DE1145732B - Pigments containing barium titanium borate and processes for their preparation - Google Patents

Description

Pigments containing barium titanium borate and processes for their preparation The present invention resides in that a pigment contains barium titanium borate or consists predominantly of such barium titanium borate. These pigments have a greater resistance to water leaching and a higher one Refractive index than the previously known barium borate pigments, such as barium metaborate and silica coated barium metaborate pigments. The invention relates to also to a process for the production of such pigments.

Are barium borates, and especially barium metaborate, in the form of If pigments are added to color carriers, colors are obtained whose films are characterized by a increased resistance to decomposition or degradation due to growth and reproduction from microorganisms and the associated accumulation of dirt. Titanium dioxide or other oil paints containing pigments, the films of which are normally calcified subject to loose removable powder on or immediately next to the film surface forms, become more resistant to such calcification phenomena if the Paint contains a barium borate pigment. The use of barium borates, including Barium borosilicate, and those obtained by the presence of such pigments in paints Advantages are described in U.S. Patent 2,818,344.

When used in water emulsion paints, barium borates show the Tendency to form larger, crystalline, hydrated particles, and they are in the aqueous phases of such emulsion paints more soluble than in drying oils or other organic carriers or solvents. By coating barium metaborate particles with hydrated amorphous silicon dioxide pigment particles can be obtained, which are less leached by water than barium metaborate particles.

Such barium metaborate pigments coated with silica possess essentially the same desirable fungitoxic efficacy as in paint films uncoated barium metaborate pigments. The solubility of barium metaborate in Water is about 0.7 g per 100 em3 at 20 ° C, while the total amount of solids, those made from barium metaborate pigments coated with silica, with formation a saturated solution can be extracted or leached by water, no longer than 0.3 g per 100 cm3 of water. If one uses the pure barium titanium borate according to the invention leached with water, the extracts contain about 0.005 g per 100 cm3 of dissolved substances (determined as barium oxide and boron trioxide) found. Under "leaching" is only here the removal of components from a mixture or from a compound Understand percolation or extraction.

The pigment of the invention sets when it is dried in a Color film is included, slower barium and borate ions in freedom ass not coated or barium metaborate coated with silica and is therefore also made from color films less leached by rain or water. Color films are also produced with it decomposed less quickly by mold and the associated accumulation of dirt as films of paints uncoated or coated with silica Barium metaborate pigments are preserved. The pigment has the desired properties the barium borate, but is for use in aqueous emulsion paints and in aqueous preparations for coating paper, textiles and similar materials is better suited than this.

The basis of the present invention is the fact that barium metaborate forms a crystalline compound with titanium dioxide, which is much less with water It is easily leached as barium metaborate, barium borosilicate or with silica coated barium metaborate, but not as insoluble and inert as barium sulfate is. Pigments consisting of or containing this compound can be used as Preservatives in paints and aqueous preparations for coating the above-mentioned materials and used for other purposes for which the more soluble barium borates are less suitable will.

The crystalline compound known as barium titanium borate corresponds to the empirical formula Ba0 - Ti02 'B2O3, which has a composition of 50.63.1 / 9 Barium oxide (Ba0), 26.38% titanium dioxide (TiO2) and 22.99 "/ o boron oxide (B203). During the leaching process, the compound appears to hydrolyze slowly, with barium and borate ions become free. Overall, this connection can be made by water at 251 C about 0.005 g per 100 em3 barium and boron components (determined as BaO and B203) be leached out. This is little more than the solubility of barium carbonate in water at this temperature.

The melting point of barium titanium borate is 1008 ± 5 ° C and its Refractive index between 1.94 and 1.96 [determined microscopically with the aid of liquids with a certain refractive index (Becke test)]. The refractive index is therefore larger than that of barium metaborate (1.54 to 1.56). The density is about 4.28 g / cm3.

In the manufacture of barium titanium borate and others of the invention Products, the proportions of the reactants are chosen so that products are obtained which consist almost exclusively of barium titanium borate or barium metaborate and barium titanium borate in a predetermined proportion.

Although it is possible to produce supplements in larger quantities Contain titanium dioxide as the stoichiometric amount required for barium titanium borate (26.38%), the excess titanium dioxide does not appear to be bound in such preparations to be. In any case, it affects the leachability of the product obtained is essentially the same as that of barium titanium borate, no. Such products, the lower than the stoichiometric amount of leachable barium and boron compounds but are not as effective as barium titanium borate in colored felts.

It is also possible to make preparations that contain barium oxide and boron trioxide with the equimolecular ratio given by barium metaborate does not match. Although such compositions are believed to be minor Containing amounts of barium titanium borate may change the nature of the other ingredients and their Leachability cannot be predicted or influenced, as is the case with those of the present invention Products is the case.

The products according to the invention therefore essentially consist of the compound referred to as barium titanium borate or mixtures of these compounds with barium metaborate. Such products can have smaller or larger amounts of unreacted Starting materials, including barium borates (except barium metaborate) and impurities or contain traces of impurities originating from the starting compounds. The impurities affect the color and leachability of barium and Borate ions from the barium titanium borate stronger than other physical and chemical Properties. The titanium dioxide content of the products according to the invention is not greater than about 26.4 percent by weight. Products with less titanium dioxide also contain barium metaborate, because the ratio of the quantities required for the production of barium titanium borate Barium and gate containing components is the same as that which is stoichiometric is required for the production of barium metaborate.

Barium titanium borate and pigments made from mixtures of barium titanium borate and barium metaborate can be conveniently prepared as follows: Mixtures of titanium dioxide and barium metaborate or mixtures of titanium dioxide and substances, from which barium metaborate is formed, such as barium hydroxide, barium sulfide and barium cerbonate as a source of barium oxide and boric acid as a jellyfish of boron trioxide, are used directly heated to temperatures above about 700 ° C. You can also do this by heating Mixtures of barium titanate and boron trioxide or substances that supply boron trioxide, such as boric acid.

In such processes, the properties of the products depend on the stoichiometric amounts of the reactants used, the temperature and the Duration of heating. In general, temperatures are between 700 and 1300 ° C and heating times from about 10 minutes to about 24 hours are favorable. As the properties de products. remain practically unchanged for longer heating times the specified maximum time of 24 hours does not represent a limit that cannot be exceeded.

A preferred method of making the products of the invention and compounds consists in heating a mixture of water containing titanium dioxide and precipitated barium metaborate. Precipitated barium metaborate can be obtained by reacting Barium sulfide or hydroxide solutions are conveniently made with sodium tetraborate solutions will. Hydrous titanium dioxide is light by hydrolysis of titanium tetrachloride or sulfate can be produced.

When heated. a mixture of barium metaborate particles. and hydrous Titanium dioxide particles are gradually driven off by water, starting at about 700 ° C the particles to sinter and go into a coherent solid mass without to melt completely or to melt together. The term "sintering" becomes the difference used by melting or calcining. The last = rem means a heating process, in which larger particles become friable and break down into smaller particles.

Mixtures of barium metaborate and titanium dioxide made in this way sintered contain substantial amounts of or consist entirely of the barium titanium borate according to the invention, depending on the size of the individual particles, the temperature and the duration of the heating. At over 900 ° C such masses Gradually coherent and melt at about 1008 ° C to a clear liquid. Although the heating temperature can in practice be increased to around 1300 ° C, which makes the subsequent powdering or grinding easier, the mass needs normally not to be made to melt completely. The by sintering products obtained by melting are crushed to obtain particles, which can be used for paints and other preparations. Instead of more reactive hydrous products obtained by hydrolysis of titanium tetrachloride or -sulfalt can also be obtained from other sources, including titanium dioxide the commercially available anatase titanium dioxide pigments, rutile titanium dioxide pigments and titanium dioxide ores, be used.

Instead of barium carbonate or hydroxide, barium sulfide can also be used be used. It can be fused directly with boric acid and titanium dioxide, wherein barium titanium borate and other products according to the invention, as described in Example 4, can be obtained. During the heating of such mixtures, hydrogen sulfide becomes and sulfur dioxide free.

The properties of any of the methods of the invention manufactured products depend on the purity of the raw materials and on one any subsequent cleaning of the products.

Example 1 Production of barium titanium borate from barium carbonate, titanium dioxide and boric acid by melting a) Production of hydrous titanium dioxide The hydrous Titanium dioxide used in this and the following examples prepared as follows: Technical grade titanium tetrachloride (TiC14) was added dropwise to a weighed amount of crushed ice in one immersed in an ice bath Beaker added. So much titanium tetrachloride was added that about 10 weight percent titanium dioxide equivalent amount was present. Was stirring then aqueous ammonium hydroxide (28% strength NH3 solution) was added until no more Precipitation occurred while the temperature was maintained at 10-20 ° C. The precipitated one water-containing titanium dioxide was then filtered off and washed several times with water, until the wash water was practically free of ammonium and chlorine ions. Before use a sample of this hydrous titanium dioxide was annealed to determine its Ti02 content to determine.

b) Mixing and melting Stoichiometric amounts of pure reagent Barium carbonate (BaC03, molecular weight 197.4), boric acid (2 moles of H3B03, molecular weight 61.84) and hydrous titanium dioxide (Ti0z, molecular weight 79.90), as above were prepared by grinding in a mortar and pestle mixed and placed in a platinum crucible. The mixture was then closed in a Muffle furnace heated to melting and above the melting temperature for about 1 hour (about 1100 ° C) held. During the heating, the contents of the crucible became from Moved from time to time to spread the yellow melted mass. During heating water and carbon dioxide were expelled. The mass was slowly crystallizing and let cool. The molten product after cooling was white and turned then pulverized. The particles thus obtained were under the polarizing microscope crystalline and showed a refractive index between 1.94 and 1.96. c) extraction of the products with water to determine their leachability The amount of substances which are leachable or extractable from the products by water became like determined as follows: 5 g of the product were poured into 100 cm3 of boiled distilled water, which was contained in a sealed polyethylene bottle, and the suspension Shaken for 20 hours at room temperature. The clear solution was then from solid residue separated by filtration and the residue an additional 100 cm3 of water added and the suspension shaken again for 20 hours and then filtered. The extraction of the product was continued in this way in order to achieve constancy to check the composition of the successive extracts.

The barium and boron content in each of the extracts obtained in this way was determined. In the case of the products according to the invention, the extracts did not contain any soluble titanium compounds, which indicates that barium titanium borate hydrolyzes only slowly on contact with water, releasing barium and borate ions. The barium and boron (as Ba0 and B, 03) contents of the extracts per 100 cm3 extract were as follows: Extraction No. Ba0 B203 (Grams per 100 cm3) (Grams per 100 cms) 1 0.076 0.056 2 0.057 0.045 3 0.018 0.015 4 0.0062 0.0056 5 0.0032 0.0035 6 0.0026 0.0030 7 0.0020 0.0025 8 0.0016 0.0023 9 0.0013 0.0020 10 0.0014 0.0024 d) X-ray analysis The lattice plane spacings of the above products, determined by conventional X-ray powder diagram analysis, were as follows: Interplanar spacing Relative intensity (d-values) Angstrom 1/1 1 - 100 5.53 98 4.24 15 3.88 74 3.00 100 2.91 16 2.74 49 2.63 26 2.52 25 2.29 10 2.16 12 2.11 18 1.86 71 1.82 41 1.61 8 1.54 19 1.37 36 1.13 17 0.99 23 In the previous table, the interplanar distances in the crystal are given in angstroms and denote the d values from Bragg's equation nx = 2 d sin0, where n is the order of diffraction (1 or another integer), A. is the wavelength of the X-rays in Angstrom and 0 mean the angle of incidence or half the angle of scatter of the rays. The relative intensity (1 / I1) is the quotient of the intensity of the individual diffraction line in arbitrary units (1) and the intensity of the strongest line in the same arbitrary unit (11).

The above X-ray results were obtained by direct measurements obtained with a spectrogoniometer equipped with a proportional counter tube where the angle measurement was carried out at a rate of 2 ° per minute became. Copper served as the source of X-rays and its radiation was passed through a nickel plate was filtered to produce radiation with an effective wavelength of 1.54 Angstroms to obtain.

The above X-ray values obtained for the product of this example are from those of barium metabcrate, barium titanate, and both anatase and Various rutile titanium dioxides. Since such values for the crystal form. and spatial Arrangement are characteristic and accordingly chemical compounds and not individual ones Characterizing elements or chemical groups, they prove that what is formed Product not just a mixture of the individual raw materials, but a chemical one Connection is. Your X-ray diagram is unique and different from the X-ray diagrams of all other compounds, the X-ray values of which have been reported or determined up to now became.

Although a line (3.00 A) in the above diagram has the same relative intensity as in the X-ray diagram of barium metaborate, the absence of other relatively strong barium metaborate lines and the presence of lines not found in the barium metaborate proves that the product is not barium metaborate is. Example 2 Preparation of a Molten Mixture of Barium Titanium Borate and Barium Metaborate Barium carbonate, hydrous titanium dioxide (prepared according to the example) and boric acid were mixed in such proportions that one mole of titanium dioxide was present in the mixture for every 2 moles of barium oxide and boron trioxide. This mixture was ground in a mortar and pestle and transferred to a platinum crucible, in which it was heated to about 1100 ° C. for 1 hour in a closed muffle furnace. The clear melt gave a after cooling. solid white, crystalline material which was ground and subjected to the leaching test described in Example 1, c). During the initial leaching of this product, barium oxide and boron trioxide appeared in a weight ratio of 2.18: 1. The weight ratio of barium oxide to boron trioxide in the barium metaborate is 2.20: 1. The weight ratio, as well as the amount of extracted material, became smaller as the product was further leached.

The following results were obtained on leaching: Extraction No. Ba0 B20 $ (Grams per 100 cm $) (grams per 100 cms) 1 0.433 0.197 2 0.444 0.203 3 0.207 0.104 4 0.088 0.064 5 0.0397 0.0310 6 0.0085 0.0067 7 0.0034 0.0029 8 0.0027 0.0018 9 0.0025 0.0021 10 0.0024 0.0016,, The contents of the first extracts show that the barium metaborate in the molten product was leached at the same rate as. it was expected for barium metaborate, and that after the seventh extraction the amounts leached were as expected for the leaching of approximately pure barium titanium borate. The residue after ten leaches was examined and its X-ray diagram was as follows: Interplanar spacing Relative intensity (d-values) Angstrom I / 11-100 5.50 18.4 4.23 21.9 3.86 73.7 3.00 100 2.74 9.6 2.63 21.1 2.52 32.4 2.29 13.2 2.16 18.4 2.11 27.2 1.85 43.9 1.83 14.9 1.61 14.9 1.53 14.9 1.37 11.4 The above X-ray data confirm that the residue after the tenth leach consists essentially of barium titanium borate.

Products such as the above containing barium metaborate together with barium titanium borate are desirable when it is necessary to initially release a large amount of barium and borate ions, as in emulsion paints where both preservation of the paint in the original container and long-lasting protection of the paint film against decomposition by Schiur melpilzw growth are desirable. Similar conditions exist in the production of protective coatings for wrapping paper and cardboard boxes for soap and similar products, which are susceptible to destruction by mold and bacteria. Example 3 Production of Sintered Barium Titanium Borate from Barium Sulphide, Hydrous Titanium Dioxide and Borax To an aqueous solution of commercially available barium sulphide, which was kept at 55 to 60 ° C in a flask with stirrer and reflux condenser, hydrous titanium dioxide (prepared according to Example 1, a )] was added in such an amount that 1 mole of TiO was present in the solution per mole of BaS, whereupon such an amount of borax (NazB407. 5 H 2 O) was added that 1 / z mole of borax was present per mole of barium sulfide. During this addition some hydrogen sulfide was released and the reaction mixture turned pale yellow. The mixture was then heated to 100 ° C over 20 minutes and heating was continued at a temperature such as to maintain gentle refluxing for an additional 4 hours, after which the mixture was cooled to 70 ° C. The solids were filtered off and washed with an amount of water approximately equal to the volume of the filtrate.

The product then formed a white amorphous solid which contained a large proportion of water. After a sample had been dried overnight in an oven between 140 and 150 ° C. and then pulverized in a mortar and pestle, the particles showed refractive indices between 1.62 and 1.80 (determined microscopically using liquids with a specific refractive index). When leached with water, as in Example 1, c), this intermediate product is not as leachable as barium metaborate and more leachable than barium titanium borate. The results of the leaching were as follows: Extraction no. Ba0 B = 03 (Grams per 100 cm3) (Grams per 100 cm :) 1 0.132 0.071 2 0.116 0.068 3 0.105 0.066 4 0.096 0.063 5 0.095 0.063 The dried product thus obtained from barium sulfide, borax and hydrous titanium dioxide was then heated to 900 ° C. for 2 to 3 hours in a platinum crucible. The product obtained was not a solid fused mass like that in Example 1, but consisted of a sintered mass of individual granulated particles, the surfaces of which were fused together at various points. They were separated from one another by caverns and had a structure similar to porous slag or the ash that forms after burning a block of coal. The sintered product, after grinding in a mortar and pestle, gave white crystalline particles with refractive indices between 1.94 and 1.96. The sintered barium titanium borate produced in this way gave, after repeated leaching as in Example 1, c) extracts which contained a total of about 0.005 g of barium oxide and boron trioxide per 100 cm3, which essentially corresponds to the leachability of the product described in Example 1. Example 4 Production of barium titanium borate from barium sulfide, hydrous titanium dioxide and boric acid 12.5 g hydrous titanium dioxide, produced by hydrolysis of titanium sulfate, with a content of 64.0 percent by weight TiO, (corresponding to 0.10 mol Tioz) were mixed with 12.4 g boric acid ( 0.20 mol) mixed by grinding. This pasty mixture was placed in a beaker and mixed with 120 g of a 14.1 weight percent solution of commercially available barium sulfide (corresponding to 0.10 mol). Hydrogen sulfide gradually developed.

The pasty mixture was then heated on a hot plate. To protect them from air, a glass funnel was placed in the beaker directly above added to the surface of the mixture and nitrogen from the top of the funnel supplied, thereby simultaneously removing water and hydrogen sulfide was relieved. The mixture was then heated to 150 ° C on the hot plate and heating continued for 2 hours until the product appeared dry. the dry mix, in which particles of free sulfur were visible, then became placed in a muffle furnace and used to oxidize the sulfur and expel the The sulfur dioxide formed was heated to 700 ° C. for 2 hours. The mixture obtained was then placed in a platinum crucible and heated until it melted, resulting in occurred about 1250 ° C.

The product of this example was virtually identical in all respects to the barium titanium borate of the previous examples. When extracting with water as in Example 1, c), the following results were obtained: Extraction No. Ba0 B203 (Grams per 100 cm3) (Grams per 100 cm3) 1 0.143 0.170 2 0.047 0.049 3 0.010 0.010 4 0.007 0.007 5 0.008 0.007 6 0.004 0.004 7 0.004 0.004 8 0.004 0.004 9 0.003 0.004 10 0.003 0.003

Claims (5)

PATENT CLAIMS: 1. Pigment, characterized by a content of Barium titanium borate with the formula BaO - TiO @ - B., 03. 2. pigment according to claim 1, consisting of barium titanium borate and mixtures of barium metaborate and barium titanium borate. 3. A method for producing the pigments according to claim 1 or 2, characterized in that that 1. titanium dioxide and barium metaborate or mixtures of barium and boron compounds, which pass into barium metaborate by heating, or z. Barium titanate and receipt compounds, which can be converted into boron trioxide by heating, in such proportions be mixed so that the titanium dioxide content of the end product is about 26.4 percent by weight does not exceed and the mixture for about 10 minutes to about 24 hours at about 700 to 1300 ° C is heated and then ground. 4. Procedure according to claim 3, characterized in that the starting material is a mixture of barium metaborate and titanium dioxide is used in approximately equimolecular proportions. 5. The method according to claim 3, characterized in that a starting material Mixture of barium sulfide, titanium dioxide and boric acid in an approximate molar ratio 1: 1: 2 is used.