JP6559595B2 - Production method of titanium dioxide composite powder and conductive composite powder, titanium dioxide composite powder and conductive composite powder - Google Patents

Description

  The present invention relates to a titanium dioxide composite powder, a method for producing a conductive composite powder, a titanium dioxide composite powder, and a conductive composite powder.

  Conductive powders are widely used in applications such as antistatic, charge control, and dustproof. For example, if conductive powder is blended in a paint and applied to an insulating material, conductivity can be imparted to the insulating material. For this reason, the coating material containing conductive powder is used as an undercoat (primer) for electrostatic coating that is widely used in automobile bodies and home appliance housings.

  In general, a coating containing conductive powder is formed by dispersing conductive powder in a solution containing a binder, and this coating is applied to various films, sheets, supports, and objects to be processed such as housings. Used by applying to. In this case, good conductivity can be obtained when the particles constituting the conductive powder are in close contact with each other, but when using conductive powder made of spherical particles, it is necessary to blend a large amount of conductive powder. is there. On the other hand, it is known that a conductive powder composed of acicular particles can obtain good conductivity with a smaller blending ratio. Therefore, Patent Document 1 discloses conductive acicular titanium dioxide in which the surface of monoclinic acicular titanium dioxide is coated with tin oxide and antimony oxide.

  However, the conductive powder composed of needle-like particles is entangled between the needle-like particles partially in the paint when the blending amount in the paint is increased. There is a problem that surface properties or surface flatness deteriorates. In addition, in order to disperse the agglomerated needle-like particles or not to agglomerate the needle-like particles, even if the paint is stirred with a strong shearing force, it becomes impossible to obtain good conductivity due to the collapse of the particle shape. There is.

JP-A-6-183737

  An object of the present invention is to provide a method for producing a titanium dioxide composite powder excellent in dispersibility, a method for producing a conductive composite powder excellent in dispersibility and conductivity, a titanium dioxide composite powder, and a conductive composite powder. is there.

  The present invention provides the following titanium dioxide composite powder and conductive composite powder production method, and titanium dioxide composite powder and conductive composite powder.

Item 1: A step of preparing a raw material mixture in which a titanium source and a potassium source are mixed in a molar ratio of TiO ₂ / K ₂ O = 2.9 to 3.3 in terms of oxide, and by firing the raw material mixture A step of preparing a potassium titanate composite powder in which acicular 4 potassium titanate particles and non-acicular 2 potassium titanate particles are integrated; and hydrated titanate composite powder by acid treatment of the potassium titanate composite powder. And a step of producing a titanium dioxide composite powder in which acicular titanium dioxide particles and non-acicular titanium dioxide particles are integrated by heat-treating the hydrated titanic acid composite powder. A method for producing a composite powder.

  Item 2. A method for producing a conductive composite powder, comprising a step of forming a conductive layer on the surface of the titanium dioxide composite powder produced by the method according to Item 1.

  Item 3. The method for producing a conductive composite powder according to Item 2, wherein the conductive layer is a conductive layer made of a tin oxide layer.

  Item 4. The method for producing a conductive composite powder according to Item 3, wherein the tin oxide layer is a tin oxide layer containing no antimony component.

  Item 5. A conductive composite powder produced by the method according to any one of Items 2 to 4.

  Item 6 A conductive composition comprising the conductive composite powder according to Item 5.

  Item 7 A coating film obtained by applying the conductive composition according to Item 6.

  Item 8 Acicular titanium dioxide particles having an average fiber length of 3 to 50 μm and an aspect ratio of 20 to 100 and non-acicular titanium dioxide particles having an average particle diameter of 3 to 30 μm and an aspect ratio of 1 to 5 are integrated. Titanium dioxide composite powder, characterized in that

  Item 9 The titanium dioxide composite powder according to Item 8, wherein at least a part of the acicular titanium dioxide particles are bound by the non-acicular titanium dioxide particles.

  Item 10 A conductive composite powder in which a conductive layer is formed on the surface of the titanium dioxide composite powder according to Item 8 or 9.

  Item 11 A conductive composition comprising the conductive composite powder according to Item 10.

  Item 12 A coating film obtained by applying the conductive composition according to Item 11.

  According to the present invention, a titanium dioxide composite powder excellent in dispersibility, and a conductive composite powder excellent in dispersibility and conductivity can be obtained.

  By using the conductive composite powder of the present invention for a paint, a coating film having excellent flatness and a low surface resistance value can be formed.

It is a scanning electron micrograph which shows the titanium dioxide composite powder obtained in Example 1 of this invention. 3 is a scanning electron micrograph showing the titanium dioxide composite powder obtained in Comparative Example 1. FIG.

  Hereinafter, preferred embodiments will be described. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments.

<Method for producing titanium dioxide composite powder>
The method for producing a titanium dioxide composite powder of the present invention is a step of preparing a raw material mixture in which a titanium source and a potassium source are mixed in a molar ratio of TiO ₂ / K ₂ O = 2.9 to 3.3. And a step of preparing a potassium titanate composite powder in which acicular potassium titanate particles and non-acicular potassium dititanate particles are integrated by firing the raw material mixture, and acid treatment of the potassium titanate composite powder And preparing a hydrated titanic acid composite powder and heat treating the hydrated titanic acid composite powder to produce a titanium dioxide composite powder in which acicular titanium dioxide particles and non-acicular titanium dioxide particles are integrated. And a process.

  Examples of the titanium source used as a raw material in the present invention include those containing titanium dioxide or compounds that produce titanium dioxide by heating. Examples of the titanium source compound include rutile, anatase, and brookite titanium dioxide; rutile ore; hydrous titania, titanium hydroxide wet cake; and the like. Among these, titanium dioxide is preferable. The particle size of the titanium source can be appropriately selected depending on the size of the target particles.

  Examples of the potassium source used as a raw material in the present invention include those containing potassium oxide or compounds that generate potassium oxide by heating. Examples of the potassium source compound include potassium carbonate, potassium hydroxide, and potassium nitrate. Among these, potassium carbonate is preferable.

The mixing ratio of the titanium source and the potassium source is a ratio of TiO ₂ / K ₂ O = 2.9 to 3.3 in terms of oxide equivalent molar ratio, preferably 2.9 to 3.2, more preferably It is 3.0-3.1. By setting the mixing ratio in the range of 2.9 to 3.3, a powder in which needle-like potassium titanate particles and non-needle-like potassium dititanate particles are formed, and irregularly shaped particles are combined with each other. Can be obtained. When the mixing ratio of the titanium source and the potassium source is less than 2.9, the ratio of the potassium dititanate particles increases, and when the mixing ratio exceeds 3.3, the ratio of the 4 potassium titanate particles increases, and the target performance. This is not preferable because it is impossible to obtain a powder having the following.

  If necessary, flux may be added to the raw material mixture for the purpose of homogenizing the reaction and crystal growth, and firing may be performed. Examples of the flux include potassium chloride, potassium fluoride, potassium molybdate, and potassium tungstate. Of these, potassium chloride is preferred. It is preferable that the addition ratio of a flux is 5-30 mass parts with respect to 100 mass parts of total amounts of a titanium source and a potassium source, and it is more preferable that it is 10-20 mass parts.

  Mixing of the titanium source and the potassium source can be performed by an arbitrary method, and examples thereof include a method of mixing using a mixing apparatus such as various mixers, tumblers, blenders and the like. Moreover, after wet-mixing, the method of granulating a mixture by the spray-dry method etc. can also be employ | adopted.

  The firing of the raw material mixture is performed using gas, electricity, etc., and the raw material mixture is preferably held at a temperature range of 800 to 1100 ° C., more preferably 900 to 1100 ° C., preferably 1 to 24 hours, more preferably 2 The firing reaction can be completed by holding for ˜6 hours. If necessary, crushing treatment may be performed after the firing reaction. By the firing, a potassium titanate composite powder in which acicular potassium tetratitanate particles and non-acicular potassium dititanate particles are integrated can be obtained.

For the acid treatment of the potassium titanate composite powder, a known method can be used if the K ₂ O component of potassium titanate can be extracted to obtain a hydrated titanate composite powder. For example, the fired product can be dispersed in water to form an aqueous slurry, and an acid can be added to the aqueous slurry and stirred. After the acid treatment, the product is washed with water if necessary, and solidified by filtration, centrifugation, or the like. Minutes may be separated from the slurry. Examples of the acid include inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid, and organic acids such as acetic acid. Two or more acids may be used in combination as required. Hydrated titanic acid composite powder can be prepared by acid treatment of potassium titanate composite powder.

  In the heat treatment of the hydrated titanic acid composite powder, preferably, the hydrated titanic acid compound is heat-treated at 80 to 350 ° C. to obtain monoclinic 8 titanic acid, and then the obtained 8 titanic acid is heated at 500 to 700 ° C. A titanium dioxide composite powder is produced by heat treatment. By performing heat treatment in this way, titanium dioxide in which acicular titanium dioxide particles and non-acicular titanium dioxide particles having a high degree of crystallinity are integrated while maintaining the particle shape before producing the hydrated titanate compound. A composite powder can be produced.

  The heat treatment time for obtaining monoclinic 8 titanic acid is not particularly limited, but is usually 0.5 to 24 hours, preferably 0.5 to 12 hours, more preferably 0.5 to 2 hours. Good. The heat treatment time for obtaining titanium dioxide particles is not particularly limited, but is usually 0.5 to 8 hours, preferably 0.5 to 4 hours, more preferably 1 to 2 hours.

  According to the method for producing a titanium dioxide composite powder of the present invention, acicular particles and non-acicular particles are generated simultaneously. For this reason, it can be set as the composite particle which a part of acicular particle | grains united by the non-acicular particle | grain and integrated. By using a titanium dioxide composite powder in which acicular titanium dioxide particles and non-acicular titanium dioxide particles are integrated, a composite powder having excellent dispersibility can be obtained.

<Titanium dioxide composite powder>
The titanium dioxide composite powder of the present invention has acicular titanium dioxide particles having an average fiber length of 3 to 50 μm and an aspect ratio of 20 to 100, and non-needle having an average particle diameter of 3 to 30 μm and an aspect ratio of 1 to 5 It is characterized in that the titanium dioxide particles are integrated. The aspect ratio in acicular titanium dioxide particles is the ratio of fiber length to fiber diameter. The aspect ratio of the non-acicular titanium dioxide particles is the ratio of the major axis to the minor axis. Since the titanium dioxide composite powder of the present invention has a structure in which acicular titanium dioxide particles and non-acicular titanium dioxide particles are integrated, it is excellent in dispersibility.

  In the titanium dioxide composite powder of the present invention, it is preferable that at least a part of the acicular titanium dioxide particles are bound and integrated by non-acicular titanium dioxide particles. By integrating in this way, it is preferable to have a so-called tetrapot-like or sea urchin-like particle structure. By having such a particle structure, at the time of coating film formation, the united and integrated parts eliminate mutual overlap, so that aggregates can be suppressed, and titanium dioxide composite particles with better dispersibility can be obtained. it can. Moreover, the formation of the conductive path with uniform dispersion can be realized by adding a smaller amount than in the comparative example.

  The titanium dioxide composite powder of the present invention can be produced by the above-described method for producing a titanium dioxide composite powder of the present invention.

<Conductive composite powder and method for producing the same>
The conductive composite powder of the present invention is characterized in that a conductive layer is formed on the surface of the titanium dioxide composite powder of the present invention. The method for producing a conductive composite powder of the present invention comprises a step of forming a conductive layer on the surface of the titanium dioxide composite powder produced by the method for producing a titanium dioxide composite powder of the present invention.

  The conductive composite powder of the present invention preferably has an oil absorption of 100 ml / 100 g or less, and the lower limit is preferably 60 ml / 100 g. If the amount of oil absorption is too small, the acicular particles may be reduced, leading to a decrease in conductivity. If the oil absorption is too large, the number of acicular particles increases, and the entanglement between the acicular particles may partially occur in the paint, resulting in an aggregate larger than the coating thickness.

  From the viewpoint of stable conductivity and whiteness, the conductive layer is preferably a tin oxide layer, and more preferably a tin oxide layer containing an antimony component. Tin oxide containing an antimony component is stable in conductivity, but has a problem of poor whiteness. For this reason, the conductive layer may be formed of a plurality of conductive layers, for example, a conductive layer in which a tin oxide layer not containing an antimony component is formed on a tin oxide layer containing an antimony component. . By being excellent in whiteness, it can be suitably used for applications where white is required not only from conductivity but also from the appearance and functional aspects.

  In the conductive composite powder of the present invention, the proportion of the conductive layer is preferably 15 to 35 parts by mass and more preferably 20 to 30 parts by mass with respect to 100 parts by mass of the titanium dioxide composite powder. By setting the proportion of the conductive layer to 15 to 35 parts by mass, excellent conductivity and whiteness can be obtained. When the conductive layer is a tin oxide layer containing an antimony component, the tin oxide layer containing the antimony component preferably contains 5 to 15% by mass of the antimony component.

  As a method for forming the conductive layer, a known method for forming a conductive layer can be used. For example, a tin compound containing an antimony component and / or a tin compound containing no antimony component on the surface of titanium dioxide particles by wet treatment. And forming a tin oxide layer containing an antimony component and / or a tin oxide layer containing no antimony component.

  Specifically, a stannic compound and an antimony compound are added to the aqueous dispersion of the titanium dioxide composite powder (base material) as a first step. The stannic compound and antimony compound are preferably added in the form of an aqueous solution. By making the stannic compound and antimony compound added to the aqueous dispersion into a water-insoluble substance such as stannic hydroxide and antimony hydroxide by hydrolysis reaction or the like, A water-insoluble substance is deposited and deposited thereon. When adding the stannic compound and the antimony compound, it is preferable to add an alkaline solution simultaneously with the addition, and to react while maintaining the pH of the aqueous dispersion in the acidic region of 2-5. By maintaining the pH in the system in the acidic region of 2 to 5, the water-insoluble substance of precipitated stannic precipitates in a form that can be uniformly coated on the base material, so that more uniform coating is possible.

  As the alkaline solution to be added, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, aqueous ammonia and the like can be used. The stannic compound and antimony compound to be added are preferably the same type of salt. That is, when tin chloride is used as the stannic compound, it is preferable to use antimony trichloride as the antimony compound. Moreover, it is preferable to add a stannic compound and an antimony compound as a mixed solution.

  After the first stage, the stannous compound is added to the aqueous dispersion as the second stage. By hydrolyzing the stannous compound added to the aqueous dispersion, a water-insoluble substance of stannous such as stannous hydroxide is precipitated, and the water-insoluble substance of stannous is converted into stannic and antimony. Deposit on the water-insoluble material. During the addition of the stannous compound, the stannous compound is reacted while adding the alkaline solution simultaneously with the addition of the stannous compound and keeping the pH of the aqueous dispersion in the acidic region of 2-5. It is preferable to make it.

  As an alkaline solution, the thing similar to the alkaline solution added at the said 1st step can be used. In general, when a stannous compound solution such as stannous chloride is added and a hydroxide is precipitated in an acidic region, the viscosity rises rapidly and it is difficult to form a uniform coating layer on the substrate. However, since the water-insoluble substance of stannic and antimony is already uniformly coated on the base material, almost no increase in viscosity is observed in the system, and the water-insoluble substance of stannous is uniformly formed on it. can do.

  The liquid temperature of the aqueous dispersion in the first stage and the second stage may be room temperature, but is preferably heated to 50 to 80 ° C. By heating, a more uniform reaction is possible.

  The addition amount of the stannic compound, the antimony compound, and the stannous compound in the first stage and the second stage is such that the antimony component in the tin oxide layer and the tin oxide layer has a desired coating amount and content. A suitable addition amount is appropriately selected.

  After completion of the first stage and second stage precipitation reactions, the aqueous dispersion is filtered, dehydrated, and dried. After drying, the water-insoluble substance deposited and deposited on the substrate is heat-treated to form a conductive layer mainly composed of tin oxide. Although the temperature of heat processing will not be specifically limited if it is the temperature which can make the coating layer on a base material into the tin oxide which has electroconductivity, Usually, it is 350-600 degreeC. Moreover, although the time of heat processing changes with process temperature etc., it is 0.5 to 5 hours normally. The heat treatment is performed in an oxidizing atmosphere containing oxygen because the water-insoluble substance of stannous, which is divalent tin, needs to be oxidized into tetravalent tin oxide. Therefore, heat treatment in the atmosphere can be performed.

<Conductive composition and method for producing the same>
The conductive composition of the present invention is characterized by containing the conductive composite powder of the present invention, and can be used in various forms. For example, a dispersion in which the conductive composite powder is dispersed in a solvent, a paint in which a binder resin (binding material) is further blended in the dispersion, and a resin composition in which the conductive composite powder and a resin are melt-kneaded can be exemplified. The conductive composite powder of the present invention is preferably used as a dispersion or paint because it has excellent dispersibility that can be dispersed without using a strong shearing force such as melt kneading.

  When the conductive composition of the present invention is used as a paint containing the conductive composite powder, a binder resin (binder) and a solvent, examples of the binder include alkyd resins, acrylic resins, polyester resins, epoxy resins, amino acids. Resins, fluororesins, modified silicone resins, urethane resins, vinyl resins and the like can be mentioned. Examples of the solvent include nonaqueous solvents such as alcohols, esters, ethers, ketones, aromatics and aliphatic hydrocarbons, water, and mixed solvents thereof. If necessary, one kind selected from colorants, fillers, dispersants, plasticizers, curing aids, antifoaming agents, thickeners, emulsifiers, ultraviolet absorbers and the like may be used alone or in combination of two or more. it can.

  The compounding amount of the conductive composite powder in the coating is preferably 10 to 100 parts by mass, more preferably 30 to 70 parts by mass with respect to 100 parts by mass of the binder.

  When the conductive composition of the present invention is used as a paint, surface flatness is obtained by applying it to an insulating object such as synthetic resin, glass or ceramics widely used in the fields of electric / electronic equipment, home appliances, automobiles, etc. And a coating film having a low surface resistance value can be formed. For example, it can be used as an undercoat paint (primer) for electrostatic coating, an antistatic paint for clean rooms, and the like.

  Examples of the object to be processed by applying the coating material to form a coating film include various synthetic resins, glass, ceramics and the like widely used in the fields of electric / electronic equipment, home appliances, automobiles, etc. Any shape such as a sheet shape, a film shape, and a plate shape may be taken. Specific examples of the synthetic resin include, but are not limited to, polyethylene resin, polypropylene resin, polycarbonate resin, polyethylene terephthalate resin, acrylic resin, methacrylic resin, polyvinyl chloride resin, polyamide resin, and phenol resin. It is not something.

  Application of the coating material to the object to be treated can be performed by a conventional method, for example, by a method such as roll coating or spin coating. Thereafter, if necessary, the solvent is evaporated by heating, and the coating film is dried and cured. At this time, heat or ultraviolet rays may be irradiated.

  Since the conductive composite powder of the present invention is excellent in dispersibility, the coating film using the conductive composite powder of the present invention is excellent in surface properties or surface flatness. Furthermore, since the conductive composite powder of the present invention has non-acicular particles partially binding the acicular particles, the coating film of the present invention is a powder containing only acicular particles or non-acicular particles. Compared with a coating film using a powder obtained by simply mixing needle-like particles, excellent conductivity can be obtained even if the blending ratio of the conductive composite powder is small.

  Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is not limited to the following examples, and can be implemented with appropriate modifications without departing from the scope of the invention.

  In the examples and comparative examples, the particle shape of the powder was determined by using a field emission scanning electron microscope (SEM) (trade name “S-4800”, manufactured by Hitachi High-Technologies) and a flow type particle image analyzer (trade name “FPIA”). -3000 ", manufactured by Sysmex).

The oil absorption of the powder was measured according to JIS K-5101-13-1. The volume resistance of the powder was measured with an electric measuring instrument (trade name “Digital Multimeter TR6871” manufactured by Advantest) after putting the sample powder in a pressure vessel and compressing it at 14 kg / cm ² . The L value of the powder was measured using a color difference meter (trade name “CR-300”, manufactured by Konica Minolta).

  The surface resistance of the coating film is an acrylic paint (trade name “Acroze Super ECO Clear”, manufactured by Dainippon Paint Co., Ltd.) with a powder and resin solid content of 40 mass% so that the powder is 35 mass% in the total solid content. ), And the resulting conductive composition was applied so that the film thickness before drying was 200 μm. After drying, the surface resistance was measured with a resistance meter (trade name “HIRESTA-AP MCP-T250”, Mitsubishi Measured by Yuka).

(Example 1)
<Manufacture of base material>
Anatase-type titanium dioxide and potassium carbonate are mixed at a ratio of 3.1: 1 (molar ratio in terms of oxide), and potassium chloride is added at 15 parts by mass as a flux to a total of 100 parts by mass of titanium dioxide and potassium carbonate. Mixed. The obtained mixture was baked at 1020 ° C. for 4 hours in an electric furnace, and then gradually cooled to obtain a white lump. The obtained lump was crushed, thawed in water, washed with water to remove the flux, and then dried to obtain a white powder. The obtained powder was found to be a composite composed of potassium dititanate (K ₂ O · 2TiO ₂ ) and potassium tetratitanate (K ₂ O · 4TiO ₂ ) by X-ray diffraction. In addition, it was confirmed by scanning electron microscope (SEM) observation that the powder was a potassium titanate composite powder in which acicular potassium titanate particles and non-acicular potassium dititanate particles were integrated.

100 g of the obtained potassium titanate composite particles were dispersed in 3500 ml of water and stirred for 5 minutes to form a slurry. 224 g of 70% by mass sulfuric acid solution was added, and the K ₂ O component was extracted while stirring for 20 minutes, then filtered, washed with water, and dried at 110 ° C. for 10 hours. The obtained powder was analyzed by X-ray diffraction and confirmed to be a monoclinic H ₂ Ti ₈ O ₁₇ phase. This was heated at 600 ° C. for 2 hours to obtain a powder as a base material for forming a conductive layer.

It was confirmed by SEM observation and X-ray diffraction that the obtained powder was titanium dioxide having a monoclinic crystal structure maintaining the shape of the potassium titanate composite powder before extraction of the K ₂ O component.

  FIG. 1 shows an SEM photograph of the obtained powder. As shown in FIG. 1, it was confirmed that the obtained powder was a titanium dioxide composite powder in which acicular titanium dioxide particles and non-acicular titanium dioxide particles were integrated. More specifically, a part (end part) of acicular titanium dioxide particles was a titanium dioxide composite powder in which the acicular titanium dioxide particles were bound and integrated by non-acicular titanium dioxide particles. Therefore, it was confirmed that the titanium dioxide composite powder has a so-called tetrapot-like or sea urchin-like particle structure.

From the flow type particle image analysis, the titanium dioxide composite powder has an average fiber length of 3 to 50 μm, an acicular titanium dioxide particle having an aspect ratio of 20 to 100, an average particle diameter of 3 to 30 μm, and an aspect ratio of 1 to 5 It was found that the non-acicular titanium dioxide particles were integrated. From the chemical analysis, the TiO ₂ purity of the titanium dioxide composite powder was 98.5% by mass.

<Formation of conductive layer>
300 g of the base material obtained above was dispersed in 3600 ml of water, and the water temperature was stirred at 80 ° C. for 10 minutes to form a slurry. To this slurry, 265 g of a stannic chloride aqueous solution (23% by mass in terms of Sn) and 15 g of antimony trichloride dissolved in 22% by mass of hydrochloric acid were added dropwise over a period of 1 hour, and at the same time. A 25% by mass aqueous sodium hydroxide solution was added dropwise separately to maintain the pH of the entire reaction solution in the range of 3-4.

  Next, 51 g of stannous chloride aqueous solution (24 mass% in terms of Sn) was dropped over 1 hour, and 25 mass% of sodium hydroxide aqueous solution was dropped separately at the same time as in the first stage, and the entire reaction solution Was kept in the range of 3-4. After completion of the dropping reaction in the second stage, the mixture was stirred for 30 minutes while maintaining the pH and liquid temperature as they were. Thereafter, the pH was adjusted to 5.

  Then, after standing to cool to room temperature, the reaction product was filtered, washed with water, and dried. The obtained dried product was heat-treated at 550 ° C. for 1 hour in the atmosphere of an oxidizing atmosphere to obtain white conductive titanium dioxide powder.

  It was confirmed that the obtained conductive titanium dioxide powder maintained the shape before the formation of the conductive layer by SEM observation. Therefore, the obtained conductive titanium dioxide powder has an average fiber length of 3 to 50 μm, an acicular particle having an aspect ratio of 20 to 100, an average particle diameter of 3 to 30 μm, and a non-needle having an aspect ratio of 1 to 5 The conductive composite powder was integrated with the particles.

The oil absorption amount of the conductive composite powder was 95 ml / 100 g, the volume resistance was 9 Ω · cm, and the L value was 77. Further, the surface resistance of the coating film using the conductive composite powder was 2 × 10 ⁵ Ω / □, and it was visually confirmed that there was no aggregate in the coating film.

(Comparative Example 1)
<Manufacture of base material>
Anatase-type titanium dioxide and potassium carbonate are mixed at a ratio of 3.5: 1 (molar ratio in terms of oxide), and potassium chloride is added at 16 parts by mass as a flux to a total of 100 parts by mass of titanium dioxide and potassium carbonate. Mixed. The obtained mixture was baked at 1020 ° C. for 4 hours in an electric furnace, and then gradually cooled to obtain a white lump. The obtained lump was crushed in water, washed with water to remove the flux, and then dried to obtain a white powder. The obtained powder was potassium tetratitanate (K ₂ O · 4TiO ₂ ) by X-ray diffraction, and was confirmed to be needle-shaped by SEM observation.

100 g of the obtained powder was dispersed in 3500 ml of water and stirred for 5 minutes to form a slurry. 224 g of 70% by mass sulfuric acid solution was added, and the K ₂ O component was extracted while stirring for 20 minutes, then filtered, washed with water, and dried at 110 ° C. for 10 hours. The obtained powder was confirmed to be a monoclinic H ₂ Ti ₈ O ₁₇ phase by X-ray diffraction. This was heated at 600 ° C. for 2 hours to obtain a powder as a base material for forming a conductive layer.

It was confirmed by SEM observation and X-ray diffraction that the obtained powder was titanium dioxide having a monoclinic crystal structure that maintained the particle shape before extraction of the K ₂ O component. FIG. 2 shows an SEM photograph of the obtained powder. As shown in FIG. 2, it was confirmed that the obtained powder was acicular titanium dioxide particles. The particle shape of the powder was needle-like particles having an average fiber length of 3 to 50 μm and an aspect ratio of 20 to 100 from flow type particle image analysis. Further, TiO ₂ purity than chemical analysis was 97.5 wt%.

<Formation of conductive layer>
The conductive layer was formed by the same method as in Example 1 to obtain a conductive titanium dioxide powder.

  It was confirmed that the obtained conductive titanium dioxide powder maintained the shape before the formation of the conductive layer by SEM observation.

The oil absorption of the conductive titanium dioxide powder was 109 ml / 100 g, the volume resistance was 208 Ω · cm, and the L value was 82. Moreover, the surface resistance of the coating film using the conductive titanium dioxide powder was 4 × 10 ⁷ Ω / □, and it was visually confirmed that the coating film had aggregates.

(Comparative Example 2)
<Manufacture of base material>
By separately mixing acicular titanium dioxide and non-acicular titanium dioxide produced at a mass ratio of 8: 2, a powder serving as a base material for forming a conductive layer was obtained.

  Acicular titanium dioxide was obtained by the same method as in Comparative Example 1.

Non-acicular titanium dioxide was obtained by pulverizing and mixing anatase-type titanium dioxide and potassium carbonate at a ratio of 2: 1 (molar ratio in terms of oxide) using a vibration mill. The obtained mixture was baked in an electric furnace at 880 ° C. for 4 hours and then gradually cooled to obtain a white lump. The obtained mass was crushed in water and then dried to obtain a white powder. The obtained powder was confirmed to be potassium dititanate (K ₂ O.2TiO ₂ ) by X-ray diffraction and non-needle shape by SEM observation.

100 g of the obtained powder of non-acicular potassium dititanate particles was dispersed in 3500 ml of water and stirred for 5 minutes to form a slurry. After adding 365 g of a 70% by mass sulfuric acid solution and extracting the K ₂ O component with stirring for 20 minutes, it was washed with water and dried at 110 ° C. for 10 hours. The obtained powder was confirmed to be a monoclinic H ₂ Ti ₂ O ₅ phase by X-ray diffraction. This was heated at 600 ° C. for 2 hours to obtain a powder of non-acicular titanium dioxide particles.

The obtained powder of non-acicular titanium dioxide particles was confirmed by SEM observation and X-ray diffraction to be titanium dioxide having a monoclinic crystal structure that maintained the particle shape before extraction of the K ₂ O component. The particle shape of the powder was non-needle particles having an average particle diameter of 3 to 30 μm and an aspect ratio of 1 to 5 based on flow-type particle image analysis. Further, TiO ₂ purity than chemical analysis was 97.5 wt%.

<Formation of conductive layer>
The conductive layer was formed by the same method as in Example 1 to obtain a conductive titanium dioxide powder. The oil absorption of the conductive titanium dioxide powder was 136 ml / 100 g. In addition, a coating film using conductive titanium dioxide powder could not be produced because many aggregates were generated in the conductive composition.

  From the above, it can be seen that by using the conductive composite powder of Example 1 according to the present invention, a conductive coating film excellent in dispersibility and conductivity and excellent in surface properties or surface flatness can be formed.

Claims (9)

Preparing a raw material mixture in which a titanium source and a potassium source are mixed in a molar ratio of TiO ₂ / K ₂ O = 2.9 to 3.3 in terms of oxide;
Preparing a potassium titanate composite powder in which acicular potassium titanate particles and non-acicular potassium dititanate particles are integrated by firing the raw material mixture;
A step of acid-treating the potassium titanate composite powder to prepare a hydrated titanate composite powder;
And a step of producing a titanium dioxide composite powder in which acicular titanium dioxide particles and non-acicular titanium dioxide particles are integrated by heat-treating the hydrated titanic acid composite powder.   The manufacturing method of electroconductive composite powder provided with the process of forming a conductive layer in the surface of the titanium dioxide composite powder manufactured by the method of Claim 1.   The method for producing a conductive composite powder according to claim 2, wherein the conductive layer is a conductive layer made of a tin oxide layer.   The method for producing a conductive composite powder according to claim 3, wherein the tin oxide layer is a tin oxide layer containing no antimony component.   Acicular titanium dioxide particles having an average fiber length of 3 to 50 μm and an aspect ratio of 20 to 100 and non-acicular titanium dioxide particles having an average particle diameter of 3 to 30 μm and an aspect ratio of 1 to 5 are integrated. Titanium dioxide composite powder characterized by the above. The titanium dioxide composite powder according to claim 5 , wherein at least a part of the acicular titanium dioxide particles are bound by the non-acicular titanium dioxide particles. The electroconductive composite powder in which the electroconductive layer was formed in the surface of the titanium dioxide composite powder of Claim 5 or 6 . The electroconductive composition containing the electroconductive composite powder of Claim 7 . The coating film formed by apply | coating the electrically conductive composition of Claim 8 .