JP6200814B2 - Tin oxide particles containing phosphorus and method for producing tin oxide sol containing phosphorus - Google Patents

Description

  The present invention relates to tin oxide particles containing phosphorus. The tin oxide particles containing phosphorus according to the present invention are suitably used as a raw material for a transparent conductive film formed by mixing conductive particles with resin or plastic, for example. The present invention also relates to a method for producing a tin oxide sol containing phosphorus.

  In the case of producing a conductive thin film using a resin, or in the case of imparting conductivity to a non-conductive material such as plastic, it is often performed to use conductive powder. As the conductive powder, for example, tin powder containing metal powder, carbon black, antimony, and the like are known. However, the conductive thin film is often required to have a high light transmittance for the purpose of confirming the position of the product in the process and for detecting abnormalities. When metal powder or carbon black is used, it is transparent. A conductive thin film cannot be obtained. Moreover, when carbon black is added to plastic, the resulting plastic itself becomes black, and the use of conductive plastic is limited. When tin oxide doped with antimony or the like is added to the plastic, the plastic becomes blue-black, and the use of the plastic is limited in the same manner as carbon black. Moreover, since antimony is a harmful substance to the human body, there is also a problem of environmental load caused by use. Therefore, various studies have been made on tin oxide not used as an element dopant having a large environmental load such as antimony.

  As this dopant element, tin oxide using phosphorus, which is an element with a small environmental load, has been proposed (see Patent Document 1). In this document, a tin oxide sol (hereinafter also referred to as “PTO”) containing phosphorus is obtained by mixing a phosphorus compound and an alkylamine such as diisopropylamine with a tin oxide sol that is a raw material, and then performing hydrothermal treatment. ing. To the obtained PTO sol, diisobutylamine is added and mixed to obtain the desired sol.

JP 2008-50253 A

However, when the transparent conductive film is formed using the sol described in Patent Document 1, it cannot be said that the electric resistance is sufficiently low to be used as the conductive powder for the conductive film, and the target 1.0 × It did not reach 10 ¹⁰ Ωcm, and there was room for improvement.

  The subject of this invention is providing the manufacturing method of the tin oxide sol containing phosphorus and the tin oxide particle | grains containing phosphorus which can eliminate the various fault which the prior art mentioned above has.

In the present invention, tin oxide particles containing phosphorus, X (nm) is a volume cumulative particle diameter D ₅₀ at a cumulative volume of 50% by volume measured by a dynamic light scattering method, and the carbon contained in the particles. When the ratio is Y (mass%), tin oxide particles containing phosphorus having an X / Y value of 3 to 50 are provided.

In the present invention, a basic aqueous solution containing a phosphorus source is added with an aqueous solution containing a divalent or tetravalent tin source to prepare a tin oxide sol containing phosphorus,
The present invention provides a method for producing a tin oxide sol containing phosphorus, wherein the sol is hydrothermally treated in an autoclave in the presence of an alkylamine or ammonia to produce tin oxide particles containing phosphorus.

  ADVANTAGE OF THE INVENTION According to this invention, the tin oxide particle containing the phosphorus which can form the electroconductive thin film whose electroconductivity is higher than before is provided. Moreover, according to this invention, the method which can manufacture suitably the sol of the tin oxide particle containing such phosphorus is provided.

1A and 1B are transmission electron microscopic images of tin oxide particles obtained in Example 1. FIG. 2A and 2B are transmission electron microscope images of the tin oxide particles obtained in Comparative Example 1. FIG.

  Hereinafter, the present invention will be described based on preferred embodiments thereof. The PTO particles of the present invention can be in the form of a powder that is an aggregate of the particles, depending on the specific application. Alternatively, it may be in the form of a sol (dispersion) in which the powder is dispersed in a medium such as water or an organic solvent.

  The PTO particles of the present invention contain phosphorus for the purpose of increasing the conductivity of the particles. The PTO particles of the present invention are considered to have a structure in which the position of an oxygen atom is substituted with a phosphorus atom in a tin oxide crystal. As is clear from the method for producing PTO particles described later, in the PTO particles of the present invention, it is considered that phosphorus as a doping element is uniformly distributed over the radial direction of the particles. The present inventor believes that such a phosphorus distribution state contributes to the improvement of the conductivity of the PTO particles of the present invention. That is, the resistance value of the PTO particles as a whole is governed by the ratio of the low-conductivity low-phosphorus part. Therefore, when the concentration of phosphorus that increases conductivity is not uniform, the high-resistance part ratio is It will rise. For this reason, it is necessary to make the phosphorus concentration uniform in the radial direction in the particles. On the other hand, in the PTO particles described in Patent Document 1 described in the background art section above, it is considered that phosphorus is unevenly distributed on the surface of the particles and in the vicinity thereof as viewed from the production method. For this reason, since the resistance value inside the particles does not decrease, the inventor believes that the PTO particles described in the document do not have sufficiently high conductivity.

By the way, although the oxide which consists only of bivalent tin turns into black, although it has electroconductivity, it cannot utilize for the use as which a transparency is requested | required, for example, the transparent conductive film used for the conveyance process of an electronic component, etc. On the other hand, an oxide made of only tetravalent tin cannot have higher conductivity than an oxide made of only divalent tin. On the other hand, the PTO particles of the present invention are white and can be used for a transparent conductive film and the like, and since they are made of tetravalent tin, the conductivity is high. As a result, it is possible to increase the conductivity. The PTO particles of the present invention exhibit only the same diffraction peak as that of tetravalent SnO ₂ when measured by powder X-ray diffraction. Therefore, most of the valence of tin in the PTO particles of the present invention is considered to be a tetravalent state with high conductivity.

  The PTO particles of the present invention contain phosphorus as a dopant, and with respect to other known dopant elements such as antimony, tantalum, niobium, tungsten, etc., it is advantageous from the viewpoint of improving conductivity that the content ratio is low. . From the viewpoint of environmental load and manufacturing cost, the PTO particles of the present invention preferably contain only phosphorus as a dopant and no other known dopants.

Further, the PTO particles of the present invention preferably have a small content of impurity elements other than the above-mentioned known dopants from the viewpoint of improving the conductivity. In particular, it is preferable that the content ratio of carbon which is an element having a large influence on the decrease in conductivity is low. However, from the viewpoint of improving the dispersibility of the PTO sol, it is necessary to add a dispersant to the sol, and as the dispersant, a carbon-containing compound such as an alkylamine is more preferable from the viewpoint of ensuring dispersibility. For this reason, carbon is inevitably mixed in the PTO particles. Therefore, there is a limit to reducing the proportion of carbon contained in the PTO particles. Thus, regarding the carbon content, the conductivity of the PTO particles and the dispersibility of the PTO sol containing the PTO particles are in a trade-off relationship. Under such circumstances, as a result of intensive studies, the present inventors surprisingly set the ratio between the particle size of the PTO particles and the carbon content ratio to a specific range, thereby improving the conductivity of the PTO particles. It was found that both dispersibility and compatibility can be achieved. Specifically, the volume cumulative particle diameter D ₅₀ in the cumulative volume 50% by volume of the PTO particles measured by dynamic light scattering method and X (nm), the proportion of carbon contained in the PTO particles Y (mass% When the X / Y value is 3 to 50, the conductivity and dispersibility of the PTO particles are compatible. From the viewpoint of making this advantageous effect more remarkable, the value of X / Y is preferably 3 to 30, and more preferably 3 to 20. The value of X, which is the particle size of the PTO particles, and the value of Y, which is the carbon content, can be controlled, for example, by producing PTO particles according to the method described later.

  The balance between the conductivity and dispersibility of the PTO particles can be achieved by the value of X / Y because the particle size is different even if the proportion of carbon contained in the PTO particles is the same. It means that the degree is different. Specifically, even if the proportion of carbon contained in the PTO particles is the same, the smaller the particle size, the higher the conductivity of the particles. Such knowledge has not been known so far, and is the first finding of the present inventors.

  The values of X and Y are preferably as follows. The value of X is preferably 1 to 50 nm, more preferably 1 to 20 nm, particularly 1 to 15 nm, especially 1 to 10 nm, provided that the value of X / Y is within the above-mentioned range. That is, the PTO particles of the present invention are very fine. On the other hand, the value of Y is 5.0% by mass, particularly 4.0% by mass or less, especially 3.0% by mass or less, especially 2.1%, provided that the value of X / Y is within the above-mentioned range. It is preferable that it is below mass%. Although the value of Y is preferably closer to 0, the lower limit of Y is preferably 1.3% by mass and more preferably 1.5% by mass in relation to the above-mentioned X / Y range. . The measuring method of the value of X and Y is explained in full detail in the Example mentioned later.

As apparent from the preferable range of the value of X described above, the PTO particles of the present invention are very fine, which means that the PTO particles have a high specific surface area. That is, since the PTO particles are fine and highly dispersed, the number of contact points between the particles increases, and the electrical resistance decreases. Specifically, BET specific surface area of the PTO particles of the present invention is preferably 100 to 300 m ² / g, more preferably 120~250m ² / g, more preferably 150 to 200 m ² / g.

  As described above, the PTO particles of the present invention have a low ratio Y of carbon as an impurity, but it is advantageous from the viewpoint of improving conductivity that the ratio of other impurity elements is also low. Specifically, in the PTO particles of the present invention, the sum of the proportions of elements contained other than phosphorus, tin, oxygen and carbon is preferably 0.001 to 1.0% by mass, more preferably 0.8. The level is as low as 001 to 0.5 mass%.

  As a result of examination by the present inventors, the PTO particles of the present invention contain phosphorus, and the ratio of phosphorus and carbon in the PTO particles also affects the conductivity of the PTO particles. . Specifically, when the ratio of phosphorus contained in the PTO particles is Z (mass%), the ratio Z / Y of this Z and the ratio Y (mass%) of carbon contained in the PTO particles is preferably 0. .3-0.7, more preferably 0.4-0.6, and the conductivity of the PTO particles is further increased. The method for measuring the value of Z will be described in detail in the examples described later.

  The value of the proportion Z of phosphorus contained in the PTO particles is preferably 0.9 to 5.0% by mass, more preferably 0.9 to 2 on the condition that the value of Z / Y is within the above range. 0.5% by mass, more preferably 0.9-2.0% by mass, and particularly preferably 0.9-1.2% by mass. By setting the ratio Z of phosphorus to 2.5% by mass or less as apparent from the comparison between Example 4 and Comparative Example 5, which will be described later, the conductivity of the PTO particles can be further enhanced. Further, the transparency can be further enhanced. The value of Z can be controlled by adjusting the amount of phosphorus source added to the reaction system and the reaction conditions in the PTO particle production method described later.

  The PTO particles of the present invention are preferably in the form of particles having a spherical shape or a rounded shape (see FIG. 1 described later). By having such a shape, when a conductive film is formed using the PTO particles as a raw material, the filling property of the PTO particles in the conductive film is improved, and the conductivity of the conductive film can be increased. On the other hand, the PTO particles described in Patent Document 1 described in the section of the background art have a rugged shape having corners according to the follow-up test of the present inventor (see FIG. 2 described later). It was found that the contact area between the particles was small due to the shape, and the conductivity of the conductive film could not be sufficiently increased.

The PTO particles of the present invention are highly transparent and conductive when formed into a film. For example, when a conductive film made of a resin having a thickness of 0.1 to 1.0 μm and a PTO particle content of 95 to 99% by mass is produced, the visible light has a total light transmittance of 85% or more, particularly It becomes a highly transparent material of 90% or more. The haze value is preferably 3 or less, more preferably 1 or less. When a film is produced under these conditions, the surface resistance value is 2 × 10 ⁸ to 8 × 10 ⁹ Ωcm under the measurement conditions of 25 ° C. and 50% RH.

  As mentioned above, the PTO particles of the present invention can also be in the form of a sol (dispersion). As the dispersion medium of the sol, water or an aqueous liquid containing a water-soluble organic solvent or an organic solvent can be used. Such a sol is useful for producing a transparent conductive film, for example. The proportion of PTO particles in the sol is preferably 5 to 45% by mass, particularly 5 to 30% by mass.

  The sol containing the PTO particles of the present invention (hereinafter also referred to as “PTO sol”) may contain only PTO particles as a dispersoid and a dispersion medium, or may be a third soluble in the dispersion medium. A component may be included. Examples of such a third component include a dispersant for PTO particles as a dispersoid, a metal salt such as a tin salt, a phosphorus-containing compound, and an alkali. In the PTO sol, the total of the proportions of the third component including the dispersant is preferably 0 to 1.0% by mass, and more preferably 0 to 0.5% by mass.

  Since the powder of the PTO particles of the present invention is white or transparent, the PTO sol that is a sol containing the powder is highly transparent in the wavelength region of visible light (400 to 800 nm). In particular, when a coating film is formed using an aqueous dispersion having high transparency, the transparency of the coating film after drying becomes extremely high.

  Next, the suitable manufacturing method of PTO sol containing the PTO particle | grains of this invention is demonstrated. This manufacturing method is roughly divided into (1) a preparation process of tin oxide sol containing phosphorus, and (2) a process of generating PTO particles by hydrothermal treatment. Further, (3) a PTO particle dispersion treatment step is performed as necessary. Hereinafter, each process is explained in full detail.

  In the step (1), an aqueous solution containing a divalent or tetravalent tin source is added to a basic aqueous solution containing a phosphorus source to prepare a tin oxide sol containing phosphorus. As the phosphorus source, a water-soluble phosphorus compound can be used. Examples of such phosphorus compounds include orthophosphoric acid and its alkali metal salts, phosphorus oxides and the like, with salts being more preferred. The ratio of the phosphorus source contained in the basic aqueous solution is preferably 0.01 to 1.0 mol / L, particularly 0.02 to 0.5 mol / L, relative to water.

  As the basic aqueous solution, an aqueous solution of an alkali metal such as sodium hydroxide, an aqueous solution of an alkaline earth metal, ammonia or the like can be used. The basic aqueous solution preferably has a pH of 11 or more, particularly 12 or more in a state containing a phosphorus source. This basic aqueous solution preferably does not contain a carbon-containing compound.

  In an aqueous solution containing a tin source added to a basic aqueous solution containing a phosphorus source, a divalent tin compound or a tetravalent tin compound is used as the tin source. As these tin compounds, it is preferable to use compounds not containing carbon. For example, it is preferable to use a tin halide such as stannous chloride or stannous chloride, or tin sulfate. When a divalent tin source is compared with a tetravalent tin source, it is preferable to use a tetravalent tin source from the viewpoint of easily obtaining uncolored PTO particles. From this viewpoint, a compound that is particularly preferably used as a tin source is stannic chloride. The ratio of the tin source contained in the aqueous solution containing the tin source is preferably 15 to 60% by mass, particularly 20 to 40% by mass as stannic chloride. It is preferable that the aqueous solution containing a tin source does not contain a carbon-containing compound.

  In this production method, it is important to add an aqueous solution containing a tin source to a basic aqueous solution containing a phosphorus source. By adopting this addition mode, a phosphorus source can be present in the reaction system from the beginning of the production of PTO particles, so that the obtained PTO particles have a uniform phosphorus distribution over the radial direction. In addition, instead of adding an aqueous solution containing a tin source to a basic aqueous solution containing a phosphorus source, conversely, a basic aqueous solution containing a phosphorus source is added to an aqueous solution containing a tin source, or a phosphorus source is included. When an aqueous solution, an aqueous solution containing a tin source, and a basic aqueous solution are added to water all at once, a PTO particle having electrical conductivity of the present invention cannot be obtained although a phosphorus source is present from the beginning of the reaction.

  When adding an aqueous solution containing a tin source to a basic aqueous solution containing a phosphorus source according to this production method, in order to prevent a high-concentration portion of the aqueous solution containing a tin source from occurring locally in the basic aqueous solution, It is preferable to add. The reaction proceeds rapidly even when the addition is performed at room temperature (20 to 25 ° C.), but if necessary, the basic aqueous solution containing a phosphorus source and / or the aqueous solution containing a tin source is added under a heated condition. Also good.

  By adding an aqueous solution containing a tin source to a basic aqueous solution containing a phosphorus source, a sol of tin oxide containing phosphorus can be obtained. As a result of the composition analysis, it was confirmed that the tin oxide was mainly composed of tetravalent tin oxide. Further, as a result of X-ray diffraction measurement, it was confirmed that the crystal had a broad diffraction peak and low crystallinity.

  The sol thus obtained is washed with water using a centrifugal separator or a solid-liquid separator to remove impurities, and then the step (2) is performed. In this step, alkylamine or ammonia is added to the sol, and the sol is hydrothermally treated in an autoclave under an autogenous pressure in the presence of these. Alkylamine and ammonia are added for the purpose of preventing particle aggregation. Either one of alkylamine and ammonia may be used, or both may be used in combination. From the viewpoint of reducing the proportion of carbon in the finally obtained PTO particles, it is preferable to use ammonia. When using an alkylamine, it is preferable to use a primary amine rather than a secondary amine or a tertiary amine from the viewpoint of reducing the carbon ratio in the PTO particles. It is also preferable to use a lower alkyl amine. If these are judged comprehensively, it is preferable to use a primary amine having a carbon number of preferably 1 to 12, more preferably 1 to 10, and still more preferably 2 to 6.

  The addition amount of ammonia or alkylamine is preferably 5 to 50% by mass, and more preferably 10 to 30% by mass with respect to tin oxide.

  In the hydrothermal treatment, it is preferable that the ratio of the solid content contained in the sol is 5 to 30% by mass, particularly 7 to 20% by mass. The temperature of the hydrothermal treatment is preferably set to 130 to 200 ° C, particularly 150 to 180 ° C. The treatment time is preferably set to 2 to 20 hours, particularly 2 to 10 hours, provided that the temperature is within this range.

  A sol containing PTO particles is obtained by the above hydrothermal treatment. Next, the dispersion processing step (3) is performed as necessary. In this step, the sol obtained in (2) is preferably subjected to a dispersion treatment after being diluted with water and / or a water-soluble organic solvent as necessary. A dispersing agent may be added during the dispersion treatment. It is preferable to use a carbon-free compound as the dispersant. By doing so, it is possible to prevent carbon from being mixed into the PTO particles. On the other hand, in the method described in Patent Document 1 described above in the background art section, since alkylamine is used as a dispersant, carbon is mixed in the obtained PTO particles and the ratio of carbon is increased. There is a tendency. Examples of the carbon-free compound used as the dispersant include ammonia.

  The dispersion treatment can be performed using, for example, a homogenizer or a stirrer. The PTO sol obtained in this way is transparent and has high stability with no precipitation observed even after storage for a long period of time. A transparent conductive film can be formed by adding a water-soluble transparent resin to the PTO sol to prepare a paint and applying the paint to a substrate.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “%” means “mass%”.

[Example 1]
(1) Preparation process of tin oxide sol containing phosphorus Trisodium phosphate dodecahydrate (26.8 g) was used as a phosphorus source. This was dissolved in sodium hydroxide solution (25% solution in 500 mL), and water was added to obtain 9000 mL of a basic aqueous solution. The pH of this basic aqueous solution was 12. Separately, stannic chloride (800 g of a 50% solution) was used as a tin source and dissolved in water to obtain 1000 mL of an aqueous solution. This aqueous solution was dropped into a basic aqueous solution over 1 hour at room temperature. During this time, the basic aqueous solution was stirred. By this reaction, a sol of tin oxide containing phosphorus was obtained. As a result of elemental analysis, it was confirmed that the tin oxide was represented by the composition formula SnO ₂ . As a result of X-ray diffraction measurement, it was confirmed that the tin oxide was amorphous.

(2) Step of producing PTO particles by hydrothermal treatment The sol obtained in the step (1) is washed until the electric conductivity becomes 300 μS / cm or less, and concentrated by a centrifuge to obtain a solid content of 13.4%. After that, n-propylamine was added by 2.4% based on the solid content. Then, hydrothermal treatment was performed in an autoclave for 3 hours under heating at 180 ° C. By this treatment, a PTO particle sol was obtained.

(3) Dispersion treatment step of PTO particles 100 mL of methanol was added to 100 mL of PTO sol (solid content: 13.4%) obtained in the step of (2), and a mixing treatment was performed to obtain a target PTO sol. .

(4) Analysis and Evaluation About the obtained PTO sol, the particle size D ₅₀ of the PTO particles by the dynamic light scattering method, the BET specific surface area of the PTO particles, the carbon content, and the phosphorus content are measured by the following methods. did. Moreover, the resistance and haze of the transparent conductive film produced using the PTO sol were measured by the following methods. The results are shown in Table 1 below. Furthermore, the TEM image of the obtained PTO particle | grains is shown to Fig.1 (a) and (b). Further, when X-ray diffraction measurement was performed on the obtained PTO particles, the same diffraction peak as that of tetravalent SnO ₂ was observed.

(A) Particle size D ₅₀
Measurement was performed using Nanotrac UPA, which is a particle size / particle size distribution measuring device of Nikkiso Co., Ltd. as a measuring device.

(B) BET specific surface area 0.5 g of PTO particles were subjected to deaeration treatment at 105 ° C. for 10 minutes, and then measured by a BET one-point method using monosorb (manufactured by Kantachrome).

(C) Carbon content ratio The carbon content was measured using a carbon analyzer (EMIA-320V manufactured by Horiba, Ltd.).

(D) Content ratio of phosphorus The powder was alkali-melted, made acidic with HCl, and measured with ICP (SII SPS5100).

(E) Resistance of transparent conductive film Methanol was added to the synthesized PTO sol (solid content 13%) (PTO sol and methanol were expressed by volume ratio and adjusted at 1: 1) to prepare a dispersion. Using the obtained dispersion, it was coated on a PET film with a bar coater and dried at 80 ° C. to form a coating film. The surface resistance of the coating film was measured using a double ring probe method (Hiresta UP manufactured by Mitsubishi Chemical Analytech).

(F) Haze of transparent conductive film The haze of the coating film was measured by an integrating sphere measurement method using NDH4000, a haze meter manufactured by Nippon Denshoku Industries Co., Ltd. The haze is calculated from (scattered light / total light transmitted light) × 100.

[Examples 2 and 3]
A PTO sol was obtained in the same manner as in Example 1 except that the amount of n-propylamine added during hydrothermal treatment was 3.0% (Example 2) and 6.0% (Example 3). About the obtained PTO sol, the same measurement and evaluation as Example 1 were performed. The results are shown in Table 1.

Example 4
Implemented except that the amount of trisodium phosphate dodecahydrate added during preparation of tin oxide sol containing phosphorus was 85.1 g and the amount of n-propylamine added during hydrothermal treatment was 8.0%. A PTO sol was obtained in the same manner as in Example 1. About the obtained PTO sol, the same measurement and evaluation as Example 1 were performed. The results are shown in Table 1.

[Comparative Example 1]
This comparative example corresponds to Example 1 of Patent Document 1. To a 5 L beaker, 1.92 L of pure water and 187.5 g of oxalic acid were added to obtain an aqueous oxalic acid solution. Under a state where this oxalic acid aqueous solution was heated to 70 ° C., 50 g of hydrogen peroxide and 25 g of metallic tin were added. Hydrogen peroxide and metallic tin were added alternately. Waiting for the reaction to finish (10 minutes), this operation was repeated 15 times to add a total of 750 g of hydrogen peroxide and 375 g of metallic tin. Thereafter, 50 g of hydrogen peroxide was added, and 260 mL of pure water and 1155 g of hydrogen peroxide were added, and the mixture was aged for 5 hours while being heated to 95 ° C., and the oxalic acid remaining in the liquid was removed. Decomposed into carbon dioxide and water. 1.35 g of diisopropylamine and 1.18 g of orthophosphoric acid are added to 500 g of the tin oxide sol thus obtained (solid content: 10.2%), and hydrothermal treatment is carried out in an autoclave at 150 ° C. for 8 hours. To obtain the desired sol. This sol was measured and evaluated in the same manner as in Example 1. The results are shown in Table 1. Furthermore, the TEM image of the obtained particle | grains is shown to Fig.2 (a) and (b).

[Comparative Examples 2 to 4]
In Example 1, the amount of trisodium phosphate dodecahydrate added at the time of preparing tin oxide sol was 150 g (Comparative Example 2), 16 g (Comparative Example 3), and 150 g (Comparative Example 4), and hydrothermal treatment Same as Example 1 except that the amount of n-propylamine sometimes added is 0.7% (Comparative Example 2), 4.0% (Comparative Example 3) and 3.0% (Comparative Example 4). Thus, a PTO sol was obtained.

[Comparative Example 5]
In Example 4, a PTO sol was obtained in the same manner as in Example 4 except that the amount of trisodium phosphate dodecahydrate added at the time of preparing the tin oxide sol was 127.8 g.

As is clear from the results shown in Table 1, the conductive film obtained from the PTO sol obtained in each example has higher conductivity than the conductive film obtained from the sol obtained in each comparative example. And it turns out that transparency is also high compared with the electrically conductive film obtained from the sol obtained in Comparative Examples 1-3. Further, as is clear from the comparison between FIG. 1 and FIG. 2, it can be seen that the PTO particles obtained in Example 1 are finer than the particles obtained in Comparative Example 1. Comparative Example 1 is as large as X / Y is also 126 because of the large D _50, is intended haze value is high low transparency due to this fact, higher coating resistance. Further, Comparative Example 3 in which the amount of n-propylamine added is large and X / Y exceeds 50 is high in resistance but high in transparency.
On the other hand, Comparative Example 4 in which D ₅₀ is as small as 0.85 μm and X / Y is 0.53 has high transparency but has high resistance because the dispersibility of the particles is too high.
As described above, when the value of X / Y is 3 to 50, it can be seen that the conductivity and dispersibility of the PTO particles are compatible.

Claims (9)

In the tin oxide particles containing phosphorus, the volume cumulative particle diameter D ₅₀ in the cumulative volume of 50% by volume of the particles measured by the dynamic light scattering method is X (nm), and the ratio of carbon contained in the particles is Y ( %), Tin oxide particles containing phosphorus having a value of X / Y of 3 to 50.   2. The tin oxide particles containing phosphorus according to claim 1, wherein the value of Z / Y is 0.3 to 0.7 when the ratio of phosphorus contained in the tin oxide particles is Z (mass%).   X is 1-50 (nm), The tin oxide particle containing the phosphorus of Claim 1 or 2.   Y is 1.3-5.0 (mass%), The tin oxide particle containing the phosphorus as described in any one of Claim 1 thru | or 3.   Z is 0.9-5.0 (mass%), The tin oxide particle containing the phosphorus as described in any one of Claim 2 thru | or 4. The tin oxide particles containing phosphorus according to any one of claims 1 to 5, having a BET specific surface area of 100 to 300 m ² / g. In a basic aqueous solution containing a phosphorus source, an aqueous solution containing a divalent or tetravalent tin source is added to prepare a tin oxide sol containing phosphorus,
A method for producing a tin oxide sol containing phosphorus, wherein the sol is hydrothermally treated in an autoclave in the presence of an alkylamine or ammonia to produce tin oxide particles containing phosphorus.   The production method according to claim 7, wherein tin chloride or tin sulfate is used as the tin source.   The production method according to claim 7 or 8, wherein a primary amine having 1 to 12 carbon atoms is used as the alkylamine.