Recycled titanium oxide

Abstract

To provide a method for producing recycled titanium oxide capable of obtaining recycled titanium oxide which has a good powder hue, has a certain range of a primary particle diameter, has a small content of transition metal as impurity, has a good coating hue and has a high hiding rate, from a resin composition containing titanium oxide.SOLUTION: A method for producing recycled titanium oxide subjects a resin composition containing titanium oxide to overheat steam treatment at 550 to 1,000°C.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing recycled titanium oxide by treating a resin composition containing titanium oxide and the recycled titanium oxide obtained thereby.

Background Art

[0002] In recent years, due to environmental problems and waste problems, the demand for recovering and recycling products consumed in the market has been increasing globally. Here, since titanium oxide is used in many products as a white pigment, attempts have been made to recover the titanium oxide and recycle it as recycled titanium oxide.

[0003] For example, Patent Document 1 includes Step 1 of preparing a raw material for a recycled titanium dioxide pigment for ink, and Step 2 of firing the raw material at a temperature of 400°C to 800°C and preparing a recycled titanium dioxide pigment for ink from the obtained fired product. The raw material in Step 1 is waste of a plastic film print containing a titanium dioxide pigment. The plastic film print has an ink coating film formed on at least one side of a plastic film substrate. The ink coating film has a white ink layer formed by a white ink containing a white pigment made of titanium dioxide and a colored ink layer formed by a colored ink containing a colored pigment other than the white ink. Further, the mass ratio of titanium dioxide to the solid content other than titanium dioxide in the white ink layer is 0.1 to 6. Furthermore, the thickness of the plastic film substrate is 10 to 60 μm. A method for producing a recycled titanium dioxide pigment for ink is described.

[0004] Patent Document 2 describes a method for recovering titanium oxide from a titanium oxide-containing plastic, which involves heat-treating the titanium oxide-containing plastic in an oxygen-containing atmosphere at 800 to 1000 °C to burn the organic components contained in the titanium oxide-containing plastic, converting the titanium oxide component contained in the titanium oxide-containing plastic into anatase type, and reusing the obtained combustion residue containing anatase type titanium oxide as a raw material for producing titanium oxide by the sulfuric acid method to recover titanium oxide.

[0005] Further, Patent Document 3 describes a method for recovering titanium dioxide, which involves crushing a vinyl chloride resin waste material containing calcium carbonate and titanium dioxide, then subjecting it to heat and dehydrochlorination treatment, washing the residue with an aqueous liquid, followed by combustion and treatment, and recovering the residue as titanium dioxide.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] These Patent Documents 1 to 3 aim to recover titanium oxide, but all of them are methods for recovering titanium oxide after firing in an air atmosphere. Through the study by the present inventors, it was found that in the method of firing in the air atmosphere, even if set at a certain temperature, since it is a combustion reaction, reaction heat is generated, and there is a risk that titanium oxide will sinter and hypertrophy. The hypertrophied titanium oxide has reduced light scattering, and the hiding power and whiteness decrease, so there are problems with the quality for recycling as recycled titanium oxide.

[0008] The present invention has been made to solve the above problems, and provides a method for producing recycled titanium oxide that can obtain recycled titanium oxide having a good powder color tone, a primary particle diameter in a certain range, a small content of transition metals as impurities, a good paint color tone, and a high hiding power from a resin composition containing titanium oxide.

Means for Solving the Problems

[0009] As a result of intensive studies by the present inventors, it has been found that the above problems can be solved by a method for producing recycled titanium oxide in which a resin composition containing titanium oxide is treated with superheated steam in a certain temperature range, and the present invention has been completed.

[0010] That is, the present invention is [1] A method for producing recycled titanium oxide, characterized in that a resin composition containing titanium oxide is treated with superheated steam at 550 to 1000°C; [2] The method for producing recycled titanium oxide according to [1], wherein the resin composition is washed with an acid before or after the superheated steam treatment; [3] The method for producing recycled titanium oxide according to [1] or [2], wherein the resin composition is pulverized after the superheated steam treatment; [4] Recycled titanium oxide recycled from a resin composition containing titanium oxide, wherein the L value of the powder color tone is 50 or more, and the D50 by TEM is 0.18 μm or more and 0.31 μm or less; [5] The recycled titanium oxide according to [4], wherein the total content of transition metals that do not dissolve in an acid is 1.0% by mass or less; [6] The recycled titanium oxide according to [4] or [5], wherein the reflectance of the powder pellet obtained by molding the recycled titanium oxide into a pellet shape is 85% or more at a wavelength of 420 nm; [7] The recycled titanium oxide according to any one of [4] to [6], wherein the L value of the paint color tone in the Lab color system of a coating film containing the recycled titanium oxide and boiled linseed oil is 85 or more, and the b value is 4.3 or less; [8] The L value of the paint color tone in the Lab color system of the coating film containing the recycled titanium oxide and boiled linseed oil is 93.5 or more, and the hiding power in the hiding power test is 99.5% or more, and the recycled titanium oxide according to any one of [4] to [7]; [9] Recycled titanium oxide recycled from a resin composition containing titanium oxide, wherein the L value of the powder color tone is 50 or more, and the D10 by TEM is 0.29 μm or less;

[10] Recycled titanium oxide recycled from a resin composition containing titanium oxide, wherein the L value of the powder color tone is 50 or more, and the D90 by TEM is 0.71 μm or less;

[11] Recycled titanium oxide recycled from a resin composition containing titanium oxide, wherein the L value of the powder color tone is 50 or more, and the difference between D90 and D10 by TEM is 0.46 μm or less;

[12] Ink containing the recycled titanium oxide according to any one of [4] to

[11] ; Regarding. [Advantages of the Invention]

[0011] According to the production method of the present invention, from a resin composition containing titanium oxide, recycled titanium oxide with good powder color tone, primary particle size in a certain range, low content of transition metal as an impurity, good paint color tone, and high hiding power can be obtained. The recycled titanium oxide thus obtained is excellent in quality and is suitably used as a white pigment. [Embodiments for Carrying Out the Invention]

[0012] The method for producing recycled titanium oxide of the present invention is characterized in that a resin composition containing titanium oxide is treated with superheated steam at 550 to 1000 ° C (sometimes referred to as "superheated steam treatment step"). The inventors of the present invention are CH 4Focusing on the fact that the chemical reaction between hydrocarbons such as and superheated steam is an endothermic reaction, and conducting intensive studies, it was found that by subjecting a resin composition containing titanium oxide to superheated steam treatment in a certain temperature range, it is possible to prevent the sintering and coarsening of titanium oxide, and it was revealed that the powder color tone becomes good. As can be seen from the comparison between the examples and comparative examples described later, in the comparative example where the reaction was carried out in air, even when the reaction temperature was set at a constant temperature, since it was a combustion reaction, reaction heat was generated. As a result, it was confirmed that the primary particle diameter (D50) of the obtained titanium oxide became a value equal to or greater than a certain value, and it was coarsened. Also, in the comparative example where the reaction was carried out in an inert atmosphere, the powder color tone of the obtained titanium oxide was not good. In contrast, in the example where a resin composition containing titanium oxide was subjected to superheated steam treatment in a certain temperature range, the powder color tone was good, the primary particle diameter (D50) was in a certain range, the content of transition metals which are impurities was small, the paint color tone was good, and it can be seen that a recycled titanium oxide with a high hiding power can be obtained. Therefore, it can be seen that the significance of adopting the method for producing recycled titanium oxide of the present invention is great. Incidentally, if the resin composition containing titanium oxide is to be subjected to superheated steam treatment in a certain temperature range, the reaction in an inert atmosphere may be combined with the superheated steam treatment.

[0013] The type of resin constituting the resin composition is not particularly limited. For example, polyolefins such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer; polyamide; polyester; polystyrene; polyurethane; polyvinyl chloride; polycarbonate; acrylic resin; epoxy resin; silicone resin and the like can be mentioned.

[0014] In the present invention, the reaction temperature in the superheated steam treatment step is 550 to 1000 °C. When the reaction temperature in the superheated steam treatment step is less than 550 °C, the reaction does not proceed sufficiently, and titanium oxide with a good powder color tone cannot be obtained. The reaction temperature in the superheated steam treatment step is preferably 580 °C or higher, more preferably 600 °C or higher, still more preferably 680 °C or higher, particularly preferably 750 °C or higher, and most preferably 780 °C or higher. On the other hand, when the reaction temperature in the superheated steam treatment step exceeds 1000 °C, there is a risk of sintering and coarsening of titanium oxide. The reaction temperature in the superheated steam treatment step is preferably 980 °C or lower, more preferably 920 °C or lower, and still more preferably 820 °C or lower.

[0015] In the present invention, the reaction time in the superheated steam treatment step is not particularly limited. The reaction time in the present invention refers to the time from the start of the superheated steam treatment while maintaining the reaction temperature in the above-mentioned superheated steam treatment step until the reaction ends. The reaction time is preferably 0.1 to 10 hours, more preferably 0.2 to 6 hours, and still more preferably 0.5 to 4 hours. Further, the means for maintaining the reaction temperature in the above-mentioned superheated steam treatment step is not particularly limited, and a method of raising the temperature with superheated steam to a desired reaction temperature is preferably employed. That is, a preferred embodiment of the present invention is to raise the temperature to a desired reaction temperature and perform the superheated steam treatment while maintaining the reaction temperature. The time until the temperature is raised is not particularly limited, and is preferably 0.1 to 4 hours, more preferably 0.2 to 3 hours, and still more preferably 0.5 to 2 hours.

[0016] In the present invention, it is a preferred embodiment to perform washing with an acid (which may be referred to as the "acid washing step") before or after the superheated steam treatment. Thereby, metal oxides, metal salts, etc. remaining after the superheated steam treatment can be removed with an acid, and it becomes possible to obtain recycled titanium oxide with high purity and good powder color tone. Among them, it is a more preferred embodiment to perform washing with an acid after the superheated steam treatment. The acid to be used is not particularly limited as long as it is a water-soluble inorganic acid or organic acid. As the inorganic acid, at least one selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, hydrofluoric acid, etc. is preferably used, and as the organic acid, at least one selected from the group consisting of acetic acid, oxalic acid, citric acid, etc. is preferably used. Among them, at least one acid selected from the group consisting of sulfuric acid, hydrochloric acid, and nitric acid is more preferably used. As a method of washing with an acid, a method of adding and mixing an aqueous solution of the above-mentioned acid to titanium oxide after the superheated steam treatment is preferably adopted. After the acid washing step, it is a preferred embodiment to perform a filtration and water washing step. As the filtration and water washing step, a known method is adopted. After the filtration and washing step, it is a preferred embodiment to perform a drying step, and the drying temperature is preferably 100 to 130 °C, more preferably 105 to 115 °C.

[0017] In the present invention, it is a preferred embodiment to perform pulverization (which may be referred to as the "pulverization step") after the superheated steam treatment. As a method of pulverization, it is preferable to pulverize with a known pulverizer or the like. The pulverizer is not particularly limited, and an ultra-centrifugal pulverizer, a ball mill, a pneumatic mill, a hammer mill, a Ryka machine, etc. can be used. By this pulverization, recycled titanium oxide having a primary particle diameter (D50) within a certain range can be obtained. The said pulverization is preferably carried out as the final step for obtaining recycled titanium oxide. Therefore, it is a preferred embodiment to perform the acid washing step before the pulverization step.

[0018] The recycled titanium oxide obtained in the present invention has an L value of the powder color tone of 50 or more, and a D50 by TEM of 0.18 μm or more and 0.31 μm or less. Since the L value of the powder color tone is a certain value or more and the D50 by TEM is within a certain range, it can be recycled as recycled titanium oxide with excellent quality. As the L value of the powder color tone, it is preferably 50 or more, more preferably 70 or more, still more preferably 85 or more, particularly preferably 92 or more, and most preferably 95 or more. The L value of the powder color tone indicates the L value in the Lab color system measured using a color difference meter for color measurement.

[0019] Also, as the D50 by TEM, it is preferably 0.18 μm or more, more preferably 0.21 μm or more, still more preferably 0.22 μm or more, and most preferably 0.23 μm or more. On the other hand, the D50 by TEM is preferably 0.31 μm or less, preferably 0.30 μm or less, and still more preferably 0.29 μm or less. The D50 by TEM means the particle diameter (median diameter) of 50% cumulative in the volume-based particle size distribution obtained by photographing a certain number of primary particles of titanium oxide using a transmission electron microscope and measuring the particle size distribution using image analysis type particle size distribution measurement software.

[0020] Also, the recycled titanium oxide obtained in the present invention has an L value of the powder color tone of 50 or more, and a D10 by TEM of 0.29 μm or less. Since the L value of the powder color tone is a certain value or more and the D10 by TEM is within a certain range, it can be recycled as recycled titanium oxide with excellent quality.

[0021] The D10 by TEM is preferably 0.29 μm or less, more preferably 0.27 μm or less, still more preferably 0.25 μm or less, and most preferably 0.24 μm or less. The D10 by TEM is preferably 0.12 μm or more, more preferably 0.16 μm or more, and still more preferably 0.20 μm or more. The D10 by TEM means the particle diameter at the cumulative 10% in the volume-based particle size distribution, which is obtained by photographing a certain number of primary particles of titanium oxide using a transmission electron microscope and measuring the particle size distribution using image analysis type particle size distribution measurement software.

[0022] In addition, the recycled titanium oxide obtained in the present invention has an L value of the powder color tone of 50 or more and a D90 by TEM of 0.71 μm or less. Since the L value of the powder color tone is a certain value or more and the D90 by TEM is in a certain range, it can be recycled as recycled titanium oxide with excellent quality.

[0023] The D90 by TEM is preferably 0.71 μm or less, more preferably 0.68 μm or less, still more preferably 0.65 μm or less, and most preferably 0.64 μm or less. The D90 by TEM is preferably 0.23 μm or more, more preferably 0.27 μm or more, and still more preferably 0.32 μm or more. The D90 by TEM means the particle diameter at the cumulative 90% in the volume-based particle size distribution, which is obtained by photographing a certain number of primary particles of titanium oxide using a transmission electron microscope and measuring the particle size distribution using image analysis type particle size distribution measurement software.

[0024] In addition, the recycled titanium oxide obtained in the present invention has an L value of the powder color tone of 50 or more and the difference between D90 and D10 by TEM (sometimes denoted as "D90 - D10") of 0.46 μm or less. Since the L value of the powder color tone is a certain value or more and the difference between D90 and D10 by TEM is in a certain range, it can be recycled as recycled titanium oxide with excellent quality.

[0025] The difference between D90 and D10 by TEM is preferably 0.46 μm or less, more preferably 0.41 μm or less, and still more preferably 0.36 μm or less. The difference between D90 and D10 by TEM is preferably 0.06 μm or more.

[0026] The total content of transition metals that do not dissolve in acid in the recycled titanium oxide obtained in the present invention is preferably 1.0% by mass or less. The total content of transition metals that do not dissolve in acid indicates the total content of transition metals remaining after the acid washing step, and the transition metals are derived from metal oxides, metal salts, etc. contained in the resin composition. Specifically, it indicates the total content of transition metals derived from CuO and Fe 2 O 3 When the content of the transition metal exceeds 1.0% by mass, the whiteness may decrease, and the quality for recycling may be insufficient. The content of the transition metal is more preferably 0.8% by mass or less, still more preferably 0.6% by mass or less, particularly preferably 0.4% by mass or less, and most preferably 0.3% by mass or less. On the other hand, the content of the transition metal is 0% by mass or more, and may be 0.005% by mass or more, 0.01% by mass or more, or 0.05% by mass or more.

[0027] The reflectance of the powder pellet obtained by molding the recycled titanium oxide obtained in the present invention into a pellet shape at a wavelength of 420 nm is preferably 85% or more. By having the reflectance above a certain level, it is possible to recycle it as recycled titanium oxide with excellent quality. The reflectance is more preferably 87% or more, still more preferably 88% or more, and particularly preferably 94% or more. The reflectance is usually 100% or less.

[0028] The recycled titanium oxide obtained in the present invention preferably has an L value of 85 or more and a b value of 4.3 or less in the paint color tone in the Lab color system of the paint film containing the recycled titanium oxide and boiled linseed oil. When the L value of the paint color tone is less than 85, there is a risk that it is insufficient as the quality for recycling, more preferably 88 or more, still more preferably 90 or more, even more preferably 92 or more, particularly preferably 93.5 or more, and most preferably 94 or more. The L value of the paint color tone is usually 99 or less. Further, when the b value of the paint color tone exceeds 4.3, there is a risk that it is insufficient as the quality for recycling, more preferably 4.2 or less, still more preferably 4.1 or less, particularly preferably 4.0 or less, and most preferably 3.9 or less. The L value and b value of the paint color tone respectively indicate the L value and b value in the Lab color system measured using a color difference meter for color measurement.

[0029] Also, the recycled titanium oxide obtained in the present invention preferably has a hiding power of 99.5% or more in the hiding power test of the paint film containing the recycled titanium oxide and boiled linseed oil. When the hiding power is less than 99.5%, there is a risk that the quality when used as a paint is insufficient, more preferably 99.6% or more, still more preferably 99.7% or more, and particularly preferably 99.8% or more. The hiding power is usually 100% or less. The hiding power is calculated by the following formula by measuring the L value in the Lab color system using a color difference meter for color measurement for the paint films painted on a white board and a black board respectively according to JIS K5600 (General Test Methods for Paints).

Equation

[0030] The recycled titanium oxide obtained in the present invention has a good powder color tone, a primary particle size within a certain range, a low content of transition metals as impurities, a good paint color tone, and a high hiding power. Therefore, it is suitably used as a white pigment in paints, inks, papers, resin compounds for molding, and the like. Among them, an ink containing the recycled titanium oxide obtained in the present invention is a more preferred embodiment. The recycled titanium oxide obtained in the present invention is obtained by recovering from a resin composition containing titanium oxide. Therefore, a method for recovering recycled titanium oxide from a resin composition containing titanium oxide is a preferred embodiment, and a resin composition containing the recycled titanium oxide obtained in the present invention is also a preferred embodiment.

Examples

[0031] Hereinafter, the present invention will be described more specifically using examples.

[0032] Production Example 1 90 g of titanium oxide, 3.3 g of phthalocyanine blue (0.5% by mass in terms of CuO based on 100% by mass of titanium oxide), 100 g of polyurethane resin, and 73.3 g of solvent were mixed at a mixing ratio, put into a 400 mL mayonnaise bottle together with 180 g of 1.5 mm glass beads, and dispersed for 1 hour using a paint conditioner (manufactured by Red Devil) to prepare an ink. The following materials were used for the blending materials. Titanium oxide: “Titax JR-707” (manufactured by Teika Co., Ltd.) Phthalocyanine blue: “Phthalocyanine Blue” (manufactured by Fujifilm Wako Pure Chemical Corporation) Polyurethane resin: “Sampleen IB-422” (manufactured by Sanyo Chemical Industries, Ltd.) Solvent: A mixed solvent of methyl ethyl ketone / isopropyl alcohol / toluene = 1 / 1 / 1 based on mass This operation was performed multiple times to prepare a total of 13 kg of ink. The obtained 13 kg of ink was spread thinly and dried at 120 ° C. for 12 hours to obtain 6 kg of a titanium oxide resin composition containing 0.5% by mass of CuO.

[0033] Production Example 2 90 g of titanium oxide, 6.6 g of phthalocyanine blue (1.0% by mass in terms of CuO relative to 100% by mass of titanium oxide), 100 g of polyurethane resin, and 73.3 g of solvent were mixed at the mixing ratio, placed in a 400 mL mayonnaise bottle together with 180 g of 1.5 mm glass beads, and dispersed for 1 hour using a paint conditioner (manufactured by Red Devil) to prepare an ink. The following materials were used for the compounding materials. Titanium oxide: “Titax JR-707” (manufactured by Teika Corporation) Phthalocyanine blue: “Phthalocyanine Blue” (manufactured by Fujifilm Wako Pure Chemical Corporation) Polyurethane resin: “Sampleen IB-422” (manufactured by Sanyo Chemical Industries, Ltd.) Solvent: A mixed solvent of methyl ethyl ketone / isopropyl alcohol / toluene = 1 / 1 / 1 on a mass basis This operation was performed multiple times to prepare a total of 13 kg of ink. The obtained 13 kg of ink was thinly spread and dried at 120 °C for 12 hours to obtain 6 kg of a titanium oxide resin composition containing 1.0% by mass of CuO.

[0034] Production Example 3 90 g of titanium oxide, 3.3 g of phthalocyanine blue (0.5% by mass in terms of CuO relative to 100% by mass of titanium oxide), 0.45 g of iron(III) oxide (0.5% by mass in terms of Fe 2 O 3 in terms of conversion relative to 100% by mass of titanium oxide), 100 g of polyurethane resin, and 73.3 g of solvent were mixed at the mixing ratio, placed in a 400 mL mayonnaise bottle together with 180 g of 1.5 mm glass beads, and dispersed for 1 hour using a paint conditioner (manufactured by Red Devil) to prepare an ink. The following materials were used for the compounding materials. Titanium oxide: “Titax JR-707” (manufactured by Teika Corporation) Phthalocyanine blue: “Phthalocyanine Blue” (manufactured by Fujifilm Wako Pure Chemical Corporation) Iron(III) oxide: “Iron(III) Oxide” (manufactured by Fujifilm Wako Pure Chemical Corporation) Polyurethane resin: “Sampleen IB-422” (manufactured by Sanyo Chemical Industries, Ltd.) Solvent: A mixed solvent of methyl ethyl ketone / isopropyl alcohol / toluene = 1 / 1 / 1 based on mass This operation was performed multiple times to produce a total of 13 kg of ink. The obtained 13 kg of ink was thinly spread and dried at 120 °C for 12 hours to obtain 6 kg of a titanium oxide resin composition containing 0.5% by mass of CuO and Fe 2 O 3 0.5% by mass.

[0035] Production Example 4 90 g of titanium oxide, 3.3 g of phthalocyanine blue (0.5% by mass in terms of CuO conversion based on 100% by mass of titanium oxide), 100 g of polyurethane resin, and 73.3 g of solvent were mixed at a mixing ratio, placed in a 400 mL mayonnaise bottle together with 180 g of 1.5 mm glass beads, and dispersed for 1 hour using a paint conditioner (manufactured by Red Devil) to produce ink. The following materials were used for the blending materials. Titanium oxide: "Titax JR-809" (manufactured by Teika Co., Ltd.) Phthalocyanine blue: "Phthalocyanine blue" (manufactured by Fujifilm Wako Pure Chemical Corporation) Polyurethane resin: "Sampleen IB-422" (manufactured by Sanyo Chemical Industries, Ltd.) Solvent: A mixed solvent of methyl ethyl ketone / isopropyl alcohol / toluene = 1 / 1 / 1 based on mass This operation was performed multiple times to produce a total of 13 kg of ink. The obtained 13 kg of ink was thinly spread and dried at 120 °C for 12 hours to obtain 6 kg of a titanium oxide resin composition containing 0.5% by mass of CuO.

[0036] Production Example 5 6 kg of the resin composition produced in Production Example 1 was cut into 1 cm squares and immersed in 30 kg of a 1% by mass sodium hydroxide solution for 1 hour. 100 L of water was added to 20 kg of the immersion product (moisture content 70% by mass), stirred for 30 minutes, and the filtered sample was washed twice with water. Then, it was dried in a dryer at 110 °C for 24 hours to obtain 6 kg of an alkali-washed resin composition of titanium oxide containing 0.5% by mass of CuO.

[0037] Example 1 1 kg of the resin composition of Preparation Example 1 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After the temperature was raised from room temperature to 150°C in 1 hour, superheated steam (600°C × 5 kg / hr) was introduced into the furnace to raise the temperature to 600°C in 1 hour, and it was held at that temperature for 1 hour to perform steam thermal decomposition of the contents. The obtained powder was pulverized to obtain recycled titanium oxide.

[0038] Example 2 1 kg of the resin composition of Preparation Example 5 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After the temperature was raised from room temperature to 150°C in 1 hour, superheated steam (700°C × 5 kg / hr) was introduced into the furnace to raise the temperature to 700°C in 1 hour, and it was held at that temperature for 1 hour to perform steam thermal decomposition of the contents. The obtained powder was pulverized to obtain recycled titanium oxide.

[0039] Example 3 1 kg of the resin composition of Preparation Example 1 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After the temperature was raised from room temperature to 150°C in 1 hour, superheated steam (800°C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800°C in 1 hour, and it was held at that temperature for 1 hour to perform steam thermal decomposition of the contents. The obtained powder was pulverized to obtain recycled titanium oxide.

[0040] Example 4 1 kg of the resin composition of Preparation Example 1 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After the temperature was raised from room temperature to 150°C in 1 hour, superheated steam (900°C × 5 kg / hr) was introduced into the furnace to raise the temperature to 900°C in 1 hour, and it was held at that temperature for 1 hour to perform steam thermal decomposition of the contents. The obtained powder was pulverized to obtain recycled titanium oxide.

[0041] Example 5 1 kg of the resin composition of Preparation Example 1 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After the temperature was raised from room temperature to 150°C in 1 hour, superheated steam (1000°C × 5 kg / hr) was introduced into the furnace to raise the temperature to 1000°C in 1 hour, and it was held at that temperature for 1 hour to perform steam thermal decomposition of the contents. The obtained powder was pulverized to obtain recycled titanium oxide.

[0042] Example 6 1 kg of the resin composition of Preparation Example 1 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.), heated from room temperature to 150°C in 1 hour, and then superheated steam (550°C × 5 kg / hr) was introduced into the furnace to heat it up to 550°C in 1 hour, held at that temperature for 1 hour, and the steam pyrolysis of the content was carried out. The obtained powder was pulverized to obtain recycled titanium oxide.

[0043] Example 7 1 kg of the resin composition of Preparation Example 1 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.), heated from room temperature to 150°C in 1 hour, and then superheated steam (580°C × 5 kg / hr) was introduced into the furnace to heat it up to 580°C in 1 hour, held at that temperature for 1 hour, and the steam pyrolysis of the content was carried out. The obtained powder was pulverized to obtain recycled titanium oxide.

[0044] Example 8 1 kg of the resin composition of Preparation Example 1 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.), heated from room temperature to 150°C in 1 hour, and then superheated steam (800°C × 5 kg / hr) was introduced into the furnace to heat it up to 800°C in 1 hour, held at that temperature for 1 hour, and the steam pyrolysis of the content was carried out. 650 mL of 50% by mass sulfuric acid was added to 500 g of the obtained titanium oxide pigment, and water was added while stirring well to make 5 L. The obtained liquid was boiled for 5 minutes while stirring and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110°C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0045] Example 9 1 kg of the resin composition of Production Example 1 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the contents. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% nitric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained liquid, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0046] Example 10 1 kg of the resin composition of Production Example 5 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the contents. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% hydrochloric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained liquid, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0047] Example 11 1 kg of the resin composition of Production Example 2 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the contents. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% sulfuric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained liquid, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0048] Example 12 1 kg of the resin composition of Production Example 2 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.), heated from room temperature to 150 °C in 1 hour, and then superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour. It was held at that temperature for 1 hour to perform steam pyrolysis of the contents. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% nitric acid was added, and water was added while stirring well to make 5 L. The obtained liquid was boiled for 5 minutes while stirring and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0049] Example 13 1 kg of the resin composition of Production Example 2 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.), heated from room temperature to 150 °C in 1 hour, and then superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour. It was held at that temperature for 1 hour to perform steam pyrolysis of the contents. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% hydrochloric acid was added, and water was added while stirring well to make 5 L. The obtained liquid was boiled for 5 minutes while stirring and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0050] Example 14 1 kg of the resin composition of Production Example 3 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.), heated from room temperature to 150 °C in 1 hour, and then superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour. It was held at that temperature for 1 hour to perform steam pyrolysis of the contents. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% sulfuric acid was added, and water was added while stirring well to make 5 L. The obtained liquid was boiled for 5 minutes while stirring and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0051] Example 15 1 kg of the resin composition of Preparation Example 3 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After heating the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the content. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% nitric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained liquid, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0052] Example 16 1 kg of the resin composition of Preparation Example 3 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After heating the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the content. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% hydrochloric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained liquid, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0053] Example 17 1 kg of the resin composition of Preparation Example 1 was placed in a small electric furnace KBF828N2 (manufactured by J-Tect Thermo System Co., Ltd.). Under a nitrogen atmosphere, the temperature was raised from room temperature to 800 °C in 1 hour and held at that temperature for 6 hours to pyrolyze the content. Then, the obtained pyrolysis product was placed in a batch-type superheated steam furnace (trade name: manufactured by Takasago Industries Co., Ltd.). After heating the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the content. The obtained powder was pulverized to obtain recycled titanium oxide.

[0054] Example 18 1 kg of the resin composition of Production Example 4 was placed in a batch-type superheated steam furnace (manufactured by Takasago Kogyo Co., Ltd.). After the temperature was raised from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the content. The obtained powder was pulverized to obtain recycled titanium oxide.

[0055] Comparative Example 1 1 kg of the resin composition of Production Example 1 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.). After the temperature was raised from room temperature to 500 °C in 1 hour, it was held at that temperature for 12 hours to bake the content. The obtained powder was pulverized to obtain recycled titanium oxide.

[0056] Comparative Example 2 1 kg of the resin composition of Production Example 1 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.). After the temperature was raised from room temperature to 600 °C in 1 hour, it was held at that temperature for 12 hours to bake the content. The obtained powder was pulverized to obtain recycled titanium oxide.

[0057] Comparative Example 3 1 kg of the resin composition of Production Example 5 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.). After the temperature was raised from room temperature to 700 °C in 1 hour, it was held at that temperature for 12 hours to bake the content. The obtained powder was pulverized to obtain recycled titanium oxide.

[0058] Comparative Example 4 1 kg of the resin composition of Production Example 1 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.). After the temperature was raised from room temperature to 800 °C in 1 hour, it was held at that temperature for 12 hours to bake the content. The obtained powder was pulverized to obtain recycled titanium oxide.

[0059] Comparative Example 5 1 kg of the resin composition of Production Example 1 was placed in a small electric furnace KBF828N2 (manufactured by JTECT Thermo System Co., Ltd.), heated from room temperature to 900 °C in 1 hour, then held at that temperature for 12 hours, and the content was fired. The obtained powder was pulverized to obtain recycled titanium oxide.

[0060] Comparative Example 6 1 kg of the resin composition of Production Example 1 was placed in a small electric furnace KBF828N2 (manufactured by JTECT Thermo System Co., Ltd.), heated from room temperature to 1000 °C in 1 hour, then held at that temperature for 12 hours, and the content was fired. The obtained powder was pulverized to obtain recycled titanium oxide.

[0061] Comparative Example 7 1 kg of the resin composition of Production Example 1 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.), heated from room temperature to 150 °C in 1 hour, then heated to 500 °C in 1 hour by introducing superheated steam (500 °C × 5 kg / hr) into the furnace, held at that temperature for 1 hour, and the steam thermal decomposition of the content was carried out. The obtained powder was pulverized to obtain recycled titanium oxide.

[0062] Comparative Example 8 1 kg of the resin composition of Production Example 1 was placed in a small electric furnace KBF828N2 (manufactured by JTECT Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour, then held at that temperature for 12 hours, and the content was fired. 650 mL of 50 mass% sulfuric acid was added to 500 g of the obtained titanium oxide pigment, and water was added while stirring well to make 5 L. While stirring the obtained liquid, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0063] Comparative Example 9 1 kg of the resin composition of Production Example 1 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour, then held at that temperature for 12 hours, and the contents were fired. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% nitric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained liquid, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0064] Comparative Example 10 1 kg of the resin composition of Production Example 5 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour, then held at that temperature for 12 hours, and the contents were fired. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% hydrochloric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained liquid, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0065] Comparative Example 11 1 kg of the resin composition of Production Example 1 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour under a nitrogen atmosphere, held at that temperature for 6 hours, and the contents were pyrolyzed. The obtained powder was pulverized to obtain recycled titanium oxide.

[0066] Comparative Example 12 1 kg of the resin composition of Production Example 1 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour under a nitrogen atmosphere, held at that temperature for 6 hours, and the contents were pyrolyzed. Then, the obtained pyrolysis product was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), heated from room temperature to 500 °C in 1 hour in air, held at that temperature for 6 hours, and the contents were fired. The obtained powder was pulverized to obtain recycled titanium oxide.

[0067] Comparative Example 13 1 kg of the resin composition of Production Example 1 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), and the temperature was raised from room temperature to 800 °C in 1 hour under a nitrogen atmosphere, held at that temperature for 6 hours, and the content was pyrolyzed. Then, the obtained pyrolysis product was placed in a small electric furnace KBF828N2 (trade name: manufactured by J-Techno Thermo System Co., Ltd.), the temperature was raised from room temperature to 800 °C in 1 hour in air, held at that temperature for 6 hours, and the content was fired. The obtained powder was pulverized to obtain recycled titanium oxide.

[0068] Comparative Example 14 1 kg of the resin composition of Production Example 4 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), the temperature was raised from room temperature to 800 °C in 1 hour, then held at that temperature for 12 hours, and the content was fired. The obtained powder was pulverized to obtain recycled titanium oxide.

[0069] Production Example 6 120 g of titanium oxide, 4.4 g of phthalocyanine blue (0.5% by mass in terms of CuO based on 100% by mass of titanium oxide), 28.8 g of alkyd resin, and 28.8 g of solvent were mixed at a mixing ratio, placed in a 400 mL mayonnaise bottle together with 300 g of 1.5 mm glass beads, and dispersed for 1 hour using a paint conditioner (manufactured by Red Devil). Then, 111.2 g of alkyd resin and 60.0 g of butylated melamine resin were added to prepare a paint. The following materials were used for the blending materials. Titanium oxide: "Titax JR-600A" (manufactured by Teika Co., Ltd.) Phthalocyanine blue: "Phthalocyanine Blue" (manufactured by Fujifilm Wako Pure Chemical Corporation) Alkyd resin: "Alkidia J-524-A" (manufactured by DIC Corporation) Butylated melamine resin: "Amidia J-820-60" (manufactured by DIC Corporation) Solvent: A mixed solvent of xylene / n-butanol = 4 / 1 on a mass basis This operation was performed multiple times to produce a total of 18 kg of paint. The obtained 18 kg of paint was thinly spread and dried at 120 °C for 12 hours to obtain 6 kg of a titanium oxide resin composition containing 0.5% by mass of CuO.

[0070] Example 19 1 kg of the resin composition of Production Example 6 was placed in a batch-type superheated steam furnace (manufactured by Takasago Kogyo Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the contents. The obtained powder was pulverized to obtain recycled titanium oxide.

[0071] Example 20 1 kg of the resin composition of Production Example 6 was placed in a batch-type superheated steam furnace (manufactured by Takasago Kogyo Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the contents. To 500 g of the obtained titanium oxide pigment, 650 mL of 50% by mass sulfuric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained solution, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0072] Example 21 1 kg of the resin composition of Production Example 6 was placed in a batch-type superheated steam furnace (manufactured by Takasago Kogyo Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the contents. To 500 g of the obtained titanium oxide pigment, 650 mL of 50% by mass nitric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained solution, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0073] Example 22 Put 1 kg of the resin composition of Production Example 6 into a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, introduce superheated steam (800 °C × 5 kg / hr) into the furnace to raise the temperature to 800 °C in 1 hour, hold at that temperature for 1 hour, and perform steam pyrolysis of the content. To 500 g of the obtained titanium oxide pigment, add 650 mL of 50 mass% hydrochloric acid, add water while stirring well to make 5 L. While stirring the obtained liquid, boil for 5 minutes and then cool to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0074] Comparative Example 15 Put 1 kg of the resin composition of Production Example 6 into a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.). After raising the temperature from room temperature to 800 °C in 1 hour, hold at that temperature for 12 hours to bake the content. The obtained powder was pulverized to obtain recycled titanium oxide.

[0075] Comparative Example 16 Put 1 kg of the resin composition of Production Example 6 into a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.). After raising the temperature from room temperature to 800 °C in 1 hour, hold at that temperature for 12 hours to bake the content. To 500 g of the obtained titanium oxide pigment, add 650 mL of 50 mass% sulfuric acid, add water while stirring well to make 5 L. While stirring the obtained liquid, boil for 5 minutes and then cool to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0076] Comparative Example 17 1 kg of the resin composition of Production Example 6 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour, then held at that temperature for 12 hours, and the contents were fired. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% nitric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained solution, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0077] Comparative Example 18 1 kg of the resin composition of Production Example 6 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour, then held at that temperature for 12 hours, and the contents were fired. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% hydrochloric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained solution, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0078] Production Example 7 120 g of titanium oxide, 4.4 g of phthalocyanine blue (0.5 mass% in terms of CuO based on 100 mass% of titanium oxide), 28.8 g of alkyd resin, and 28.8 g of solvent were mixed at a mixing ratio, placed in a 400 mL mayonnaise bottle together with 300 g of 1.5 mm glass beads, and dispersed for 1 hour using a paint conditioner (manufactured by Red Devil). Then, 111.2 g of alkyd resin and 60.0 g of butylated melamine resin were added to prepare a paint. The following materials were used for the blending materials. Titanium oxide: “Titax JR-805” (manufactured by Tayca Corporation) Phthalocyanine blue: “Phthalocyanine Blue” (manufactured by Fujifilm Wako Pure Chemical Corporation) Alkyd resin: “Alkidia J-524-A” (manufactured by DIC Corporation) Butylated melamine resin: “Amidia J-820-60” (manufactured by DIC Corporation) Solvent: A mixed solvent of xylene / n-butanol = 4 / 1 based on mass This operation was performed multiple times to produce a total of 18 kg of paint. The obtained 18 kg of paint was thinly spread and dried at 120 °C for 12 hours to obtain 6 kg of a titanium oxide resin composition containing 0.5% by mass of CuO.

[0079] Example 23 1 kg of the resin composition of Preparation Example 7 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the contents. The obtained powder was pulverized to obtain recycled titanium oxide.

[0080] Example 24 1 kg of the resin composition of Preparation Example 7 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the contents. To 500 g of the obtained titanium oxide pigment, 650 mL of 50% by mass sulfuric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained liquid, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0081] Example 25 1 kg of the resin composition of Preparation Example 7 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and it was held at that temperature for 1 hour to perform steam pyrolysis of the contents. To 500 g of the obtained titanium oxide pigment, 650 mL of 50% by mass nitric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained liquid, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0082] Example 26 1 kg of the resin composition of Preparation Example 7 was placed in a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.), heated from room temperature to 150 °C in 1 hour, and then superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, held at that temperature for 1 hour, and the steam pyrolysis of the content was carried out. 650 mL of 50 mass% hydrochloric acid was added to 500 g of the obtained titanium oxide pigment, and water was added while stirring well to make 5 L. The obtained liquid was boiled for 5 minutes while stirring and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0083] Comparative Example 19 1 kg of the resin composition of Preparation Example 7 was placed in a small electric furnace KBF828N2 (manufactured by J-Tect Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour, and then held at that temperature for 12 hours to bake the content. The obtained powder was pulverized to obtain recycled titanium oxide.

[0084] Comparative Example 20 1 kg of the resin composition of Preparation Example 7 was placed in a small electric furnace KBF828N2 (manufactured by J-Tect Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour, and then held at that temperature for 12 hours to bake the content. 650 mL of 50 mass% sulfuric acid was added to 500 g of the obtained titanium oxide pigment, and water was added while stirring well to make 5 L. The obtained liquid was boiled for 5 minutes while stirring and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0085] Comparative Example 21 1 kg of the resin composition of Production Example 7 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour, then held at that temperature for 12 hours, and the contents were fired. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% nitric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained solution, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0086] Comparative Example 22 1 kg of the resin composition of Production Example 7 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour, then held at that temperature for 12 hours, and the contents were fired. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% hydrochloric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained solution, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0087] Production Example 8 90 g of titanium oxide, 3.3 g of phthalocyanine blue (0.5 mass% in terms of CuO based on 100 mass% of titanium oxide), 100 g of polyurethane resin, and 73.3 g of solvent were mixed at a mixing ratio, put into a 400 mL mayonnaise bottle together with 180 g of 1.5 mm glass beads, and dispersed for 1 hour using a paint conditioner (manufactured by Red Devil) to prepare an ink. The following materials were used for the blending materials. Titanium oxide: “Titax JR-405” (manufactured by Tayca Corporation) Phthalocyanine blue: “Phthalocyanine Blue” (manufactured by Fujifilm Wako Pure Chemical Corporation) Polyurethane resin: “Sampleen IB-422” (manufactured by Sanyo Chemical Industries, Ltd.) Solvent: A mixed solvent of methyl ethyl ketone / isopropyl alcohol / toluene = 1 / 1 / 1 on a mass basis This operation was performed multiple times to produce a total of 13 kg of ink. The obtained 13 kg of ink was thinly spread and dried at 120 °C for 12 hours to obtain 6 kg of a titanium oxide resin composition containing 0.5% by mass of CuO.

[0088] Example 27 1 kg of the resin composition of Production Example 8 was placed in a batch-type superheated steam furnace (manufactured by Takasago Kogyo Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and the temperature was maintained at that level for 1 hour to perform steam pyrolysis of the contents. The obtained powder was pulverized to obtain recycled titanium oxide.

[0089] Example 28 1 kg of the resin composition of Production Example 8 was placed in a batch-type superheated steam furnace (manufactured by Takasago Kogyo Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and the temperature was maintained at that level for 1 hour to perform steam pyrolysis of the contents. To 500 g of the obtained titanium oxide pigment, 650 mL of 50% by mass sulfuric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained solution, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0090] Example 29 1 kg of the resin composition of Production Example 8 was placed in a batch-type superheated steam furnace (manufactured by Takasago Kogyo Co., Ltd.). After raising the temperature from room temperature to 150 °C in 1 hour, superheated steam (800 °C × 5 kg / hr) was introduced into the furnace to raise the temperature to 800 °C in 1 hour, and the temperature was maintained at that level for 1 hour to perform steam pyrolysis of the contents. To 500 g of the obtained titanium oxide pigment, 650 mL of 50% by mass nitric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained solution, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0091] Example 30 Put 1 kg of the resin composition of Production Example 8 into a batch-type superheated steam furnace (manufactured by Takasago Industries Co., Ltd.), heat it from room temperature to 150 °C in 1 hour, then introduce superheated steam (800 °C × 5 kg / hr) into the furnace to heat it to 800 °C in 1 hour, hold it at that temperature for 1 hour, and perform steam pyrolysis of the content. To 500 g of the obtained titanium oxide pigment, add 650 mL of 50 mass% hydrochloric acid, add water while stirring well to make 5 L. While stirring the obtained liquid, boil it for 5 minutes and then cool it to room temperature. Filter the obtained sample, wash it with 5 L of water, and dry it in a dryer at 110 °C for 5 hours. Crush the obtained powder to obtain recycled titanium oxide.

[0092] Comparative Example 23 Put 1 kg of the resin composition of Production Example 8 into a small electric furnace KBF828N2 (manufactured by J-Tect Thermo System Co., Ltd.), heat it from room temperature to 800 °C in 1 hour, then hold it at that temperature for 12 hours to bake the content. Crush the obtained powder to obtain recycled titanium oxide.

[0093] Comparative Example 24 Put 1 kg of the resin composition of Production Example 8 into a small electric furnace KBF828N2 (manufactured by J-Tect Thermo System Co., Ltd.), heat it from room temperature to 800 °C in 1 hour, then hold it at that temperature for 12 hours to bake the content. To 500 g of the obtained titanium oxide pigment, add 650 mL of 50 mass% sulfuric acid, add water while stirring well to make 5 L. While stirring the obtained liquid, boil it for 5 minutes and then cool it to room temperature. Filter the obtained sample, wash it with 5 L of water, and dry it in a dryer at 110 °C for 5 hours. Crush the obtained powder to obtain recycled titanium oxide.

[0094] Comparative Example 25 1 kg of the resin composition of Production Example 8 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour, then held at that temperature for 12 hours, and the contents were fired. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% nitric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained liquid, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0095] Comparative Example 26 1 kg of the resin composition of Production Example 8 was placed in a small electric furnace KBF828N2 (manufactured by J-Techno Thermo System Co., Ltd.), heated from room temperature to 800 °C in 1 hour, then held at that temperature for 12 hours, and the contents were fired. To 500 g of the obtained titanium oxide pigment, 650 mL of 50 mass% hydrochloric acid was added, and water was added while stirring well to make 5 L. While stirring the obtained liquid, it was boiled for 5 minutes and then cooled to room temperature. The filtered sample was washed with 5 L of water and dried in a dryer at 110 °C for 5 hours. The obtained powder was pulverized to obtain recycled titanium oxide.

[0096] Evaluation 1: Evaluation of powder color tone 5 g of titanium oxide obtained in Examples 1 to 30 and Comparative Examples 1 to 26 was press-molded into pellets at 100 MPa to obtain a titanium oxide molded body having a diameter of 3 cm and a thickness of 0.3 cm. The powder color tone (L, a, b) of the titanium oxide molded body was measured using a color difference meter ZE2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). The obtained results are summarized in Tables 1 and 2.

[0097] Evaluation 2: Evaluation of particle size (D50, D10, D90 by TEM) Regarding the titanium oxides obtained in Examples 1 to 30 and Comparative Examples 1 to 26, more than 500 primary particles of the titanium oxide were photographed using a JEM-1230 transmission electron microscope (manufactured by JEOL Ltd.), and the particle size distribution was measured using image analysis type particle size distribution measurement software Mac-View (manufactured by Mountech Co., Ltd.). D50, D10, D90, and the difference between D90 and D10, "D90 - D10", were evaluated. The obtained results are summarized in Tables 1 and 2.

[0098] Evaluation 3: Evaluation of the amount of transition metals (CuO, Fe 2 O 3 ) that are insoluble in acid To 25 g of the titanium oxide obtained in Examples 1 to 30 and Comparative Examples 1 to 26, 32.5 mL of 50% by mass sulfuric acid or 50% by mass hydrochloric acid or 50% by mass nitric acid was added, and water was added while stirring well to make the volume 250 mL. While stirring the obtained solution, it was boiled for 5 minutes and then cooled to room temperature. The slurry was filtered, washed with water, and dried to remove transition metals that dissolve in acid. 5 g of the titanium oxide containing transition metals that are insoluble in acid obtained thereby was press-molded into pellets at 100 MPa to obtain a titanium oxide molded body having a diameter of 3 cm and a thickness of 0.3 cm. The elemental composition was measured using a desktop wavelength dispersive X-ray fluorescence analyzer Supermini (manufactured by Rigaku Corporation), and the amount of transition metals (CuO, Fe 2 O 3 ) that are insoluble in acid was measured. The obtained results are summarized in Tables 1 and 2.

[0099] Evaluation 4: Evaluation of the reflectance (%) at 420 nm by the powder pellet molded body The titanium oxides obtained in Examples 1 to 30 and Comparative Examples 1 to 26 were press-molded into pellets at 100 MPa to obtain a titanium oxide molded body having a diameter of 3 cm and a thickness of 0.3 cm. Using a spectrophotometer HITACHI U-4100 (manufactured by Hitachi, Ltd.), the reflectance curve in the wavelength range of 300 nm to 700 nm was measured with a BaSO 4 standard tablet as a reference. The reflectance at 420 nm was evaluated from the obtained reflectance curve. The obtained results are summarized in Tables 3 and 4.

[0100] Evaluation 5: Evaluation of paint color tone and hiding power test (hiding power) using boiled linseed oil For 1.5 g of titanium oxide obtained in Examples 1 to 30 and Comparative Examples 1 to 26, 1.5 mL of boiled linseed oil was added. The obtained sample was dispersed with a hot plate stirrer for 15 seconds. This dispersion was repeated a total of 4 times. The obtained dispersed paste was applied to a hiding power test paper for general paint test methods JIS K5600 using a 1.5-mil film applicator. The paint color tone on a white board and a black board was measured using a color difference meter ZE2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). The hiding power was calculated from the following formula. The obtained results are summarized in Tables 3 and 4.

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Number

[0102]

Table 1

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Table 2

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Table 3

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Table 4

[0106] As shown in Tables 1 to 4, the recycled titanium oxides of Examples 1 to 30 obtained by treating a resin composition containing titanium oxide with superheated steam in a certain temperature range have the following properties: (1) The L value of the powder color tone is high and the powder color tone is good; (2) The particle size (D50 by TEM) does not increase and the primary particle size is in a certain range; (3) The content of acid-insoluble transition metals, which are impurities, is low; (4) The L value of the paint color tone (white board) with boiled linseed oil is high, the b value is low, and the paint color tone is good; (5) It can be seen that all the required qualities of titanium oxide as a white pigment, such as high hiding power, are satisfied. On the other hand, the recycled titanium oxides of Comparative Examples 1 to 26 obtained by heat-treating a resin composition containing titanium oxide in air or an inert atmosphere or treating it with superheated steam outside a certain temperature range do not satisfy the quality of titanium oxide as a white pigment, such as (1) the L value of the powder color tone is low; (2) the particle size (D50 by TEM) is large and the primary particle size is hypertrophied; (3) the content of acid-insoluble transition metals is high; (4) the L value of the paint color tone (white board) with boiled linseed oil is low and the b value is high.

Claims

1. A method for producing recycled titanium oxide, comprising treating a resin composition containing titanium oxide with superheated steam at 550 to 1000°C.

2. 2. The method for producing recycled titanium oxide according to claim 1, wherein washing with an acid is carried out before or after the superheated steam treatment.

3. 3. The method for producing recycled titanium oxide according to claim 1, wherein the titanium oxide is pulverized after the superheated steam treatment.

4. The recycled titanium oxide is obtained by recycling a resin composition containing titanium oxide, and has an L value of powder color tone of 50 or more and a D50 measured by TEM of 0.18 μm or more and 0.31 μm or less.

5. 5. The recycled titanium oxide according to claim 4, wherein the total content of transition metals insoluble in acid is 1.0 mass % or less.

6. 6. The recycled titanium oxide according to claim 4, wherein the recycled titanium oxide is molded into a powder pellet having a reflectance of 85% or more at a wavelength of 420 nm.

7. 6. The recycled titanium oxide according to claim 4 or 5, wherein a coating film containing the recycled titanium oxide and boiled linseed oil has a paint color tone L value of 85 or more and a b value of 4.3 or less in the Lab color system.

8. The recycled titanium oxide according to claim 4 or 5, wherein a coating film containing the recycled titanium oxide and boiled linseed oil has an L value of 93.5 or more in the paint color tone in the Lab color system and a hiding rate of 99.5% or more in a hiding rate test.

9. 1. A recycled titanium oxide obtained by recycling a resin composition containing titanium oxide, the recycled titanium oxide having an L value of powder color tone of 50 or more and a D10 value of 0.29 μm or less by TEM.

10. 1. A recycled titanium oxide obtained by recycling a resin composition containing titanium oxide, the recycled titanium oxide having an L value of powder color tone of 50 or more and a D90 of 0.71 μm or less by TEM.

11. The recycled titanium oxide is obtained by recycling a resin composition containing titanium oxide, and has an L value of powder color tone of 50 or more and a difference between D90 and D10 measured by TEM of 0.46 μm or less.

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