JP2845649B2 - Method for producing spinning solution and conductive 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 method for producing a conductive tin oxide fiber and a spinning solution used for the method.

[0002]

2. Description of the Related Art In gas sensors, it has been strongly desired to provide tin oxide in the form of fibers from the viewpoint of improving sensitivity and response speed. Further, carbon fibers and the like are added for the purpose of imparting conductivity to the polymer material. However, when carbon is used, there is a problem that the material itself cannot be colored because it is black. Was. For this reason, powders of metal fibers and metal oxides have been added. Although the metal fiber has high conductivity, there is a disadvantage that the conductivity of the fiber is reduced due to oxidation or corrosion of the fiber surface over a long period of time. In addition, since conventional metal oxide powders are not as conductive as metal fibers, they must be added in relatively large amounts to impart conductivity to polymer materials.
There is a disadvantage that the intrinsic properties of the polymer material are reduced. Attempts have been made to add tin oxide having excellent chemical resistance and heat resistance in the form of a powder having conductivity. By the way, it is known that the effect of imparting conductivity increases as the aspect ratio of the material imparting conductivity increases. For this reason, it has been required to convert highly conductive tin oxide into fibers. However, it has been difficult to produce fibers by the conventional solid-state reaction method. Therefore, JP-60-5997, in JP-60-161337, JP-6 2 158 199, a method of producing a tin oxide has been proposed by the melt deposition. However, with these methods 1000
It requires high temperatures above ℃ and reaction times of many days. Moreover, the shape of the obtained tin oxide fiber has a diameter of 1
μm or less, and the length was limited to 3 mm. Since the diameter of the fiber is too small, it is difficult to handle the fiber, and when used as a composite material, there is a problem that its function cannot be sufficiently exerted and its use is limited. In addition, it was difficult to produce a paper-like material because the major axis was too small.

[0003]

Therefore, the diameter and / or
Alternatively, the present inventors have conducted intensive studies on the production of conductive tin oxide fibers having a large major axis and a low electric resistance value.

[0004]

As a result, it is surprising that the use of a solution mainly composed of a tin salt compound and an alcohol instead of using an expensive, unstable and difficult-to-handle tin alkoxide as a raw material. In addition, they have found that tin oxide fibers having high conductivity can be obtained easily and extremely inexpensively, and the present invention has been completed.

That is, the present invention provides a compound represented by the general formula: ROH, wherein R represents an unsubstituted or substituted alkyl group, an unsubstituted or substituted alkenyl group, or an unsubstituted or substituted aryl group.
An alcohol represented by the general formula SnXa · bH ₂ O (wherein X
Is Cl atom, Br atom, I atom, F atom, OH group, SO ₄ group, NO
Indicates ₃ group or CH ₃ COO radical, a represents an integer of 1 to 4, b is 0
And a spinning solution characterized by being dissolved a tin compound represented by an integer of from 6 to 6) and a Group V element compound of the Periodic Table. Another invention is to spin the spinning solution, Next, a method for producing a conductive tin oxide fiber is characterized by performing a heat treatment.

Next, the present invention will be described more specifically.

In the alcohol represented by the general formula ROH used in the present invention, R represents an unsubstituted alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group and an octyl group;
Unsubstituted alkyl groups such as methoxyethyl group, 2-ethoxyethyl group, 2-hydroxyethyl group, 1-methoxy-2-propyl group, methoxyethoxyethyl group, 2-phenylethyl group, phenylmethyl group, and unsubstituted allyl groups Substituted alkenyl groups such as alkenyl group, 2-methyl-2-propenyl group, 3-methyl-3-butenyl group, unsubstituted aryl groups such as phenyl group, or methoxyphenyl group, ethoxyphenyl group, methylphenyl group, ethylphenyl And a substituted aryl group such as a group.

Specific examples of the substituent in the above-mentioned substituted alkyl group, substituted alkenyl group or substituted aryl group include alkoxyl groups such as methoxy group and ethoxy group, hydroxyl group, phenyl group and the like which are shown in the above-mentioned specific examples of R. And an alkyl group such as an aryl group, a methyl group, and an ethyl group, as well as 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-propen-1-ol, 3-methyl-3-butene-
Examples thereof include 1-ol, phenol, methoxyphenol, ethoxyphenol, cresol, and ethylphenol.

Particularly, methyl alcohol and ethyl alcohol are preferable because of high solubility of the tin compound. The above-mentioned alcohols are usually used alone, but they have high reactivity with tin compounds,
Alternatively, a mixture of two or more alcohols can be used to control the solubility and the like of the tin compound.

In order to improve the stability of the spinning solution,
Compounds having two or more carbonyl groups, such as acetylacetone, ethyl acetoacetate and diethyl malonate, can also be used as an auxiliary. Furthermore, organic polymers such as polyethylene oxide and polyvinyl alcohol can be added to adjust the viscosity and the like.

In the tin compound represented by the general formula SnXa.bH ₂ O used in the present invention, X represents Cl, Br, I, F, OH, SO ₄ , NO ₃ or CH ₃ COO A represents an integer of 1 to 4, and b represents an integer of 0 to 6. Of these, tin chloride and tin bromide are preferred in terms of price and stability. Specifically, SnCl ₂ , SnCl ₂ .2H ₂ O, SnB
r ₂ , SnI ₂ , SnF ₂ , SnSO ₄ , Sn (CH ₃ COO) ₂ , Sn (NO ₃ ) _{2 and the} like, and particularly, SnCl ₂・ 2 H ₂₀ , SnCl ₂ , SnBr ₂ are preferably used. . Further, the above tin compound modified with an organic compound, for example, Sn (CH ₃ ) ₂ Cl ₂ or the like can also be used.

The mixing ratio of the tin compound and the alcohol is not particularly limited as long as the tin compound is uniformly dissolved in the alcohol. However, when the ratio of the tin compound is too low, the spinning property is not exhibited, so that it is necessary to concentrate the alcohol, and the alcohol is wasted. On the other hand, if the concentration of the tin compound is too high, precipitation occurs, and a uniform spinning solution cannot be obtained. Therefore, the mixing ratio varies depending on the type of the tin compound and the alcohol used, but generally, the usage ratio of the tin compound to the alcohol is 0.02 to
0.5 is preferred.

The group V element compound of the periodic table (hereinafter referred to as group V compound) used in the present invention functions to improve conductivity by being contained in the final product. Specific examples include compounds of Group V elements of the periodic table such as vanadium compounds, niobium compounds, tantalum compounds, antimony compounds, and bismuth compounds. As a vanadium compound, VB
r ₃ , VCl ₂ , VCl ₃ , VCl ₄ , VOBr ₂ , VOBr ₃ , VOCL ₃ , V
_{F 3, VF 4, VF 5} , VI 3 6H 2 O, include alkoxides of vanadium, as the niobium compound, NbCl
₅ , NbBr ₅ , NbF ₅ , NbOCl ₃ and alkoxides of niobium. Examples of tantalum compounds include TaBr ₅ , TaCl ₅ ,
Alkoxides of tantalum are mentioned, and examples of the antimony compound include alkoxides of SbCl ₃ , SbCl ₅ , SbBr ₃ , antimony oxychloride, or antimony,
Examples of the bismuth compound include BiCl ₃ , BiI ₂ , bismuth alkoxide, and the like. These group V compounds eventually become oxides by the heat treatment described later and form a solid solution in the tin oxide.

When it is desired to impart conductivity to the tin oxide fiber, the compounding ratio of the above group V compound is preferably 0.1 to 25 mol% with respect to tin oxide in terms of oxide. If the ratio is too low, the resulting tin oxide fiber will have low conductivity, and if it is too high, the effect of imparting conductivity will be small.

The method of dissolving the tin compound and the group V compound and the alcohol is not particularly limited, and is a method in which alcohol is added dropwise to the tin compound and the group V compound with stirring, or the tin compound and the group V compound are added to the alcohol with stirring. A dissolving method or the like can be used.

It is also preferable to add water to the solution containing the alcohol, tin compound and group V compound as main components. The amount of addition varies depending on the mixing ratio of the solution, and is not particularly limited. Generally, it is a criterion that no precipitation occurs in the solution. Spinning can be performed without adding water, but it is preferable to add water in a molar ratio of 0.01 to 1 with respect to the total amount of the alcohol, tin compound and group V compound from the viewpoint of the stability of the gel fiber.

Furthermore, acids such as hydrochloric acid, nitric acid and acetic acid, compounds having a carbonyl group such as acetylacetone, and ammonia and the like may be appropriately used as a catalyst and a complexing agent.

The spinning method is not particularly limited, and a conventional spinning method can be used. For example, there is a method of extruding a spinning solution from a spinning nozzle. The major axis, the diameter, and the like of the obtained fiber can be arbitrarily controlled by adjusting the viscosity of the spinning solution or the speed of extruding the spinning solution from the spinning nozzle.

The heat treatment of the gel fiber obtained by spinning is performed at a temperature at which conductivity can be imparted to the gel fiber. The gel fiber as spun from the spinning solution is an insulator as it is, and conductivity is developed by heating the gel fiber. The heat treatment temperature is not particularly limited as long as it is within a temperature range in which conductivity can be imparted to the obtained fiber. In general, when the heat treatment temperature is low, an organic substance such as alcohol, water, or the like remains in the gel fiber, and the group V compound does not form an oxide and does not form a solid solution with tin oxide. Does not occur.
If the heat treatment temperature is too high, the group V compound in the fiber volatilizes and the conductivity decreases, the decomposition of tin oxide progresses, and the crystal grains in the fiber grow too much and the strength decreases. Therefore, the heat treatment temperature is 2
A temperature range from 50C to 1550C is preferred. More preferably, the heat treatment is preferably performed at a temperature of 300 ° C to 1500 ° C. The heat treatment is usually performed in air, but when it is desired to obtain a highly conductive fiber, the heat treatment is performed in a reducing atmosphere such as nitrogen, argon, hydrogen, a mixed gas of argon and hydrogen, or in a vacuum. be able to.

In the heat treatment, it is desirable to remove volatile components such as water and alcohol present in the gel fiber by drying to obtain a good conductive fiber. Such drying may be performed simultaneously with the heat treatment, but it is more preferable to perform the drying before the heat treatment in order to obtain a good conductive fiber. In these cases, the drying temperature is preferably performed at a temperature as low as possible in order to prevent occurrence of cracks in the obtained fiber.However, when an alcohol 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. A general drying temperature is preferably in the range of room temperature to 300 ° C.

The specific resistance of the conductive tin oxide fiber obtained according to the present invention varies greatly depending on the type and addition amount of the group V compound, the firing atmosphere and the firing temperature.
Values of 10 ³ to 10 ⁻¹ ohm · cm can be taken.

The conductive tin oxide fiber obtained according to the present invention can take either crystalline or amorphous form, but crystalline is preferable from the viewpoint of conductivity.

[0024]

The present invention provides a method for producing a conductive tin oxide fiber and a spinning solution used for the method. This spinning solution is made of an inexpensive material without using an expensive, unstable and difficult to handle tin alkoxide, and is a very useful spinning solution. By using this spinning solution, it becomes possible to industrially produce tin oxide fibers having high conductivity, which could not be produced hitherto, at extremely low cost. Further, a fiber having a large aspect ratio can be extremely easily and freely manufactured by the present method.

Further, by the completion of the present invention, a high-sensitivity gas sensor, which has been difficult to apply with a bulk or powdered tin oxide obtained by a conventional manufacturing method, or a conductive polymer material having excellent durability, etc. It can be used for composite materials.

[0026]

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

EXAMPLE 1 10 g (0.05 mol) of stannous chloride (SnCl ₂ ) and 1 g (0.004 mol) of antimony trichloride (SbCl ₃ ) were added to 100 m of methanol.
(2.47 mol) to obtain a homogeneous solution. This solution
The solution was concentrated by keeping it in a dryer kept at 40 ° C. to obtain a highly viscous sol. The tip of a glass rod was immersed in this sol, and was pulled up in an atmosphere with a relative humidity of 55% while changing the pulling speed, whereby a large number of gel fibers having a length of about 1 m were spun. After leaving the obtained fiber at room temperature for 1 day, 2
The temperature was raised to 120 ° C. at a rate of ° C./min and kept at that temperature for 30 minutes. Thereafter, the temperature was raised to 500 ° C. at a rate of 10 ° C./min, and the temperature was maintained for 30 minutes to perform a heat treatment. The resulting off <br/> Aiba over have a diameter in the range of 1 [mu] m to 2 mm depending on the pull rate, by fluorescent X-ray analysis, that antimony is present in the fiber substantially charge composition as confirmed. As a result of X-ray diffraction, it was confirmed that tin oxide had a peak, and antimony did not show a peak of its oxide or the like, and it was dissolved in tin oxide. The specific resistance of the obtained fiber was about 8 × 10 ⁻¹ ohm · cm.

Example 2 13.9 g (0.05 mol) of stannous bromide (SnBr ₂ ) and 1 g (0.004 mol) of antimony trichloride (SbCl ₃ ) were added to 100 m of methanol.
(2.47 mol) to obtain a homogeneous solution. This solution
The solution was concentrated by keeping it in a dryer kept at 40 ° C. to obtain a highly viscous sol. The tip of a glass rod was immersed in this sol, and was pulled up in an atmosphere with a relative humidity of 55% while changing the pulling speed, whereby a large number of gel fibers having a length of about 1 m were spun. After leaving the obtained fiber at room temperature for 1 day, 2
The temperature was raised to 120 ° C. at a rate of ° C./min and kept at that temperature for 30 minutes. Thereafter, the temperature was raised to 500 ° C. at a rate of 10 ° C./min, and the temperature was maintained for 30 minutes to perform a heat treatment. The obtained fiber has a diameter in the range of 1 μm to 2 mm depending on the pulling speed, and the results of fluorescent X-ray analysis and X-ray diffraction confirm that it is crystalline tin oxide in which antimony is dissolved. Was. The specific resistance of the obtained fiber is about 8 × 10 ^-1 ohm
・ It was cm.

EXAMPLE 3 11.3 g (0.05 mol) of stannous chloride dihydrate (SnCl ₂ · 2H ₂₀ ) and 1 g (0.004 mol) of antimony trichloride (SbCl ₃ ) are dissolved in 100 ml (2.47 mol) of methanol. This gave a homogeneous solution. This solution was kept in a drier kept at 40 ° C., and the solution was concentrated to obtain a highly viscous sol. By dipping the tip of a glass rod into this sol and pulling it up in various atmospheres at a relative humidity of 55% with various pulling speeds, the length is about 1 m.
Was spun many times. After leaving the obtained fiber at room temperature for one day, the temperature was raised to 120 ° C. at a rate of 2 ° C./min and kept at that temperature for 30 minutes. Then at a rate of 10 ° C / min
The temperature was raised to 500 ° C., and the temperature was maintained for 30 minutes to perform a heat treatment. The resulting fiber has a diameter in the range of 1 μm to 2 mm depending on the pulling speed,
The result of X-ray diffraction confirmed that it was crystalline tin oxide in which antimony was dissolved. The specific resistance of the obtained fiber was about 8 × 10 ⁻¹ ohm · cm.

Example 4 The procedure of Example 1 was repeated except that 5 ml of water was added. The obtained fiber is about 1 m in length and has a diameter in the range of 1 μm to 2 mm depending on the pulling speed. From the results of fluorescent X-ray analysis and X-ray diffraction, it is found that crystalline tin oxide with solid solution of antimony is used. It was confirmed that there was. The specific resistance of the obtained fiber was about 8 × 10 ⁻¹ ohm · cm. Example 5 Instead of methanol, 100 ml of ethanol and 1 g of SbCl _{3 were used.}
Was performed in the same manner as in Example 1 except that 1.13 g of Sb (OC ₂ H ₅ ) ₃ was added instead of The resulting fiber is 1m long
According to the results of X-ray fluorescence analysis and X-ray diffraction, it was confirmed that antimony was crystalline tin oxide in a solid solution.
The specific resistance of the obtained fiber was about 8 × 10 ⁻¹ ohm · cm.

Example 6 Instead of methanol, 2-methyl-2-propene-1-
The procedure was performed in the same manner as in Example 1 except that all was used and concentration was performed using a rotary evaporator. The obtained fiber is 1 m long and 1 μm to 2 m depending on the pulling speed.
m, and the result of fluorescent X-ray analysis and X-ray diffraction confirmed that it was crystalline tin oxide in which antimony was dissolved. The specific resistance of the obtained fiber is about 8
× 10 ^-1 ohm · cm.

Example 7 The procedure of Example 1 was repeated, except that 3-methyl-3-buten-1-ol was used instead of methanol, and that the mixture was concentrated using a rotary evaporator. The obtained fiber is 1 m long and 1 μm to 2 mm depending on the pulling speed.
And the results of fluorescent X-ray analysis and X-ray diffraction confirmed that it was crystalline tin oxide in which antimony was dissolved. The specific resistance of the obtained fiber is about 8 ×
It was 10 ^-1 ohm · cm.

Example 8 The procedure of Example 1 was repeated, except that 2-methoxyethanol was used instead of methanol, and that the mixture was concentrated using a rotary evaporator. The obtained fiber is 1 m in length, has a diameter in the range of 1 μm to 2 mm depending on the pulling speed, and is a crystalline tin oxide in which antimony is dissolved as a solid solution according to the results of fluorescent X-ray analysis and X-ray diffraction. It was confirmed that. The specific resistance of the obtained fiber is about 8 × 10 ^-1 ohmcm
Met.

Example 9 The same procedure as in Example 1 was carried out except that 2-ethoxyethanol was used instead of methanol, and that the mixture was concentrated using a rotary evaporator. The obtained fiber is 1 m in length, has a diameter in the range of 1 μm to 2 mm depending on the pulling speed, and is a crystalline tin oxide in which antimony is dissolved as a solid solution according to the results of fluorescent X-ray analysis and X-ray diffraction. It was confirmed that. The specific resistance of the obtained fiber is about 8 × 10 ^-1 ohmcm
Met.

Example 10 The same procedure as in Example 1 was carried out except that 1-methoxy-2-propanol was used instead of methanol, and that the mixture was concentrated using a rotary evaporator. The obtained fiber is 1 m in length, has a diameter in the range of 1 μm to 2 mm depending on the pulling speed, and is a crystalline tin oxide in which antimony is dissolved as a solid solution according to the results of fluorescent X-ray analysis and X-ray diffraction. It was confirmed that. The specific resistance of the obtained fiber is about 8 × 10
It was ^-1 ohm.cm.

Example 11 The procedure of Example 1 was repeated, except that ethylene glycol was used instead of methanol, and that the mixture was concentrated using a rotary evaporator. The resulting fiber is length
At 1 m, it had a diameter in the range of 1 μm to 2 mm depending on the pulling speed. From the results of fluorescent X-ray analysis and X-ray diffraction, it was confirmed that antimony was a crystalline tin oxide in a solid solution. The specific resistance of the obtained fiber is about 8 × 10 ^-1 ohmcm
Met.

Example 12 The procedure of Example 1 was repeated, except that benzyl alcohol was used instead of methanol, and the mixture was concentrated under heating under reduced pressure. The resulting fiber has a length of 1 m, a diameter in the range of 1 μm to 2 mm depending on the pulling speed, and a fluorescent X
From the results of X-ray and X-ray diffraction, it was confirmed that the solution was crystalline tin oxide in which antimony was dissolved. The specific resistance of the obtained fiber was about 8 × 10 ⁻¹ ohm · cm.

[0038] Instead of Example 13 antimony trichloride (SbCl ₃₎ 1g (0.004 mol), except using TaCl ₅ 0.945g (0.002 6 moles) was carried out in the same manner as in Example 1. The resulting fiber is length
It has a diameter in the range of 1 μm to 2 mm depending on the pulling speed at 1 m. From the results of fluorescent X-ray analysis and X-ray diffraction, it was confirmed that tantalum was crystalline tin oxide with a solid solution almost as charged. Was done. The specific resistance of the obtained fiber is about 8
× 10 ² ohm · cm.

[0039] Instead of Example 14 antimony trichloride (SbCl ₃₎ 1g (0.004 mol), except using NbCl ₅ 0.712g (0.002 6 moles) was carried out in the same manner as in Example 1. The resulting fiber is length
It has a diameter in the range of 1 μm to 2 mm depending on the pulling speed at 1 m. From the results of fluorescent X-ray analysis and X-ray diffraction, it was confirmed that niobium was crystalline tin oxide with a solid solution almost as charged. Was done. The specific resistance of the obtained fiber is about 8 ×
It was 10 ² ohm · cm.

Comparative Example 1 The procedure of Example 1 was repeated except that antimony trichloride (SbCl ₃ ) was not added. The resulting fiber is 1m long
According to the drawing speed, it had a diameter in the range of 1 μm to 2 mm depending on the pulling speed, and as a result of X-ray diffraction, it was confirmed to be crystalline tin oxide. The specific resistance of the obtained fiber is about 8 × 10 ⁴ oh m
・ It was cm.

Claims (2)

(57) [Claims] 1. An alcohol represented by the general formula ROH (wherein R represents an unsubstituted or substituted alkyl group, an unsubstituted or substituted alkenyl group, or an unsubstituted or substituted aryl group), and a general formula SnXa・ BH ₂ O (where X is Cl atom, Br atom, I atom, F atom, OH group, SO ₄ group, NO ₃ group or CH ₃ CO
Represents an O group, a represents an integer of 1 to 4, b represents an integer of 0 to 6), and a tin compound represented by the following formula: Spinning solution. 2. A method for producing a conductive tin oxide fiber, comprising spinning the spinning solution according to claim 1, and then subjecting the spinning solution to heat treatment.