MXPA99011039A - Agents for unsticking paint, and sedimentation agents - Google Patents

Abstract

The invention relates to agents for unsticking paint, and/or sedimentation agents, containing amorphous alumina and/or alumina in pseudo-boehmite or boehmite form with a crystallite size of 0.1 to 15 nm and/or their hydrates and hydroxyalkyl polysaccharides.

Description

AGENTS TO REMOVE PAINT AND AGENTS OF SED MENTATION DESCRIPTION OF THE INVENTION This invention is related to a desespegante of paint and a sedimentation agent based on alumina nanoc r i s t ina s amorphous and / or hydrates of alumina. When applying lacquers, waxes, or similar coating materials containing organic substances which are not soluble in water, it sometimes happens that not all the material reaches the article intended to be coated. Especially when car bodies are painted, the paint that was sprayed excessively is deposited in the paint booths. The spray of paint or lacquer formed in these booths when articles are spray-painted, such as automobile bodies, is cleaned by an air flow, which produces recirculated water in contact with the excessive spray or a curtain of air. water, or is removed by other wet paint dew separators. To prevent adherent paint residues from clumping in the cleaning system and clogging the spray eliminators, the rolling heads and recirculation pumps, the spraying and sedimentation agents are used to make the particles paint coagulate in the wash water and precipitate. It is desirable to obtain a non-sticky, easily removable sediment in a single working cycle. Until now, many different additives have been tested as flocculants, coats of coats or coagulants. For example, it is known to use inorganic additives that contain aluminum, such as aluminum silicates, Xuminium sulfates, aluminum chlorides, aluminum oxides, aluminum hydroxides, or montmorillonites. In addition, a large number of organic auxiliaries are known which can be used alone or in combination with the aforementioned inorganic additives, for example, polyacrylamides, polymers, inorganic alcohols, po 1 oxides. ia 1 qu i 1 ene s, starches or cellulose. The use of smectite montmorillonites in combination with marble and cellulose limestone hydrate as a paint stripping agent is described in DE-A-34 21 270. US Patents 4,564,464 and 4,504,395 describe sespesants for high-content paint. solids, which contain bentonite, particularly hectorite as a main component and are mixed for economic reasons with montmorillonite or alumina bars and which also contain the usual additives, such as foam depressants and coagulants. The disadvantages of all of the prior art paint sspecs are their different effects on the different types of lacquers, such as NC, polyacrylate, polyester, or PU waxes and lacquers. In addition, when used for high solids, widely used, lacquer-based lacquers are inefficient because quantities of up to 50% by weight, based on the weight of the sprayed paint, are required to perform the function. of ses pe anna. DE 38 17 251 (EP 0 342 339) suggests the use of alumina-based paint samples (A1203) of the type of eudoboehmi tao boehmite in an amorphous X-ray form or with crystallites with a size of 2 to 15 nm. It has been reported in such a patent that much smaller quantities are required as compared to those of spe sis that contain bentonite and that such a system can be used as a one-component system or in combination with the customary defoamers or fuses. polymeric testosterone. The polymeric deflocculant Praestol 2415 (copolymer of a c r i 1 ami da / a c r i t o) manufactured by Stockhausen is described in the patent. Accordingly, it is an object of the present invention to provide a novel paint stripping agent and a settling agent that enable the efficient de-scrubbing function of lacquers that are used today particularly in the production of automobiles., that can be manufactured easily, and that are able to remove the lacquer to be d_estpeased from the water in a more efficient and faster way than until now. According to the present invention, the problem is solved by providing a composition, which contains: (a) one or more aluminum compounds in the form of amorphous alumina and / or alumina type s eudoboehmi tao boehmite having an average size of crystallite of between 0.1 to 15 nm and / or hydrates thereof, and (b) one or more hydroxy to 1 qui 1 polysaccharides, particularly hydroxide 1 qui 1 cellulose, having 0.5 to 6, particularly 2 to 4 groups hydroxyalkyl per unit ring on average, where the hydroxyalkyl groups, independently of one another, have from 2 to 6, particularly from 2 to 4 carbon atoms, with a weight percentage varying from 100: 2 to 100: 20, based on the ratio of total aluminum (as A1203) to hydroxy to Iqu i 1 polysaccharide. The aforementioned aluminum compounds can be dispersed in aqueous solutions, preferably, the hydroxides to which the polysaccharides have an average molecular weight of 20,000 to 800,000, particularly from 30,000 to 120,000 g / moles. The aluminum compound, such as A1203 may contain 1 to 20% by weight of hydrolysable aluminum salts which can be added to the composition before, or preferably after, the synthesis of alumina. in contact with water, they release the aluminum valencies, which in turn build Al-OH or Al-O bonds, while the counter-ion is released.The examples are A1 (N03) 3, A1C13, A12 (S04) 3 , A1 (HC00) 3, and A1 (CH3C00) 3. The composition can be used in spray booths as a concentrated / powdery aqueous solution or emulsion, substantially as a dry substance. , preferably contains from 2 to 25% by weight, particularly from 3 to 14% by weight of the aluminum compound, such as A1203, based on the total weight of the aqueous composition Preferably, the aqueous composition contains from 3 to 30% by weight , particularly from 6 to 25% by weight of dry mass in total. n is suitable as a paint stripping and / or settling agent and is preferably used in a weight ratio of composition, based on the dry mass, to the paint in the range of 0.2: 100 to 20: 100, particularly 1 : 100 to 10: 100, that is, in amounts of 0.2 to 20% by weight, particularly of 1 to 10% by weight, based on the weight of the lacquer to be disengaged. The desespesante must be specifically sold and stored in an anhydrous or concentrated form. In addition to paints or lacquers, other coating materials, such as waxes, corrosion inhibitors, or undercoats, can be weighed in the same way using the aforementioned proportions. The paint thinner is suitable for a wide variety of lacquers, paints, or other coating materials that can be sprayed and which can be used as a concentrated aqueous emulsion or as a powder, where each component alone or the entire composition it can be added to the washing water in the spray booths or to any other wet paint spray. The aluminas or hydrates of alumina used are either amorphous products in X-rays or s or udobo ehmi t a s or boehmites with crystallite sizes of 0.1 to 15 nm, particularly 0.3 to 15 nm (measured by X-ray diffraction in the reflector 0.21). The alumina particles having sizes according to this invention are positively charged and are capable of binding the lacquer particles which are usually negatively charged and making them flocculating. The ehmi t is a crystalline alumina that exhibits the typical boehmite reflections which, however, change slightly as a result of a larger amount of crystallization water. The boehmite has a value of 0.611 nm, while the eudoboehmi t has a value d greater than 0.611 nm, most less than 0.64 nm with the hkl reflection of 020.

The aluminas or alumina hydrates of this invention can be dispersed in water or acids. The particles formed by dispersion in water preferably have sizes in the range from 5 to 1,000 nm, particularly from 5 to 500 nm, and more preferably from 5 to 100 nm, for an amount greater than 90% by weight. The alumina s / h i d a s t s of alumina employed in accordance with this invention may contain water, which is linked either crystallographically or physically. The physical and chemical properties of alumina hydrates largely depend on the conditions of the manufacturing process. The alumina amines which can be dispersed in water or acids have been manufactured by the hydrolysis of aluminum alcoholate at a pH with a range of 1 to 11 particularly preferred. Various processes for producing the alumina s / hi dries of alumina of this invention are described below. To be able to produce aluminas that can be dispersed in water, preferably C2 to C12 aluminum alcoholates, are hydrolyzed with water having a pH in the range of 1 to 6. The resulting alumina can be dispersed in water or in dilution acids. The thus obtained alumina agglomerates can optionally be decomposed by dilution acids, such as hydrochloric acid, nitric acid, acetic acid, formic acid, propionic acid, chloroacetic acid, and lactic acid. They can additionally be decomposed to their primary particles by adding aluminum salts and / or by hydrothermal aging. Instead of dispersing the resulting aluminas in acid, it is also possible to spray the acids in the alumina agglomerates so that they can be used directly as aluminas that can be dispersed in water. In addition, alumina can be produced by adding gaseous acids as set forth in DE-A-24 08 233. In the case where electrolyte-free emulsions are employed, the hydrolyzed aluminas can also be processed to form electrolyte-free emulsions by applying a force highly shearing, for example, that which occurs in colloid mills. The aluminas manufactured by hydrolysis can also be produced after a special treatment by precipitation from aluminum and alumina salts, or by any of the processes described herein and can also additionally contain such aluminum salts, which can be added afterwards. or during the production of hydrates from alumina to alumina. Examples of aluminum salts are A1 (N03) 3, A1C13, Al2 (S04) 3, A1 (HC00) 3, and A1 (CH3C00) 3. According to DE 24 08 233-C2, the boehmite which can be dispersed in acid which is commercially available, can be subsequently treated, for example, by exposure to gaseous acids, such as hydrogen chloride N02, in a fluidized bed . By adding water to the powders prepared in this manner, emulsions having a high dispersibility are obtained. According to EP 0 505 896 A1, commercially available alumina hydrates of different crystalline structures (eg, mono or alumina trihydrates) are used to produce boehmite which can be dispersed in water. A dissolving process, the highly crystalline aluminum component reacts with a large amount of nitric acid, at a pH value of less than 3.5 and at elevated temperature and pressure. The resulting boehmite alumina hydrates are crystalline and can be dispersed in water. Such materials present in crystallite sizes greater than 6 nm (measured in reflector 021). According to the process set forth in DE 43 37 643 (WO 95/12547), the amorphous or non-toxic alumina that can be dispersed in water of tria 1 coho 1 at os of aluminum or of mono or di to 1 Coho 1 partially substituted aluminum atoms are converted by hydrolysis and polycondensation to temperatures of 60 ° C to 110 ° C in the presence of specific amounts of monovalent organic or inorganic acids or their anhydrides as inhibitors of polymerization to produce alumina hydrates na non-crystalline 1 i s not having an amorphous or boehmite structure. The polymerization inhibitors can be inorganic acids, particularly hydrochloric acid, or HCl gas, nitric acid, or N02 gas, carbonic acid or CO2, or organic acids, particularly formic acid, acetic acid, propionic acid or the anhydrides thereof, or short chain organic monovalent acids. Such processes are particularly suitable to reduce the water quality while simultaneously maintaining or improving water dispersibility. By incorporating such polymerization modifiers it is possible to avoid the three-dimensional bonding of the Al -OH groups. An additional amount of acid can be added to the resulting alumina hydrate and, optionally, the aqueous alumina hydrate suspensions are they can undergo a hydrothermal post-aging in which the alumina hydrate particles are stabilized without altering their structures in such a way that the subsequent drying step will prevent the aggregation of primary agglomerates. The formation of larger primary agglomerates deteriorates the spectrum of properties of the composition with respect to the paint stripping agent. Such processes allow to produce in a direct way hydrated alumina of boehmite nano c r i s t a 1 ina showing a low tendency to agglomeration of first particles and having a crystallite size of <4.0 nm (measured in reflector 021). These alumina hydrates can be dispersed in water and produce transparent translucent emulsions. EP 0 342 339-Al and WO 95/12547 are explicitly incorporated herein for reference. The hydr oxia 1 qui 1 polysaccharides are derived polysaccharides which, for example, are obtained by the reaction of polysaccharide compounds with epoxy compounds, such as an ethylene oxide, butylene oxide or propylene oxide. They may comprise one or more hydroxyalkyl groups, based on a saccharide ring unit. After reaction with a hydroxyl group of the saccharide ring the hydroxyalkyl group can form an ether linkage or an additional ether linkage with a hydroxyl group of a hydroxyalkyl group already incorporated. The incorporation of the hydroxy alkyl groups usually occurs randomly. Preferably, the hydroxyalkyl groups comprise secondary hydroxyl groups. The unit of g 1 uc op anus if it gives hydroxypropyl cellulose (CAS name: 2-hydroxypropyl cellulose, CAS-RN 9004-64-2) with three hydroxypropyl groups is given as a example.

Unit of ß-D- 1, 4-g 1 ucop ir year of hydroxypropylcellulose For example, suitable hydroxyl and 1alkyl polysaccharides have a matrix of amylopectin, amylose, dextran, xanthan, glycogen, or cellulose, the latter being particularly preferred The hydroxyalkyl group of the hydroxides to which the polysaccharides can have from 2 to 6, preferably from 2 to 4 carbon atoms. Hydroxypropylcellulose is particularly preferred. In addition, the paint thinners of this invention can contain, as mentioned above, for example from 0 to 10% by weight, preferably from 3 to 6% by weight of acids, such as hydrochloric acid, nitric acid, formic acid, acid acetic acid, lactic acid, chloroacetic acid, and / or propionic acid, which require as counter-ion the equivalent amount of aluminum or alumina ions. Optionally, paint coatings can also contain customary foam depressants or any other polymeric cell. E jsp 500 ml of water and 5 ml of lacquer were placed in a mixer to be disengaged.

After intensive mixing, for 5 minutes, 100 ml of the mixture was transferred to a 130 ml polyethylene cylinder provided with a layer. 0.2 ml of deseshing paint emulsion containing 7.5% A1203 was added. The cylinder was placed upside down in a rotating apparatus where it was rotated for 30 minutes at 60 rpm. The cylinder was removed from the apparatus and the mixture was allowed to rest for 5 minutes, after which the height of the de-weaning lacquer deposit was measured in m. After 10 and 30 minutes of rest, part of the supernatant fluid was pipetted out of the top of the cylinder. The transmission of the supernatant was measured using a photometer (1 cm cuvette, wavelength 450 nm). The efficiencies of several of the paint s are compiled in the following tables and are illustrated in the graphs attached to them. Paint compositions (as aqueous solutions) contain: Paint Defroster 1 (Comparative Example) Solution P3 Alumina 7.5% by weight (as A1203) Paint Defroster 2 Solution P3 Alumina 7% by weight (as A1203 ) Aluminum nitrate 1.05% by weight (based on an amount of Al (N03) 3 x 9 H20 used, which is equal to 0.25% by weight as A1203) Hydroxypropylcellulose 0.5% by weight (Klucel® EF) paint 3 Alumina 7.5% by weight (as A1203) Hydroxypropylcellulose 0.5% by weight (Klucel® EF) The P3 solution of alumina manufactured by RWE-DEA AG für Mineraloel und Chemie according to the process established in DE 43 37 643 is commercially available . The alumina in the paint thinner 3 was prepared by hydrolysis of 250 g of 6.4% by weight of solution of aluminum hexanolate in hexanol at 90 ° C in 500 ml of 2.78% nitric acid. The resulting amorphous X-ray powder contained 50.5% by weight of alumina and 22.7% by weight of nitrate. The aqueous phase was spray dried after the separation phase. Klucel® EF is a product produced by Aqualon with an average molecular weight of 80,000 g / mole (determined by size exclusion chromatography (SEC)).

Claims (9)

1. composition suitable as detackifier paint and / or sedimentation agent containing (a) one or more aluminum compounds in the form of: - amorphous alumina and / or alumina type s eudoboehmi boehmite tao having a crystallite size average 0.1 to 15 nm, as measured by the X-ray diffraction in the 021 reflector, and / or the hydrates thereof, and (b) one or more hydroxyl 1 1 polysaccharides, particularly hydr ox 1 1 cellulose, which has 0.5 to 6 groups of hydroxyl 1 to 1 or per ring unit on average, where the hydroxyalkyl groups, independently of each other, have 2 to 6 carbon atoms, with a weight percentage that varies from 100: 2 to 100: 20, based on the total aluminum average, calculated as A1203, at the hydr oxia 1 qui 1 polysaccharide.

2. Composition according to claim 1, characterized in that the hydroxy to 1 qu and 1 polysaccharide is hydroxypropyl cellulose.

3. Composition according to the rei indication 1, characterized in that the hydroxy to which the polysaccharide has an average molecular weight of 20,000 to 800,000 g / moles.

4. Composition according to any of the preceding claims, characterized in that 1 to 20% by weight of the aluminum compound, calculated as A1203, consists of a hydrolysable aluminum salt or water added in this form to the composition. Composition according to any of the preceding claims, characterized in that the composition additionally contains water. 6. Composition according to claim 5, characterized in that the composition contains from 2 to 25% by weight of the aluminum compound, calculated as A1203, as a s or 1 aqueous ion / emu 1 s ion. 7. Composition according to claim 5 or 6, characterized in that the aqueous composition contains from 3 to 30% by weight of more dry. 8. Use of the composition according to any of the preceding claims, such as paint stripping and / or sedimentation agent. 9. Use of the composition as a paint thinner and / or sedimentation agent according to claim 8, wherein the composition is used in a weight percentage of composition, based on the dry mass, for coating material to be weighed from 0.2: 100 to 20: 100.