Treatment of vanadium yellow pigments with carbohydrate-based syndets to improve ion resistance in an alkaline medium

Abstract

A composition can exhibit improved ion resistance and color stability. The composition includes a pigment made of bismuth vanadate (BiVO.sub.4). The pigment is in the form of particles coated with at least one O-functionalized carbohydrate, where the O-functionalized carbohydrate is at least one of an ether of a carbohydrate and an ester of a carbohydrate. The carbohydrate is at least one of a monosaccharide and an oligosaccharide. The oligosaccharide is at least one of an oligosaccharide having two to ten monosaccharides, a sugar alcohol, a sugar acid, and a lactone of the sugar acid.

Claims

1: A composition, comprising: a pigment comprising bismuth vanadate (BiVO.sub.4), wherein the pigment is in the form of particles coated with at least one O-functionalized carbohydrate, wherein the O-functionalized carbohydrate is at least one member selected from the group consisting of an ether of a carbohydrate and an ester of a carbohydrate, wherein the carbohydrate is at least one member selected from the group consisting of a monosaccharide and an oligosaccharide, and wherein the oligosaccharide is at least one member selected from the group consisting of an oligosaccharide having two to ten monosaccharides, a sugar alcohol, a sugar acid, and a lactone of the sugar acid.

2: The composition according to claim 1, wherein a) the ether of the O-functionalized carbohydrate is selected from the group consisting of ethers of aliphatic alcohols having 1 to 36 carbon atoms, b) the ester of the O-functionalized carbohydrate is selected from the group consisting of esters of aliphatic carboxylic acids having 1 to 36 carbon atoms.

3: The composition according to claim 2, wherein a) the aliphatic alcohol having 1 to 36 carbon atoms is at least one member selected from the group consisting of a linear fatty alcohol, a branched fatty alcohol, and an unsaturated fatty alcohol, and b) the aliphatic carboxylic acid having 1 to 36 carbon atoms is at least one member selected from the group consisting of a linear fatty acid, a branched fatty acid, and an unsaturated fatty acid.

4: The composition according to claim 1, wherein (i) the monosaccharide is at least one member selected from the group consisting of an aldose, a ketose, a cyclic hemiacetal, and a cyclic hemiketal (ii) the oligosaccharide is at least one member selected from the group consisting of a disaccharide, a trisaccharide, a tetrasaccharide, a pentasaccharide, a hexasaccharide, a heptasaccharide, an octasaccharide, a nonasaccharide, and a decasaccharide, (iii) the sugar alcohol is at least one member selected from the group consisting of D-sorbitol, D-mannitol, and dulcitol, and (iv) the sugar acid is at least one member selected from the group consisting of D-gluconic acid, D-saccharic acid, D-mannosaccharic acid, mucic acid, D-gluconic acids, and a lactone thereof.

5: The composition according to claim 1, wherein the O-functionalized carbohydrate is at least one member selected from the group consisting of an aliphatic alkyl O-sugar ether having 1 to 36 carbon atoms in the alkyl group, a glycoside having 1 to 36 carbon atoms in the alkyl group, a sugar ester having 1 to 36 carbon atoms in the acyl group.

6: The composition according to claim 1, wherein the O-functionalized carbohydrate is at least one alkyl O-glucopyranoside having 1 to 36 carbon atoms in the alkyl group.

7: The composition according to claim 1, wherein the O-functionalized carbohydrate is at least one alkyl O-D-glucopyranoside of a linear or branched fatty alcohol.

8: The composition according to claim 1, wherein the ether of a carbohydrate is at least one member selected from group consisting of a glycosidic monosaccharide and a glycosidic oligosaccharide.

9: The composition according to claim 1, wherein the pigment further comprises at least one member selected from the group consisting of molybdenum oxide, tungsten oxide, aluminium, phosphorus, zirconium, and iron.

10: The composition according to claim 1, wherein the pigment is in the form of particles having a particle size distribution, d.sub.50, of not less than 0.1 m to 10 m.

11: The composition according to claim 1, wherein the O-functionalized carbohydrate comprises at least one member selected from the group consisting of a cetearyl glucoside; an ethylhexyl glucoside; methylglucose isostearate; cetyl glucoside; stearyl glucoside; caprylyl glucoside; lauryl glucoside; a cacryl glucoside; a myristyl glucoside; a decyl glucoside; a cocoglucoside, which is an alkyl polyglucoside based on coconut oil and glucose, sorbitan laurate; sorbitan stearate; sorbitan tristearate; sorbitan laurate; sorbitan sesquicaprylate; sucrose stearate.

12: The composition according to claim 1, wherein the pigments in the form of particles coated with at least one O-functionalized carbohydrate, the composition has a content of 0.05% to 50% by weight of the at least one O-functionalized carbohydrate and the composition has a content of 99.95% to 50% by weight of the pigment in the overall composition.

13: The composition according to claim 1, wherein the pigment in the form of particles coated with the at least one O-functionalized carbohydrate, and a) the difference (dL) in the L value by the CIE-Lab system before and after storage of the pigments at 18 to 23 C. over 7 days in an aqueous solution containing alkaline earth metal ions and/or alkali metal ions in the form of a suspension, determined as dL=L (before storage)L (after storage), has a value of dL=18 to 0, and/or b) the difference (dL) in the L value by the CIE-Lab system of a dried layer of the pigments before and after contact with an aqueous solution containing alkaline earth metal ions and/or alkali metal ions at elevated temperature, determined as dL=L (before contact)L (after contact), has a value of dL=18 to 0, and/or c) the difference (dL) in the L value by the CIE-Lab system before and after contact with an aqueous solution containing alkaline earth metal ions and/or alkali metal ions and having a pH of not less than 9, determined as dL=L (before contact)L (after contact), has a value of dL=18 to 0.

14: A process for producing the composition according to claim 1, the process comprising: mixing, in the presence of a protic fluid, a pigment that comprises bismuth vanadate and is in particulate form with at least one O-functionalized carbohydrate selected from the group consisting of an ether of a carbohydrate and an ester of a carbohydrate, wherein the carbohydrate is at least one member selected from the group consisting of a monosaccharide, an oligosaccharide having two to ten monosaccharides, a sugar alcohol, a sugar acid, and a lactone of the sugar acid.

15: A formulation, comprising: a composition according to claim 1, a binder, water, and optionally at least one of an additive and a further pigment.

16. (canceled)

Description

WORKING EXAMPLES

[0060] Substances According to the Invention

TABLE-US-00001 TABLE 1 Product INCI (referred to hereinafter as syndet) 1 TEGO Care C 90 Cetearyl Glucoside 2 TEGO Tens G 826 Ethylhexyl Glucoside 3 TEGO SML Sorbitan Laurate 8 TEGO SMS Sorbitan Stearate 7 TEGO STS Sorbitan Tristearate 8 TEGO Care LTP Sorbitan Laurate 11 ISOLAN IS Methylglucose Isostearate 12 ANTIL SOFT SC Sorbitan Sesquicaprylate 13 TEGO Care SE 121 Sucrose Stearate 14 Glucopon 425 N Caprylyl Glucoside 15 GLUCOPON 600 UP Lauryl Glucoside 16 Glucopon 225 DK Caprylyl/Capryl Glucoside 17 GLUCOPON 420 UP Caprylyl Glucoside (and) Myristyl Glucoside 18 Glucopon 215 UP Caprylyl Glucoside (and) Decyl Glucoside 19 Glucopon 650 EC Coco-Glucoside 20 Sucrose 21 Methyl glycoside 22 Sorbitol

Example 1

[0061] The substances according to the invention can be applied to the pigment surfaces in various ways. The wetting of the pigments takes place rapidly owing to an affinity, which is known to the person skilled in the art, of the syndets to hydrophobic surfaces, particularly in the presence of water. Mention is made here by way of example of wetting in a dual asymmetric centrifuge; many other standard methods of mixing solids and liquids are possible.

[0062] 10 g of vanadium yellow (vanadium yellow from Cappelle, Belgium, namely Lysopac Orange 6820B) were mixed with 2.7 g of carbohydrate-based syndet 1 or O-functionalized carbohydrate and 2 g of water in a dual asymmetric centrifuge (Hauschild DAC 150 FVZ) at 2500 rpm for 3 min. The resultant heat of friction and associated reduction in viscosity of the carbohydrate-based syndet promotes the mixing process. The moist mixture was freed of water at 60 C. in a standard air circulation oven for 16 h. As the last step, the modified vanadium yellow was ground in a blade mill (Retsch Grindomix GM200) at 10 000 rpm for 10 seconds.

Examples 2 to 22

[0063] Example 1 was repeated using the reactants listed in Table 2.

TABLE-US-00002 TABLE 2 Amount [g] of vanadium Weight Amount [g] yellow Amount [g] ratio Ex. CBS.sup.1 of CBS.sup.1 (VDY) of water CBS:VDY 1 1 2.7 10 2 21.2:78.8 2 2 2.7 10 2 21.2:78.8 3 3 2.7 10 2 21.2:78.8 6 6 2.7 10 2 21.2:78.8 7 7 2.7 10 2 21.2:78.8 8 8 2.7 10 2 21.2:78.8 11 11 2.7 10 2 21.2:78.8 12 12 2.7 10 2 21.2:78.8 13 13 2.7 10 2 21.2:78.8 14 14 2.7 10 2 21.2:78.8 15 15 2.7 10 2 21.2:78.8 16 16 2.7 10 2 21.2:78.8 17 17 2.7 10 2 21.2:78.8 18 18 2.7 10 2 21.2:78.8 19 19 2.7 10 2 21.2:78.8 20 20 2.7 10 2 21.2:78.8 21 21 2.7 10 2 21.2:78.8 22 22 2.7 10 2 21.2:78.8 .sup.1carbohydrate-based syndet (CBS)

Non-Inventive Comparative Examples

[0064] As comparative example C1, commercially available vanadium yellow from Cappelle, Belgium, namely Lysopac Orange 68208 (uncoated vanadium yellow) is used. Comparative example C2 is a vanadium yellow protected by a noninventive method, Lysopac Orange 6821B (C2 has an inorganic coating).

Application Examples

[0065] Testing Procedure:

[0066] The vanadium yellow pigments that have been coated with carbohydrate-based syndets, i.e. O-functionalized carbohydrates, were suspended in 10% sodium hydroxide solution.

[0067] Since the vanadium yellow pigments having non-inventive modification show a certain resistance to pure sodium hydroxide solution, but not to foreign cations (particularly of main group 2), in alkaline solution, typical fillers were added to the test mixture. Table 3 lists the fillers used.

[0068] The ratio of vanadium yellow pigment to filler/NaOH solution (10%) was kept constant in all experiments (1:1:15).

TABLE-US-00003 TABLE 3 Fillers Raw material Composition Millicarb OG CaCO.sub.3 Blance fixe micro BaSO4 Mondo Finntalc M10E SQ Mg.sub.3Si.sub.4O.sub.10(OH).sub.2 Quarzwerke Tremin 939-100 Ca.sub.3[Si.sub.3O.sub.9] ESST ground wollastonite Norzinco Harzsiegel Standard zinc white ZnO

[0069] Production:

[0070] The formulation constituents are weighed out in transparent 20 ml screw top bottles according to the above formulations and homogenized on a neoLab tumbling/rolling mixer for 5 minutes. The samples are then stored at room temperature.

[0071] Test Methods:

[0072] In order to assess the performance of the carbohydrate-based syndets, the colour strength obtained was measured after storage at room temperature (in a closed vessel) for one week.

[0073] Colorimetry:

[0074] The colour of the reaction mixture was measured with an X-Rite instrument (model: X-Rite SP 60). In order to be able to detect the colour values, the reaction mixtures had to be photographed in order then to be able to undertake measurements on the printed images. For this purpose, it was necessary to define the photography and printing conditions. The photographs were taken from the side, in an illuminated fume hood as far away as possible from daylight windows. Photographs were taken with a PRAKTIKA LM16-Z24S in the flower imaging mode. The images were printed in unprocessed form on a SHARP MX-2640N PCL6 in standard quality.

[0075] The values known as the L*a*b* values according to the CIE-Lab system (CIE=Commission Intemationale de l'Eclairage) were determined for all samples. The CIE-Lab system is useful as a three-dimensional system for quantitative description of the colour loci. In this system, the colours green (negative a* values) and red (positive a* values) are plotted on one axis, and the colours blue (negative b* values) and yellow (positive b* values) on the axis arranged at right angles thereto. The value C* is formed from a* and b* as follows: C*=(a*2+b*2)0.5 and is used to describe violet color loci. The two axes cross at the achromatic point. The vertical axis (achromatic axis) is crucial for the brightness, varying from white (L=100) to black (L=0). The CIE-Lab system can be used to describe not just colour loci but also colour separations via the specification of the three coordinates.

TABLE-US-00004 TABLE 4 Comparison of conventional vanadium yellow, vanadium yellow treated in a non-inventive manner (Comparative Examples C1 and C2) and vanadium yellow pretreated in accordance with the invention (CBS 1 to 22). Carbohydrate-based syndet L after L before (CBS) storage storage dL 1 73.55 60.23 13.32 2 70.03 60.99 9.04 3 76.71 60 16.71 6 70.83 60.14 10.69 7 68.56 60.24 8.32 8 71.93 59.97 11.96 11 70.14 60.6 9.54 12 68.35 59.69 8.66 13 71.48 60.15 11.33 14 63.9 60.94 2.96 15 65.5 60.38 5.12 16 64.59 59.96 4.63 17 62.65 59.8 2.85 18 61.09 60.37 0.72 19 61.23 60.01 1.22 20 71.02 59.64 11.38 21 72.72 60.08 12.64 22 75.54 60.97 14.57 C 1 83.11 60.33 22.78 C 2 81.05 60.15 20.90

[0076] Colour Measurements on the Carbohydrate-Based Syndets of Examples 1 to 22:

[0077] What are desired here are low L* values (brightness values), which show maintenance of the orange hue of the solid constituents of the reaction mixture, i.e. the bismuth vanadate-containing pigments coated with O-functionalized carbohydrates, in the presence of aqueous 10% by weight NaOH solution. It is found that the carbohydrate-based syndets used in accordance with the invention, as compared with the non-inventive comparative examples, assure lower L* values and hence higher hue stability, recognizable by the lower dL=L before testL after test.

Application Examples

[0078] In addition, the pigments according to the invention comprising carbohydrate-based syndets 1 to 22 from Table 2 were tested with the non-inventive comparative examples in a commercial exterior facade paint.

[0079] The retention of hue after exposure to hot sodium hydroxide solution (10% NaOH in water) on the finished coating surface is assessed by the method described in the examples above, the hue measurement method (L value).

TABLE-US-00005 TABLE 5 Formulation of the white exterior wall paint Raw material Percent by weight % Description Deionized water 33.05 Tego Foamex 855 0.20 Defoamer ACTICIDE MBS 0.15 Biocide CALGON N new 0.05 Water softener TEGO Dispers 715 W 0.30 Dispersing additive AMP-90 0.10 2-Amino-2-methyl-1- propanol KRONOS 2310 12.5 TiO.sub.2 SOCAL P 3 10.00 CaCO.sub.3 OMYACARB 5 GU 15.00 CaCO.sub.3 OMYACARB 2 GU 10.00 CaCO.sub.3 MICA TG 3.00 Muscovite: K Al.sub.2 [AlSi.sub.3O.sub.10(OH).sub.2] SIPERNAT 820 A 2.00 SiO.sub.2 DOWANOL DPnB 1.00 Solvent ACRONAL S 790 12.00 Binder RHEOLATE 278 0.65 Rheology additive TOTAL 100.00

[0080] The foreign ions that have been added in Examples 23-40 of Table 6 in the form of fillers that are typical of coatings are present in homogeneous distribution in the coating formulation in this example.

[0081] To this mixture are added 5 g of vanadium yellow pigment or 5+X g, i.e. 5 g*0.1% to 100%, X=0.0005 to 5 g, of the pigments treated in accordance with the invention, where X is the amount of the carbohydrate-containing syndet used for protection, and this is stirred in at a shear rate of 10 m/s by means of a DISPERMAT CV from Getzmann for 10 minutes. The 150 m system applied by means of a coating bar is dried at room temperature over 7 days.

[0082] To test the bismuth and vanadium pigment-containing coatings for hue stability to alkaline medium and foreign ions, a 10% by weight sodium hydroxide solution was made up. This was heated to 80 C., and 5 ml of the hot sodium hydroxide solution in each case were dripped onto the horizontal, fully dried coating. The liquid is to be applied to the coating such that it comes to rest on the coating as a coherent accumulation without dividing. In order to minimize concentration of the sodium hydroxide solution as a result of evaporation, a vessel matched to the volume of the sodium hydroxide solution is directly placed over the alkali.

[0083] The process is set up in the same way for all samples and the duration of exposure for 60 minutes is observed accurately.

[0084] Thereafter, the sodium hydroxide solution is washed off the coating completely with a jet of cold water.

[0085] The evaluation is effected by the method described in Examples 23-40, directly on the exposed, fully dried location in the coating.

[0086] As has already become clear in Table 4, the compounds according to the invention have a noticeably different profile of properties compared to the non-inventive comparative examples, in such a way that the hue after exposure, as apparent from Table 6, is maintained only with pigments treated in accordance with the invention.

TABLE-US-00006 TABLE 6 Inventive CBS use examples and use examples of Comparative Examples C1 and C2 Carbohydrate-based L L syndet after before Example (CBS) contact contact dL 23 1 71.88 59.64 12.24 24 2 71.22 59.12 12.10 25 3 75.99 60.01 15.98 28 6 70.65 60.25 10.40 29 7 68.37 60.41 7.96 30 8 71.66 59.99 11.67 33 11 69.36 60.49 8.87 34 12 68.79 58.56 10.23 35 13 71.04 59.87 11.17 36 14 63.12 59.31 3.81 37 15 65.98 60.1 5.88 34 16 64.1 59.27 4.83 35 17 62.01 60.07 1.94 36 18 61.88 60.58 1.30 37 19 60.99 59.89 1.10 38 20 71.52 60.2 11.32 39 21 71.22 59.5 11.72 40 22 75 59.66 15.34 Comparative Example C 1 83.99 59.38 24.61 Comparative Example C 2 80.44 59.77 20.67

[0087] The above experiments demonstrate the efficacy of the O-functional carbohydrates as a protective coating for bismuth vanadate-containing particulate pigments with respect to bleaching in the presence of alkali metal and/or alkaline earth metal. On the basis of the above measurement results, it is found that the alkyl-O-functional carbohydrates, especially the glycosides of fatty alcohols, with L* values of 60.99 to 65.98, enable particularly high colour stability of the treated pigments. But the sorbitan esters of fatty acids as acyl-O-functional carbohydrates also show good L* values in the range from 68.35 to 71.93, a good colour stability of the treated pigments.

[0088] FIG. 1 shows a visualization of the measurement results from Examples 36, 37, 38 and 39 compared to the results of the application-oriented Comparative Examples 1 and 2 from Table 6.

[0089] The different behaviour of the bismuth vanadate pigments from CE 1, and from a mixture that has been coated in accordance with the invention and a physical mixture with O-functional carbohydrates, in water, Is shown in FIGS. 2a, 2b and 2c. FIG. 2a shows the behaviour of the unmodified bismuth vanadate pigments from CE 1 in water, which precipitate out as an insoluble deposit. FIG. 2c shows a purely physical mixture of the pigments and the O-functionalized carbohydrates in water without coating of the pigments with the O-functionalized carbohydrates. The homogeneous distribution of the water-soluble bismuth vanadate pigments coated in accordance with the invention with the O-functionalized carbohydrates (syndet:pigment, 21.2% by weight to 78.8% by weight) in water is very clearly apparent in FIG. 2b.