JPS5945606B2 - Method for producing iron(3)zinc oxide pigment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing zinc oxide (I) pigment, which has good resin aging resistance, dispersibility, and hue, and is used as a pigment for coloring resins or paints.

Iron oxide (■) zinc pigment is well known as a tan pigment, and as a pollution-free yellow pigment that does not contain harmful elements, its demand is increasing as an alternative to toxic yellow lead and cadmium yellow pigments. It's coming. However, as the demand increases, higher quality and higher performance are required, and improvements are particularly desired in resin aging resistance, dispersibility, and color clarity. Iron oxide (■) zinc pigment with spinel structure is
It is industrially produced by heating and firing a mixture of zinc oxide powder and ferric oxide or iron oxyhydroxide powder at 850 to 950°C (see, for example, US Pat. No. 2,904,395). ).

Also known is a method of firing a mixed hydroxide obtained by neutralizing a ferric salt and a zinc salt.
(See Publication No. 00). However, the iron()zinc oxide pigments obtained by these methods are not necessarily sufficient in terms of resin aging resistance, dispersibility, and hue.

On the other hand, a wet manufacturing method has been proposed for the purpose of improving the dispersibility of iron ()zinc oxide pigments.
(See Japanese Patent Publication No. 1771 and Japanese Patent Publication No. 53-31480).

However, although the pigment obtained by the wet method has better dispersibility than the dry method, it is inferior to the dry method in terms of resin aging resistance and hue.
An iron()zinc oxide pigment that satisfies all hues has not been obtained.

Therefore, the present inventors have developed a method for manufacturing iron () zinc oxide pigments that satisfies all of resin aging resistance, dispersibility, and hue using a dry method. I have considered it extensively.

As a result, regarding the resin aging resistance of iron () zinc oxide pigments, it is thought that iron () oxide present in pigment particles or its dissociation products accelerate resin aging during heat molding, and therefore In order to improve the properties, it is said that it is necessary to prevent the formation of complex oxides caused by the presence of an excess of iron () oxide () relative to the composition of the zinc pigment, or by the partial decomposition of the Subinel phase. I gained knowledge. One way to achieve this is to add zinc oxide in excess of the stoichiometric amount of the iron()zinc oxide composition, but in this case, the hue shifts to the reddish brown side and the iron()zinc oxide pigment It has disadvantages in that it has an unfavorable hue and tends to contain free zinc oxide. In order to solve this problem, the present inventors added zinc ortho titanate having a 4-2 spinel structure to an iron()zinc oxide pigment having a 2-3 spinel structure at 850 to 950°C. A detailed study has been carried out on the mutual reaction and solid solution at relatively low temperatures.

As a result, zinc ortho titanate containing an excess of titanium with respect to the iron oxide ()zinc composition: Zn2TlO4・NT
By combining 1% by weight or less of a phosphorus compound or an alkali compound, or both, with a composition containing iO2 at a ratio of 0.1 to 10%, the hue can be improved and the aging resistance of the resin can be improved. It has been found that iron()zinc oxide pigments can be obtained which exhibit excellent properties. Next, the configuration of the present invention will be explained. Iron ()zinc oxide containing zinc oxide in excess of the stoichiometric amount is, for example, iron ()zinc oxide; ZnFeO4O. Zinc oxide for 95 moles; ZnO
As shown in the X-ray diffraction diagram in Figure 1, the product obtained by uniformly mixing iron oxyhydroxide powder and zinc white powder with a composition such that 0.05 mole excess of Although a zinc phase is present in the mixture of this proportion, e.g.
．． When 0.25 mol of titanium oxide or titanium hydroxide is blended and fired, as shown in the X-ray diffraction diagram of FIG. 2, excess zinc oxide is also dissolved in the solid solution, yielding a spinel single-phase product.

This is apparently due to the reaction of ZnO and TiO2 to form zinc ortho titanate, but it has not been confirmed whether this is a solid solution in ZnFeO4.
The iron()zinc oxide pigment obtained in this way has a hue that is different from the reddish-brown color that occurs when an excess of zinc oxide is contained, due to the reaction of excess zinc oxide with titanium oxide to form zinc ortho titanate. It became yellow, which is the hue of the original tan pigment, and the hue was more yellow than the conventional one. However, iron oxide () which was formed by adding TiO2 to form zinc ortho titanate.
Even with zinc pigments, resin aging resistance and dispersibility were still insufficient. Therefore, when a small amount of a phosphorus compound or an alkali compound was added as an additive for crystal stabilization to the above formulation and the mixture was heated and formed, an iron()zinc oxide pigment with a good hue mainly consisting of a spinel phase was obtained. Moreover, this pigment had extremely good dispersibility even by ordinary pulverization methods, and also had excellent resin aging resistance.

As described above, the present invention uses zinc oxide (iron oxide); excess zinc oxide and titanium oxide with respect to the composition of ZnFeO4 in a composition of the chemical formula Zn2TiO4.NTiO2.
An iron()zinc oxide pigment characterized by blending each material so that the ratio is 1 to 10 mol%, further adding 1% by weight or less of a phosphorus compound or an alkali compound, and heating and baking. According to the manufacturing method, according to the present invention, iron()zinc oxide pigments with improved dispersibility can be produced economically and inexpensively by dry processing, since the dispersibility is good even without the generally known water hydration treatment. The iron()zinc oxide pigment obtained according to the present invention has good hue and resin aging resistance.

Further, in the present invention, the same effect can be obtained even when previously calcined zinc ortho titanate is added to iron ()zinc oxide. Suitable iron sources for use in the present invention include iron oxyhydroxide and iron oxide ().
Preferably α-iron oxyhydroxide is suitable.

This α-iron oxyhydroxide can be produced by various methods, but
Preferably, α-iron oxyhydroxide obtained by the method described in US Pat. No. 2,939,767 is suitable. As the zinc compound, zinc oxide, zinc hydroxide, zinc carbonate, zinc sulfate, organic acid zinc, etc. can be used, but zinc oxide is industrially convenient.

The titanium compound added to react with the zinc compound to form zinc ortho titanate is titanium oxide (
Anatase type, rutile type, brookite type, ortho titanium hydroxide, titanium metahydroxide) TlOSO4. TiCl4
．． Although water-soluble titanium compounds such as Ti(NO3)4 and organic titanium compounds such as isopropyl titanate and butyl titanate can be used, commercially available titanium oxide or titanium metaoxide (commercially available metatitanic acid) is conveniently used industrially. be done.

The proportion of zinc ortho titanate produced by the reaction of zinc oxide and titanium oxide is based on the zinc ferrite composition.
The composition of chemical formula Zn2TiO4・NTiO2 is 0.1 to 1
0 mol% is appropriate, and the amount of ZnO added to achieve this ratio is 0.2 to 20 m01%, preferably 1 to 11 m01
%, the solar capacity of TiO2 is 0.2 to 30 m01%, preferably 1 to 15 m01%. In addition, even if Zn2TiO4/NTiO2 is blended in a ratio exceeding 10 mol% to iron ()zinc oxide, the hue is improved, but the hue is the same as that diluted with titanium oxide, and the coloring power is also reduced, so solid solution is not used. It becomes less worthwhile to make pigments. Suitable additives for crystal stabilization include phosphorus compounds, alkali metal compounds, and compounds containing both phosphorus and alkali metal. Phosphous acid, metaphosphorous acid, pyrophosphorous acid, hypophosphoric acid, salts thereof, organic phosphoric acid esters, etc. can be used.As alkaline compounds, potassium hydroxide, sodium hydroxide, potassium carbonate, carbonic acid, etc. can be used. Sodium, potassium hydrogen carbonate, sodium hydrogen carbonate, potassium sulfate, sodium sulfate, potassium hydrogen sulfate, sodium hydrogen sulfate,
Potassium nitrate, sodium nitrate, potassium fatty acid, sodium fatty acid, potassium oxyorganic acid, sodium oxyorganic acid, etc. can be used, and for compounds containing both phosphorus and alkali, potassium phosphate, sodium phosphate, phosphoric acid, and dipotassium hydrogen can be used. , disodium hydrogen phosphate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, etc. can be used, but in order to keep the PH of the fired pigment near neutral,
Preference is given to potassium dihydrogen phosphate and sodium dihydrogen phosphate.

In addition, the amount of these additives as oxides is 0.0% relative to the pigment.
01 to 1% by weight, preferably 0.05 to 0.7% by weight is appropriate; if it is added more than 1% by weight, the water-soluble content in the pigment will increase, which is undesirable, and the water-soluble content will be lowered below a certain limit. In order to achieve this, it is necessary to wash the fired pigment with water, which is undesirable because it increases the cost. Next, details will be explained using examples.

Example 1 Aqueous suspension of α-iron oxyhydroxide (LL-XLO manufactured by Titan Kogyo) 84,57 corresponding to 0.475 mol of iron oxide () 800 dVC 0.525 mol of JIS No. Zinc White 42
．． Add 8y while stirring.

To this, 0.05 mol of titanium oxide pigment (Titan Kogyo K)
A-10) 47 was added and stirred for 20 minutes at 2000 rpm with a TK Homodisper (RE type manufactured by Tokushu Kika) to obtain a uniformly dispersed water suspension. Next, an aqueous solution of sodium dihydrogen phosphate corresponding to 0.2% by weight of P2O5 on a solid basis was added to this suspension, and the slurry obtained by filtration and dehydration was dried at 120°C. This dried product was heated to 900℃
After heating for about 30 minutes at a temperature of 400℃ for about 20 minutes.
After cooling slowly to ℃, pulverize. As a result of X-ray diffraction analysis of the pigment powder thus obtained, it mainly showed a spinel phase. In addition, 3 parts of this pigment powder was added to 80 parts of commercially available polyethylene resin (manufactured by Mitsui Chemicals, Izex 5000S), kneaded with a 6-inch diameter test roll for 155 cm and 3 minutes, and then molded into a 1-inch thick mold. I created a sheet. The number of specks indicating the finely dispersed pigment in this sheet was about 0 to 1 in a circle with a diameter of 3.5 cm.
Next, this molded sheet piece was placed in a gear type aging test tank (hot air circulation type) maintained at 250°C for 10 minutes, and then taken out and observed, and it was found that there was only slight discoloration.

The hue value measured by a color difference meter (Suga Test Instruments Model AUD-CH-2) before the aging test was L = 46.2a = 25.3b = 27.8
After aging test L = 45.5a = 24.5b = 27,
5, the color difference ΔE before and after the aging test was 1.07. This comparison value is based on the conventional method of tanning (Titan Kogyo T)
For AN-10), L=41.8a=23.4b=2
5.3, after aging test L = 39.4a = 20.3b
=23.8ΔE=4.03, and the number of specs was 10. As mentioned above, products made using this manufacturing method are
Significant improvements in resin aging resistance and dispersibility were observed.

Example 2 JIS No. 1 zinc white 81.6r and titanium oxide pigment 80.6
t was made into an aqueous suspension of 800 d, stirred for 20 minutes in a TK homodisper to mix uniformly, and then filtered and dehydrated to obtain a slurry, which was then dried at 120°C.

This dried product is heated at a temperature of 900° C. for about 30 minutes to finely grind the white pigment obtained. 1.65P of the zinc ortho titanate pigment thus obtained was added to 0.4
α-iron oxyhydroxide 8 corresponding to 95 moles of iron oxide ()
Add 0.495 mol of JIS No. Zinc White 40.3P to the aqueous suspension 800'FlLl of 8.07 with stirring.

TK Homo Day Spa 2000r. p. Stir at m for 20 minutes to obtain a uniformly dispersed aqueous suspension. Next, an aqueous solution of sodium dihydrogen phosphate corresponding to 0.3% by weight of P2O5 on a solid basis was added to this suspension, followed by filtration and dehydration, and the slurry was dried at 120°C. 90% of this dried material
After heating at a temperature of 0°C for about 30 minutes, it is slowly cooled to 400°C over about 20 minutes, and then pulverized. Next, for 80 parts of commercially available polyethylene resin! Three parts of this pigment powder was added, and a molded sheet was prepared and tested in the same manner as in Example 1.

As a result, L = 44.7a = 22.8b = 27.0, and after the gear type aging test, L = 43.5a = 21.4b =
26.3 and ΔE=1.90. Example 3
When potassium carbonate corresponding to 0.3% by weight of K2O is used as an additive in an aqueous suspension uniformly dispersed in the same manner as in Example 1, the hue L = 46.5a = 25.0b = 28
．． Hue L=45.8a=24.1 after aging test for 0
b=27.6 and ΔE=1.23.

Further, the dispersibility of the polyethylene resin was tested according to Example 1, and the results were good with 1 to 2 specs. Example 4 0.503 mol of zinc white 41.1 t is added to 800 ml of an aqueous suspension of 88.4 f of α-iron oxyhydroxide (corresponding to 0.497 mol of iron oxide) with stirring.

To this, 0.08 mol of titanium oxide 0.64r was added and mixed vigorously, and the homogeneously dispersed water suspension was filtered and dehydrated to form a slurry containing 0.30% by weight of P2O5 and 0.30% by weight on a solid basis.
After treatment with an aqueous solution of sodium dihydrogen phosphate corresponding to 12% Na2O, it was dried at 120°C. This dried product was heated at a temperature of 900° C. for about 30 minutes, slowly cooled, and then ground to obtain a tan pigment powder. Next, 3 parts of this pigment powder was added to 80 parts of a commercially available polyethylene resin, and a molded sheet was prepared in the same manner as in Example 1 and tested.

As a result, the number of specs is less than 1, and the hue value is L=4.
4.8a=23.4b=27.0, and after the gear type aging test, L=43.8a=22.2b=26.8. The color difference showed ΔE=1.76. Example 5 A uniformly dispersed aqueous suspension was prepared in the same proportion as in Example 4, and P was added as an additive instead of sodium dihydrogen phosphate.
2O, O. 30%, K2OO. Even when potassium dihydrogen phosphate equivalent to 28% was used, the number of specs was 1 or less, and the hue value was L-44.7a=23.8b=27.0.

The hue after the aging test is L=44.2a=22.5b=26
．． 7ΔE=1.46, indicating good aging resistance. Example 60.497 moles of iron oxide (α)
-0 to 800 mt of water suspension of 88.4 t of iron oxyhydroxide
．． 66.4P zinc carbonate equivalent to 503 moles of zinc oxide
Add while stirring.

0.008 mol of titanium oxide 0.64f was added to this, mixed vigorously, and the uniformly dispersed water suspension was filtered and dehydrated to form a slurry, which corresponds to 0.3% by weight of P2O5 on a solid basis. After treating an aqueous solution of sodium dihydrogen phosphate, 12
It was dried at 0°C. This dried material was heated to a temperature of 900℃ for about 30 minutes.
After heating for a minute and slowly cooling, the mixture was crushed to obtain a tan pigment powder. Next, a molded sheet of polyethylene resin was made and tested in the same manner as in Example 1.

The hue value is L=44.2a=22.5b-26.7, and after gear aging test L=43.8a=22.2b-
26.4, and the color difference was ΔE-1.76.
Example 7 α- corresponding to 0.495 moles of iron oxide ()
0.0 to 800 ml of an aqueous suspension of iron oxyhydroxide 88.07.
505 moles of zinc white 41.1 t are added with stirring.

A washed anatase type titanium hydroxide aqueous suspension corresponding to 0.01 mole of titanium oxide (0.87) is added to this and mixed in the same manner as in Example 1 to obtain a uniformly dispersed aqueous suspension. . This aqueous suspension contains 0.3% by weight of P2 on a solid basis.
After adding an aqueous solution of sodium dihydrogen phosphate corresponding to O5, the slurry obtained by filtration and dehydration was dried at 120°C. The hue of the molded sheet produced by the same process as in Example 1 is L-44,5a-24.7b=26.9, and the hue after the aging test is L=43.6a=24.0b=2.
It was 6.5ΔE-1.17. Table 1 shows a list of hue values in the above embodiments.

In all cases, the b/a value, which indicates the degree of yellowness, was excellent.

[Brief explanation of the drawing]

Figure 1 shows the X-ray diffraction of a mixture of iron oxyhydroxide powder and zinc oxide powder, whose composition is 0.05 mole excess of zinc oxide relative to 0.95 mole of zinc ferrite, and heated and fired. Figure 2 shows a mixture of the above proportions with 0.
2 is an X-ray diffraction diagram of a product prepared by blending 0.25 moles of titanium oxide and heating and baking it.

Claims (1)

[Claims] 1. After mixing zinc oxide powder and ferric oxide or iron oxyhydroxide powder, the mixture is heated and fired at 850 to 950°C to produce an iron (III) zinc oxide pigment having a spinel structure. In the method, the mixture has the general formula Zn_2T
A titanium compound that forms zinc ortho titanate containing an excess of titanium oxide represented by iO_4-nTiO_2 and a compound containing phosphorus as an additive for crystal stabilization, a compound containing an alkali metal, or a combination of phosphorus and an alkali metal. Iron (III) oxide which has a hue mainly composed of a spinel phase, good resin aging resistance and dispersibility, and is characterized by being fired with the addition of any of the compounds containing at the same time.
Method for producing zinc pigment. 2 The composition of the mixture of zinc oxide powder and ferric oxide or iron oxyhydroxide powder is ZnO:Fe_2O_ in molar ratio.
3. The method of claim 1, wherein 3 is in the range 50:50 to 70:30. 3 The amount of titanium compound added to form zinc ortho titanate containing excess titanium oxide is
The method according to claim 1, wherein the amount is in the range of 0.2 to 30 mol% in terms of O_2. 4. The method according to claim 1 or 3, wherein the titanium compound added to form the zinc ortho titanate containing an excess of titanium oxide is either titanium oxide or titanium oxyhydroxide. 5 The titanium compound added is zinc ortho titanate obtained by pre-calcination, and the amount added is 0.
．． The method according to claim 1, wherein the amount is in the range of 1 to 10 mol%. 6. The method according to claim 1, wherein the additive for crystal stabilization is an alkali dihydrogen phosphate salt. 7. The method according to claim 1, wherein 0.1 to 0.4% by weight of a phosphorus compound as P_2O_5 is used as an additive for crystal stabilization. 8. The method according to claim 1, wherein a potassium compound of 0.1 to 0.4% by weight as K_2O is used as an additive.