particularly limited. For example, a method of dissolving metal tin, a soluble metal compound, a soluble polymer compound, and a soluble Group V compound simultaneously or sequentially in a solvent such as alcohol while blowing hydrogen halide under stirring can be used. The temperature condition at the time of dissolution is not particularly limited, and is usually room temperature to
Although it is carried out within the boiling temperature range of the solvent, it is also effective to reflux the solvent in order to promote the dissolution.

In order to further improve the stability of the tin oxide fiber spinning solution of the present invention, acetylacetone,
A compound having two or more carboxyl groups such as ethyl acetoacetate and diethyl malonate, or an organic acid such as tartaric acid, succinic acid, and lactic acid may be appropriately contained as a tin complexing agent, and spinnability is further improved. It is also possible to add compounds for increasing the amount.

The spinning method is not particularly limited, and a conventional spinning method can be used. For example, a method of extruding a tin oxide fiber spinning solution from a spinning nozzle may be used. The major axis, the diameter, etc. of the obtained fiber can be arbitrarily controlled by adjusting the viscosity of the spinning solution, the nozzle diameter, the speed at which the spinning solution is extruded from the spinning nozzle, and the like.

The heat treatment of the gel fiber removes an organic solvent such as alcohol or water from the gel fiber to strengthen the skeleton of the fiber, and in some cases,
It is carried out at a temperature for further crystallization. The gel fiber as-spun from the spinning solution for tin oxide fiber does not show sufficient mechanical strength as it is. The mechanical strength is developed by heating the gel fiber. The heat treatment temperature is not particularly limited as long as it is within a temperature range capable of imparting mechanical strength to the obtained fiber. When the heat treatment temperature is low, a solvent such as alcohol, water, etc. remains in the fiber, so that sufficient mechanical strength does not occur. Also, if the heat treatment temperature is too high, the decomposition of tin oxide proceeds,
Alternatively, there arises a problem that the crystal grains in the fiber grow too much and the strength decreases. For the above reason, the heat treatment temperature is preferably in the range of 250 to 1550 ° C. More preferably, heat treatment at a temperature of 300 to 1500 ° C. is preferable.

When it is desired to add the Group V compound to improve the conductivity of the obtained fiber, the heat treatment is also necessary. The gel fiber as it is spun from the tin oxide fiber spinning solution is an insulator as it is, and the conductivity is exhibited by heating the gel fiber. The heat treatment temperature is not particularly limited as long as it is within a temperature range capable of imparting conductivity to the obtained fiber. Generally, when the heat treatment temperature is low, organic substances such as alcohols and other organic solvents, water, etc. remain in the fiber, and the Group V compound does not form an oxide and does not form a solid solution with tin oxide. Therefore, conductivity does not occur. If the heat treatment temperature is too high, the group V compound in the fiber is volatilized to lower the conductivity, the decomposition of tin oxide proceeds, the crystal grains in the fiber grow too much, and the strength decreases. Occurs.
Therefore, the heat treatment temperature is preferably in the temperature range of 250 ° C to 1550 ° C. More preferably, the temperature is 300 ° C to 15 ° C.
It is preferable to perform heat treatment at a temperature of 00 ° C.

The heat treatment is usually carried out in air, but when it is desired to obtain a fiber having particularly high conductivity, the heat treatment is carried out in a reducing atmosphere such as nitrogen, argon, hydrogen, or a mixed gas of argon and hydrogen, or in vacuum. Processing can be performed.

Further, during the heat treatment, the volatile components of the organic solvent such as water and alcohol existing in the gel fiber are
Removal by drying is desirable to obtain good tin oxide fibers. Such drying may be performed at the same time as the heat treatment, but it is preferable to perform the drying before the heat treatment in order to obtain a good fiber. In these cases, the drying temperature is preferably as low as possible in order to prevent the occurrence of cracks in the obtained fiber, but when a solvent having a high boiling point is used as the solvent, it is too low. It takes a long time to dry and is not effective. Generally, the drying temperature is preferably in the range of room temperature to 300 ° C.

The specific resistance value of the tin oxide fiber obtained from the spinning solution for tin oxide fiber containing the Group V compound varies greatly depending on the kind of the Group V compound, the addition amount, the firing atmosphere, the firing temperature, etc. 10 ³ to 10 ^-1
A value of Ω · cm can be taken. A value of 10 ⁻⁴ Ω · cm can be obtained by firing in a reducing atmosphere.

The tin oxide fiber obtained by the present invention may be crystalline or amorphous.
From the viewpoint of conductivity, crystalline is preferable.

[0052]

According to the method of the present invention, a spin liquid for tin oxide fiber having excellent spinnability can be obtained even when inexpensive metal tin is used, and the spin liquid is spun and then heat-treated to form tin oxide. An industrial method for producing fibers has been established.

[0053]

EXAMPLES The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Metal tin 474.8 was added to 2046 g of a methanol solution in which hydrogen chloride was blown to adjust the hydrogen chloride concentration to 6.0 wt%.
When g (4.0 mol) was added and the mixture was stirred without blowing oxygen and air, metallic tin was completely dissolved in 10 days. Then, antimony trichloride (SbCl ₃ ) 48.1
g (0.211 mol) and tetraethoxysilane 92.5
g (0.444 mol) was added and dissolved. As a result of measuring the amount of chlorine ions by ion chromatography and measuring the amounts of tin and antimony by plasma emission analysis,
The atomic ratio [X / (Sn + Sb)] was 0.95. This solution was concentrated to prepare a highly viscous spinning solution. The spinning solution was extruded from the nozzle by applying pressure and continuously wound on a drum. After leaving the obtained gel fiber at room temperature for 1 day, the temperature was raised to 400 ° C. at a rate of 1 ° C./min, and then to 800 ° C. at a rate of 2 ° C./min, and the temperature was set to 1 ° C.
It was held for 20 minutes for heat treatment. The obtained fiber had an average diameter of 30 μm, and it was confirmed by fluorescent X-ray analysis that antimony and silica were present in the fiber according to the charged composition. Further, as a result of X-ray diffraction, it was confirmed that it had a peak of tin oxide, and that the peak of antimony was not found in the oxide thereof and was dissolved in tin oxide. The specific resistance of the obtained fiber was 1 Ω · cm on average. The tensile strength of the fiber was 40 MPa on average. The gel fiber immediately after spinning was left for 2 hours in an atmosphere of relative humidity of 85%, but the fiber shape was maintained without softening.

Example 2 Metal tin 474.8 was added to 2046 g of a methanol solution having hydrogen chloride concentration adjusted to 6.0 wt% by blowing hydrogen chloride.
g (4.0 mol) was added, and the mixture was stirred while blowing 200 ml / min of oxygen gas through a tube equipped with a glass filter at the tip. Metal tin was completely dissolved in 24 hours. After that, antimony trichloride (SbCl ₃ ) 4
8.1 g (0.211 mol) and tetraethoxysilane 9
2.5 g (0.444 mol) was added and dissolved. As a result of analysis in the same manner as in Example 1, [X / (Sn + Sb)] was 0.95. This solution was concentrated to prepare a highly viscous spinning solution. The spinning solution was extruded from the nozzle by applying pressure and continuously wound on a drum. The obtained gel fiber was heat-treated under the same conditions as in Example 1.
The obtained fiber had an average diameter of 30 μm, and it was confirmed by fluorescent X-ray analysis that antimony and silica were present in the fiber according to the charged composition. Also,
As a result of X-ray diffraction, it was confirmed that it had a peak of tin oxide and that antimony was not dissolved in tin oxide without a peak of its oxide or the like. Fiber obtained
The average specific resistance was 1 Ω · cm. The tensile strength of the fiber was 40 MPa on average. The gel fiber immediately after spinning was left for 2 hours in an atmosphere of relative humidity of 85%, but the fiber shape was maintained without softening.

Example 3 204.8 g of a methanol solution in which hydrogen chloride was blown to adjust the hydrogen chloride concentration to 6.0 wt% and 474.8 g of tin metal.
(4.0 mol) was added, and the mixture was stirred while blowing air at 200 ml / min through a tube equipped with a glass filter at the tip, and metallic tin was completely dissolved in 5 days.
After that, 48.1 g of antimony trichloride (SbCl ₃ ).
(0.211 mol) and tetraethoxysilane 92.5 g
(0.444 mol) was added and dissolved. As a result of analysis in the same manner as in Example 1, [X / (Sn + Sb)] was 0.95. This solution was concentrated to prepare a highly viscous spinning solution. The spinning solution was extruded from the nozzle by applying pressure and continuously wound on a drum. The obtained gel fiber was heat-treated under the same conditions as in Example 1. The specific resistance of the obtained fiber was 1 Ω · cm on average. The tensile strength of the fiber was 40 MPa on average. The gel fiber immediately after spinning was left for 2 hours in an atmosphere of relative humidity of 85%, but the fiber shape was maintained without softening.

Example 4 474.8 g (4.0 mol) of metallic tin and 34% of 36% hydrochloric acid
1 g was added to 1920 g (60 mol) of methanol, and 200 ml / m was passed through a tube having a glass filter at the tip.
When stirring while blowing in oxygen gas of in, metallic tin was completely dissolved in 24 hours. Then, 48.1 g (0.211 mol) of antimony trichloride (SbCl ₃ ) and 92.5 g (0.444 mol) of tetraethoxysilane were added and dissolved. As a result of the same analysis as in Example 1, [X /
(Sn + Sb)] was 0.95. This solution was concentrated to give a spinning solution composed of a highly viscous sol. The spinning solution was extruded from the nozzle by applying pressure and continuously wound on a drum. The obtained gel fiber was heat-treated under the same conditions as in Example 1. The specific resistance of the obtained fiber was 1 Ω · cm on average. The tensile strength of the fiber was 40 MPa on average. The gel fiber immediately after spinning was left for 2 hours in an atmosphere of relative humidity of 85%, but the fiber shape was maintained without softening.

Example 5 Metal tin (Sn) 47 was added to 2433 g of a methanol solution in which hydrogen chloride was blown to adjust the hydrogen chloride concentration to 6.0 wt%.
4.8 g (4.0 mol) was added, and the mixture was stirred while blowing 200 ml / min of oxygen gas through a tube equipped with a glass filter at the tip, and metallic tin was completely dissolved in 24 hours. As a result of the same analysis as in Example 1, [X /
(Sn + Sb)] was 0.95. This solution was concentrated to prepare a highly viscous spinning solution. The spinning solution was extruded from the nozzle by applying pressure and continuously wound on a drum. The obtained gel fiber was heat-treated under the same conditions as in Example 1. The specific resistance of the obtained fiber was 8 × 10 ⁴ Ω · cm on average. The tensile strength of the fiber was 11 MPa on average. The gel fiber immediately after spinning was left for 2 hours in an atmosphere of relative humidity of 85%, but the fiber shape was maintained without softening.

Example 6 Metal tin 474.8 was added to 2020 g of a methanol solution whose hydrogen chloride concentration was adjusted to 4.9 wt% by blowing hydrogen chloride.
g (4.0 mol) was added, and the mixture was stirred while blowing 200 ml / min of oxygen gas through a tube equipped with a glass filter at the tip, and metallic tin was completely dissolved in 2 days. Then, antimony trichloride (SbCl ₃ ) 48.
1 g (0.211 mol) and tetraethoxysilane 92.
5 g (0.444 mol) was added and dissolved. As a result of analysis in the same manner as in Example 1, [X / (Sn + Sb)] is 0.8.
Met. This solution was concentrated to prepare a highly viscous spinning solution. The spinning solution was extruded from the nozzle by applying pressure and continuously wound on a drum. The obtained gel fiber was heat-treated under the same conditions as in Example 1. The obtained fiber had an average diameter of 30 μm, and it was confirmed by fluorescent X-ray analysis that antimony and silica were present in the fiber according to the charged composition. Further, as a result of X-ray diffraction, it was confirmed that it had a peak of tin oxide, and that the peak of antimony was not found in the oxide thereof and was dissolved in tin oxide. The specific resistance of the obtained fiber was 1 Ω · cm on average. The tensile strength of the fiber was 40 MPa on average. The gel fiber immediately after spinning was left for 2 hours in an atmosphere of relative humidity of 85%, but the fiber shape was maintained without softening.

Example 7 474.8 g of tin metal was added to 2225 g of a methanol solution in which hydrogen chloride was blown to adjust the hydrogen chloride concentration to 10 wt%.
(4.0 mol) was added and the mixture was stirred while blowing 200 ml / min of oxygen gas through a tube equipped with a glass filter at the tip, and metallic tin was completely dissolved in 2 days. Then, antimony trichloride (SbCl ₃ ) 48.1
g (0.211 mol) and tetraethoxysilane 92.5
g (0.444 mol) was added and dissolved. As a result of analysis in the same manner as in Example 1, [X / (Sn + Sb)] was 1.6. This solution was concentrated to prepare a highly viscous spinning solution. The spinning solution was extruded from the nozzle by applying pressure and continuously wound on a drum. The obtained gel fiber was heat-treated under the same conditions as in Example 1. The obtained fiber had an average diameter of 30 μm, and it was confirmed by fluorescent X-ray analysis that antimony and silica were present in the fiber according to the charged composition. Further, as a result of X-ray diffraction, it was confirmed that it had a peak of tin oxide, and that the peak of antimony was not found in the oxide thereof and was dissolved in tin oxide. The specific resistance of the obtained fiber was 1 Ω · cm on average. The tensile strength of the fiber was 40 MPa on average. The gel fiber immediately after spinning was left for 2 hours in an atmosphere of relative humidity of 85%, but the fiber shape was maintained without softening.

Comparative Example 1 474.8 g (4.0 mol) of metallic tin (Sn) was added to 2287 g of methanol and stirred without blowing oxygen or air, but after 10 days, metallic tin did not dissolve and remained undissolved. It was

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-5-117906 (JP, A) JP-A-5-179512 (JP, A) JP-A-9-95824 (JP, A) JP-A-9- 95825 (JP, A) JP 10-168666 (JP, A) JP 64-27635 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) D01F 9/08

Claims (4)

(57) [Claims] 1. A method for producing a tin oxide fiber spinning solution, which comprises dissolving metal tin in an organic solvent in the presence of hydrogen halide, and then concentrating the solution. 2. The method for producing a tin oxide fiber spinning solution according to claim 1, wherein air or oxygen is blown into the liquid phase when the metallic tin is dissolved. 3. The amount of hydrogen halide dissolved in an organic solvent is such that the atomic ratio [X / (Sn + M)] {in the formula, X, Sn,
M represents the number of atoms of halogen, tin, and Group V elements of the periodic table, respectively, which are present in the spinning solution, and M can be zero}
Is 0.6 to 2.0. 3. The method for producing a tin oxide fiber spinning solution according to claim 1, wherein 4. A method for producing a tin oxide fiber, which comprises spinning the spinning solution for tin oxide fiber obtained by the method according to claim 1, 2 or 3, and then heat treating the spinning solution.