JPS6260424B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bright primrose yellow monoclinic bismuth vanadate (bismuth vanadate) for pigments and a process for its production. Pigments are small, insoluble solid particles that are mixed into paints, plastics, and inks to impart color and/or opacity to them. Ideally, pigments should have the following properties: (1) tinting strength, i.e., the small amount of colored pigment required to produce color when mixed with white pigment; (2) intensity, i.e., the purity or dullness of the hue. (3) lightfastness, i.e., the resistance of the pigmented article to color change when exposed to sunlight; and (4) resistance to smearing, i.e., the change in color within the pigmented article. Less movement. Furthermore, in many applications it is desirable for pigments to have a high degree of hiding power, ie, the ability to effectively opacify the article to which they are applied. Intensity yellow pigments currently widely used include many organic materials such as lead chromate, cadmium sulfide, nickel titanate, and certain azo compounds. Although lead chromate and cadmium sulfide have a high degree of hiding power, there is currently a tendency to avoid the use of these compounds as pigments as they are considered toxic. Nickel titanate also has a high degree of hiding power, but does not have the tinting power and high intensity desired in high performance pigments. Although organic pigments generally exhibit high coloring power, they often have poor hiding power and also poor bleed resistance. Therefore, it is non-toxic and has a high degree of hiding power.
What is needed is a yellow pigment that has high strength, a high degree of intensity, and good lightfastness, and that does not bleed in organic solvents or vehicles. Bismuth vanadate usually occurs naturally in an orthorhombic form called puttierite. Puttierite is a dull yellow-brown ore that is not useful as a pigment. This puttierite is the same color as limonite, a dull yellow-brown iron oxide. This limonite has never been produced as a light colored pigment with high intensity, despite repeated attempts. Methods for the synthesis of bismuth vanadate are described in various publications. For example, IMGottlieb and CR
Rowe, (“Preparation and Thermal Properties
of Bismuth Orthovanadate”, Thermal
Analysis, Vol.2, Proceedings Third ICTA
DAVOS (1971), pp, 303-311;) RSRoth
and JWWaring, “Synthesis an Stability of
Bismutotalite, Stibiotantalite and
Chemically Similar ABO ₄ Compounds”， The
American Mineralogist, Vol.48 (Nov.-Dec.,
1963), pp.1348-56; HESwanson et al.,
“Standard X-Ray Diffraction Powder
Patterns”, National Bureau of Standards
Report, No.7592 (Aug., 1962); Eduard Zintl
and Ludwig Vanino, “Process For The
Manufacture of Pure Bismuth Vanadate”; German Patent No. 422,947 (1925). However, all of the above succeeded in producing bismuth vanadate as a light-colored yellow pigment, as was the case with yellow-brown iron oxide. According to the present invention, the color is primrose yellow, is non-toxic, has high hiding power, high tinting power, high intensity and good light fastness, and is free from organic solvents or coloring agents. A monoclinic bismuth vanadate is provided for pigments that do not smear in pigments.The bright primrose yellow bismuth vanadate for pigments has a pure monoclinic crystal structure as determined by X-ray diffraction. and exhibits an increase in reflectance of at least about 65 units at wavelengths between 450 and 525 nm using type illumination, and an increase in reflectance of at least about 60% (preferably about 64
%), with a green filter reflectance of approximately 2
-22 m ² /g surface area, and the masstone lightfastness of the paint is such that after 44 hours of exposure in a Fade-Ometer, the reflectance decreases by no more than about 11%. . The present invention also provides a method for producing this bismuth vanadate pigment. This method
( _NO3 ) _3.5H2O in _nitric acid solution and a solution of an alkali salt of vanadate in an aqueous base chosen from sodium hydroxide and _potassium hydroxide, preferably _Na3VO4
solution while adjusting the mixing conditions to ensure equimolar mixing of both solutions under turbulent flow conditions to obtain a bismuth vanadate gel suspended in a solution containing dissolved alkali nitrate salts. , mixing; at this time, the molar ratio of Bi ³⁺ and VO ₄ ^3- in this suspension is about 0.95:1.00 to 1.10:1.00, and the specified concentrations of the acid solution and the base solution are adjusted before mixing. and the pH of the suspension is about 1.0 to 8.0, preferably 1.5 to 2.0.
If necessary, the pH of said suspension is adjusted with an alkali hydroxide salt chosen from sodium hydroxide and potassium hydroxide, or optionally with an acid chosen from nitric acid and sulfuric acid. adjust to about 1.9-3.6; separate the gel from this suspension; wash the gel with water until it contains less than 20% of the theoretical yield of bismuth vanadate alkali nitrate; Then, the gel was heated to about 200-500℃, about 0.4
It consists of kariyaki (calcination) for about 3 hours. This invention relates to monoclinic bismuth vanadate for pigments and a method for producing the same. This pigmentary monoclinic bismuth vanadate is a bright primrose yellow with a high degree of intensity and
It has high tinting strength and good light resistance. The pigmentary bismuth vanadate of the present invention is entirely in a monoclinic crystalline phase as determined by X-ray diffraction. X-ray diffraction measurements were performed using a Debye-Sierer powder camera with a Norelco model 12045B X.
The C _uK produced by operating the wire device at 40KV/20mA
= Made by exposure to radiation for 6 hours. Monoclinic bismuth vanadate is available from the U.S. Department of Commerce.
National Bureau of Standards (NBS)
“Standard X′Ray Diffraction Power
However, the X-ray data are listed in terms of interplanar distances rather than reflection angles. Fortunately, interplanar distances and reflection angles are related by a simple equation. nλ = 2d sin θ For n = 1 (1st order diffraction) and λ = 1.54 Å (Kα radiation of copper), this equation becomes θ = sin ^-1 (1.54/2d). Using this equation, we can convert the interplanar distance of the NBS data to the 2θ value recorded on our diffractometer, thus 2θ = 2sin ^-1 (1.54/2d). , using this formula, we obtain an excellent match between the NBS data and the spectra of the claimed invention product. The monoclinic converted data are compared in the following table. [Table] 1 Measured The reflection angle always deviates by 0.3-0.5° from the converted reflection angle. This is within the experimental error range based on the sample mount, calculations from the chart, etc. 2. The main reflection of the tetragonal system is This is not detected in the product of the invention, indicating the absence of tetragonal crystals. Based on this data, it can be concluded that the bismuth vanadate of the invention is monoclinic. Bismuth vanadate for pigments is 450−
It shows a large increase in reflectance in the visible spectral region of 525 nm. This indicates that this bismuth vanadate has a primrose yellow color and a high degree of intensity and high tinting power. As used herein, "reflectance" is a comparison of the specular and diffuse reflections of a known standard to those of a test sample using a type of illumination. The reflectance was measured using Cary's 14 meter, which was equipped with an integrating sphere coated with Eastman's white reflectance measurement paint No. 6080.
Measure with a type spectrophotometer. The test samples were 10% by weight of bismuth vanadate of the present invention, 90% by weight of barium sulfate, and a standard sample for reflectance measurement manufactured by Eastman.
No. 6091 and mix it until it becomes a uniform powder. Next, the reflectance of Eastman reflectance measurement standard sample No. 6091, which is a known standard, is compared with the reflectance of the test sample. In the visible spectral region from 450 to 525 nm, the pigment-grade bismuth vanadate-containing sample of the present invention is a standard sample for Eastman reflectance measurements.
Reflectance of No.6091 over the entire visible spectrum
At least about 65 on a scale of 100
Indicates an increase in unit reflectance. In fact, a large number of test samples exhibit an increase in reflectance of at least about 70 units or more. The greater the change in reflectance in a particular spectral region, the greater the intensity and tinting power of the test sample. The intensity and lightfastness of bismuth vanadate pigments in paints are measured in paint drawdowns with complete obscurity. The paint is made by dispersing the pigment in the binder using a Hoover muller in a pigment to binder weight ratio of 2:1. The composition of the binder is ``Superior Varnish''.
and Drier Company, Marchantsville, New
98.9 parts by weight of transparent varnish #2 made by "Jersey", 1 part by weight of lead-containing Nuodex dryer (containing 24% lead), and 0.1 part by weight of manganese of manganese-containing Nuodex dryer (containing 6% lead). be. This drawdown is done at a temperature of 25
72°C in a well-ventilated room with a humidity of less than 50%.
Dry for 120 hours. Intensity is determined by the green filter reflectance of the mass tone drawdown.
Intensity is expressed as a percentage of green filter reflectance measured as follows.
i.e. Gardiner Multipurpose
Reflectometer, Serial No. 40, (Gardiner
Laboratory, Inc., Bethesda, Md.).
A standard sample for white reflectance measurement set at 86.1,
General passing through a green tristimulus filter equipped with a Gardiner Reflectometer
Measurements are made using the light of Electric's CVS projector lamp. This Gardiner
The Multipurpose Reflectometer is designed by Richard S.
National Bureau by Hunter, November 1940
of Standards Research Paper RP1345 and National Bureau of Standards Circular dated July 30, 1942, also by Richard S. Hunter.
Described in C429. The higher the reflectance percentage of the drawdown, the higher the color intensity. The intensity of the bismuth vanadate of the present invention is at least about 60%, preferably
It has a green filter reflectance of 64%. Lightfast Atlas Dry Paint Drawdown
Determined by continuous exposure for 44 hours in a Color Fade-Ometer FDA-P model. Gardiner mentioned above
A Multipurpose Reflectometer is used for measurements within 1 hour before exposure and 1 hour after exposure (end). % of reflectance after exposure to initial reflectance
The drop is expressed as a percentage of darkening by the fadeometer. The lower the % darkening of the fadeometer, the better the lightfastness of the pigment. The bismuth vanadate of the present invention generally has a concentration of about 11
% or less, preferred exhibiting a fadeometer darkening (%) of about 7% or less. The surface area of bismuth vanadate is approximately 2-22 m ² /g
It is. A surface area of about 8-22 m ² /g is desirable for use in film-forming compositions such as paints and inks. For use in plastic compositions, a surface area of about 2-4 m ² /g is desirable as higher thermal stability is desired. The surface area is calculated using the Perkin-Elmer Shell Model using techniques recommended by the manufacturer.
Measure with a 212C soap meter. Bismuth vanadate for pigments is about 0.8 mole or less of Bi dissolved in nitric acid to about 4.0 normal or less.
(NO ₃ ) ₃ ·5H ₂ O solution, preferably about 0.2 mol/Bi(NO ₃ ) ₃ ·5H ₂ O dissolved in about 1.0N nitric acid, and a solution of an alkali vanadate salt, preferably water. It is prepared by mixing sodium oxide and a solution of sodium vanadate at a concentration of about 32 molar or less in an aqueous base of about 1.6 normal or less selected from potassium hydroxide. The upper limit of the concentration of the reaction solution depends on its solubility. However, the thinner the solution, the easier it is to adjust the equimolar mixture. A preferred embodiment is the use of a solution of about 0.2 mol/Na ₃ VO ₄ in about 1.0 normal aqueous sodium hydroxide solution. These solutions are preferably mixed at a temperature of about 20°C to 30°C, but can also be mixed at temperatures of 10-100°C. The molar ratio of Bi ³⁺ to VO ₄ ^3- is about 0.95:1.00 to about
1.10:1.00, preferably about 0.98:1.00 to 1.02:1.00. Like this Bi ³⁺ or
Use one with slightly more VO ₄ ^3- . The specified concentrations of acid and chlorine solutions are
Adjust the pH to approximately 1.0-8.0 before mixing. A PH of about 1.5-2.0 is preferred as this produces a gel that provides a pigmentary monoclinic bismuth vanadate product with the best intensity and/or lightfastness. A preferred method of mixing the solutions is in a flow reactor which produces very rapid cumulative mixing under highly turbulent conditions. Cumulative mixing means that small, substantially stoichiometric amounts react at one time. This prevents the relatively large concentration gradients and stoichiometric imbalances that occur when large amounts of reactants are mixed at once. Such an imbalance causes undesirable side reactions. Convenient devices for achieving this result are tee mixers or flow reactors. When a solution of Bi(NO ₃ ) _{3.5H 2} O and a solution of alkali vanadate are mixed under the above conditions, a suspension of bismuth vanadate gel in the alkali nitrate (sodium nitrate, potassium nitrate or both) solution is obtained. A turbidity forms. As used herein, "bismuth vanadate gel" refers to a precipitate of bismuth vanadate oxide that contains occluded water, is hydrated, and is x-ray amorphous. After gel formation, if the pH of the suspension is outside the range of 1.9 to 3.6, the pH must be adjusted to this range. In other words, if the pH of the suspension is less than about 1.9, adjust the pH with an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution to raise the pH.
If the pH exceeds 3.6, adjust the pH with an acid selected from nitric acid and sulfuric acid to lower it. The pH of the suspension is preferably adjusted to 3.3 to 3.5. This is because this range produces a gel that yields a pigmentary monoclinic bismuth vanadate that has desirable lightfastness and thermal stability when calcined. Although under some circumstances bismuth vanadate gel is stable at room temperature for several hours before pH adjustment, it is desirable to rapidly adjust the pH of the suspension to within the final pH range described above. This gel is then separated from the suspension. This is preferably done by filtration. Collect this gel, and if it contains more than about 20% of the theoretical yield of bismuth vanadate alkali nitrate, the gel must be washed with water until its content is less than about 20%. . The amount of alkali nitrate remaining in the gel is approximately 5
-7% is desirable. Next, this gel is heated at about 200 to 500℃ to about 0.4-3
Bake for a while. Preferably around 380 to 460
It is roasted for about 1 hour at ℃. This bismuth vanadate pigment is entirely in a monoclinic phase as confirmed by X-ray diffraction. Another method for producing monoclinic bismuth vanadate for pigments consists of mixing the following solutions. i.e. below 4.0 regulation, preferably about 1.0
with a solution of up to about 0.8 mol/, preferably about 0.2 mol/Bi(NO ₃ ) ₃ ·5H ₂ O in a specified aqueous nitric acid solution; an alkali salt of vanadate (sodium vanadate or potassium vanadate), preferably water Approximately selected from sodium oxide and potassium hydroxide
A solution of up to about 0.32 moles/Na ₃ VO ₄ in up to 1.6 normal aqueous base, more preferably a solution of about 0.2 moles/Na ₃ VO ₄ in about 1.0 normal sodium hydroxide; These solutions are preferably mixed at 20-30°C, but can also be mixed at 10-100°C. The molar ratio of Bi ³⁺ and VO ₄ ^3- is approximately 0.90:1.00 to
1.10:1.00, preferably about 0.98:1.00 to 1.05
, which indicates that either Bi ³⁺ or VO ₄ ^3- can be used even if there is excess. The symbol VO ₄ ^3- is used herein to represent a pentavalent vanadium species in aqueous solution, but does not imply the particular pentavalent vanadium ion present at a particular PH or vanadium concentration. The normality of acid and base solutions is the PH of the reaction mixture
Adjust before mixing so that the ratio is approximately 1.0−11.0. A PH of about 1.5-4.0 is preferred as this produces a gel that provides a pigmentary monoclinic bismuth vanadate product with the best intensity and/or lightfastness. These solutions were initially described in order to achieve equimolar cumulative mixing of the solutions under highly turbulent conditions and to produce a suspension of bismuth vanadate gel in an alkali nitrate salt solution. Must be mixed according to the mixing procedure described in the method. Until the pH of the suspension stabilizes at approximately 2.2−6.0,
The gel should not be removed from its suspension. That is, if the pH of the suspension is less than about 2.2, the pH is adjusted with sodium hydroxide or potassium hydroxide solution.
Adjust so that the pH increases, and if the pH exceeds about 6.0, adjust the pH with an acid selected from nitric acid and sulfuric acid to lower it. Although under some circumstances bismuth vanadate gel is stable at room temperature for several hours before pH adjustment, it is desirable to rapidly adjust the pH of the suspension to within the final pH range described above. This gel is then separated from the suspension. this is,
It is preferably carried out by filtration. Collect this gel and if it contains more than about 10% of the theoretical yield of bismuth vanadate alkali nitrate, its content is about
The gel must be washed with water until it is less than 10%. The gel is then heated in water at a temperature of about 60°C to about 200°C for at least 0.2 hours, preferably at a temperature of about 90°C to about 100°C for about 1 to 2 hours to transform the gel into a monoclinic vanadium pigment. Convert to bismuth acid. While performing aqueous ripening, the pH of the suspension
2.2 by adding a suitable acid or base if necessary.
It should be kept between 3.0 and 6.0, preferably between 3.0 and 3.5. Acids suitable for use include nitric acid, sulfuric acid, hydrochloric acid, hydrogen bromide or phosphoric acid. Bases suitable for use include aqueous sodium hydroxide or potassium hydroxide. It will be appreciated that for temperatures above about 100°C, heating must be carried out under pressure. When extra vanadium is used, especially when the molar ratio of Bi ³⁺ to VO ₄ ^3- is in the range 0.90
-0.95:1.00, the pigment was washed in water at 50°C to 100°C for 15 to 30 minutes with an aqueous base chosen from sodium hydroxide and potassium hydroxide for 15 to 30 minutes while maintaining the pH at 8.0–9.5. The pigment must be washed by suspending it in water. After maturation is complete, the pigment is filtered and dried, for example at about 130°C. The product is a bright primrose yellow bismuth vanadate whose overall monoclinic phase is confirmed by X-ray diffraction. In each of the above methods, pH adjustment may be performed after the gel is removed from the suspension. However, it is better to suspend the gel in water to make it easier to adjust the pH of the gel. Once the pH of the gel is adjusted appropriately, it is stable for about one week at room temperature under certain conditions. In each of the above methods, in an aqueous base selected from sodium hydroxide and potassium hydroxide,
V ₂ O ₅ , Na ₃ VO ₄ , Na ₄ V ₂ O ₇ , NaVO ₃ , or
An alkali vanadate salt solution can be prepared by dissolving a pentavalent vanadium compound such as K ₃ VO ₄ . After making the bismuth vanadate pigment by any of the methods described above, the lightfastness of the pigment can be improved by enveloping it in a dense amorphous silica coating or by treatment with aluminum pyrophosphate. The silica coating is U.S. Reissue Patent No. 27818 by Werner (a reissue patent of U.S. Patent No. 3,437,502);
U.S. Patent No. 3,639,133 to Linton; also by Linton
It can be carried out in known manner, such as taught in US Pat. No. 3,370,971 by Iler; and US Pat. The following examples illustrate the invention. All parts, percentages, and ratios are by weight unless otherwise specified. Example 1 Nine samples are made according to the following procedure. Na ₃ VO ₄ dissolved in 200 ml of 1.0N NaOH
(7.58 g) of Bi(NO ₃ ) _{3.5H 2} O (20 g)
Dissolve in 200 ml of 1.0N HNO ₃ and pour into the stirred solution over about 2 minutes. The mixture is stirred vigorously and a fine yellow-orange precipitate forms immediately. Then set the PH of the mixture to 2.0
Adjust to 3.5 with specified NaOH. The mixture is stirred for 0.5 h, filtered, washed with 400 ml of distilled water and filtered again. The bismuth vanadate gel remaining on the filter paper is collected and baked at 400℃ for 1 hour to produce monoclinic BiVO ₄ for pigments. The average green filter reflectance of these nine bismuth vanadate samples was 68.0 and the average fadeometer darkening was 11.0% after 44 hours exposure.
It is. Prepare 8 samples according to the following procedure. Repeat the above steps, changing only the next step.
That is, Na ₃ VO ₄ dissolved in NaOH and Bi(NO ₃ ) ₃ .5H ₂ O dissolved in HNO ₃ were mixed at a pressure of about 40 psi (2.8 Kg/cm ² ) using a T-type mixer with an inner diameter of 1 mm. Mix for 2 minutes to achieve equimolar turbulent mixing. The average green filter reflectance of these eight bismuth vanadate pigment samples was 69.0, and the average fadeometer darkening after 44 hours exposure was
It is 6.7%. This sample shows that equimolar turbulent mixing improves the lightfastness of bismuth vanadate pigments. Example 2 The following ingredients were placed in a T-type mixer with an inner diameter of 1 mm.
Mix at a pressure of 40 psi (2.8 Kg/cm ² ) for approximately 2 minutes to form a mixture. (i) Bi(NO ₃ ) ₃・5H ₂ O in 200 ml of 4.0N HNO ₃
(78.4g), then 60ml of 2.0N HNO ₃
and diluted with 545 ml of water, and (ii) Na ₃ VO ₄ (30.3 g) in 500 ml of 1.6N NaOH.
Dissolve and then dilute this with water to 800ml. Add enough HNO ₃ to component (i) or add enough aqueous NaOH to component (ii) so that the PH of the two mixtures is in the range of about 1.5-2.0. 0.5
The mixture is squirted into 3 beakers containing 1200 ml of water adjusted to PH 2.3 with normal HNO ₃ . Stir the contents of the beaker for 1 minute and dilute with 0.5N NaOH.
Adjust pH to 3.2. Next, adjust the pH to 3.4 and keep it that way for 30 minutes. The contents are filtered and washed with 250 ml of water, then again with 250 ml of water. After filtration, the bismuth vanadate gel is collected from the filter paper and divided into three equal samples. Each sample is converted to pigmentary monoclinic BiVO ₄ according to the method in Table 1 and tested for the properties described. [Front] Grilled
1) Reflectance change in % after 44 hours of exposure to the fadeometer.
This indicates that the monoclinic bismuth vanadate pigment made by heating in water has better light resistance than the sample made by kariyaki. Furthermore, it is shown that the bismuth vanadate pigment made by heating in water has a larger surface area than the kariyaki sample, indicating a higher coloring strength per unit weight. Example 3 The following ingredients were placed in a T-type mixer with an inner diameter of 1 mm.
Mix at a pressure of 40 psi (2.8 Kg/cm ² ) for approximately 2 minutes to form a mixture. (i) Bi(NO ₃ ) ₃・5H ₂ O in 204 ml of 4.0N HNO ₃
(80.0g), then 20ml of 2.0N HNO ₃
and diluted with 581 ml of water, and (ii) Na ₃ VO ₄ (30.3 g) in 500 ml of 1.6N NaOH.
Dissolve and then dilute this with water to 800ml. Add enough HNO ₃ to component (i) or add enough aqueous NaOH to component (ii) so that the PH of the two mixtures is in the range of about 1.5-2.0. 0.5
The mixture is squirted into 3 beakers containing 1200 ml of water adjusted to PH 2.3 with normal HNO ₃ . Stir the contents of the beaker for 1 minute and dilute with 0.5N NaOH.
Adjust pH to 3.2. Next, adjust the pH to 3.4 and keep it that way for 30 minutes. After filtration, collect the bismuth vanadate gel from the filter paper and divide the sample into four equal parts.
Sample A and sample B are not washed. For sample C, each time
Wash on the filter paper twice with 250 ml of water. Sample D
Re-filter each time with 250 ml of water, and
Suspend twice. Each sample is converted to monoclinic bismuth vanadate by calcining at 450° C. for 1 hour. (The exact amount and method of water used to wash the bismuth vanadate gel should be adjusted so that the amount of NaNO ₃ listed in Table 2 remains in each sample.) [Table] This table The data described in 2 shows the effect of the sodium nitrate remaining in the gel before kariyaki. This data shows that the surface area of pigmentary bismuth vanadate made from gels decreases as the amount of sodium nitrate in the gel increases. This reduction in surface area is accompanied by a reduction in strength per unit (weight). The preferred particle surface area for thermal stability is 2-4 m ² /g. Example 4 The following ingredients were mixed in a T-type mixer with an inner diameter of 1 mm.
Mix at a pressure of 40 psi (2.8 Kg/cm ² ) for approximately 2 minutes to form a mixture. (i) Bi(NO ₃ ) ₃・5H ₂ O in 204 ml of 4.0N HNO ₃
(80.0g), then 20ml of 2.0N HNO ₃
and diluted with 581 ml of water, and (ii) Na ₃ VO ₄ (30.3 g) in 500 ml of 1.6N NaOH.
Dissolve and then dilute this with water to 800ml. Sufficient HNO ₃ is added to component (i) or sufficient aqueous NaOH is added to component (ii) such that the PH of the mixture of the two components is in the range of about 1.5-2.0. Pour the mixture into 3 beakers containing 1200 ml of water adjusted to PH _{2.3 with 0.5N HNO 3} .
Stir the contents of the beaker for 1 minute and adjust to 0.5N.
Adjust the pH to 3.2 with NaOH. Next, adjust the pH to 3.4 and keep it that way for 30 minutes. The contents, a suspension of bismuth vanadate gel, are filtered and washed twice on filter paper with 500 ml each of water. After filtration, the bismuth vanadate gel collected from the filter paper is calcined at 450°C for 1 hour to convert it to monoclinic bismuth vanadate. This product is designated as sample A. Sample B is made by following the same procedure as Sample A except for the following steps. That is, after filtering the suspension,
The process involves resuspending the gel in 500 ml of water, filtering it, suspending it in 500 ml of water again, and filtering it again. Sample C is made by resuspending 10 g of Sample A in 500 ml of water, filtering, resuspending in 500 ml of water, filtering, and drying at 140°C. Table 3 shows the relative thermal stability of pigments in plastics for various contents of sodium nitrate. [Table] The results listed in Table 3 indicate that the lack of sodium nitrate in the gel before calcination has an adverse effect on the thermal stability of bismuth vanadate produced during gel calcination. It shows. Table 2
Considering the results listed in Table 3, the adjustment of the amount of sodium nitrate in the gel before calcining will improve the thermal stability for the production of high quality pigment bismuth vanadate, especially for use in plastic coloring. If required, it will be recognized as being of essential importance. Example 5 A mixture is made by mixing the following ingredients in a T-mixer. (i) Bi (NO ₃ ) ₃・5H ₂ O in 4.0 regulation HNO ₃ of 12.78
(10.731 lbs = 4.872 Kg) and then diluted with water to 51.1, and (ii) 31.94 containing 7.210 lbs (3.273 Kg) of NaOH.
Dissolve V ₂ O ₅ (2.049 lb = 0.930 Kg) in water, then dilute this to 51.1 with water to make a solution of sodium vanadate and sodium hydroxide.The inner diameter of the T-type mixer is bismuth nitrate. in the aisle of
0.118 inches (0.299cm), 0.192 inches (0.488cm) at the sodium vanadate passage and at the outlet
It is 0.192 inch (0.488 cm). Bismuth nitrate enters through its legs. The solution is mixed for about 15 minutes while applying a pressure of about 15 psi (1.05 Kg/cm ² ) from one side of the T-mixer to the other. Sufficient water is added so that the pH of the two-component mixture is approximately 1.5 to 2.0.
Add HNO ₃ to component (i) or enough NaOH
Add the aqueous solution to component (ii). Pour the mixture into a 45 gallon (170) tank containing 7 gallons (26.5) of water adjusted to a pH of 2.2 with HNO ₃ . Stir the contents of the tank for several minutes, then 2.0 normal
Adjust the pH to 3.2 with NaOH. The contents are then stirred for 15 minutes, filtered, then washed with 20 gallons (75.7) of water, then filtered again. Collect the bismuth vanadate gel from the filter cloth and then add it to HNO ₃
Stir in a tank containing 70 bond (31.8 kg) of water adjusted to pH 3.1. The contents of the tank are approximately 40
Heat to 95℃ for 1 minute and hold at that temperature for 120 minutes with pH 3.1. The product, pigment grade bismuth vanadate, is separated by filtration, washed twice with 20 gallons of water, and dried at 140°C. Repeat the above procedure four times to obtain approximately 28 pounds (12.7 Kg) of pigment. 25 lbs (11.3 Kg) of pigment was mixed with 567 g of a 28% sodium silicate solution (40-42
first at 2000 psi (140 Kg/cm ² ), then at 5000 psi in 104 lb (47.2 Kg) of water containing
Gaulin Submicron at a pressure of (350Kg/cm ² )
Pass through a homogenizer to disperse. This mixture is then heated and kept at 90°C, then the pH is adjusted to 9.6 with 2.0N NaOH. 62.5 pounds (28.4
Kg) 28% of 14.497 lbs (6.5816Kg) in water
A solution containing sodium silicate is added to the mixture over a period of 4 hours. At the same time, the PH of that mixture is about 45
to the mixture at such a rate that it drops to 9.4 minutes after
Dilute sulfuric acid solution (71.25 lbs (32.35 Kg) in water,
2.299 lb (1.361 Kg) of concentrated sulfuric acid). Next, immediately PH the mixture to 2.0 normal NaOH.
Increase to 9.6. This pH adjustment operation continues for 4 hours after silicate addition. After this 4 hour addition is complete, the pH is
Lower to _9.0 with _H2SO4 and hold for 60 minutes, then lower the PH to 7.0. Then the temperature of the mixture is still 90
in 15 pounds (6.8Kg) of water while at °C.
Add an aqueous solution containing 3.75 pounds (1.70 Kg) of Al ₂ (SO ₄ ) _{3.18H 2} O over 10 minutes. Then this PH
falls to 2.0−3.0. Then 10 with 2.0 normal NaOH
Increase its PH to 6.0 after minutes. The product is then filtered while still hot, and 2
Wash twice and dry at 140℃. Chemical analysis and electron micrographs show that the pigment particles are coated with silica. Table 4 shows the measurement results of pigment intensity and light resistance before and after silica coating. [Table] Shows reflectance change in %.
This sample shows that the silica-encased pigmentary bismuth vanadate has improved lightfastness as determined by phaedeometer exposure. Example 6 The following ingredients were placed in a T-type mixer with an inner diameter of 1 mm.
Mix at a pressure of 40 psi (2.8 Kg/cm ² ) for approximately 2 minutes to form a mixture. (i) Bi(NO ₃ ) ₃・5H ₂ O in 200 ml of 2.0N HNO ₃
(40.0 g), then diluted with water to 405 ml, and (ii) Na ₃ VO ₄ (15.16 g) in 200 ml of 2.0N HNO ₃ .
g) and then diluted with water to 400ml. Add enough HNO ₃ to component (i) or add enough aqueous NaOH to component (ii) so that the PH of the mixture of the two components is about 1.5-2.0.
4 with 1200ml of water adjusted to PH3.0 with _HNO3
Pour the mixture into a beaker. Stir the contents of the beaker for 1 minute and adjust the pH to 3.4 with 0.5N NaOH. The mixture was then stirred for 15 minutes, filtered and
Wash with 500 g of water and filter again. Collect bismuth vanadate from the filter paper and divide it into two equal samples: Sample A and Sample B. Stir sample A in a beaker containing 800 ml of water and adjust the pH of the mixture to 3.3 to 3.3 with HBr or NaOH.
Adjust to 3.4. The mixture is then boiled for 90 minutes while maintaining the pH between 3.3 and 3.4. Separate the bismuth vanadate pigment by filtration, wash with 500 ml of water and heat at 130 °C until dry. Heat sample B in an open crucible at 400℃ for 90 minutes. Sample C is made following the same procedure as Sample A.
However, 42.0g of Bi(NO ₃ ) _{3.5H 2} O is used instead of 40.0g. Sample D is made following the same procedure as Sample B.
However, as before, 40.0g of Bi(NO ₃ ) ₃・5H ₂ O
Use 42.0g. Sample E is prepared by mixing the following ingredients in a 1 mm ID T-mixer at a pressure of 40 psi (2.8 Kg/cm ² ) for approximately 2 minutes. (iii) Add Bi(NO ₃ ) ₃ to 52 ml of concentrated HNO ₃ and 400 ml of water.
Dissolve 5H ₂ O (88.0g) and then add 800g of this with water.
ml and (iv) V ₂ O ₅ in 600 ml of water containing 53.0 g of NaOH.
(15.0g) and then diluted with water to 800ml to create a solution of sodium vanadate and sodium hydroxide. Add enough HNO ₃ to component (iii) or add enough NaOH aqueous solution to component (iv) so that the PH of the two mixtures is about 1.5 to 2.0. PH at HNO ₃
Pour the mixture into 4 beakers containing 1200 ml of water adjusted to 2.2. The contents of the beaker are 1
Stir for a minute and adjust the pH to 3.3 with 0.5N NaOH. This mixture was then stirred for 15 minutes, filtered and
Wash with 500 ml of water and filter again. Collect the bismuth vanadate gel from the filter paper and stir it in a beaker containing 500 ml of water. The PH of the mixture is then adjusted to 3.3 to 3.4 with HNO ₃ or NaOH and the mixture is boiled for 90 minutes while keeping the PH constant at that value. Separate the bismuth vanadate pigment by filtration, wash with 500 ml of water and heat at 130 °C until dry. Sample F is made following the same procedure as Sample B.
However, instead of using 40.0g of Bi(NO ₃ ) _{3.5H 2} O, 44.0g is used. Sample G is made following the same procedure as Sample A.
However, instead of using 40.0g of Bi(NO ₃ ) _{3.5H 2} O, 46.0g is used. Sample H is made following the same procedure as Sample B.
However, as before, 46.0g of Bi(NO ₃ ) _{3.5H 2} O was used instead of 40.0g. Sample I is prepared by mixing the following ingredients in a 1 mm ID T-mixer at a pressure of 40 psi (2.8 Kg/cm ² ) for approximately 2 minutes. (v) Bi(NO ₃ ) ₃ in 56 ml of concentrated HNO ₃ and 400 ml of water.
Dissolve 5H ₂ O (72.0g) and then add 800 g of this with water.
ml and (vi) V ₂ O ₅ in 600 ml of water containing 53.30 g of NaOH.
(15.0g) and then diluted with water to 800ml to create a solution of sodium vanadate and sodium hydroxide. A sufficient amount of HNO ₃ is added to component (v) or a sufficient amount of aqueous NaOH is added to component (vi) such that the pH of the two mixtures is about 1.5 to 2.0.
4 with 1200ml of water adjusted to PH2.2 with _HNO3
Squirt the mixture into a beaker. Stir the contents of the beaker for 1 minute and adjust the pH with 0.5N NaOH.
Adjust to 3.3. Then stir the mixture for 15 minutes and
And filter. Bismuth vanadate from filter paper
Collect the gel. This gel was stirred in a beaker containing 500ml of water, and the pH of the mixture was adjusted to _HNO3 or
Adjust to 3.1 with NaOH. While keeping the pH at 3.1,
Boil this mixture for 120 minutes. Separate the bismuth vanadate precipitate by filtration and resuspend in 400 ml of water. Then increase the temperature to 50℃,
Raise the pH to 8.0 and hold for 10 minutes. Separate the bismuth vanadate pigment by filtration, wash with 500 ml of water and heat at 130 °C until dry. Sample J is prepared by mixing the following ingredients in a 1 mm inner diameter T-mixer at a pressure of 40 psi (2.8 Kg/cm ² ) for approximately 2 minutes. (vii) Bi(NO ₃ ) ₃ in 56 ml of concentrated HNO ₃ and 400 ml of water.
Dissolve 5H ₂ O (72.0g) and then add 800 g of this with water.
ml and (viii) V ₂ O ₅ in 600 ml water containing 53.30 g NaOH.
(15.0g) and then diluted with water to 800ml to create a solution of sodium vanadate and sodium hydroxide. A sufficient amount of HNO ₃ is added to component (v) or a sufficient amount of aqueous NaOH is added to component (vi) to bring the pH of the two mixtures to about 1.5 to 2.0.
Pour this mixture into 4 beakers containing 1200 ml of water adjusted to 2.2 with HNO ₃ . Stir the contents of the beaker for 1 minute and adjust its pH with 0.5N NaOH.
Adjust to 3.3, then stir the mixture for 15 minutes, filter, wash with 500 ml of water and filter again.
Collect the bismuth vanadate gel from the filter paper. This gel is calcined in an open crucible at 400°C for 60 minutes. Table 5 compares the intensity and light resistance of the samples. [Table] The data listed in Table 5 shows that in the production of bismuth vanadate, if the molar ratio is outside the limits disclosed in the present invention, it will adversely affect the properties of the bismuth vanadate produced. This indicates that the product will not be pigmentary as defined above. Example 7 The previously prepared samples were characterized by reflectance spectra and differential thermal analysis (DTA) measurements. These measurement results are shown in Table 6 together with the drawdown intensity values. Table: Example 8 The following ingredients are mixed in a T-mixer to form a mixture. (i) 12.78 4.0 regulation HNO ₃ to Bi(NO ₃ ) ₃・5H ₂ O
(10.731 lbs = 4.872 Kg) and then diluted with water to 51.1, and (ii) 31.94 containing 7.210 lbs (3.273 Kg) of NaOH.
V ₂ O ₅ (2.049 lb = 0.930 Kg) was dissolved in water, and then diluted to 51.1 with water to form a solution of sodium vanadate and sodium hydroxide. The inner diameter of the T-type mixer is the passage of bismuth nitrate.
0.118 inch (0.299 cm), 0.192 inch (0.488 cm) at sodium vanadate passage and 0.192 at outlet
inch (0.488cm). Bismuth nitrate enters through its legs. While applying a pressure of approximately 15 psi (1.05 Kg/cm ² ) from one side of the T-mixer to the other,
Mix the solution for a minute. The pH of the two-component mixture is approximately
Contains enough HNO ₃ to be 1.5 to 2.0.
(i) or add enough NaOH aqueous solution to the ingredients.
Add to (ii). Pour the mixture into a 45 gallon (170) tank containing 7 gallons (26.5) of water adjusted to a pH of 2.2 with HNO ₃ . Stir the contents of the tank for a few minutes, then adjust the pH with 2.0N NaOH.
Adjust to 3.2. The contents are then stirred for 15 minutes, filtered, then washed with 20 gallons (75.7) of water, then filtered again. Six 100 g samples are each suspended in six 300 g of water. The PH of each suspension is adjusted to the value indicated in Table 7 by adding the required amount of HNO ₃ or NaOH and maintained at the indicated PH for approximately 15 minutes. Next, the suspension is filtered, the gel is taken out and baked at 400°C for 1 hour. Its crystal phase, intensity and light resistance were measured and the results are listed in Table 7. [Table] Expresses emissivity change in %.

Claims (1)

[Claims] 1. When 90% by weight of barium sulfate is mixed uniformly, barium sulfate occupies the entire visible spectrum in the wavelength range of 450 to 525 nm.
Bright primrose yellow synthetic monoclinic bismuth vanadate for pigments that exhibit an increase in reflectance of at least about 65 units on a scale of 100 units of reflectance. 2. The bismuth vanadate of claim 1, wherein the increase in powder reflectance is at least about 70 units. 3. Bismuth vanadate according to claim 1, wherein the light resistance in paint exhibits a decrease in reflectance of less than about 11% after 44-hour phaseometer exposure. 4. Bismuth vanadate according to claim 1, wherein the lightfastness in paint exhibits a decrease in reflectance of less than about 7% upon exposure to a 44-hour fadeometer. 5. The bismuth vanadate according to claim 1, wherein the intensity in paint exhibits a green filter reflectance of at least about 60%. 6. The bismuth vanadate of claim 1, wherein the intensity in the paint exhibits a green filter reflectance of at least about 64%. 7. Bismuth vanadate according to claim 1, wherein the lightfastness in a paint exhibits a decrease in reflectance of less than about 7% after 44-hour exposure to a fadeometer, and the intensity in the paint shows at least about
Bismuth vanadate with 60% green filter reflectance. 8. Bismuth vanadate according to claim 2, wherein the lightfastness in paint shows a decrease in reflectance of less than about 7% after 44 hour exposure with a fadeometer, and the intensity in paint shows at least about
Bismuth vanadate with 64% green filter reflectance. 9. A method for producing bright primrose yellow synthetic monoclinic bismuth vanadate for pigment use, which comprises the following steps A to E. A nitric acid solution of Bi(NO ₃ ) _{3.5H 2} O and a solution of an alkali vanadate salt dissolved in an aqueous base selected from sodium hydroxide and potassium hydroxide,
Mix; precipitate the suspended bismuth vanadate gel in a solution containing dissolved alkali nitrate ^;
The molar ratio of VO ₄ ^3- is 0.95:100 to 1.10:1.00, and the normality of the acid solution and base solution is adjusted before mixing so that the pH of the mixture is 1.0 to 8.0. B. Adjust the pH of the suspension to 1.9 to 3.6. C. Remove the gel from the suspension. D. Wash the gel with water until the alkali nitrate content of the gel is 20% by weight or less based on the theoretical yield of bismuth vanadate. E. Bake this gel at a temperature of 200 to 500°C for 0.4 to 3 hours. 10 A method for producing bismuth vanadate according to claim 9, wherein the moles of Bi ³⁺ and VO ₄ ^3- are
The manufacturing method is 0.98:1.00 to 1.02:1.00. 11. A method for producing bismuth vanadate according to claim 9, which adjusts the pH of the B stage to 3.3 to 3.5. 12. A method for producing bismuth vanadate according to claim 9, wherein the gel is washed with water until the gel contains 5 to 7% by weight of alkali nitrate. 13. A method for producing bismuth vanadate according to claim 9, wherein the gel is calcined at 380 to 460°C for about 1 hour. 14. A method for producing bismuth vanadate according to claim 9, wherein the molar ratio of Bi ³⁺ and VO ₄ ^3- is from 0.98:1.00 to 1.02:1.00;
Adjust the pH to 1.5 to 2.0, and adjust the pH to stage B.
3.3 to 3.5, washing the gel with water until the content of alaryl nitrate in the gel is 5 to 7%, and calcining the gel at a temperature of 380 to 460°C for 1 hour. 15. A method for producing bismuth vanadate according to claim 14, which comprises dissolving Na ₃ VO ₄ in an aqueous sodium hydroxide solution.