JPS5950606B2 - Production method of heat-resistant yellow pigment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a heat-resistant yellow pigment obtained by adding an alkaline earth metal to zinc, titanium, and iron as main components, and firing the pigment. be.

Conventionally, yellow pigments made of inorganic substances, such as yellow lead and cadmium yellow, are well known.
These pigments contain toxic lead, chromium, cadmium, etc. as main raw materials, and from the viewpoint of preventing pollution during the production or use of pigments, there has been a strong desire for colorless pigments to replace the above pigments in recent years. .

The present inventors have conducted research on yellow pigments made of inorganic substances for many years, and using zinc oxide, titanium oxide, and iron oxide as raw materials, (2n+m)ZnO, which is obtained by firing a mixture of these raw materials, has been developed. nTio.

, mFe. O. (Japanese Patent Application No. 55-85408) has been established for a yellow pigment made of a complex oxide having the following composition (0<nTm<1). The inventor of the present invention refers to the color resistance of colored resins of 1 or less as "heat resistance" when various synthetic resins are colored using a composite oxide of zinc, titanium, and iron having the above composition.

- We have been conducting repeated studies to further improve this. Then, various metals are added as additives to a mixture of the main raw materials, zinc oxide, titanium oxide, and iron oxide, and then fired to produce a composite oxide. After pulverizing, heat-resistant and yellow pigments are produced. After examining its compatibility as a composite oxide, we found that when an alkaline earth metal is added to form a composite oxide, the heat resistance is significantly improved, and the color tone is also better than that of a composite oxide without the addition of an alkaline earth metal. They found that there is not much difference compared to the yellow pigment.Theoretical explanation of the mechanism of heat resistance improvement when an alkaline earth metal is added to form a composite oxide and used as a yellow pigment has not yet been elucidated. However, as can be seen from the ΔE values shown in Examples and Comparative Examples described later, it has extremely excellent heat resistance.
Next, the conditions of the method of the present invention will be explained in detail.

First, to explain the blending ratio of each raw material of zinc oxide, titanium oxide, and iron oxide, each raw material has a composition of the product of zinc oxide, titanium oxide, and iron oxide (2n+
m) 0<N in ZnO, NTiO2, MFe2O3
The blending ratio must satisfy the condition fm<1.

The composite oxide with the above composition is based on the standard color chart (JIS Z872
l)" hue 4VR~IOYR, brightness 5~8, saturation 6
It becomes a yellow pigment with a color tone in a range of about 12 to 12.
Note that when Nfm approaches 0, the color tone becomes close to 4VR5/11, and conversely, when Nfm approaches 1, the color tone becomes close to 9VR8/8. If the above ratio is not met, the pigment will lose its sharpness and will not be suitable as a yellow pigment. Next, the amount of alkaline earth metal added will be explained.

The amount of alkaline earth metal added varies depending on the type of alkaline earth metal selected.

That is, when barium is selected, 15% by weight of BaO based on the raw material mixture, when strontium is selected, 5% by weight of SrO, and when calcium is selected, . If 3% by weight of CaO and magnesium are selected, the upper limit of the amount of MgO added must be 5% by weight. If the amount added exceeds the above upper limit, no matter which metal is selected, the color tone of the resulting composite oxide will increase in red and blackness and lose clarity, making it unsuitable as a yellow pigment. I end up. on the other hand,
When barium, strontium or magnesium is selected, the lower limit of the amount added is BaONSrO, .
The effect of improving heat resistance occurs when MgO is about 1% by weight, and when calcium is selected, about 0.5% by weight as CaO. In addition to the above, if the amount added is within the lower limit, it is possible to obtain a yellow pigment that has excellent heat resistance and a good color tone. In addition, within the range of the above-mentioned addition amount, it is desirable to adjust it to a large amount when the above-mentioned Nfm is close to 1, and to a small amount when Nfm is close to 0. As for the types of alkaline earth metals used, oxides, hydroxides, carbonates, etc. of the respective metals are industrially easy to use.
In addition, as the iron oxide raw material which is the main raw material mentioned above, Fe2
Any of O3, Fe3O4, FeOOH, etc. can be used.

In addition, zinc oxide is commonly used as a raw material for zinc oxide, but
Zinc carbonate, zinc hydroxide, etc. can also be used. Titanium oxide (TiO2) is commonly used as a titanium oxide raw material.

Next, to explain the firing temperature, it is 850 to 1100℃.
It is necessary to bake within the temperature range of .

However, even in this case, it is desirable to slightly adjust the temperature range by selecting the alkaline earth metal mentioned above. That is, when barium or calcium is selected as the alkaline earth metal, a temperature range of 900 to 1100°C is desirable, and when strontium or magnesium is selected, a temperature range of 850 to 1000°C is desirable.
In either case, firing at a temperature above the upper limit is undesirable, as excessive particle growth due to firing of the composite oxide product will make subsequent pulverization difficult, and furthermore, the color tone will lack clarity. . On the other hand, if it is below the lower limit, the formation of the complex oxide will be insufficient, resulting in deterioration of color tone or no improvement in heat resistance, which is not preferable. In addition, the pulverization performed after firing is performed using a particle powder suitable for using the composite oxide as a pigment, for example, using a BET method with a specific surface area of 4.
~ 6m/g, and a special pulverizer is not necessary.

For example, a crusher such as a vibrating mill can be used. Next, the present invention will be explained with reference to Examples and Comparative Examples.

In addition, in Examples and Comparative Examples, the ΔE value is a value measured by the method shown below. 0.2 g of yellow pigment was kneaded into 40 g of low-density polyethylene (F-019 manufactured by Ube Industries, Ltd.) using a hot roll at a temperature of 120°C.
The test piece was molded to a thickness of mm to obtain a heat resistance test piece, wrapped in an aluminum wheel, and heated for 10 minutes in a gear type opener set at about 280°C.

L, A, . of the test pieces before and after heating. The b value is measured using a color difference meter, and the rate of color change (ΔE) due to heating is determined using the following formula. ΔE = L2 + ΔA2 + Δb' However, ΔL = (L value before heating) - (L value after heating), Δa - (a value before heating) -
(a value after heating), Δb - (b value before heating) - (b value after heating). Example 1 355g of zinc oxide, 123g of titanium oxide, and 232g of iron oxide
ZnO: 60 mol%, TiO2: 20%
, Fe2O3: 20 mol% raw material blend.

Next, 60 g of the above raw material mixture was weighed, and 2.1 g of calcium carbonate (2.0 g as CaO) was added to the raw material mixture.
Corresponds to % by weight. ) in an electric furnace.
The composite oxide was baked at a temperature of 000° C. for 2 hours to obtain a composite oxide. The obtained composite oxide was pulverized with a vibration mill to obtain a yellow pigment as a powder having a specific surface area of 5.1 mZ/g by the BET method. 0.5 g of the obtained yellow pigment and 0.5 g of castor oil were kneaded with a Huba set mala to form a paste. 4.5 g of Kuriyaratsuka was added to this, kneaded to form a paint, and a 5 mil coating was applied on mirror coated paper. The coating film obtained by applying with an applicator and drying is 6 of the "Standard Color Chart (JISZ872L)".
．． It exhibited a color tone corresponding to 0YR6.2/10.5.

Further, the ΔE value measured by the method described above was 0.57. Examples 2 to 12 and Comparative Examples 1 to 3 Yellow pigments were obtained in the same manner as in Example 1 by varying the blending ratio of the raw material mixture, the type and amount of alkaline earth metal, and the firing temperature.

Claims (1)

[Claims] 1. Zinc oxide, titanium oxide and iron oxide, the composition of the product of these three is (2n+m)ZnO, nTiO_2, m
For a raw material blend that satisfies the condition of Fe_2O_3 (0<[n/n+m]<1),
After adding alkaline earth metals as additives, 850-1
A method for producing a heat-resistant yellow pigment, which comprises firing at a temperature of 100°C to produce a composite oxide, and intoxicating this. 2. The method for producing a heat-resistant yellow pigment according to claim 1, wherein the alkaline earth metal is barium. 3. The method for producing a heat-resistant yellow pigment according to claim 1, wherein the alkaline earth metal is strontium. 4. The method for producing a heat-resistant yellow pigment according to claim 1, wherein the alkaline earth metal is calcium. 5. The method for producing a heat-resistant yellow pigment according to claim 1, wherein the alkaline earth metal is magnesium.