JPS6136782B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a stable ultramarine blue and a method for producing the same,
More specifically, a new stable ultramarine is formed by sealing the surface sulfur of ultramarine particles with a zinc compound, and the ultramarine is treated with a zinc compound, the treatment is followed by firing, or the firing is followed by water. This article relates to a new method for producing stable ultramarine blue that involves drying after dispersion. Gunjio is an inorganic pigment that usually exhibits a beautiful blue color with a reddish tinge.It was originally made from natural lapis lazuli, but recently it has been produced artificially. Ultramarine is sodium aluminum silicate containing sulfur, and is generally represented by the following compositional formula. Na _(8-9) Al ₆ Si ₆ O ₂₄ S _(2-4) Ultramarine has a hydrophilic and oleophobic composition, is stable in air up to about 250℃, and has excellent ion exchange and catalytic abilities. have Some of the sulfur in ultramarine is in the active radical form, and differences in the radical state and oxidation state of this sulfur cause changes in the color tone of ultramarine, and in addition to the reddish blue mentioned above, it also has a purple tinge. There are some that are yellowish and some that are greenish. Ultramarine is used in building materials, paints, printing inks, paints,
It is used as a blue coloring agent in a wide range of applications such as paper, textile products, cosmetics, detergents, etc., and has been gaining importance in recent years because its hue is extremely clear and it is harmless to humans and animals. However, ultramarine blue has serious deficiencies as a colorant. That is, ultramarine blue is generally stable against alkalis, but extremely weak against acids, and as a result of the reaction between radical sulfuric acid and acid, hydrogen sulfide is generated under acidic conditions, and the color gradually decomposes and fades to white. Ultramarine blue also generates hydrogen sulfide when subjected to mechanical shearing force such as crushing or heat. The hydrogen sulfide generated in this way causes problems such as secondarily deteriorating container materials such as aluminum and causing odor to products in the field of cosmetics and the like. In order to overcome these drawbacks, several proposals have been made to improve the stability of ultramarine.
Recent examples include, for example, a method of treating ultramarine blue with sodium silicate and an organic acid to form amorphous silica on the surface (Japanese Patent Application Laid-open No. 1983-95632);
There is a method of forming an acid-resistant polymer film on the surface of ultramarine (Japanese Patent Publication No. 50-27483). Although these conventional methods improve the acid resistance of ultramarine to a certain extent, they are also not sufficient. In view of the above circumstances, the present inventors have conducted intensive research to develop a stable ultramarine blue with sufficient acid resistance. After learning of the fact that hydrogen generation is effectively suppressed, we conducted further studies and unexpectedly discovered that treatment alone with a zinc compound has a significant suppressive effect, leading to the present invention. That is, the present invention aims to provide a stable ultramarine blue and a method for producing the same, and the gist thereof is as follows. (1) Stable ultramarine blue in which the surface sulfur of ultramarine particles is sequestered with zinc compounds. (2) A method for producing stable ultramarine blue (referred to as "Product A"), which involves treating ultramarine blue with a zinc compound in an aqueous medium. (3) A method for producing a more stable ultramarine blue (referred to as "Product B"), which comprises firing the treated product following the treatment in (2) above. (4) A method for producing stable ultramarine blue with good water dispersibility (referred to as "Product C"), in which, following the firing in (3) above, the fired product is dispersed in water and then dried at about 10 to 105°C. Product B and Product C both have ultramarine particles whose surface sulfur is capped with a zinc compound, and are included in the stable ultramarine of the specific invention described in item 1 above. In the present invention, blocking means that by coating the surface of the ultramarine particles with a zinc compound, the radical sulfur on the surface of the ultramarine particles and the zinc compound chemically react, and the radical nature of some or all of the radical sulfur is removed. means. When sequestered, the total amount of sulfur in the ultramarine particles remains unchanged, and a portion of the radical sulfur changes from radical to ionic. This reduction in radical sulfur can be confirmed by the ESR spectrum described below. The stable ultramarine blue according to the present invention is stable against acid, heat, and mechanical shearing force, and does not decompose due to these actions and substantially does not generate hydrogen sulfide. Therefore, it can be used, for example, under acidic conditions. It does not alter the quality of container materials such as aluminum, nor does it cause odor to cosmetics. In addition to such modification, in the case of Product B, the surface sulfur is blocked and the particle surfaces are coated with zinc oxide as a result of calcination, so that the stability is further improved. Product C is
Approximately 2
Since it contains % by weight of water, it has good water dispersibility. Such a stable ultramarine blue is expected to be used in a wide range of applications because the restrictions on the use of conventional ultramarine blues are removed. The present invention will be explained in further detail. In the stable ultramarine blue according to the present invention, the surface sulfur of the ultramarine particles is sequestered with zinc salt, which indicates that the ESR
(electron spin resonance). Surface sulfur is radical sulfur that exists on the surface of the ultramarine crystal lattice, and unlike the sulfur (including radical sulfur) that exists inside the crystal lattice, this sulfur has various effects on other substances. Easy to have type activity. This active surface sulfur decomposes under the action of acid, heat, and mechanical shearing force and generates hydrogen sulfide, but when the surface sulfur combines with zinc compounds and becomes sequestered, the ultramarine is stabilized. Decomposition does not occur even when an acid or the like acts on it, and the generation of hydrogen sulfide is suppressed. However, even if the surface sulfur is blocked, there is no change in the original characteristics of ultramarine, and there is no difference in color tone, basic structure, etc. between stabilized ultramarine and untreated ultramarine. The stable ultramarine according to the present invention is a powder, and its particle size is not particularly limited, but is usually 0.1 to 20 μm, preferably 0.3 to 2 μm for blue ones, and 2 to 10 μm for reddish blue ones. be. The zinc compound that sequesters surface sulfur is the same as that used in the treatment, and it does not matter whether it is inorganic or organic as long as it achieves the purpose of stabilization. Zinc complexes can also be included in such zinc compounds. For example, one or more of zinc chloride, zinc hydroxide, zinc oxide, zinc sulfate, zinc nitrate, zinc acetate, zinc citrate, etc. can be used. However, some or all of the zinc compounds may change during the treatment process; for example, zinc chloride partially changes to zinc hydroxide in the presence of caustic alkali, and this substance changes to zinc oxide when fired. Therefore, in this case, the zinc compound present in the stable ultramarine blue and the zinc compound actually used in the treatment are of different types. The amount of the zinc compound present in the stable ultramarine of the present invention can be appropriately determined from a practical standpoint, and is approximately 0.1 to 20% by weight, preferably ~8% by weight as zinc. If it is less than 0.1% by weight, effective stability cannot be imparted to ultramarine blue, and if it exceeds 20% by weight, the original color tone of ultramarine blue will be impaired. Although surface sulfur can be blocked only by the zinc compound, if desired, an appropriate amount of alkali silicate or polymeric substance may be present. Examples of such polymeric substances include water-soluble or water-insoluble substances, such as polyvinyl alcohol, polyacrylic acid, polyethylene glycol, polyvinylpyrrolidone, polyamide, polyvinyl acetate, and polyacrylic acid ester. The stable ultramarine blue according to the present invention may be in any form as long as the surface sulfur of the ultramarine particles is blocked with a zinc compound. Therefore, in the form of an isolated powder, as well as in the form of a dispersion in an aqueous medium or as a mixture with other substances, approximately the surface of the ultramarine particles As long as ultramarine blue in which sulfur is sequestered with a zinc compound and stabilized exists, it is still an object of the present invention. The starting material ultramarine used in the production method of the present invention is a powder, and a sufficiently pulverized fine powder is preferable. Usually, particles with a particle size of about 0.1 to 20 microns are used. Zinc compounds are used as surface sulfur sequestrants, and as mentioned above, zinc chloride, zinc hydroxide, zinc oxide, zinc sulfate, zinc nitrate, zinc acetate, zinc citrate, etc. can be mentioned. One or more of these can be used. Such ultramarine powder is dispersed in an aqueous medium and treated with a zinc compound. A typical aqueous medium is water, but an appropriate amount of another aqueous solvent such as methyl alcohol, ethyl alcohol, acetone, etc. may be added thereto as appropriate. Usually, an aqueous medium is added in an amount of about 1 to 10 times, preferably about 4 to 6 times, the amount of ultramarine blue, and stirred well to uniformly disperse it to form a slurry. At this time, dispersion can be promoted by adding a dispersant or using ultrasonic waves. The slurry is preferably kept alkaline due to the nature of ultramarine. The above-mentioned dispersion may be carried out at room temperature, but it can also be carried out at a temperature of about 90°C for the sake of subsequent processing. A zinc compound is gradually added to the uniformly dispersed slurry in the form of a solid or an aqueous solution while stirring well. The amount of zinc compound added is about 0.1 to 20% by weight of zinc, preferably about 2% by weight based on the treated ultramarine.
~8% by weight. If it is less than about 0.1% by weight, sufficient stability cannot be imparted to ultramarine;
If it exceeds this weight percentage, the original color tone of ultramarine blue will be lost. At this time, it is preferable to keep the slurry PH alkaline, and especially when adding the zinc compound as an acidic aqueous solution, the PH is preferably adjusted to the alkaline side using caustic alkali, alkali carbonate, or the like. Unless contrary to the purpose of the present invention, alkali silicates, water-soluble polymeric substances such as polyvinyl alcohol, polyacrylic acid, polyethylene glycol, polyvinylpyrrolidone, etc., and water-insoluble polymeric substances such as polyamide, polyvinyl acetate, etc. One or more types of polyacrylic esters may be used in combination. After treatment with a zinc compound, optionally decanting to remove water, the product is dried separately in a conventional manner to obtain a treated product. The obtained stable ultramarine blue (Product A) has the surface sulfur of the ultramarine particles blocked with a zinc compound, and exhibits high stability against acids, heat, and mechanical shearing forces. When product A thus obtained is fired, a fired ultramarine (product B) having an extremely high degree of stability is obtained. As mentioned above, in Product B, the active surface sulfur is blocked, and the particle surface is coated with zinc oxide as a result of sintering, so the stability against acids, heat, and mechanical shearing forces is further improved. ing. Firing at about 110-250℃, particularly preferably about 200℃
C. for about 0.5 to 24 hours, particularly preferably about 3 to 7 hours. In fired ultramarine product B, the particle surface is coated with zinc oxide as described above, but no matter what type of zinc compound is used in the initial treatment, as long as the treatment is carried out on the alkaline side, the particles are essentially the same after firing. Becomes zinc oxide. Thus, product B has further improved stability due to the firing process, and has extremely useful pigment properties for general use. However, since moisture is removed by baking and the adsorption capacity is increased, when Product B is used in cosmetics and other fields, active ingredients and fragrance ingredients may sometimes be unnecessarily adsorbed. Therefore, if Product B is further dispersed in water and then dried at a temperature of approximately 10 to 105°C to a certain level of water content, and then soaked with water appropriately, the excessive adsorption capacity can be alleviated, and yet An ultramarine blue (product C) is obtained which has a very high degree of stability against shear forces. To obtain product C, for the fired product (product B),
Approximately 3 to 6 times the amount of water is added and thoroughly stirred to ensure uniform dispersion, and then separated and dried in a conventional manner. Since the purpose of this step is to impregnate the fired product with an appropriate amount of water, drying is carried out at a temperature of about 10 to 105°C for an appropriate period of time in order to keep the moisture content to a certain level. The moisture content after drying can be appropriately determined depending on the intended use of the product, but Product C obtained by drying at about 105°C contains about 2% by weight of water and exhibits extremely good water dispersibility. Next, the present invention will be explained by examples, but the present invention is not limited thereto. Example 1 100 parts of ultramarine blue powder was added to 500 parts of water with stirring and uniformly dispersed, and the slurry was heated to 90°C and maintained at pH 10 with caustic soda. Separately, zinc chloride 8
An aqueous solution of zinc chloride dissolved in 50 parts of water was gradually added to the slurry with stirring. During addition, the pH of the slurry was adjusted to 8 to 10. 2
After stirring for an hour, the slanted palm and treated product were washed twice with water, filtered and dried to obtain 105 parts of stable ultramarine blue. ESR (electron spin resonance) findings on the obtained stable ultramarine blue confirmed that the surface sulfur of the ultramarine particles was blocked by zinc compounds. That is, when the ESR spectrum of untreated ultramarine was measured at room temperature, a broad and high radical sulfur peak was detected around the g value of 2.029. On the other hand, in the stable treated ultramarine, a radical sulfur peak with a size 4/5 of the spectrum measured for untreated ultramarine was observed at the same position. The decrease in the magnitude of this peak indicates that the surface radical sulfur in the stable ultramarine blue of the present invention is blocked by the zinc compound. The ultramarine blue obtained here was stable, and as shown by the results of the hydrogen sulfide detection method and silver plate blackening test described below, it was extremely superior in acid resistance and heat resistance to untreated products. A stable ultramarine blue was obtained by carrying out the same processing operations as in Example 1 under the conditions listed in the table below.

[Test method]

(1) Hydrogen sulfide detection method Attach a 50ml dropping funnel and a simple gas detection tube that can detect hydrogen sulfide to a 200ml three-neck round bottom flask with a magnetic stirrer, connect the detection tube to a hydrogen sulfide pump, and detect the generated hydrogen sulfide gas. is always aspirated at a constant pressure. The above gas detection tube has a scale printed directly on it, allowing direct reading of 0.1 to 2.0% hydrogen sulfide. Measurement is performed using this measuring device in the following manner.
Place 0.5 g of ultramarine in a three-necked round-bottomed flask and uniformly disperse it in 5 ml of ion-exchanged water.
Next, add 5 ml of 1N hydrochloric acid at once through the funnel, and stir with a magnetic stirrer. The amount (%) of hydrogen sulfide generated when ultramarine is dispersed by acid is read using a detection tube. (2) Silver plate blackening test method Ultramarine blue and silver plate were heated for 2 days at 80°C in a sealed container.
℃, and visually observe the degree of blackening of the silver plate due to hydrogen sulfide generated during that time.
The color of the silver plate at the time of blanking is set as 0, the overall blackening in the case of untreated ultramarine is set as 5, and the degree of blackening is evaluated in the range of 0 to 5. [Results and Evaluation] (1) The results of the hydrogen sulfide detection method are as shown in the drawing. In the product A obtained in Example 1 of the present invention, the detected amount of hydrogen sulfide did not reach even 0.5% by volume after 2 minutes, and in the case of Product B of Example 7 and Product C of Example 8, The amount was only about 0.2% by volume, and in addition, no hydrogen sulfide was generated after 2 minutes in all products A to C. On the other hand, untreated or sodium silicate-treated ultramarine rapidly generates hydrogen sulfide, and the amount detected after 2 minutes reaches approximately 1.5% by volume, and the detection tube reaches the full scale in less than 4 minutes. reached 2.0%. According to the above results, the stable ultramarine of the present invention is untreated and 5%
It can be seen that the acid resistance is extremely superior to that treated with sodium silicate. (2) In the silver plate blackening test, the ultramarine obtained in Example 1 of the present invention received a score of 0 (no change), while the untreated ultramarine received a score of 5 (full blackening). According to these results, it can be seen that the product of the present invention has extremely excellent heat resistance. Taking all the above into account, it is clear that all of the products of the present invention are extremely superior in acid resistance and heat resistance, and therefore have remarkable stability, compared to conventional ultramarine blues.

[Brief explanation of the drawing]

The drawing is a chart showing the relationship between the detected amount of hydrogen sulfide and the required detection time in the hydrogen sulfide detection method for stable ultramarine blue of the present invention and conventional ultramarine blue.

Claims (1)

[Scope of Claims] 1. Stable ultramarine blue in which surface sulfur of ultramarine particles is blocked with a zinc compound. 2. A method for producing stable ultramarine blue in which the surface sulfur of ultramarine particles is blocked with a zinc compound, characterized by treating ultramarine blue with a zinc compound in an aqueous medium. 3. A method for producing more stable ultramarine blue in which the surface sulfur of ultramarine particles is blocked with a zinc compound, characterized by treating ultramarine blue with a zinc compound in an aqueous medium and then calcining the treated product. 4 Ultramarine blue particles are treated with a zinc compound in an aqueous medium, the treated product is then calcined, and the calcined product is further dispersed in water and then dried at about 10 to 105°C. A method for producing ultramarine blue that is sequestered with water and is stable and has good water dispersibility.