MXPA98010435A - Silicco acido de precipitac - Google Patents

Abstract

The precipitated silica presents the following physico-chemical parameters: BET surface according to DIN 66131 m2 / g 400-600; DBP number according to DIN 53601 g / 100 g 300-360; Tamping weight according to DIN 53194 g / l 70-140; of grindometer according to ISO 1524æm 15-50; Index of granulometric distribution I measured with Malvern < 1.0: Index of granulometric distribution I = d90-d10 about 2d50. It can be prepared by grinding a precipitation silica according to German Patent Application DE-A 31 44 299 in a swirl screen or in a fluid bed counter-batch mill. A polyethylene wax emulsion can be added before milling, the precipitated silica then having the following physicochemical parameters: BET surface according to DIN 66131 m2 / g 351-600; DBP number according to DIN 53601% 300-360; carbon% 1-8; Tamping weight according to DIN 53194 g / l 70-140; Grindometer value according to ISO 1524æm 15-50; Index of particle size distribution I < 1.0. Silicic precipitation acids can be used as opacifying agents in lac systems

Description

SILICON PRECIPITATION ACID DESCRIPTION OF THE INVENTION The invention relates to precipitated silica, a process for its preparation as well as its use as an opacifying agent S The use of synthetic precipitated silica or silica gel as opacifying agents is known (DE-PS 24 14 478, DE-PS 17 67 332, DE-OS 16 69 123, DE-AS 15 92 865. DE-A 38 15670). The opaque power of silicic acid depends on several factors, such as, for example, the type of silicic acid, the grain size, the grain size distribution, the calculation index and also the lacquering system. They are of special significance the shape of the grains of the secondary particles of the silicic acid and the distribution thereof. A series of requirements are formulated for the silicic acids that are used as opaque agents in addition to a high efficiency that is manifested in the reduction of the degree of gloss compared to the non-opaque lacquer film. For example, np thickening must occur excessive lacquering system due to the incorporated silicic acid. In the relevant cases of thin coats of lacquer, a smooth surface should be obtained, imperfections which adversely affect the quality of the surface should be avoided. German Patent Application DE-A 31 44 299 discloses precipitation silicas, as well as as well as a process for the preparation of these precipitation silicas, which are distinguished by the following physicochemical characteristics: S BET surface according to DIN 66131 m2 / g 400-600 DBP number according to DIN 53601% 320-360 and BET surface according to DIN 66131 m2 / g 400-600 DBP number according to DIN 53601% 310-360 Tamping weight according to DIN 53194 g / l 75-120 Alpine sieve residue "> 63 μm wt.% 0.1 For the preparation of these silicas A transverse Alpine drum mill or a jet mill is used for the milling following a spray drying. This document also mentions that these silicic precipitation are valuable opacifying agents with high effectiveness for lacquers Precipitating silicas, which are manufactured with this type of mill, produce a rough surface roughness of the finished lacquer due to marked imperfections. The Gpndometer value (according to ISO 1524) in Black stove-drying lacquer is for the known precipitated silica acids > Therefore, these precipitated silicas are usable as opacifying agents only in a limited manner. There is then a need to obtain a precipitated silicic acid which does not present these disadvantages, - Reason for the present invention is a precipitated silicic acid, which is characterized by the following physical-chemical parameters BET surface according to DIN 66131 m2 / g 400-600 DBP number according to DIN 53601 g / 100 g 300-360 Rolled weight according to DIN 53194 g / l 70-140 Gpndometer value according to ISO 1524 μm 15-50 granulométic I distribution index measured with Malvern < 1, 0 index granulométpca distribution I = 2d? Another object of the present invention is a process for preparing the precipitated silica according to the present invention with the physical-chemical parameters - BET surface according to DIN 66131 m2 / g 400-600 DBP number according to DIN 53601 g / 100 g 300-360 Tamping weight according to DIN 53194 g / l 70-140 Value of gpndometer according to ISO 1524 μm 15-50 distribution index granulometa I measured with Malvern < 1, 0 index granulométpca distribution I = that is characterized because it is milled a silicic acid that has the following physicochemical characteristics: BET surface according to DIN 66131 m2 / g 400-600 DBP number according to DIN 53601% 340-380 Rammed weight according to DIN 53194 g / l 180-220 Screening residue Alpine0 > 63 μm% by weight 25-60 by means of a sieve mill or a fluid bed counterjet mill. The starting silicic acid is described in the Application Document of German Patent DE-A 31 44 299 In a typical embodiment of the invention, a ZPS sieve mill (Zirkoplex ® Alpine Aktiengesellschaft, D-8900 Augsburg) or an AFG fluid bed counter windmill can be used. In another more developed embodiment of the present invention, the precipitated silica can be sifted in accordance with the present invention, in order to select a fraction of a certain graph. lometry In a preferred embodiment of the invention, the precipitation silicic acid can have a grain size distribution according to FIG. 1 The sieving can be carried out, for example, with an ultra-fine Turboplex ATP sieve (Alpine Aktiengesellschaft, D-8900 Augsburg) .

Another object of the present invention is a precipitated silicic acid coated with an emulsion of polyethylene wax, which is characterized by the following physical-chemical parameters BET surface according to DIN 66131 m2 / g 351-600 DBP number according to DIN 53601% 300- 360 Carbon content% 1 -8 Tamping weight according to DIN 53194 g / l 7-140 Gnometer value according to ISO 1524 μm 15-50 distribution index granulometry trpiccaa II < 1.0 This precipitation silicic acid can be prepared using a precipitation silicic acid having the following physical and chemical characteristics BET surface according to DIN 66131 m / g 400-600 DBP number according to DIN 53601% 340-380 Ramped weight according to DIN 53194 g 180-220"Alpine0 sieve residue> 63 μm wt% 25-60 by mixing it with polyethylene wax emulsion, drying and grinding it by means of a sieve mill or a fluid bed counterjet mill. In the embodiment of the invention, the precipitated silica can be made to fluidify the filter cake by the action of cutting forces, mixed with emulsion of polyethylene wax, spray dried and ground by means of a sieve mill or a counterjet mill. fluid bed As the starting silicic acid, a precipitated silicic acid can preferably be used according to the Al patent application. emanating from DE-A 31 44 299 The precipitated silica according to the present invention possesses the following advantages The qualities of the precipitated silica according to the present invention are particularly in their high opacifying efficiency, in addition to other advantages such as high surface smoothness of the dry lacquer, high transparency and little effect on the rheology (viscosity) of the lacquer. Figure 1 shows the distribution of the granulometry of the sifted precipitated silica. Figure 2 shows the distribution of the granulometry of the precipitated silicic acid according to the present invention in comparison with the distribution of the granulometry of the precipitated silica according to the invention. with German Patent Application DE-A 31 44 299. EXAMPLES Example 1 A precipitated silica, prepared according to Example 1 of German Patent Application DE 31 44 299 is milled by varying the unit production load and the parameters of process such as number of turns of the sifter, production of r jlioß or grinding air, in a sieve mill Zirkoplex ® ZPS 100 of the firm Alpine. The test parameters, the physical-chemical data and the technological results of the lacquer, which were obtained on black lacquer for drying in an oven, are shown in Table 1. Example 2 A precipitated silicic acid, prepared according to the Example 1 of German Patent Application DE 31 44 299 is milled by varying the unit production load and the process parameters such as number of turns of the sieve, mill production or grinding air, in a fluid bed co-grinding mill AFG 200 / 1 of the signature Alpine. The test parameters, the physical-chemical data and the technological results of the lacquer, which were obtained on black lacquer for drying in an oven, are shown in Table 2.

Example 3 Precipitation silicas prepared according to Example 1 co well with Example 2c (see Table 1 and Table 2) were sieved on a fine Turboflex ATP 50 sieve to obtain a finer fraction and a coarser fraction. Process quantities, the physical data and the results of the technical evaluation on the lacquer, which were determined on black lacquer for drying in an oven, are shown in table 3. Example 4 (Comparison example) The unmilled silicic acid, dried by spraying, prepared according to the German Patent Application DE 31 44 299 according to Example 6 is milled in an Alpine transverse drum mill of the UP 630 type The physical-chemical and technological data of the lacquer of the product obtained are combined in Table 4 Example 5 (Comparative Example) The unmilled, spray-dried silicic acid prepared according to German Patent Application DE 1 44 299 according to Example 9 is milled. by means of an air jet mill of the Micrognnding MC 500 type. The physical-chemical and technological data of the lacquer of the product obtained are listed in table 4. The activity or opacification efficiency of the precipitated silicas acids prepared in accordance with Examples 1 -3 are analyzed on a black stove-drying lacquer. In addition, the degree of brightness according to Lange is evaluated with a reflection angle of 60 or 85 ° and the value of the Grindometer according to Hegman. For the determination of the degree of brightness, which is a measure of the opacification power of the precipitated silicic acid tested, the brightness meter according to B Lange is used The brightness meter according to B. Lange uses as an angle of incidence and reflection one of 60 ° or 85 ° The measured brightness degrees are expressed in percentages The lower this value is, the better is the opacifying power of the precipitated silicic acid. Consequently, less opaque agent must be used to achieve a certain degree of brightness or a desired opaque effect. The determination of the Grindometer value is achieved by means of a Gpndometer value of Gpndometer. which is measured in μm (microns) is a measure for the larger particles that are found after the incorporation and mixing of the precipitated silica into the finished lacquering composition, ready to be applied. It can be related to the formation of irregularities. in the dry lacquer layer, so that with the help of the Gpndometer it is possible to anticipate undesirable irregularities or the size of the drops of the sprayed lacquer (ISO 1524). The surface quality of the lacquer film is determined by means of of the method of palpation by cutting of the firm Hommelwerke and is expressed as average rugosity value (Ra) according to D?, ^ 4768/1, DIN 4762/1 E and average roughness depth (RZD) according to DIN 4768/1 Lacquer Black drying oven used has the following composition Parts in Dßso Black smoke paste Tack 1 8,0 Jagalyd R40, 60% in xylene 50,8 Maprenal MF 800, ai 55% in butanol 25,9 Additive for Baysilone lacquers OL to 17 , 1% in xylene 2.0 Diluent 13.3 100.0 Diluent. Xilepo 75.0 Butapol 10.0 Ethoxypropanol 15,0 100.0 4 g of precipitated silica were mixed with stirring in 100 g of lacquer with a paddle stirrer at 2000 r.p.m. for 10 minutes. The viscosity of the mixture was regulated with xylene for a draining time of 20 sec (DIN, 4 mm nozzle). The lacquer was applied to a sheet by spraying with a dry film thickness of approximately 30 μm, leaving it to air and dried in an oven at 180 ° for 30 minutes Example 6 The technological application properties of the precipitated silicas were analyzed. according to Examples 1a-c, a silicic acid prepared according to German Patent DE 38 15 670 as well as a commercially available product (Nipsil 1009) in two additional test systems Lacquer CC Parts by weight Alftalat AN 950, 60% Solvesso 150 / butyl glycol 29,30 Solvesso 150 2,60 Titanium oxide Kronos 2059 33,60 Aerosil R 972 0.20 Dispersion. 40 hours in ball mill KU 5, 60 rpm, 4900 g alubit spheres of 19 mm Alftalat AN 950, 60% in Solvesso 150 / but? Glycol 13,00 Maprenal MF 900, 100% 8,10 Maprenal MF 577 , 50% in butanol 0.80 Butylghcol 2.00 Solvesso 150 2.90 Xiieno 6.70 DOW CORNING PA 57 0.60 p-Toluene-sulphoic acid, 20% in butanol 0.30 In total 100.00 Before application were dispersed in 150 parts by weight of lacquer 3.2 g of opaque agent with a paddle stirrer at 2000 rpm DD lacquer Parts in Dßso CAB 381 - 0.5 0.3 98% Butyl Acetate 11, 0 Acetate of ethoxypropyl 16.5 Desmophen 800 15,0 Desmophen 1100 20.0 Mowilit, 50% ethyl acetate 3.0 Baysilone lacquer additive 0, 1 Xylene 34.1 In total 100.00 First, 0.3 parts were dissolved by weight of CAB 381 - 0.5 by carefully adding them to 11.0 parts by weight of 98% butyl acetate and 16.5 parts by weight of ethoxypropyl acetate with the rapid stirrer. The remaining components were then added in the indicated sequence, homogenizing by stirring. Before the application the glossy lacquer was homogenized by the paddle stirrer. The opaque agent was dispersed in 100 parts by weight of lacquer (see quantity in Table 6) with a paddle agitator at 2000 rp After a deaeration time of 15 minutes, 50 g of the Desmodur L 75 hardener were added, homogenizing 2 minutes at 1000 r p.m. with the paddle agitator The mix was applied with a scraper with 200 micrometers of gap width, on a perfectly clean glass plate until then as well as on a lacquered / black glass plate with high gloss. The results of the checks on the lacquer CC are listed in Table 5 and those corresponding to the lacquer DD in Table 6. For the purposes of making comparisons, the silicic acids have been used according to German Patent DE 38 15 670 and the product of sale NIPSIL E 1009. The comparison of the obtained values can be done through the tables. w k1 or 1 to 2 tx or 3 of precipitated silica, prepared according to Example 1c of precipitated silicic acid, prepared according to Example 2c l tt O l * 4 C tt or 6 DD Example 7 Opaqueous efficiency is determined in different coating systems, the preparation and application of the lacquers being carried out in respectively analogous conditions. A high opaque efficiency means that the need (concentration) of opaque agent is small to reach a certain degree of opacity. gloss (measured at an angle of 60 °) The determination of the opaque efficiency of unknown opacifying agents is carried out in a relative manner, ie in comparison with known opacifying agents, so as to avoid variations in the determination of the degree of gloss (motivated by the preparation and application of the lacquer). An important physical-chemical parameter, which decisively influences the opacifying efficiency of silicic acid, is the distribution of the silicic acid granulometry. In principle it is valid that with the same precipitation procedures the opacifying efficiency of the silicic acid of precipitation decreases as the particle size decreases (and vice versa) The fine fractions of precipitated silicic acid show an opaque efficiency lower than a fraction of grinding thicker The high opacifying efficiency of the precipitated silicic acid according to the present invention has been verified in different coating systems, as indicated below tt O 7. Alkyd-melamine lacquer test for lacquers: alkylamide according to indications duct of Example 2c shows a greater opacity efficiency than the Syloid ED 5, even though this product is more the product 2a is more effective than the Nipsil E 1009 and that the Syloid ED 3 s > w o 7 (continued) »Tt o the 8 tests in DD lacquer lacquer DD lacquer theme according to instructions Syloid ED 3 comparison pipe c. = not determined tt or i? the 9 tests in DD lacquer ema of lacquer lacquer DD according to instructions Nipsil E 1009 comparison pipe c = not determined K > tt or A la 10 Coating coating tests ema lacquer coil Coating coating lacquer according to indications or) K »tt o 11 Tests in an acrylic dispersion (aqueous) lacquer theme Acrylic dispersion (MB 2399-134), watery, from Rohm & Haas comparison duct AQ 75 N M The determination of the grain size is carried out by means of a laser beam diffractometer from Malvern. Before the measurement, the silicic acid is dispersed in water with stirring and ultrasound, subsequently transferring the silicic acid dispersion by means of a pump to the beam path ( cuvette) of the Sheen measuring instrument "is the difference in the degree of brightness measured with an angle of 85 ° and the degree of brightness measured with an angle of 60 ° The determination of the viscosity is carried out by means of a 4 mm DIN glass The drainage time of the lacquer is measured in seconds in accordance with DIN 53 211 Mean Lacquer CC Coating Coating Lacquer DD Lacquer Desmodur Desmophen Desmodulation Desmodur isocyanate-based hardener Desmophen pohalcohol as a binder Desmodur / Desfibíbhen are registered trademarks of Bayer AG CAB Cellulose acetobutyrate A / M alkyd / melamine lacquer Example 8 Coating with emulsion of polyethylene wax Precipitating silica is prepared according to DE-OS 31 44 299, example 1 The filter cake (solids content 10.8% by weight) fluidized by the action of cutting forces is mixed with wax emulsion (5% wax based on silicic acid) and intensively stirred for an additional 30 minutes. The emulsion is carried out in an autoclave equipped with a disperser and steam-heated. In this, 4.8 parts by weight of an alkyl polyglycol ether (Marlowet® CFW) are initially dissolved at 100 ° C., 0 parts by weight of water at approximately 100 ° C. Then 14.2 parts by weight of low pressure ethylene wax are added and heated to 130 ° C. When reaching 130 ° C the disperser is connected and dispersed for 30 minutes, maintaining the temperature in this lapse between 130 ° C and 140 ° C. After stopping the disperser and cooling to about 110 ° C the ready emulsion is removed. The polyethylene wax used is characterized by the following properties- "Average molecular weight 1000 Freezing point 100-104 ° C Drip point 110-117 ° C Density (g / cm3) 0.93 The suspension of silicic acid thus coated with wax dry in a fast dryer (for example, in a spray dryer) by atomization (for example nozzles of two materials at 2.8 bar of air pressure) The grinding of the dried product is carried out in a mechanical sieve mill of the ZPS type 50 from Alpine The physical and chemical characteristics are reproduced in Table 12. Table 12 Table 13: Alkyd-melamine lacquer *) Degussa commercial products Table 14. DD lacquer *) Commercial products of Degus * sa It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (1)

1. CLAIMS 1 Silicic acid precipitation, characterized by the following physical-chemical parameters BET surface according to DIN 66131 m2 / g 400-600 DBP number according to DIN 53601 g / 100 g 300-360 Rolled weight according to DIN 53194 g / l 70-140 Value of gpndometer according to ISO 1524 μm 15-50 granulometric distribution index I measured with Malvern < 1, 0 index of granulométpca distribution I = 2dso 2 Procedure for the preparation of precipitated silicic acid with the following physico-chemical characteristics BET surface according to DIN 66131 m2 / g 400-600 DBP number according to DIN 53601 g / 100 c 300-360 Tamping weight according to DIN 53194 g / l 70-140 Gpndometer value according to ISO 1524 μm 15-50 granulométic I distribution index measured with Malvern < 1, 0 granulometic distribution index I = 2dso according to claim 1, characterized in that a precipitated silicic acid having the following physical-chemical properties is milled. BET surface according to DIN 66131 m2 / g 400-600 DBP number according to DIN 53601% 340-380 Tamping weight according to DIN 53194 g / l 180-220"Alpine0 sieve residue> 63 μm% by weight 25-60 by means of a sieve mill or a fluid bed counterjet mill. 3. Precipitated silicic acid coated by means of a polyethylene wax emulsion, characterized in that it has the following physical-chemical parameters: BET surface according to DIN 66131 m2 / g 351-600 DBP number according to DIN 53601% 300-360 Carbon content% 1-8 Tamping weight according to DIN 53194 g / l 70-140 Grindometer value according to ISO 1524 μm 15-50 granulométpca distribution index I < 1, 0 - 4. Process for the production of a precipitated silicic acid coated by means of a polyethylene wax emulsion according to claim 3, characterized in that a precipitation silicic acid having the following physicochemical properties: Surface BET according to DIN 66131 m2 / g 400-600 DBP number according to DIN 53601% 340-380 Tamping weight according to DIN 53194 g / l 180-220 ° Alpine0 sieving residue > 63 μm% by weight 25-60 is mixed with poiyethylene wax emulsion, dried and milled by means of a sieve mill or a fluid bed counterjet mill. 5. Process according to claim 4, characterized in that the silicic acid of the container is prepared, the cake is fluidized ... filtered by the action of cutting forces, mixed with emulsion of polyethylene wax. it is dried by atomization and milled by means of a sieve mill or a fluid bed counterjet mill. 6. Use of the precipitated silica according to claim 1 or 3 as an opaque agent in lacquer systems.