JP5255359B2 - Precursor solution for film formation - Google Patents

Description

  The present invention, for example, has excellent storage stability that is suitably used when forming a titanium oxide transparent conductive film using niobium or tantalum as a dopant or an antireflection film containing niobium oxide or tantalum oxide by a coating method. It is related with the precursor solution for film formation provided with.

It is known that pentavalent niobium or tantalum belonging to group VA of the periodic table is useful as a dopant for increasing the conductivity of a titanium oxide-based transparent conductive film, for example. Moreover, those metal oxides are utilized as a constituent material of an antireflection film.
Methods of forming such metal oxide thin films such as a niobium or tantalum-doped titanium oxide transparent conductive film or an antireflection film made of niobium oxide or tantalum oxide can be broadly divided into sputtering and PLD (pulse laser deposition). ) Method of forming a film in a vacuum system, and a method of heating after applying a slurry or solution containing metal oxide particles to a substrate, but the former film forming method in a vacuum system is large-scale. Equipment is necessary and the cost of equipment is increased, and as a result, the product cost is inevitably increased. Therefore, in recent years, the latter coating method suitable for industrial mass production is promising in that it can be implemented at low cost by a simple operation using existing equipment.

When forming a niobium or tantalum-doped titanium oxide thin film or a metal oxide film containing niobium or tantalum such as a niobium oxide or tantalum oxide thin film by a coating method, hydrogen peroxide is added to the niobium compound or tantalum compound as a precursor. A reaction product peroxylated by reaction (ie peroxy complex) is used.
For example, the present inventor has recently proposed a method for producing a transparent conductive substrate comprising a transparent conductive film made of titanium oxide doped with niobium or tantalum by peroxidation by reacting a titanium compound with hydrogen peroxide. A precursor solution containing a reaction product obtained by reacting a niobium compound or a tantalum compound with hydrogen peroxide and peroxidation is applied on a transparent substrate and subjected to an annealing treatment in a reducing atmosphere. Among them, a proposed product (Japanese Patent Application No. 2007-280071) uses a reaction product (peroxy complex of niobium or tantalum) obtained by reacting a niobium compound or a tantalum compound with hydrogen peroxide and peroxidizing it as a doping material. .

  However, in general, a peroxy complex produced by reacting hydrogen peroxide with a metal compound is unstable. Therefore, when left at room temperature or higher, decomposition tends to proceed and oxygen derived from the peroxy group tends to be released. As a result, gelation or white turbidity is likely to occur, and in some cases, there is a possibility of causing serious drawbacks in coating properties, film adhesion, and transparency. Therefore, until now, when using a reaction product (peroxy complex) obtained by reacting hydrogen peroxide with a metal compound as a precursor solution for film formation, it should be used immediately after preparation or at room temperature when stored. Although it has been handled under various restrictions such as cooling to (for example, 0 ° C. or lower), a peroxy complex that can be stably maintained at room temperature for a long period of time has been demanded in order to remove such restrictions. . This is not limited to the case where the metal species is niobium or tantalum, but the same applies to titanium peroxy complexes.

  There have been few reports on the stability of niobium or tantalum peroxy complexes, but titanium peroxy complexes that have been widely used as film-forming materials and adhesive coatings in the photocatalyst field and have been studied relatively well. With regard to, various reports have been made on the stability of the solution (see, for example, Patent Document 1). According to this, it is known that the optimum reaction ratio between the titanium compound and hydrogen peroxide for obtaining a stable titanium peroxy complex is 1: 1. That is, a titanium peroxy complex having a structure in which one atom of peroxide ion is bonded to one atom of titanium exhibits the best storage stability.

  However, even if the titanium peroxy complex is stabilized at the optimum reaction ratio described above, if the solid content concentration is increased, sufficient stability cannot be obtained yet. For example, the solid content concentration is 2% by weight. In general, it would gel within one day at room temperature. When used as a film-forming material, in order to obtain a sufficient film thickness by a single application, it is usually desirable to set the solid content concentration to a certain level. Therefore, the titanium peroxy complex is used at room temperature for several days even at high concentrations. There is a need for further stability improvements that can be preserved.

  While the stability of the titanium peroxy complex is as described above, it is difficult to ensure sufficient stability for the niobium or tantalum peroxy complex as well, such as the titanium compound and hydrogen peroxide described above. Even if the optimal ratio (1: 1) is applied to the optimal ratio of niobium compound or tantalum compound and hydrogen peroxide, it can be stably stored at room temperature for several days when the solid content concentration increases. There wasn't.

Special table 2007-532469

  The present invention has been made in view of the above circumstances, and provides a film forming precursor solution having excellent storage stability that enables formation of a film containing niobium or tantalum by a coating method. The purpose is to do.

  The present inventor has intensively studied to solve the above problems. As a result, when the hydrogen peroxide is reacted with the niobium compound or the tantalum compound, the ratio of the niobium compound or tantalum compound to hydrogen peroxide is determined based on the conventional knowledge (that is, the optimum ratio of the stable titanium peroxy complex is 1: 1). When the specific range deviating from the ratio that is presumed to be preferable (that is, the same 1: 1 as the titanium peroxy complex) was set, a peroxy having extremely excellent storage stability, contrary to expectations. It was found that a complex was obtained. And if it was the peroxy complex provided with the high stability which exceeded this expectation, it discovered that solid content concentration could be raised to 8.5 weight%, and completed this invention.

（式（１）中、Ｒ¹〜Ｒ⁶は、Ｈまたはアルキル基を表し、各々同じであってもよいし異なっていてもよい。Ｘは、−ＯＨまたは−ＯＲ（ただし、Ｒはアルキル基を表す）を表す。）

（式（２）中、Ｒ¹〜Ｒ⁵は、Ｈまたはアルキル基を表し、各々同じであってもよいし異なっていてもよい。Ｘは、−ＯＨまたは−ＯＲ（ただし、Ｒはアルキル基を表す）を表す。）

（式（３）中、Ｒ¹〜Ｒ⁷は、Ｈまたはアルキル基を表し、各々同じであってもよいし異なっていてもよい。Ｘは、−ＯＨまたは−ＯＲ（ただし、Ｒはアルキル基を表す）を表す。）

（式（４）中、Ｙは、置換基を有していてもよい炭素数３〜６のアルキレン基を表す。）

（式（５）中、Ｙは、置換基を有していてもよい炭素数３〜６のアルキレン基を表す。）
（ｉｉｉ）前記溶剤は、３−メトキシ−１−ブタノール、３−メトキシ−３−メチル−１−ブタノール、ジアセトンアルコール、４−ヒドロキシ−２−ブタノン、５−ヒドロキシ−２−ペンタノン、テトラヒドロフラン−２−カルボン酸、２−メチル−１，３−プロパンジオール、γ−ブチロラクトン、δ−バレロラクトン、ε−カプロラクトンからなる群より選ばれる少なくとも１種である、前記（ｉｉ）記載の膜形成用前駆体溶液。 That is, this invention consists of the following structures.
(I) a reaction product obtained by reacting 2.5 to 3.5 moles of hydrogen peroxide with 1 mole of niobium compound or tantalum compound, and having a solid content concentration of 8.5% by weight or less. A precursor solution for film formation characterized by the following.
(ii) The film forming precursor solution according to the above (i), which also contains a solvent represented by any one of the following general formulas (1) to (5).

(In Formula (1), R < ¹ > -R < ⁶ > represents H or an alkyl group, and may respectively be the same or different. X is -OH or -OR (However, R is an alkyl group. Represents).)

(In Formula (2), R < ¹ > -R < ⁵ > represents H or an alkyl group, and may respectively be the same or different. X is -OH or -OR (However, R is an alkyl group. Represents).)

(In Formula (3), R < ¹ > -R < ⁷ > represents H or an alkyl group, and may respectively be the same or different. X is -OH or -OR (However, R is an alkyl group. Represents).)

(In formula (4), Y represents an alkylene group having 3 to 6 carbon atoms which may have a substituent.)

(In formula (5), Y represents a C3-C6 alkylene group which may have a substituent.)
(Iii) The solvent is 3-methoxy-1-butanol, 3-methoxy-3-methyl-1-butanol, diacetone alcohol, 4-hydroxy-2-butanone, 5-hydroxy-2-pentanone, tetrahydrofuran-2 -Film forming precursor according to (ii) above, which is at least one selected from the group consisting of carboxylic acid, 2-methyl-1,3-propanediol, γ-butyrolactone, δ-valerolactone, and ε-caprolactone solution.

  According to the present invention, it is possible to provide a film-forming precursor solution containing a niobium or tantalum peroxy complex having excellent storage stability, whereby a niobium or tantalum-doped titanium oxide thin film, niobium oxide or A metal oxide film containing niobium or tantalum such as a tantalum oxide thin film can be formed by a coating method. Specifically, the film-forming precursor solution can be stably maintained for several days at room temperature without causing gelation or clouding, and can be used immediately after preparation, or less than room temperature (for example, 0 ° C. or less). The film can be used for film formation without any particular restriction such as being cooled and stored. Furthermore, under the excellent stability of the film-forming precursor solution, the solid content concentration can be increased as compared with the prior art, so that the film thickness formed by a single coating can be set larger during film formation. This is also advantageous.

  The film forming precursor solution of the present invention comprises a reaction product obtained by reacting hydrogen peroxide with a niobium compound or a tantalum compound, that is, a complex (peroxy complex) formed by peroxylating the niobium compound or the tantalum compound. Including. This peroxy complex becomes niobium oxide or tantalum oxide by heating alone, and becomes a metal oxide precursor which becomes titanium oxide doped with niobium or tantalum by heating with, for example, a titanium peroxy complex.

  In the present invention, the reaction product is obtained by reacting 2.5 to 3.5 moles of hydrogen peroxide with 1 mole of niobium compound or tantalum compound. Preferably, 2.8 to 3.2 mol of hydrogen peroxide is reacted with 1 mol of niobium compound or tantalum compound. Thereby, a reaction product (peroxy complex) having excellent stability is obtained, and the precursor solution of the present invention is, for example, at room temperature (20 ± 5 ° C.) for 10 days or more, preferably 15 days or more, more preferably It can be stored stably for a long period of 20 days or longer, more preferably 30 days or longer. When the amount of hydrogen peroxide reacted with the niobium compound or the tantalum compound is less than the above range, the storage stability of the peroxy complex is lowered, and the precursor solution is allowed to stand at room temperature for several hours to several days (for example, 1 hour). When held for about 4 days, gelation or white turbidity occurs. In particular, when the amount of hydrogen peroxide is larger than the above range, excessive free hydrogen peroxide decomposes to generate heat, and the stability of the liquid is greatly reduced.

  The film-forming precursor solution of the present invention has a solid content concentration of 8.5% by weight or less, more preferably 8.0% by weight or less, still more preferably 7.5% by weight or less, and even more preferably 7.% by weight. 0% by weight or less. Since the peroxy complex contained in the precursor solution of the present invention has excellent storage stability, even if it is set to such a relatively high solid content concentration, gelation or turbidity will occur for several days at room temperature. It can be stably held without being generated. The lower limit of the solid content concentration is not particularly limited, but is preferably 2% by weight or more, and more preferably 4% by weight or more in consideration of, for example, applicability during film formation. In addition, solid content concentration here means the ratio (weight%) which the weight of the niobium compound or tantalum compound used when obtaining the precursor solution occupies in the total weight of the precursor solution.

  When the reaction product is obtained by reacting niobium compound or tantalum compound with hydrogen peroxide, the reaction with hydrogen peroxide (that is, peroxylation reaction) is performed by, for example, dissolving the niobium compound or tantalum compound in an appropriate solvent. It can be carried out by adding a hydrogen peroxide solution having a concentration of about 1 to 60% by weight while stirring as necessary. The reaction time of the peroxylation reaction is usually about 1 second to 60 minutes, preferably about 5 minutes to 20 minutes. Since the peroxylation reaction with hydrogen peroxide usually involves intense heat generation, it is desirable to carry out the reaction while cooling (specifically, keeping the internal temperature at −10 ° C. or lower). After the reaction, aging may be maintained while further cooling to −10 ° C. or lower.

  The niobium compound is not particularly limited as long as it contains an Nb atom as a niobium source. For example, niobium chloride, niobium alkoxide (methoxide, ethoxide, etc.), niobium metal, niobium hydroxide, and the like can be used. On the other hand, the tantalum compound is not particularly limited as long as it contains Ta atoms as a tantalum source. For example, tantalum chloride, tantalum alkoxide (methoxide, ethoxide, etc.), metal tantalum, tantalum hydroxide, or the like can be used. Of the above, titanium alkoxide, niobium alkoxide, and tantalum alkoxide are unstable substances that react immediately upon contact with moisture, and thus are preferably handled in a dry (low humidity) atmosphere.

  As the niobium compound or tantalum compound, a hydroxide is preferably used. That is, niobium hydroxide or tantalum hydroxide is used as a raw material, or niobium compounds or tantalum compounds other than these hydroxides are used, and alkali or water is added in advance before reacting with hydrogen peroxide. Then, the generated hydroxide precipitate may be collected and washed. Thus, in the case of a peroxy complex obtained by reacting a hydroxide with hydrogen peroxide, there is no organic site containing carbon atoms in the formed film. In the case of use as conductivity, it is not necessary to decompose and volatilize the organic part by heating to a high temperature in consideration of conductivity and the like, and the heating temperature at the time of film formation can be set to a relatively low temperature, which is preferable. For example, when a niobium compound or tantalum compound other than a hydroxide is used as it is and reacted with hydrogen peroxide, an organic site exists in a part of the obtained peroxy complex, and this organic site is decomposed. In order to volatilize, it is necessary to heat to a temperature of at least 400 ° C. or more, preferably about 500 to 600 ° C.

  The solvent that can be used for the peroxylation reaction with hydrogen peroxide is not particularly limited, and for example, water-based or alcohol-based water-soluble solvents such as water, methanol, ethanol, propanol, butanol, and ethylene glycol are used. Of course, a solvent having a specific structure represented by any one of the general formulas (1) to (5) described below may be used as the solvent used in the peroxylation reaction.

  The film-forming precursor solution of the present invention preferably further contains a solvent represented by any one of the general formulas (1) to (5) (hereinafter also referred to as “specific solvent”). The specific solvent functions to stabilize the peroxy complex in the precursor solution, thereby further improving the storage stability of the solution. In addition, the specific solvent volatilizes quickly by applying the precursor solution to the substrate and heating at the time of film formation, and organic components derived from the specific solvent remain in the formed film. Therefore, the remaining organic components are not carbonized by heating to lower the transparency of the film or affect the film function such as conductivity.

In the formulas (1) to (3), examples of the alkyl group as an example of R ^{1 to} R ⁶ , R ^{1 to} R ⁵ , or R ^{1 to} R ⁷ include, for example, a methyl group, an ethyl group, a propyl group, and butyl Groups and the like. In the formulas (1) to (3), the same applies to the alkyl group represented by R in —OR, which is an example of X.
In the formulas (4) and (5), examples of the alkylene group having 3 to 6 carbon atoms which may have a substituent represented by Y include a propylene group, a butylene group, a pentylene group and a hexylene group. Can be mentioned.

When the compounds represented by the formulas (1) to (3) coexist with the reaction product, they are bonded at a bidentate between two oxygen atoms that the compound has and a metal atom of a peroxy complex. A covalent bond and a coordination bond having different forces are generated to form a stable 6-membered ring or 7-membered ring structure, and the peroxy group can be surrounded and protected by the bridge structure. Moreover, since there is only one strong covalent bond in the cross-linked structure formed here, organic molecules can be easily detached from metal atoms by heating, and organic components may remain in the resulting film. Absent.
When the compounds represented by the formulas (4) and (5) coexist with the reaction product, they are coordinated in a bidentate between the two oxygen atoms that the compound has and the metal atom of the peroxy complex. In addition, the peroxy group can be sterically protected by the bulky structure of the 5-membered to 8-membered ring of the compound. In addition, since the bond between the metal atom and the oxygen atom formed here is very weak, the organic molecule is easily detached from the metal atom by heating, and the organic component does not remain in the obtained film.

  The specific solvent may be any organic compound such as alcohol, alkoxy alcohol, carboxylic acid, ester, etc., as long as it has the specific structure represented by the general formulas (1) to (5). Specifically, 3-methoxy-1-butanol, 3-methoxy-3-methyl-1-butanol, diacetone alcohol (4-hydroxy-4-methylpentan-2-one), 4-hydroxy-2- At least one selected from the group consisting of butanone, 5-hydroxy-2-pentanone, tetrahydrofuran-2-carboxylic acid, 2-methyl-1,3-propanediol, γ-butyrolactone, δ-valerolactone, and ε-caprolactone Preferably there is. Among these, 3-methoxy-1-butanol is particularly preferable because the effect of improving the storage stability of the precursor solution is remarkably high.

The said specific solvent should just coexist with the said reaction product (peroxy complex) finally, for example, may be contained in a precursor solution by using as a solvent in the peroxylation reaction by the hydrogen peroxide mentioned above. Then, the reaction product may be contained in the precursor solution by using it as a solvent added for the purpose of dilution so as to have a solid content concentration described later.
When the specific solvent is also contained, the content is not particularly limited, but is preferably 15 to 80% by weight with respect to the total amount of the solvent in the precursor solution.

  The film forming method using the film forming precursor solution of the present invention is not particularly limited. For example, the film forming precursor solution of the present invention is used alone or, for example, a known titanium peroxy complex (containing a titanium compound). The reaction product obtained by reacting hydrogen oxide) may be mixed, applied to a substrate, and heated. When the film forming precursor solution of the present invention is applied alone, a thin film of niobium oxide or tantalum oxide suitable for an antireflection film or the like can be formed. On the other hand, it is mixed with a peroxy complex of titanium and applied. In this case, a niobium or tantalum-doped titanium oxide thin film suitable for a transparent conductive film or the like can be formed.

  The application method for applying the precursor solution on the substrate is not particularly limited as long as it is a method that enables uniform wet coating, and a conventionally known method can be employed. For example, a capillary coating method, a spin coating method, a slit die coating method, a spray coating method, a dip coating method, a roll coating method, a screen printing method, a flexographic printing method, a bar coater method, and the like can be employed.

  The heating method after applying the precursor solution and the conditions thereof may be appropriately set according to the composition of the solution and the heat resistance of the substrate to be used, and are not particularly limited. For example, normal temperature to 500 ° C., preferably May be heated at a temperature of 400 ° C. or lower, usually for about 1 minute to 1 hour. Also, the atmosphere for heating is not particularly limited. For example, when conductivity is imparted to the obtained film, it is preferably performed in a reducing atmosphere. For example, when the solid content concentration of the applied precursor solution of the present invention is low, the solvent (specific solvent) may be volatilized in advance by means of vacuum drying, reduced pressure drying or the like before heating.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by this Example.

Example 1
In an argon gas atmosphere, 0.75 g of niobium pentaethoxide was dissolved in 9.56 g of dehydrated ethanol, and 0.8 g of hydrogen peroxide solution having a concentration of 30% by weight (based on 1 mol of niobium pentaethoxide) was obtained. Hydrogen peroxide (corresponding to 3.0 mol of hydrogen peroxide) was gradually added under stirring, and after completion of the addition, the mixture was stirred for 5 minutes to cause peroxo-reaction. The reaction was conducted while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution was controlled so as not to exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (1).
When the obtained precursor solution was housed in a glass narrow mouth bottle and the mouth of the bottle was opened, the state when left at room temperature (20 ± 5 ° C.) for 15 days was visually observed, A transparent solution state was maintained without causing turbidity or cloudiness.

(Example 2)
A film-forming precursor solution similar to that in Example 1 was produced except that the amount of hydrogen peroxide relative to the niobium compound was changed at the same solid content concentration as in Example 1.
That is, 0.75 g of niobium pentaethoxide was dissolved in 9.69 g of dehydrated ethanol in an argon gas atmosphere, and 0.67 g of hydrogen peroxide solution having a concentration of 30% by weight (to 1 mol of niobium pentaethoxide was added). (Corresponding to 2.5 mol of hydrogen peroxide) was gradually added with stirring, and after the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. As in Example 1, the reaction was performed while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution did not exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. Was controlled as follows. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (2).
When the obtained precursor solution was housed in a glass narrow mouth bottle and the mouth of the bottle was opened, the state when left at room temperature (20 ± 5 ° C.) for 15 days was visually observed, A transparent solution state was maintained without causing turbidity or cloudiness.

(Example 3)
A film-forming precursor solution similar to that in Example 1 was produced except that the amount of hydrogen peroxide relative to the niobium compound was changed at the same solid content concentration as in Example 1.
That is, 0.75 g of niobium pentaethoxide was dissolved in 9.43 g of dehydrated ethanol in an argon gas atmosphere, and 0.93 g of hydrogen peroxide solution having a concentration of 30% by weight (to 1 mol of niobium pentaethoxide was added). (Corresponding to 3.5 mol of hydrogen peroxide) was gradually added with stirring, and after the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. As in Example 1, the reaction was performed while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution did not exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. Was controlled as follows. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (3).
When the obtained precursor solution was housed in a glass narrow mouth bottle and the mouth of the bottle was opened, the state when left at room temperature (20 ± 5 ° C.) for 15 days was visually observed, A transparent solution state was maintained without causing turbidity or cloudiness.

(Comparative Example 1)
A film-forming precursor solution similar to Example 1 was produced, except that the amount of hydrogen peroxide relative to the niobium compound was changed outside the scope of the present invention at the same solid content concentration as in Example 1.
That is, 0.75 g of niobium pentaethoxide was dissolved in 9.82 g of dehydrated ethanol in an argon gas atmosphere. (Corresponding to 2.0 mol of hydrogen peroxide) was gradually added under stirring, and after completion of the addition, the mixture was stirred for 5 minutes to cause peroxo-reaction. As in Example 1, the reaction was performed while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution did not exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. Was controlled as follows. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (C1).
When the obtained precursor solution was accommodated in a glass narrow mouth bottle and left at room temperature (20 ± 5 ° C.) with the mouth of the bottle opened, gelation was visually observed after 4 days. It was. That is, the usable time (pot life) of the obtained precursor solution at room temperature was less than 4 days.

(Comparative Example 2)
A film-forming precursor solution similar to Example 1 was produced, except that the amount of hydrogen peroxide relative to the niobium compound was changed outside the scope of the present invention at the same solid content concentration as in Example 1.
That is, 0.75 g of niobium pentaethoxide was dissolved in 1.35 g of dehydrated ethanol in an argon gas atmosphere, and 9.01 g of hydrogen peroxide solution having a concentration of 30% by weight (to 1 mol of niobium pentaethoxide was added). (Corresponding to 5.0 mol of hydrogen peroxide) was gradually added with stirring. After the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. As in Example 1, the reaction was performed while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution did not exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. Was controlled as follows. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (C2).
The obtained precursor solution was housed in a glass narrow mouth bottle and left at room temperature (20 ± 5 ° C.) with the bottle mouth open. After 6 hours, gelation was visually observed. It was. That is, the usable time (pot life) of the obtained precursor solution at room temperature was less than 6 hours.

Example 4
A film-forming precursor solution was produced in the same manner as in Example 1 except that the composition of the solvent was changed at the same solid content concentration and hydrogen peroxide amount as in Example 1.
That is, 0.75 g of niobium pentaethoxide was dissolved in a mixed solvent of 7.56 g of dehydrated ethanol and 2 g of 3-methoxy-1-butanol in an argon gas atmosphere, and the resulting solution was peroxidized at a concentration of 30% by weight. Hydrogen water 0.8g (equivalent to 3.0 moles of hydrogen peroxide with respect to 1 mole of niobium pentaethoxide) was gradually added with stirring. After the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. As in Example 1, the reaction was performed while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution did not exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. Was controlled as follows. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (4).
When the obtained precursor solution was accommodated in a glass narrow mouth bottle and the mouth of the bottle was opened and left standing at room temperature (20 ± 5 ° C.) for 20 days, the gel was visually observed. A transparent solution state was maintained without causing turbidity or cloudiness.

(Example 5)
A film-forming precursor solution was produced in the same manner as in Example 1 except that the composition of the solvent was changed at the same solid content concentration and hydrogen peroxide amount as in Example 1.
That is, 0.75 g of niobium pentaethoxide was dissolved in a mixed solvent of 5.56 g of dehydrated ethanol and 4 g of 3-methoxy-1-butanol in an argon gas atmosphere, and the resulting solution was peroxidized at a concentration of 30% by weight. Hydrogen water 0.8g (equivalent to 3.0 moles of hydrogen peroxide with respect to 1 mole of niobium pentaethoxide) was gradually added with stirring. After the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. As in Example 1, the reaction was performed while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution did not exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. Was controlled as follows. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (5).
When the obtained precursor solution was housed in a glass narrow mouth bottle and the mouth of the bottle was opened, the state when left at room temperature (20 ± 5 ° C.) for 30 days was visually observed. A transparent solution state was maintained without causing turbidity or cloudiness.

(Example 6)
A film-forming precursor solution was produced in the same manner as in Example 1 except that the composition of the solvent was changed at the same solid content concentration and hydrogen peroxide amount as in Example 1.
That is, 0.75 g of niobium pentaethoxide was dissolved in a mixed solvent of 3.56 g of dehydrated ethanol and 6 g of 3-methoxy-1-butanol in an argon gas atmosphere, and the resulting solution was peroxidized at a concentration of 30% by weight. Hydrogen water 0.8g (equivalent to 3.0 moles of hydrogen peroxide with respect to 1 mole of niobium pentaethoxide) was gradually added with stirring. After the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. As in Example 1, the reaction was performed while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution did not exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. Was controlled as follows. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (6).
When the obtained precursor solution was housed in a glass narrow mouth bottle and the mouth of the bottle was opened, the state when left at room temperature (20 ± 5 ° C.) for 30 days was visually observed. A transparent solution state was maintained without causing turbidity or cloudiness.

(Example 7)
A film-forming precursor solution was produced in the same manner as in Example 1 except that the composition of the solvent was changed at the same solid content concentration and hydrogen peroxide amount as in Example 1.
That is, 0.75 g of niobium pentaethoxide was dissolved in a mixed solvent of 2.56 g of dehydrated ethanol and 7 g of 3-methoxy-1-butanol in an argon gas atmosphere, and the resulting solution was peroxidized at a concentration of 30% by weight. Hydrogen water 0.8g (equivalent to 3.0 moles of hydrogen peroxide with respect to 1 mole of niobium pentaethoxide) was gradually added with stirring. After the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. As in Example 1, the reaction was performed while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution did not exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. Was controlled as follows. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (7).
When the obtained precursor solution was housed in a glass narrow mouth bottle and the mouth of the bottle was opened, the state when left at room temperature (20 ± 5 ° C.) for 30 days was visually observed. A transparent solution state was maintained without causing turbidity or cloudiness.

(Example 8)
A film-forming precursor solution was produced in the same manner as in Example 1 except that the composition of the solvent was changed at the same solid content concentration and hydrogen peroxide amount as in Example 1.
That is, 0.75 g of niobium pentaethoxide was dissolved in 9.56 g of 3-methoxy-1-butanol in an argon gas atmosphere, and 0.8 g of niobium hydrogen peroxide having a concentration of 30% by weight was added to the resulting solution. (Equivalent to 3.0 moles of hydrogen peroxide per mole of ethoxide) was gradually added under stirring. After the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. As in Example 1, the reaction was performed while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution did not exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. Was controlled as follows. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (8).
When the obtained precursor solution was housed in a glass narrow mouth bottle and the mouth of the bottle was opened, the state when left at room temperature (20 ± 5 ° C.) for 30 days was visually observed. A transparent solution state was maintained without causing turbidity or cloudiness.

Example 9
A film-forming precursor solution similar to that of Example 1 was produced, except that the amount of hydrogen peroxide relative to the same niobium compound as in Example 1 was changed to increase the solid content concentration by changing the composition and amount of the solvent.
That is, 0.75 g of niobium pentaethoxide was dissolved in a mixed solvent of 2.56 g of dehydrated ethanol and 6 g of 3-methoxy-1-butanol in an argon gas atmosphere, and the resulting solution was peroxidized at a concentration of 30% by weight. Hydrogen water 0.8g (equivalent to 3.0 moles of hydrogen peroxide with respect to 1 mole of niobium pentaethoxide) was gradually added with stirring. After the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. As in Example 1, the reaction was performed while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution did not exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. Was controlled as follows. The reaction product having a solid concentration of 7.41% by weight thus obtained was used as a film-forming precursor solution (9).
When the obtained precursor solution was housed in a glass narrow mouth bottle and the mouth of the bottle was opened, the state when left at room temperature (20 ± 5 ° C.) for 30 days was visually observed. A transparent solution state was maintained without causing turbidity or cloudiness.

(Example 10)
A film-forming precursor solution similar to that of Example 1 was produced, except that the amount of hydrogen peroxide relative to the same niobium compound as in Example 1 was changed to increase the solid content concentration by changing the composition and amount of the solvent.
That is, 0.75 g of niobium pentaethoxide was dissolved in 8 g of 3-methoxy-1-butanol in an argon gas atmosphere, and 0.8 g of niobium pentaethoxide having a concentration of 30 wt% was added to the resulting solution. (Equivalent to 3.0 mol of hydrogen peroxide per 1 mol) was gradually added with stirring, and after the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. As in Example 1, the reaction was performed while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution did not exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. Was controlled as follows. The reaction product having a solid content concentration of 7.85% by weight thus obtained was used as a film-forming precursor solution (10).
When the obtained precursor solution was housed in a glass narrow mouth bottle and the mouth of the bottle was opened, the state when left at room temperature (20 ± 5 ° C.) for 15 days was visually observed, A transparent solution state was maintained without causing turbidity or cloudiness.

(Comparative Example 3)
The same precursor for film formation as in Example 1 except that the amount of hydrogen peroxide with respect to the same niobium compound as in Example 1 was changed and the solid content concentration was increased outside the scope of the present invention by changing the composition and amount of the solvent. A solution was prepared.
That is, 0.75 g of niobium pentaethoxide was dissolved in 7 g of 3-methoxy-1-butanol in an argon gas atmosphere, and 0.8 g of niobium pentaethoxide having a concentration of 30% by weight was added to the resulting solution. (Equivalent to 3.0 mol of hydrogen peroxide per 1 mol) was gradually added with stirring, and after the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. As in Example 1, the reaction was performed while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution did not exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. Was controlled as follows. The reaction product having a solid content concentration of 8.77% by weight thus obtained was used as a film-forming precursor solution (C3).
The obtained precursor solution was housed in a glass narrow mouth bottle and left at room temperature (20 ± 5 ° C.) with the bottle mouth open. After one day (24 hours), the gel was visually observed. Observed. That is, the usable time (pot life) of the obtained precursor solution at room temperature was less than one day.

(Example 11)
In an argon gas atmosphere, 0.4 g of tantalum pentaethoxide is dissolved in a mixed solvent of 3.1 g of dehydrated ethanol and 2 g of 3-methoxy-1-butanol, and a hydrogen peroxide solution having a concentration of 30% by weight is obtained in the resulting solution. 0.34 g (corresponding to 3.0 mol of hydrogen peroxide with respect to 1 mol of tantalum pentaethoxide) was gradually added with stirring, and after the addition was completed, the mixture was stirred for 5 minutes to cause a peroxo reaction. The reaction was conducted while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution was controlled so as not to exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. The reaction product having a solid concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (11).
When the obtained precursor solution was accommodated in a glass narrow mouth bottle and the mouth of the bottle was opened and left standing at room temperature (20 ± 5 ° C.) for 20 days, the gel was visually observed. A transparent solution state was maintained without causing turbidity or cloudiness.

(Example 12)
A film-forming precursor solution similar to that in Example 11 was produced, except that the amount of hydrogen peroxide relative to the tantalum compound was changed at the same solid content concentration as in Example 11.
That is, 0.4 g of tantalum pentaethoxide was dissolved in a mixed solvent of 3.17 g of dehydrated ethanol and 2.0 g of 3-methoxy-1-butanol in an argon gas atmosphere, and the resulting solution had a concentration of 30% by weight. Hydrogen peroxide solution 0.27g (corresponding to 2.5 moles of hydrogen peroxide per mole of tantalum pentaethoxide) was gradually added with stirring, and after the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. It was. The reaction was conducted while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution was controlled so as not to exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (12).
When the obtained precursor solution was accommodated in a glass narrow mouth bottle and the mouth of the bottle was opened, the state when left at room temperature (20 ± 5 ° C.) for 10 days was visually observed. A transparent solution state was maintained without causing turbidity or cloudiness.

(Example 13)
A film-forming precursor solution similar to that in Example 11 was produced, except that the amount of hydrogen peroxide relative to the tantalum compound was changed at the same solid content concentration as in Example 11.
That is, 0.4 g of tantalum pentaethoxide was dissolved in a mixed solvent of 2.94 g of dehydrated ethanol and 2.0 g of 3-methoxy-1-butanol in an argon gas atmosphere, and the resulting solution had a concentration of 30% by weight. Hydrogen peroxide solution 0.5g (corresponding to 3.5 moles of hydrogen peroxide per mole of tantalum pentaethoxide) was gradually added with stirring. After the addition was completed, the mixture was stirred for 5 minutes to allow peroxo-reaction. It was. The reaction was conducted while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution was controlled so as not to exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (13).
When the obtained precursor solution was accommodated in a glass narrow mouth bottle and the mouth of the bottle was opened, the state when left at room temperature (20 ± 5 ° C.) for 10 days was visually observed. A transparent solution state was maintained without causing turbidity or cloudiness.

(Comparative Example 4)
A film-forming precursor solution similar to Example 11 was produced, except that the amount of hydrogen peroxide relative to the tantalum compound was changed outside the scope of the present invention at the same solid content concentration as Example 11.
That is, 0.4 g of tantalum pentaethoxide was dissolved in a mixed solvent of 2.2 g of dehydrated ethanol and 3.1 g of 3-methoxy-1-butanol in an argon gas atmosphere, and the resulting solution had a concentration of 30% by weight. 0.14 g of hydrogen peroxide solution (corresponding to 1.25 mol of hydrogen peroxide per 1 mol of tantalum pentaethoxide) was gradually added with stirring. After the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. It was. The reaction was conducted while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution was controlled so as not to exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (C4).
When the obtained precursor solution was placed in a glass narrow mouth bottle and left at room temperature (20 ± 5 ° C.) with the bottle mouth open, gelation was visually observed after 2 days. It was. That is, the usable time (pot life) of the obtained precursor solution at room temperature was less than 2 days.

(Comparative Example 5)
A film-forming precursor solution similar to Example 11 was produced, except that the amount of hydrogen peroxide relative to the tantalum compound was changed outside the scope of the present invention at the same solid content concentration as Example 11.
That is, 0.4 g of tantalum pentaethoxide was dissolved in a mixed solvent of 1.8 g of dehydrated ethanol and 2.52 g of 3-methoxy-1-butanol in an argon gas atmosphere, and the resulting solution had a concentration of 30% by weight. Hydrogen peroxide solution 0.14 g (corresponding to 10 mol of hydrogen peroxide with respect to 1 mol of tantalum pentaethoxide) was gradually added with stirring, and after completion of the addition, the mixture was stirred for 5 minutes to cause peroxo reaction. The reaction was conducted while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution was controlled so as not to exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (C5).
The obtained precursor solution was housed in a glass narrow mouth bottle and left at room temperature (20 ± 5 ° C.) with the bottle mouth open, and gelation was observed visually after 3 hours. It was. That is, the usable time (pot life) of the obtained precursor solution at room temperature was less than 3 hours.

(Example 14)
A film-forming precursor solution similar to that of Example 11 was produced, except that the composition of the solvent was changed with the same solid content concentration and the amount of hydrogen peroxide relative to the tantalum compound as in Example 11.
That is, 0.4 g of tantalum pentaethoxide was dissolved in 5.1 g of dehydrated ethanol in an argon gas atmosphere, and 0.34 g of hydrogen peroxide solution having a concentration of 30% by weight (1 mol of tantalum pentaethoxide was added to the obtained solution). (Corresponding to 3.0 mol of hydrogen peroxide) was gradually added under stirring, and after completion of the addition, the mixture was stirred for 5 minutes to cause peroxo-reaction. The reaction was conducted while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution was controlled so as not to exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. The reaction product having a solid content concentration of 6.75% by weight thus obtained was used as a film-forming precursor solution (14).
When the obtained precursor solution was accommodated in a glass narrow mouth bottle and the mouth of the bottle was opened, the state when left at room temperature (20 ± 5 ° C.) for 10 days was visually observed. A transparent solution state was maintained without causing turbidity or cloudiness.

(Comparative Example 6)
The same precursor for film formation as in Example 11 except that the amount of hydrogen peroxide with respect to the same tantalum compound as in Example 11 was changed to increase the solid content concentration outside the scope of the present invention by changing the composition and amount of the solvent. A solution was prepared.
That is, 0.4 g of tantalum pentaethoxide was dissolved in a mixed solvent of 1.53 g of dehydrated ethanol and 2.29 g of 3-methoxy-1-butanol in an argon gas atmosphere, and the resulting solution had a concentration of 30% by weight. Hydrogen peroxide water 0.34g (corresponding to 3.0 moles of hydrogen peroxide per 1 mole of tantalum pentaethoxide) was gradually added with stirring. After the addition was completed, the mixture was stirred for 5 minutes to cause peroxo-reaction. It was. The reaction was conducted while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution was controlled so as not to exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. The reaction product having a solid content concentration of 8.77% by weight thus obtained was used as a film-forming precursor solution (C6).
The obtained precursor solution was housed in a glass narrow mouth bottle and left at room temperature (20 ± 5 ° C.) with the bottle mouth open. After one day (24 hours), the gel was visually observed. Observed. That is, the usable time (pot life) of the obtained precursor solution at room temperature was less than one day.

Claims (3)

  It contains a reaction product obtained by reacting 2.5 to 3.5 moles of hydrogen peroxide with 1 mole of niobium compound or tantalum compound, and has a solid content concentration of 8.5% by weight or less. A precursor solution for film formation. The film forming precursor solution according to claim 1, which also contains a solvent represented by any one of the following general formulas (1) to (5).

(In Formula (1), R < ¹ > -R < ⁶ > represents H or an alkyl group, and may respectively be the same or different. X is -OH or -OR (However, R is an alkyl group. Represents).)

(In Formula (2), R < ¹ > -R < ⁵ > represents H or an alkyl group, and may respectively be the same or different. X is -OH or -OR (However, R is an alkyl group. Represents).)

(In Formula (3), R < ¹ > -R < ⁷ > represents H or an alkyl group, and may respectively be the same or different. X is -OH or -OR (However, R is an alkyl group. Represents).)

(In formula (4), Y represents an alkylene group having 3 to 6 carbon atoms which may have a substituent.)

(In formula (5), Y represents a C3-C6 alkylene group which may have a substituent.)   The solvent is 3-methoxy-1-butanol, 3-methoxy-3-methyl-1-butanol, diacetone alcohol, 4-hydroxy-2-butanone, 5-hydroxy-2-pentanone, tetrahydrofuran-2-carboxylic acid The film forming precursor solution according to claim 2, which is at least one selected from the group consisting of 2-methyl-1,3-propanediol, γ-butyrolactone, δ-valerolactone, and ε-caprolactone.