JP5416532B2 - Acicular tin oxide fine powder and method for producing the same - Google Patents

Description

  The present invention relates to acicular tin oxide fine powder having excellent conductivity and a method for producing the same. More specifically, the present invention relates to an excellent high-functional material that can be applied in various fields of application as a filler for conductive paints or conductive resins and can achieve high added value.

  Conductive filler material is used as a conductivity-imparting agent or antistatic agent for plastics, rubber, fiber, etc., and further as a conductivity-imparting agent for supports of recording materials such as electrophotographic copying paper and electrostatic recording paper. Is done.

  At present, as the conductive material, a so-called ion conduction type such as a surfactant or an ionic conductive material and a so-called electron conduction type such as carbon or oxide-based conductive powder are often used.

  In particular, the electron-conducting type has higher conductivity stability with respect to humidity and temperature than the ion-conducting type, so in recent years, for example, materials in various fields such as paints, inks, plastics, and fibers. As an antistatic conductivity imparting agent for products and products, it is very effectively used as an environment-independent material.

Examples of the electron conduction type include oxide materials such as carbon materials, indium-tin (ITO) powders, antimony-tin (ATO) powders, SnO ₂ , aluminum-zinc (AZO) oxides. In addition, materials having a surface coated with these compositions are known.

  In general, when a conductive agent containing conductive powder is applied and used, the conductive powder is filled in rubber, plastics, paper or the like or dispersed in a solution containing a binder. A coating solution is used, and this coating solution is applied to various films, sheets, supports, and objects to be processed such as a casing. In that case, in order to obtain good conductivity, it is necessary to increase the content of the conductive powder so that at least adjacent powders are in close contact with each other. When a spherical powder or the like is used, it is necessary to mix a large amount of conductive powder. Here, the needle-like or fiber-like conductive powder is advantageous in that the conductive path can be effectively formed even with a small amount of the conductive powder per unit area or unit volume. Therefore, various powders having acicularity have been developed.

  First, various types of fibrous conductive antimony tin oxide have been proposed. For example, in order to produce conductive stannic oxide fibers, tin oxalate is heated at a very low temperature (Patent Document 1), or antimony tin oxide is evaporated using copper as a solvent and introduced into a low temperature portion. It is known that it is produced by a method such as producing a spinning solution with a tin compound and spinning (Patent Document 3). In either case, the short axis is as thick as about 0.5 μm, or the industrial productivity is extremely low.

  Furthermore, it is also known that the conductive material is coated on a powder having a fibrous form (Patent Documents 4 and 5). However, since these materials are coated on the base material, the particle system becomes large, and cannot be used for applications where a resin compound is formed into a thin film or the like, so-called light thinness is required. When used, there is a problem that the coating film becomes uneven and cannot be used.

  Moreover, although fibrous ITO powder is also known (Patent Documents 6, 7, 8, and 9), there is a problem in that it can be used because of its high cost.

  Therefore, the minor axis average particle diameter is 0.005 to 0.05 μm, the major axis average particle diameter is 0.1 to 3 μm, the aspect ratio is 5 or more, and the silicon component is contained. Needle-like conductive tin oxide fine powder or needle-like conductive antimony-containing tin oxide fine powder has been proposed (Patent Documents 10 and 11). However, since these particles are too small, the specific surface area becomes large, and when used as a filler, there is a problem that flexibility is lost and resin strength is deteriorated.

JP-A-56-120519 JP 62-158199 A Japanese Patent Laid-Open No. 5-117906 JP-A-11-241271 International Publication No. 2005/008685 JP-A-6-293515 JP-A-6-293517 Japanese Patent Laid-Open No. 7-232920 Japanese Patent Laid-Open No. 10-17325 JP-A-8-23112 JP-A-8-217445

  Therefore, as a result of earnest research, the inventors of the present invention, when producing acicular conductive powder, by adding cerium to tin oxide, high conductivity, white acicular tin oxide fine powder, Using this acicular conductive tin oxide fine powder, it was found that even when added in a small amount, the surface resistivity is low and a thin white coating film can be formed, and the present invention has been completed.

The present invention relates to a needle-like tin oxide fine powder and a method for producing the same, which have solved the above problems with the following configuration.
(1) Acicular tin oxide having a minor axis average particle diameter of 20 to 200 nm, an aspect ratio of 3 or more, and containing 0.1 to 10% of cerium on a mass basis with respect to tin. Fine powder.
(2) Powder volume resistivity is less 1 × 10 ⁸ Ω · cm, the (1) acicular tin oxide fine powder according.
(3) The acicular tin oxide fine powder according to the above (1) or (2), which contains 10% or less of fluorine by mass.
(4) The acicular tin oxide powder according to the above (1) or (2) containing 10% or less of antimony on a mass basis, and (5) the thickness of 10 μm containing 20% of the acicular tin oxide fine powder on a mass basis. The acicular tin oxide fine powder according to any one of the above (1) to (4), wherein the polyethylene resin sheet has a volume resistivity of 10 ¹⁰ Ω · cm or less when formed into a polyethylene resin sheet.
(6) A fired product containing a tin component, a cerium component and an alkali metal halide is fired at a temperature higher than the melting point of the alkali metal halide and at 1200 ° C. or lower, and then the soluble salts of the obtained fired product The manufacturing method of the acicular tin oxide fine powder containing cerium which removes.

  According to the present invention (1), a needle-like white tin oxide fine powder capable of imparting conductivity can be provided, and according to the present invention (2), a needle-like white tin oxide having high conductivity can be provided. A fine powder can be provided. Using this acicular tin oxide fine powder, a white and thin coating film having a low surface resistivity can be formed. Moreover, according to this invention (6), the acicular tin oxide fine powder of this invention (1) can be manufactured easily.

2 is a transmission electron micrograph of acicular tin oxide fine powder obtained in Example 1. FIG.

  Hereinafter, the present invention will be specifically described based on embodiments. Unless otherwise indicated,% is based on mass unless otherwise specified.

[Acicular tin oxide fine powder]
The acicular tin oxide fine powder of the present invention has a minor axis average particle diameter of 20 to 200 nm, an aspect ratio of 3 or more, and 0.1 to 10% of cerium on a mass basis with respect to tin. Features. This acicular tin oxide fine powder is mainly composed of stannic oxide, and when oxygen defects are present in the stannic oxide, conductivity is imparted to the acicular antimony tin oxide fine powder.

  Here, the average particle diameter is a mass average particle diameter obtained by observing a transmission electron micrograph (magnification of 100,000 times) (n = 50). When the minor axis average particle diameter is 20 nm or more, good conductivity, good dispersibility in water and whiteness are exhibited, and when it is 200 nm or less, the smoothness of the coating film containing acicular tin oxide fine powder is obtained. To increase. Moreover, in this invention, a fine powder means a thing with a short-axis average particle diameter of 200 nm or less.

When the aspect ratio is 3 or more, good conductivity is imparted to a coating film using acicular tin oxide fine powder. Here, the aspect ratio is obtained by observing a transmission electron micrograph (magnification of 100,000 times) and calculating (major axis average particle diameter / minor axis average particle diameter) (n = 50). In the present invention, the “needle shape” includes not only the needle shape defined by the physical property values of the present invention but also a similar shape such as a fiber shape, a column shape, a rod shape and the like. In addition, it is preferable from a viewpoint of favorable electroconductivity that the long-axis average particle diameter of acicular tin oxide fine powder is 25 nm-10 micrometers, and 25 nm-4 micrometers are more preferable. Moreover, 1-100 m < ² > / g is preferable and, as for the specific surface area of acicular oxide fine powder, 5-50 m < ² > / g is more preferable.

  When cerium is 0.1% or more by mass with respect to tin, a transparent acicular powder having a minor axis average particle diameter of 20 to 200 nm and an aspect ratio of 3 or more can be obtained. Good electroconductivity is acquired as it is the following. Mass quantitative analysis of cerium and tin in acicular tin oxide fine powder is performed by ICP method.

  The acicular tin oxide fine powder preferably contains 10% or less of fluorine on a mass basis, more preferably 1 to 5%. Oxygen defects in stannic oxide are stabilized by the presence of fluorine, and the conductivity of acicular tin oxide fine powder can be stabilized. If the amount of fluorine in the acicular tin oxide fine powder is more than 10%, the amount of free fluorine or fluoride that is not doped into stannic oxide increases, and the current-carrying path between the acicular tin oxide fine powder is hindered. Decreases. Mass quantitative analysis of fluorine in acicular tin oxide fine powder is performed in the same manner as cerium and tin. In addition, even if fluorine is 0%, high conductivity can be imparted to the acicular tin oxide fine powder by reduction of stannic oxide with stannous ions or the like.

  Further, the acicular tin oxide fine powder preferably contains 10% or less of antimony on a mass basis, and more preferably contains 1 to 5%. Due to the presence of antimony, oxygen defects in the stannic oxide are stabilized, and the conductivity of the acicular tin oxide fine powder can be stabilized. If the amount of antimony in the acicular tin oxide fine powder is more than 10%, the amount of free antimony or antimony compound that is not doped with stannic oxide increases, and the current path between the acicular tin oxide fine powder is hindered. Decreases. The mass quantitative analysis of antimony in the acicular tin oxide fine powder is performed in the same manner as cerium and tin. In addition, even if antimony is 0%, high electroconductivity can be provided to acicular tin oxide fine powder by reduction | restoration of stannic oxide by a stannous ion etc.

Acicular tin oxide fine powder of the powder volume resistivity, 1 × is not more than 10 ⁸ Omega · cm, the coating film using the acicular tin oxide fine powder, the surface resistivity of 10 ⁹ to exert an antistatic effect It is possible to suppress the amount of acicular tin oxide fine powder mixed in the coating film necessary to obtain Ω / □, and it is possible to maintain the physical properties such as the total light transmittance of the coating film. 1 × 10 ³ Ω · cm or less is more preferable. Here, the powder volume resistivity, the sample was placed powder into a cylindrical toroidal PP made of insulating jig, pressurized with 100 kgf / cm ² to both ends of the opening by a brass electrode of the cylinder, the resistance value between the brass electrodes measured by a digital multimeter, which than calculates the powder volume resistivity.

When the thickness of 10μm coating containing 20% acicular tin oxide fine powder on a mass basis, the volume resistivity of the polyethylene resin sheet is not more than ¹⁰ 10 Ω · cm, the acicular tin oxide fine powder clear It is preferable for use as a conductive film. At this time, a coating film should just contain 19-21% of acicular tin oxide fine powder by mass reference | standard, and the remainder of a coating film is binder resin mentioned later. The film thickness is measured in the range of 9.5 to 10.4 μm. Here, the volume resistivity of the coating is measured by Mitsubishi Chemical analytic Tech Ltd. Hiresta UP (4-terminal method).

  The acicular tin oxide fine powder of the present invention preferably has a color tone of 70 or more in L value in the Lab color system. Here, the L value of the acicular tin oxide fine powder is measured using, for example, an apparatus (SM-7-IS-2B) manufactured by Suga Test Instruments Co., Ltd. In addition, since the acicular oxide fine powder of the present invention does not have a strong photocatalytic activity like titanium oxide used as a white pigment, the resin in the coating film is decomposed even if it is added to the resin and used for the coating film. There is no worry to promote.

  The acicular tin oxide fine powder has 70% or more of the total mass, the minor axis average particle diameter of 20 to 200 nm, the aspect ratio of 3 or more, and 0.1% by mass of cerium with respect to tin. It is preferable to contain 10%.

〔Production method〕
The method for producing the acicular tin oxide fine powder of the present invention,
A to-be-fired product containing a tin component, a cerium component and an alkali metal halide is fired at a temperature higher than the melting point of the alkali metal halide and 1200 ° C. or lower, and then the soluble salts of the obtained fired product are removed. It is characterized by that.

  First, a precursor for producing a material to be fired is generated. The precursor includes a tin component and a cerium component. The tin component is preferably a tin hydroxide and / or a dehydrate thereof.

  The tin compound for the raw material of the tin component used here includes tin halides such as tin chloride, tin oxide, tin hydroxide, or tin inorganic acid salts (such as stannous salts) such as tin sulfate and tin nitrate. , Stannic salts) and the like, and these may be used alone or in admixture of two or more. Examples of stannous salts include stannous fluoride, stannous chloride, stannous borofluoride, stannous sulfate, stannous oxide, stannous nitrate, tin pyrophosphate, tin sulfamate, and stannic acid. Examples thereof include inorganic salts such as salts, and organic salts such as stannous alkanol sulfonate, stannous sulfosuccinate, and stannous aliphatic carboxylate. Examples of stannic salts include the respective stannic salts of the above stannous salts. However, since there are those that are gases and those that are sparingly soluble, it is common to use liquid stannic chloride. Among them, it is industrially desirable to use a hydrochloric acid aqueous solution of stannic chloride. Tin hydroxide is obtained by dropping an aqueous hydrochloric acid solution of tin chloride into an alkali. The tin component can also be obtained by hydrolysis. This hydrolysis method may be a method known to those skilled in the art.

  As the cerium compound for the raw material of the cerium component, in addition to inorganic salts such as cerium trichloride, cerium hydroxide, cerium oxide, and cerium carbonate, organic cerium can also be used, and these can be used alone or in combination of two or more. May be. Among them, cerium carbonate is industrially preferable because it dissolves in an alkali. Specifically, the cerium component is contained by dissolving cerium carbonate in an alkaline aqueous solution and then performing a neutralization reaction.

  The precursor is more preferably a hydroxide of tin containing a cerium component and / or a dehydrate thereof, and uniform needle-like fine particles can be obtained by mixing the cerium component and tin. Can do. This method can be performed by various methods using a solution of each compound. For example, (a) a hydrochloric acid aqueous solution of a tin compound and an alkaline aqueous solution of a cerium compound are neutralized in hot water at 70 to 90 ° C. in parallel so as to maintain a pH of approximately 7, respectively, and cerium (B) Coprecipitation of a mixed hydroxide by adding a hydrochloric acid aqueous solution of a tin compound to the alkaline aqueous solution of the cerium compound and neutralizing it. And (c) a method in which an alkaline aqueous solution of a cerium compound is added to a hydrochloric acid aqueous solution in a tin compound for neutralization, and a mixed hydroxide is coprecipitated. Among these methods, the method (a) is particularly desirable industrially. In this case, the neutralization reaction solution is preferably maintained at a pH of 5 to 10.

  Further, the precursor may be composed of a tin hydroxide and / or a dehydrate thereof, and a cerium component, a tin hydroxide and / or a dehydrate thereof, and a cerium hydroxide and / or its It can also consist of a dehydrated product. In this case, the precursor may be prepared by a method known to those skilled in the art.

  The cerium in the material to be fired is preferably added in an amount of 0.1 to 10%, more preferably 0.3 to 5%, and particularly preferably 0.5 to 3% on a mass basis with respect to tin. If it is less than 0.1%, acicularity cannot be obtained, and even if it is added more than 10%, the effect of addition is small, and cerium oxide is liberated. Moreover, it is not economically advantageous.

  It is desirable to add a certain amount of cerium compound in order to obtain better acicularity. However, if a large amount of cerium compound remains in the product after firing, it is undesirable because it adversely affects conductivity and is soluble. It is preferable to remove the cerium compound and remove an unnecessary amount of the cerium compound.

  Examples of the alkali used in the alkaline aqueous solution of the cerium compound include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate, carbonates and ammonia, and these are used alone or in two kinds. You may mix and use the above.

  The neutralization reaction can be performed in water, hot water, or alcohol, and is preferably performed in hot water. Here, ethanol, methanol, etc. are mentioned as alcohol.

  Next, the obtained precursor is subjected to normal washing, drying, pulverization and the like, and then mixed with an alkali metal halide to produce a fired product.

  Various alkali metal halides can be used, and examples thereof include sodium chloride, potassium chloride, and lithium chloride. These may be used alone or in combination.

  The amount of alkali metal halide used is preferably 10% or more, more preferably 25% or more, and particularly preferably 75 to 160%, based on the mass of the precursor tin. If it is lower than 10%, good acicular particles cannot be obtained, and if it is higher than 160%, the effect of addition does not appear, and the surplus portion is washed in a subsequent step, which is not economical.

  The precursor and the alkali metal halide can be mixed by various methods. For example, the precursor and the alkali metal halide treated as described above can be mixed with a mixing stirrer such as a Henschel mixer. Further, after this mixing, it is preferable to perform pulverization with a dry pulverizer from the viewpoint of the acicularity of the tin oxide fine powder.

  At this time, various regulators can be added for the purpose of regulating the properties of the tin oxide fine powder. For example, a potassium salt or the like can be added for the purpose of adjusting the acicularity of the acicular fine powder.

  Firing is carried out at a temperature not lower than the melting point of the alkali metal halide and not higher than 1200 ° C., preferably 800 to 1200 ° C. When the firing temperature is lower than the melting point of the alkali metal halide, the acicularity of the particles is lowered, and when it exceeds 1200 ° C., grain growth is promoted, the minor axis diameter becomes thicker, tin oxide fine powder, and The smoothness of the used coating film is impaired. Examples of the melting point of the alkali metal halide include NaCl at 800 ° C., KCl at 776 ° C., LiCl at 606 ° C., and these may be used alone or in admixture of two or more.

  Firing is preferably performed in an inert gas atmosphere in which water vapor or alcohol vapor is present and oxygen is excluded. Examples of the inert gas include nitrogen gas and argon gas. Examples of alcohol vapor include ethanol vapor and methanol vapor.

  A method for introducing water vapor or alcohol vapor into the inert gas atmosphere is not limited. Water vapor or alcohol vapor may be introduced into the inert gas atmosphere of the heat treatment furnace, and the precursor may be left in a slurry state or may be in a moist state with appropriate drying. Alternatively, the inert gas may be bubbled through water or alcohol.

  The vapor pressure of water vapor or alcohol vapor is preferably 30% or more of the saturated vapor pressure in that the tin oxide fine powder is reduced and the conductivity becomes high. In order to perform the heat treatment while maintaining the vapor pressure, it is preferable to use a closed heat treatment furnace.

  Moreover, it is preferable to heat by removing oxygen from the inert gas atmosphere. Conventionally, a heat treatment method using an inert gas containing oxygen is known. However, when oxygen is contained, a low-resistance powder cannot be obtained stably and the conductivity is not uniform. Oxygen is preferably 1% or less with respect to the inert gas.

  The firing time is not particularly limited, but is suitably 30 minutes to 5 hours.

  Next, the fired product is treated with water, acid or alkali aqueous medium to remove soluble salts. Various acids can be used as the acid used here, and examples thereof include inorganic acids and organic acids, among which inorganic acids such as hydrochloric acid, sulfuric acid and hydrofluoric acid are preferable. Here, examples of the soluble salts that can be removed with water or an aqueous alkali solution such as NaOH and KOH include the cerium compound, and examples of the soluble salts that can be removed with an aqueous acid solution include Na and K.

  The processed product obtained by removing the soluble salts as described above is, as necessary, for example, after removing the insufficient acicularity by centrifugal sedimentation treatment or various classification means, followed by normal filtration, Wash, dry, finish pulverize, etc.

  By the above, the acicular conductive tin oxide fine powder having a minor axis average particle diameter of 20 to 200 nm, an aspect ratio of 3 or more, and containing 0.1 to 10% of cerium on a mass basis with respect to tin. Can be obtained.

  Moreover, it is preferable from a viewpoint of electroconductivity improvement to reduce a to-be-fired processed material with a stannous ion. As an example of the method of reducing with stannous ions, there is a method of mixing a material to be fired in a stannous ion-containing aqueous solution, washing with water and drying. Further, there is a method in which a fired product is mixed in a stannous ion-containing aqueous solution to form a paste, and the slurry or dried product is heated in a non-oxidizing atmosphere containing water vapor or alcohol vapor.

  Moreover, it is preferable that the to-be-fired processed material is fluorine-treated. In the fluorine treatment, it is more preferable that the material to be fired contains a fluorine source by a wet method.

  As the fluorine source, ammonium fluoride, ammonium silicofluoride, ammonium hydrofluoride, tin fluoride, fluorostannic acid, hydrogen fluoride, hydrofluoric acid, boron fluoride, bromine fluoride, etc. can be used. These may be used alone or in admixture of two or more.

  Specifically, a method of using a fluorine source containing tin as a part of a raw material of tin hydroxide containing cerium, and a fluorine source is included when producing a tin hydroxide containing cerium. The method of keeping it etc. is mentioned.

  Moreover, it is also preferable to perform a fluorine treatment after removing the soluble salts of the fired product. This fluorine treatment can be performed in the same manner as the fluorine treatment of the article to be fired.

  Fluorine can also be introduced by subjecting the acicular conductive tin oxide fine powder after firing to fluorine treatment. Examples of the fluorine treatment include a method of wet-treating acicular tin oxide fine powder with an aqueous solution containing a fluorine source.

  The fluorine treatment is more preferably a method of performing a heat treatment after these wet treatments. The temperature of this heat treatment is preferably 300 to 550 ° C. from the viewpoint that fluorine can be sufficiently diffused. Further, it is preferable that a fluorine treatment reaction further proceeds by flowing an inert gas (nitrogen gas, argon gas, or the like) containing nitrogen gas or hydrogen or water vapor during the heat treatment.

Since the doping amount of fluorine can be controlled by adjusting the addition amount of the fluorine source, the heat treatment temperature, the heat treatment time, etc., a conductive tin oxide powder having a powder volume resistivity reduced to a desired range is produced. be able to. In addition, this fluorine treatment is more preferable from the viewpoint of improving conductivity when combined with the reduction with the stannous ion.

  On the other hand, when antimony is contained in the object to be fired, a precursor for producing the object to be fired is first generated. The precursor includes a tin component, a cerium component, and an antimony component. The tin component is preferably a tin hydroxide and / or a dehydrate thereof. The antimony component is preferably a hydroxide and / or a dehydrate thereof. The tin compound for the raw material of the tin component used here is as described above.

Examples of the antimony compound for the raw material of the antimony component used include antimony halides such as antimony chloride, antimony oxide, antimony hydroxide, and inorganic acid salts such as antimony sulfate, antimony nitrate, and the like. You may mix and use 2 or more types. Preferably, an aqueous solution of antimony chloride in hydrochloric acid is used.

  The precursor is more preferably an antimony-tin hydroxide containing a cerium component and / or a dehydrated product thereof. By mixing the cerium component and antimony-tin, a uniform needle shape is obtained. Fine particles can be obtained. This method can be performed by various methods using a solution of each compound. For example, (a) neutralizing an aqueous solution of antimony compound and tin compound with hydrochloric acid and an alkaline solution of cerium compound in parallel with each other so as to maintain a pH of about 7 in hot water of 70 to 90 ° C. And a method of co-precipitation of antimony-tin hydroxide containing a cerium component, (b) water mixed by neutralizing an aqueous solution of antimony-tin compound with hydrochloric acid in an alkaline solution of cerium compound A method of coprecipitation of an oxide, a method of (c) neutralizing an aqueous solution of cerium compound in an aqueous solution of hydrochloric acid in an antimony-tin compound, and coprecipitation of a mixed hydroxide. Can be mentioned. Among these methods, the method (a) is particularly desirable because it has little variation. In this case, it is preferable to maintain the neutralization reaction solution at a pH of 5 to 10. The tin component and the antimony component can also be obtained by hydrolyzing a mixed solution of tin chloride and antimony chloride. This hydrolysis method may be a method known to those skilled in the art.

  In addition, the precursor may be composed of an antimony-tin hydroxide and / or a dehydrate thereof and a cerium component, and the tin hydroxide and / or the dehydrate thereof, the antimony hydroxide and / or the dehydrate thereof. Or a cerium component, or a hydroxide of tin and / or a dehydrate thereof, an antimony hydroxide and / or a dehydrate thereof, and a cerium hydroxide and / or a dehydrate thereof. You can also. In this case, the precursor may be prepared by a method known to those skilled in the art.

  Antimony in the article to be fired is preferably added in an amount of 0.1 to 10%, more preferably 0.3 to 5%, and particularly preferably 0.5 to 3% on a mass basis with respect to tin. If the amount is less than 0.1%, conductivity cannot be obtained, and a decrease in conductivity of the conductive acicular antimony tin oxide fine powder in an alkaline atmosphere cannot be suppressed. On the other hand, when it exceeds 10%, acicular particles cannot be obtained and become spherical particles.

  The acicular tin oxide fine powder of the present invention can be dispersed in an aqueous medium and used as an aqueous dispersion. Here, in addition to water, the aqueous medium may include a dispersant and a liquid that is soluble with water.

  The solid content concentration of the aqueous dispersion is 0.1 to 50% on a mass basis, preferably 1 to 40%, more preferably 5 to 30%, and the pH of the aqueous dispersion is 4 to 12, preferably 5 to 5. 10. Here, the solid content includes acicular tin oxide fine powder and a dispersant.

  The acicular tin oxide fine powder of the present invention can be used as a conductive coating composition for conductive paints or magnetic paints. In this case, acicular tin oxide fine powder is mixed with a binder containing a binder resin and water or a solvent to obtain a coating composition. Here, as the binder resin, for example, polyvinyl alcohol resin, vinyl chloride-vinyl acetate resin, acrylic resin, epoxy resin, urethane resin, alkyd resin, polyester resin, ethylene vinyl acetate copolymer, acrylic-styrene copolymer, fiber Examples thereof include natural resins such as organic resins, phenol resins, amino resins, fluororesins, silicone resins, petroleum resins, shellacs, rosin derivatives, and rubber derivatives.

  The compounding amount of the acicular tin oxide fine powder in the binder is 1 to 200 parts by mass, preferably 10 to 100 parts by mass, and more preferably 10 to 50 parts by mass with respect to 100 parts by mass of the binder resin.

  In the case of a conductive paint, by applying the paint to an insulating substrate such as paper or a polymer film, the conductive coating is light, transparent and surface smooth, and has excellent adhesion on the substrate. Films can be formed into various antistatic coatings, electrostatic recording paper, electrophotographic copying paper, and the like.

  In addition, when the acicular tin oxide fine powder of the present invention is applied to a conductive coating composition for aqueous coatings, the acicular tin oxide fine powder, or the solubility produced in the manufacturing process of the acicular tin oxide fine powder. An aqueous dispersion can be prepared from the treated product after removing the salts. When the aqueous dispersion is used for coating, it is preferable to reduce the dispersion energy at the time of coating and the dehydration and drying energy in the production process of fine acicular tin oxide powder. The compounding amount of the solid content of the aqueous dispersion is 3 to 200 parts by mass, preferably 10 to 100 parts by mass with respect to 100 parts by mass of the binding resin. Here, the same resin as the binder resin can be used as the binding resin.

  The conductive composition thus obtained has high conductivity with a smaller blending amount with respect to the binder resin or the binding resin than the conductive composition containing the conventional spherical conductive powder. In addition, it has excellent transparency and is economically advantageous.

  Since acicular tin oxide fine powder can be used in such a small amount, it can be used as a coating composition capable of forming a transparent and conductive coating film without causing a decrease in the adhesive strength of the binder resin or binding resin. be able to.

  Further, when the coating composition is used for a conductive paint containing a high concentration of acicular tin oxide fine powder, desired conductivity can be obtained even with a thin coating film.

  Examples of the substrate on which the coating composition of the present invention is applied to form a coating film include various synthetic resins, glass, ceramics and the like that are widely used in various fields including electric and electronic devices. These can be in any shape such as sheet, film, plate and the like. Specific examples of the synthetic resin include polyethylene, polypropylene, polycarbonate, polyethylene terephthalate (PET) resin, acrylic resin, methacrylic resin, polyvinyl chloride, polyester resin, polyamide resin, and phenol resin, but are not limited thereto. Is not to be done.

  Application | coating or printing to the board | substrate of the coating composition of this invention can be performed by methods, such as roll coating, spin coating, screen printing, an applicator, by a conventional method. Thereafter, the coating composition is heated as necessary to evaporate water or the solvent, and the coating film is dried and cured. At this time, you may irradiate a heating or an ultraviolet-ray.

  The thickness of the coating film formed with the coating composition of the present invention is preferably 0.05 to 50 μm and more preferably 0.1 to 10 μm from the viewpoint of surface resistance and whiteness.

  In addition, the needle-shaped conductive tin oxide fine powder of the present invention is blended in plastics, rubber, fiber, etc. as a conductivity-imparting material or substrate, and conductive plastics, conductive paint, magnetic paint, conductive rubber, conductive It can be used as a conductive resin composition such as a conductive fiber.

  When used as conductive plastics, various resins such as so-called general-purpose plastics and engineering plastics can be used as molding resins. Examples of general-purpose plastics include polyethylene, vinyl chloride resin, polystyrene, Examples include polypropylene, methacrylic resin, and urea / melamine resin. Examples of the engineering plastic general-purpose plastics include phenol resin, unsaturated polyester resin, hard vinyl chloride resin, ABS resin, and AS resin. Examples of engineering plastics include epoxy resin, polyacetal, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polyphenylene ether, polyphenylene sulfide, polysulfone, and fluororesin. Examples of super engineering plastics include diallyl phthalate resin, silicone resin, polyimide resin, polyamideimide, bismaleimide triazine, polyamino bismaleimide, olefin vinyl alcohol copolymer, polyoxybenzylene, polymethylpentene, polyether. Examples include sulfone, polyetherimide, polyarylate, polyetheretherketone, and the like, and the needle-like conductive tin oxide fine powder is blended in these molding resins.

  When used as a conductive rubber, examples of molding resins include silicone rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, butyl rubber, butadiene-acrylonitrile rubber, ethylene-propylene-diethane polymer, and ethylene-propylene rubber. , Fluoro rubber, ethylene-vinyl acetate copolymer, chlorinated polyethylene, acrylic rubber, chloroprene rubber, urethane rubber, polysulfide rubber, chlorosulfonated polyethylene rubber, epichlorohydrin rubber, etc. A conductive tin oxide fine powder is blended.

  When used as a conductive fiber, for example, a needle-shaped conductive tin oxide fine powder is blended with a fusible fiber such as a polyamide resin, a polyester resin, a polyolefin resin, a polyvinyl resin, or a polyether resin as a molding resin. To do.

  The compounding quantity of the acicular conductive tin oxide fine powder to the molding resin is 3 to 200 parts by mass, preferably 10 to 100 parts by mass with respect to 100 parts by mass of the molding resin.

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

[Example 1]
A solution in which 50 g of stannic chloride pentahydrate was dissolved in 50 ml of 3N hydrochloric acid aqueous solution was dropped into 1 liter of 90 ° C. ion-exchanged water in which 50 g of sodium hydroxide was dissolved to form a precipitate. The precipitate was filtered, and then washed with water until the specific conductivity of the filtrate was 10 (mS / m) or less to prepare a cake.

  After the produced cake was dried at 110 ° C. for 12 hours, 5 parts by mass of cerium oxide powder and 50 parts by mass of sodium chloride powder were added to 100 parts by mass of the dried product, and both were uniformly mixed and pulverized. . This mixture was put in an electric furnace, heated in the atmosphere at a heating rate of 10 ° C./min, and fired at 900 ° C. for 3 hours.

  The fired product was washed with ion exchange water at 80 ° C. to remove soluble salts, and then dried and pulverized to obtain a target acicular conductive tin oxide fine powder.

[Example 2]
A solution in which 50 g of stannic chloride pentahydrate and 1.8 g of cerium trichloride were dissolved in 50 ml was dropped into 1 liter of 90 ° C. ion-exchanged water in which 50 g of sodium hydroxide was dissolved to form a precipitate. The precipitate was filtered, and then washed with water until the filtrate had a specific conductivity of 10 (mS / m) or less to prepare a cake.

  After drying the produced cake at 110 degreeC for 12 hours, 50 mass parts sodium chloride was added with respect to 100 mass parts of this dried material, and both were mixed and ground uniformly. This mixture was put in an electric furnace, heated in the atmosphere at a heating rate of 10 ° C./min, and fired at 900 ° C. for 3 hours.

  The fired product was washed with ion exchange water at 80 ° C. to remove soluble salts, and then dried and pulverized to obtain a target acicular conductive tin oxide fine powder.

Example 3
A solution prepared by dissolving 50 g of stannic chloride pentahydrate and 1.8 g of cerium trichloride in 50 ml of 3N hydrochloric acid solution and a solution of 50 g of sodium hydroxide in 100 g of ion-exchanged water were added to 1 l of 90 ° C. ion-exchanged water at a pH. Were simultaneously added dropwise to form a precipitate in the range of 5 to 8. The precipitate was filtered, and then washed with water until the specific conductivity of the filtrate was 10 (mS / m) or less to prepare a cake.

  After drying the produced cake at 110 degreeC for 12 hours, 50 mass parts sodium chloride was added with respect to 100 mass parts of this dried material, and both were mixed and ground uniformly. This mixture was put in an electric furnace, heated in the atmosphere at a heating rate of 10 ° C./min, and fired at 900 ° C. for 3 hours.

  The obtained baked product was washed with ion exchange water at 80 ° C. to remove soluble salts, and then dried and pulverized to obtain the desired acicular conductive tin oxide fine powder.

Example 4
10 g of acicular fine conductive tin oxide powder obtained in Example 3 was dispersed in 20 g of ion-exchanged water in which 1 g of stannous fluoride was dissolved, filtered, dried, and treated with stannous fluoride. A fine conductive tin oxide fine powder was obtained.

Example 5
10 g of the acicular conductive tin oxide fine powder obtained in Example 3 was mixed with 10 g of ion-exchanged water in which 1 g of stannous fluoride was dissolved to make a paste. This was put in a quartz boat, this quartz boat was placed in a quartz tube furnace, and before raising the temperature, nitrogen gas saturated with water vapor through water was flowed at 0.3 (l / min) for 30 minutes to exclude oxygen. Thereafter, while the nitrogen gas was flowing, the temperature was increased at a rate of temperature increase of 10 ° C./min, and heat treatment was performed at 500 ° C. for 1 hour to obtain a fluorine-treated needle-like conductive tin oxide fine powder.
Example 6
A solution in which 50 g of stannic chloride pentahydrate and 0.05 g of antimony trichloride are dissolved in 50 ml of 3N hydrochloric acid aqueous solution is dropped into 1 liter of 90 ° C. ion-exchanged water in which 50 g of sodium hydroxide is dissolved to form a precipitate. did. The precipitate was filtered, and then washed with water until the specific conductivity of the filtrate was 10 (mS / m) or less to prepare a cake.

  After the produced cake was dried at 110 ° C. for 12 hours, 5 parts by mass of cerium oxide powder and 50 parts by mass of sodium chloride powder were added to 100 parts by mass of the dried product, and both were uniformly mixed and pulverized. . This mixture was put in an electric furnace, heated in the atmosphere at a heating rate of 10 ° C./min, and fired at 900 ° C. for 3 hours.

  The fired product was washed with ion exchange water at 80 ° C. to remove soluble salts, and then dried and pulverized to obtain a target acicular conductive antimony tin oxide fine powder.

Example 7
A solution prepared by dissolving 50 g of stannic chloride pentahydrate and 0.22 g of antimony trichloride in 50 ml was dropped into 1 liter of ion-exchanged water at 90 ° C. in which 50 g of sodium hydroxide and 1.8 g of cerium carbonate were dissolved. Generated. The precipitate was filtered, and then washed with water until the filtrate had a specific conductivity of 10 (mS / m) or less to prepare a cake.

  After drying the produced cake at 110 degreeC for 12 hours, 50 mass parts sodium chloride was added with respect to 100 mass parts of this dried material, and both were mixed and ground uniformly. This mixture was put in an electric furnace, heated in the atmosphere at a heating rate of 10 ° C./min, and fired at 900 ° C. for 3 hours.

  The fired product was washed with ion exchange water at 80 ° C. to remove soluble salts, and then dried and pulverized to obtain a target acicular conductive antimony tin oxide fine powder.

Example 8
A solution in which 50 g of stannic chloride pentahydrate and 0.9 g of antimony trichloride are dissolved in 50 ml of 3N hydrochloric acid solution, and a solution in which 50 g of sodium hydroxide and 1.8 g of cerium carbonate are dissolved in 100 g of ion-exchanged water are heated at 90 ° C. It was simultaneously added dropwise to 1 l of ion exchange water so that the pH was in the range of 5 to 8, and a precipitate was formed. The precipitate was filtered, and then washed with water until the specific conductivity of the filtrate was 10 (mS / m) or less to prepare a cake.

    After drying the produced cake at 110 degreeC for 12 hours, 50 mass parts sodium chloride was added with respect to 100 mass parts of this dried material, and both were mixed and ground uniformly. This mixture was put in an electric furnace, heated in the atmosphere at a heating rate of 10 ° C./min, and fired at 900 ° C. for 3 hours.

The obtained baked product was washed with ion exchange water at 80 ° C. to remove soluble salts, and then dried and pulverized to obtain a target acicular conductive antimony oxide / tin fine powder.
Example 9
A solution prepared by dissolving 50 g of stannic chloride pentahydrate, 4.5 g of antimony trichloride and 2.4 g of cerium trichloride in 50 ml of 3N hydrochloric acid aqueous solution, and a solution of 50 g of sodium hydroxide in 100 g of ion-exchanged water, Were simultaneously added dropwise to 1 liter of ion-exchanged water so that the pH was in the range of 5 to 8, and a precipitate was formed. The precipitate was filtered, and then washed with water until the specific conductivity of the filtrate was 10 (mS / m) or less to prepare a cake.

  After drying the produced cake at 110 degreeC for 12 hours, 50 mass parts sodium chloride was added with respect to 100 mass parts of this dried material, and both were mixed and ground uniformly. This mixture was put in an electric furnace, heated in the atmosphere at a heating rate of 10 ° C./min, and fired at 900 ° C. for 3 hours.

  The obtained baked product was washed with ion exchange water at 80 ° C. to remove soluble salts, and then dried and pulverized to obtain a target acicular conductive antimony oxide / tin fine powder.

[Examples 10 to 13, Reference Example 1]
Under the conditions shown in Table 1, in the same manner as in Example 5, a fluorine-treated acicular conductive tin oxide fine powder was obtained.

  A transmission electron micrograph of the acicular conductive tin oxide fine powder obtained in Example 1 is shown in FIG.

[Comparative Example 1]
As shown in Table 2, conductive tin oxide powder was obtained in the same manner as in Example 5 except that sodium chloride was not used.

[Comparative Example 2]
As shown in Table 2, conductive tin oxide powder was obtained in the same manner as in Example 5 except that cerium was not used.

  The conductive tin oxide powders obtained in Comparative Example 1 and Comparative Example 2 were both granular, and no needle shape was obtained.

[Test Example 1]
Wherein each of Examples 1 to 13, for each conductive fine powder prepared in Reference Example 1 and Comparative Example 1-2, (1) transmission electron micrograph (magnification of 100,000) of the observation to the minor axis diameter The weight average particle diameter was determined, and the aspect ratio was calculated based on it. Table 3 shows the weight average particle diameter of the minor axis diameter (described as “minor axis diameter”) and the aspect ratio. FIG. 1 shows a transmission electron micrograph of the acicular tin oxide fine powder obtained in Example 1.

Further, (2) each sample powder is put into a cylindrical donut-shaped PP insulating jig, both ends of the opening are pressurized with a cylindrical brass electrode at 100 kg / cm ² , and the resistance value between the brass electrodes is determined by Yokogawa Hokushin Electric Co., Ltd. Ltd. digital multimeter (model number: Model 2502A) was measured with and calculated powder volume resistivity. These results are shown in Table 3. In Table 3, for example, “5.0E + 06” represents “5.0 × 10 ⁰⁶ ”. The L value of the powder was measured using a device manufactured by Suga Test Instruments Co., Ltd. (SM-7-IS-2B).

[Test Example 2]
20 g of each conductive fine powder obtained in Examples 1 to 13 , Reference Example 1 and Comparative Examples 1 to 2 was dispersed in 180 g of water. A bead mill was used to prepare the dispersion.

  Next, the aqueous dispersion was stirred and mixed in 50 g of a water-soluble paint (product name: Hydran AP-40) manufactured by DIC having a resin solid content concentration of 60 wt% to prepare a coating composition.

These coating compositions were applied to bar coater no. 3 was applied to a polyester film so that the coating thickness was 6.87 (μm) and the coating amount was 6.87 × 10 ⁻⁴ (ml / cm ² ), followed by natural drying at 80 ° C. for 30 minutes. A test sheet was prepared. A sheet having a coating thickness of 10 μm can be similarly produced.

The volume resistivity of these test sheets and (Ω · cm), was measured using a Mitsubishi Chemical analytic Tech Ltd. Hiresta UP (4-terminal method). These results are shown in Table 3.

As apparent from Table 3, in all of Examples 1-13, a needle-like powder of the aspect ratio in the minor axis average particle diameter is 50~100nm 5-15, a powder volume resistivity 10～500000Omu · It was as low as cm, and the L value was 70 to 82 and white. The volume resistivity of the coating film using these was also as low as 5 × 10 ⁶ to 1 × 10 ⁹ Ω · cm. On the other hand, in Comparative Example 1 in which sodium chloride was not used and in Comparative Example 2 in which Ce was not contained, both became granular powders, and the L value was not 65,75 and sufficient whiteness, and a coating film using these. the volume resistivity of a 1 × 10 ¹² Ω · cm or more, were measurable range of the instrument. In Reference Example 1 where Ce was 12% by mass, the powder was a rod-like powder and a granular powder.

  As described above, the acicular tin oxide fine powder of the present invention is highly conductive and white, using this acicular conductive tin oxide fine powder, the surface resistivity is low even with a small amount of addition, A thin white coating film could be formed.

Claims (6)

  An acicular tin oxide fine powder having a minor axis average particle diameter of 20 to 200 nm, an aspect ratio of 3 or more, and containing 0.1 to 10% of cerium on a mass basis with respect to tin. Powder volume resistivity, 1 × or less 10 ⁸ Ω · cm, acicular tin oxide fine powder according to claim 1, wherein.   The acicular tin oxide fine powder according to claim 1 or 2, which contains 10% or less of fluorine by mass.   The acicular tin oxide powder according to claim 1 or 2, which contains 10% or less of antimony on a mass basis. When the thickness of 10μm polyethylene resin sheet containing 20% acicular tin oxide fine powder on a mass basis, the volume resistivity of the polyethylene resin sheet is less than ¹⁰ 10 Ω · cm, any one of claims 1 to 4 The acicular tin oxide fine powder according to 1.   A to-be-fired product containing a tin component, a cerium component and an alkali metal halide is fired at a temperature higher than the melting point of the alkali metal halide and 1200 ° C. or lower, and then the soluble salts of the obtained fired product are removed. And a method for producing acicular tin oxide fine powder containing cerium.