FI58506C - FRAMEWORK FOR THE FRAME STATION OF TITANT DIOXIDE PIGMENT WITH OAKAD CLIMATE CONTAINERS - Google Patents

Description

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Federal Republic of Germany Förbundsrepubliken Tyskland (DE) P 222352U.1 (71) Kronos Titan-GmbH, 5090 Leverkusen 1, Federal Republic of Germany Förbundsrepubliken lyskland (DE) (72) Hans-Hermann Luginsland, Opladen, Gerhard Rieckir, Bergisch-Ne

Gunter Werding, Faurndau Kreis Göppingen, Federal Republic of Germany För-bundsrepubliken Tyskland (DE) (7U) Oy Kolster Ab (5U) Method for the production of weather-enhanced titanium dioxide pigment

The invention relates to a process for the preparation of a weather-resistant titanium dioxide pigment by post-treatment, in which water-soluble salts of aluminum and zirconium and optionally one or more aqueous solids and other hydrophilic then the suspension is neutralized and the pigment thus treated is isolated by filtration, washed, dried and ground. Such a pigment, when added to varnishes, improves weather resistance and in particular chalk resistance and gloss retention.

Improving the weatherability of titanium dioxide pigments by post-treatment has long been known. Thus, for example, the ground pigment is slurried in water with a dispersant, optionally wet ground and / or sorted and then water-soluble silicate and / or water-soluble aluminum salt, and / or other metal salts and alkalis are added, filtered, washed, dried and ground. In addition to silicates and aluminum salts, a large number of other salts have been proposed, e.g., magnesium, zinc, titanium, zirconium, and cerium salts. Thus, for example, aluminum and titanium salts and silicates are used in particular.

2 58506

But the weather resistance achieved by such post-treatment is not sufficient in all cases. Admittedly, a rutile pigment with improved weather resistance and gloss retention can be prepared by post-treating the pigment twice as described above (DT-PS 1 198 950) · But the disadvantage of this method is that a large number of treatment steps are required, so the method is relatively cumbersome and expensive.

Significant efforts have now been made to improve weather resistance and gloss retention with just one simple after-treatment. Thus, the titanium dioxide pigment was post-treated by adding zirconium salt after precipitation of titanium, aluminum and possibly silicon compounds. With this addition of zirconium salt, the improvement in weather resistance and gloss retention was insignificant. However, it was surprisingly found that weather resistance and gloss stability can be significantly improved by adding zirconium salt before post-treatment before other post-treatment agents and immediately precipitating it on the pigment surface at least in part as zirconia hydrate.

Thus, a post-treatment method for a titanium dioxide pigment with improved weather resistance and gloss retention was invented. The process is characterized in that the post-treatment is one-step and the zirconium salt is added before the other substances and the zirconium is at least partially precipitated as zirconium dioxide hydrate on the titanium dioxide dipigment before the other oxide hydrates and / or optionally when the suspension is acidic, basic substance or basic reactive mixture until the reaction is neutral, and when the suspension is basic, acidic substance or acid-reactive mixture is added until the reaction is neutral, after which the pigment is filtered, washed, dried and ground in a manner known per se .

With the method according to the invention, it is possible to obtain rutile pigments with a single simple post-treatment, the weather resistance and gloss retention of which are as good as the high cost of the latter method previously achievable with the double post-treatment.

Very good results are already obtained by using only zirconium and aluminum salts. But in addition, one or more finishing agents can also be used. A special embodiment of the process according to the invention is characterized in that, in addition to the aluminum and zirconium salts, a titanium salt and / or a zinc salt and / or a silicate are used in the post-treatment.

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Hydroxides or carbonates of alkali metals and alkaline earth metals, ammonia or ammonium carbonate can be used as basic reactants in the neutralization of the suspension. Suitable acid-reactive substances are acids, e.g. hydrochloric acid or sulfuric acid. A particularly preferred embodiment of the invention is characterized in that the basic or acidic reactant used in neutralizing the suspension is essentially one or more substances which, on neutralization, also form a colorless and sparingly soluble oxyhydrate or other colorless and sparingly soluble compound. Examples of basic reactants are alkali silicate and alkali aluminate. Examples of suitable acid-reactive substances are acid-reactive salts of aluminum and titanium, e.g. chlorides and sulphates. The advantage of this embodiment is that the neutralizing agent can be saved. It is clear that both types, i.e. basic or acid-reactive neutralizing agents, can be used simultaneously or at different times.

It is essential that at least a portion of the zirconia hydrate be immediately precipitated on the titanium dioxide pigment before other oxyhydrates or other sparingly soluble compounds are precipitated. When post-treated, e.g., an alkaline pigment suspension, generally having a pH of 9-10, usually precipitates immediately after the addition of (usually acid-reactive) zirconium salt to 0.5% by weight of zirconia hydrate based on the amount of pigment used as zirconia, thereby changing the pH acidified. If the pigment slurry is not so basic, or if it is desired to precipitate more zirconia dihydrate from the beginning, it is preferable to adjust the pH of the suspension to the precipitation zone of the zirconia hydrate after the addition of the zirconium salt and other finishes.

All substances used in the post-treatment can be used in conventional amounts. The zirconium salt is already effective in an amount of 0.2% by weight based on the zirconia and the amount of pigment used. The upper limit of the amount to be used is not strictly limited, but for cost reasons it should not normally exceed 1 weight - #. A very preferred amount is about 0.5% by weight.

The process according to the invention can be carried out with a titanium diode pigment prepared in a desired manner. This pigment can be prepared in a variety of ways, e.g. by the sulphate method or the chloride method.

In detail, the post-treatment can be carried out, for example, as follows: The titanium diode pigment, possibly with the addition of a dispersing aid, is slurried in water and possibly wet-milled and / or sorted. A zirconium salt, e.g. zirconyl chloride or zirconium sulphate, is then preferably added to the slurry with thorough stirring. After this optionally added neutralizing agent, the aluminum salt and optionally one or more additional metal salts and / or optionally water-soluble silicate, e.g. alkali metal silicate, are also added in any order. It is most convenient to add all the substances as aqueous solutions. Optionally, when the suspension reacts with an acidic base, a basic reactant (e.g., alkali or ammonia and / or alkali aluminate) is added until at least the reaction is neutral. In contrast, when the suspension reacts basic, an acid-reactive substance (e.g., an acid or an acid-reactive salt) is added until at least a neutral reaction. The pigment thus obtained is filtered, washed, dried and ground.

If desired, the pigment can be treated with organic substances in a known manner after the addition of inorganic substances.

To test the titanium dioxide pigments prepared according to the invention, they were added to the varnishes and the dependence of their chalking and gloss on the duration of the age test was determined. The detailed method was as follows:

To prepare the paste, 75 g of titanium dioxide pigment and 50 g of medium-oil fatty acid-modified alkyd resin were fed twice through a three-roll mill. An additional 94 g of resin and 24 »7 g of a solution» containing 160 parts of lacquerene »40 parts of ethyl glycol acetate and 24 parts of ethyl glycol were mixed with 75 g of this paste, to which bedding and small amounts of silicone oil and film inhibitor were added in the usual manner. The mixture was applied to a steel plate, dried for one hour and varnished for one hour at 90 ° C.

The lubricating surfaces were irradiated with carbon arc lamps in a weather test cabinet at 2G minute intervals, during which time the samples were irradiated for 17 minutes and sprayed with water for 3 minutes. Chalking was determined according to DIN 33139. The measure of the chalkability was the time taken for the visible onset of chalking. The measure of gloss retention was the time required to lower the maximum gloss to $ 23 of the original value.

The following examples further illustrate the invention. Unless otherwise stated, the finishing agents were used as aqueous solutions of zirconyl chloride, titanyl sulfate, water glass, aluminum sulfate and zinc sulfate at a concentration of 100 g / l calculated from the respective oxide.

Example 1

The rutile pigment prepared according to the sulfate method to which sodium hydroxide, sodium hexametaphosphate and monoisopropanolamine as dispersants were added was soaked in deionized water. The work-up was carried out by heating at 60 [deg.] C. 17 l of a suspension obtained (corresponding to 5 kg of 5,550,506 titanium dioxide) having a pH of 9 · 5 · With constant stirring and maintaining this temperature, 150 ml of a zirconyl chloride solution corresponding to $ 0.3 calculated on the pigment used. After the addition, it was stirred for 10 minutes. The pH then dropped to 2.

Then successively the following were added: 1) 500 ml of titanyl sulphate solution corresponding to 1 l of titanium dioxide and calculated on the pigment used and then stirred for 10 minutes, 2) 500 ml of water glass solution corresponding to: 1 ml of silica and calculated on the pigment used and stirred for 10 minutes ml of aluminum sulphate solution corresponding to $ 2 alumina and calculated on the pigment used and then stirred for 10 minutes and 4) dilute ammonia solution to pH 8.4 and after the addition was stirred for 30 minutes.

The suspension was filtered, washed again with deionized water and dried in an oven at 120 ° C for 15-20 hours. The pigment was then finely ground in a jet mill.

Example la

The rutile pigment of Example 1 was prepared as described in Example 1 for work-up.

In this case, the following substances are added successively and after each addition are stirred for 10 minutes: 1) 500 ml of titanyl sulphate solution, 2) 500 ml of water glass solution, 3) 1000 ml of aluminum sulphate solution, 4) dilute sodium hydroxide solution to pH 9, 5) 150 ml of zirconyl chloride solution, ammonia solution to pH 8.4.

Based on the pigment used, the additions corresponded to 1 u /> TiO 2 »1 SiO 2, 25 56 Al 2 O 5 and 0.3 96 ZrO 2.

The pigment was then treated according to Example 1.

Example 2

The procedure was as in Example 1, but with the difference that the amount of zirconyl chloride solution added was 500 ml, corresponding to 166 zirconia and calculated on the pigment used.

Example 2a

Example 2 was repeated with the difference that the addition of zirconyl chloride took place as in Example 1a after aluminum sulphate and sodium hydroxide. However, the amount is 1 ° fo calculated as zirconia and the pigment used.

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Example 2b

The procedure was as in Example 2a, but with the difference that neither sodium hydroxide solution nor zirconyl chloride was added and that the amount of aluminum sulphate solution added was 1500 ml, which corresponds to 5 AlgO 2 based on the pigment used.

The gloss retention and chalk resistance of all products were determined as described above. The results are shown in the table.

Table Post-treatment- Initiation of gloss Eg substance x) stability xx) 1 0.3% ZrOo 1% TiO 2 17 ** 5.5 1% SiO 2 2 f Al 2 O 3

1a 1% T1O2 12.3 30, U

1% SiOp 2% A12Oo 0.3% ZrO 2 2 1% ZrO 2 19.3 »5 1% TiO 2 1% SiO 2 2% Al 2 O 3 2a 1% TiO 2 15 ** 2,3 1 JC SiO 2 2 l Al 2 O 3 1% ZrO 2 2b 1% TiO 2 '„1% SiO2 13 39.1 3% Al2O3 x) Time in days to start chalking xx) Time in days to decrease the maximum gloss to $ 25

It can be seen from the table that the zirconyl chloride post-treatment achieves a certain improvement in chalk resistance and gloss retention when zirconyl chloride is added after other post-treatment agents (cf. Example 2a to Example 2b), but this improvement is only minor and does not replace zirconium salt. In contrast, surprisingly, a strong improvement in chalk resistance and gloss retention is achieved by adding zirconyl chloride not after other post-treatment agents but before them (cf. Examples 1 and 2 to Examples 1a and 2a).

The following are further examples of the implementation of the method according to the invention:

Example 3

Rutile pigment prepared according to the chloride method was prepared for work-up according to Example 1. Then 1) 250 ml of zirconyl chloride solution, 2) 500 ml of titanyl sulphate solution, 3) 1300 ml of aluminum sulphate solution were added.

The amounts added corresponded to 0.5 ^ ZrOg, ^ ^ 3 $> AlgO ^ based on the pigment used.

After each addition, stir for 10 minutes. Ammonia addition and pigment treatment were performed as in Example 1.

Example 4

Example 3 was repeated with the difference that after the addition of aluminum sulphate and before the addition of ammonia, 250 ml of zinc sulphate solution were added, corresponding to 0.5 l of JSnO, based on the pigment used.

Example 5

Rutile pigment prepared according to the chloride method was prepared for work-up according to Example 1. The following substances were added successively to 20 liters of suspension (corresponding to 6 kg of rutile pigment): 1) 300 ml of zirconyl chloride solution, 2) 600 ml of titanyl sulphate solution, 3) 770 ml of sodium aluminate solution containing 175 g of Al 2 O / 1, 4) 450 ml of aluminum sulphate and 450 ml of aluminum sulphate. with 100 g of AlgO 2 and 66.7 g of ZnO per liter.

After each addition, stir for 10 minutes. After these additions, the pH of the suspension was 7 * 5, so the addition of ammonia was unnecessary. The amounts of post-treatment agents used corresponded to 0.5 ^ ZrO ^, 1 i <> TiO ^, 3 $ Al ^ Qj (total) and 0.5 $ ZnO, based on the pigment used.

Example 6

Example 5 was repeated with the difference that 450 ml of the aluminum sulphate solution used in Examples 1-4 was used instead of the solution containing aluminum sulphate and zinc sulphate. The amounts of post-treatment agents used corresponded to 0.5 S & ZrO 2, 166 TiO 2 and 5 AlgO 2 based on the pigment used. The pigments prepared according to Examples 3-6 also had excellent weather resistance.

Claims (5)

58506 θ A process for preparing a weatherproof titanium dioxide pigment by post-treatment, comprising adding to a aqueous suspension of a titanium dioxide pigment prepared in a desired manner water-soluble salts of aluminum and zirconium and optionally one or more silicic acid and the suspension is neutralized and the pigment thus treated is isolated by filtration, washed, dried and ground, characterized in that the post-treatment is a single step and the zirconium salt is added before other substances and zirconium is precipitated at least in part as zirconia hydrate only after all the metal salts and / or silicate have been added is it optionally added when the suspension is acidic, e an alkaline substance or an alkaline-reactive mixture until the reaction is neutral, and when the suspension is basic, an acidic substance or an acid-reactive mixture is added until the reaction is neutral, after which the pigment is filtered, washed, dried and ground in a manner known per se. Process according to Claim 1, characterized in that titanium salt and / or zinc salt and / or silicate are used in the post-treatment in addition to aluminum and zirconium salts. Process according to Claims 1 and 2, characterized in that one or more substances are used as neutralizing, basic or acid-reactive substance or mixture of substances, which on neutralization form a colorless and sparingly soluble oxide hydrate or other colorless and sparingly soluble compound. Process according to Claims 1 to 3, characterized in that after the addition of the zirconium salt and before the addition of the other finishing agents, the pH of the suspension is adjusted to the precipitation range of the zirconium dioxide hydrate. Process according to Claims 1 to J +, characterized in that the amount of zirconium salt added is 0.2 to 1% by weight, and preferably about 0.5% by weight, based on the zirconium dioxide and pigment used.