A concentrated liquid adjuvant and fertilizer composition containing a nitrogen source, an ampholytic surfactant, a drift control agent/deposition aid, and a carrier is disclosed. The concentrated composition is phase stable, and provides a nitrogen source and/or adjuvant, and a drift control agent/deposition aid, in a single package.

The present invention relates to a concentrated liquid adjuvant and fertilizer containing a nitrogen source and a drift control agent/deposition aid. The present composition is phase stable over extended storage periods.
Dry and liquid adjuvants and fertilizers are available to both the agricultural and nonagricultural markets, and each type of product has its advantages and disadvantages. For example, dry adjuvants and fertilizers have the advantages of containing a high concentration of active ingredients, and the ability to incorporate various ingredients into the composition to increase the efficacy of the composition. However, many dry adjuvants and fertilizers have a disadvantage in that they must be dissolved before use, which can be hazardous and require substantial mixing and long dissolving times.
In addition, the use of dry fertilizers and adjuvants are problematic because their solubility in water varies with various water qualities throughout the United States. Water temperatures, pH hardness, and mineral content all affect the ease of dispersing or dissolving the fertilizer and adjuvants into the spray mixture. This unpredictable solubility has been a problem for end users applying herbicides to kill weeds. The end users typically prepare herbicidal mixtures using cold water, under varying conditions, and frequently outdoors where solubility problems cannot be satisfactorily resolved. The end users then face the problem of applying a suspension of fertilizer and adjuvant in water with the herbicide. The suspension can plug conveying lines, or cause an uneven application of the fertilizer and herbicide on vegetation, which results in an uneven kill rate and directly exposes an end user preparing the solution to undesirable herbicide and fertilizer contact.
In addition, significant differences in particle sizes between the individual components in a dry product can result in particle separation during shipping and/or storage. This leads to a nonhomogeneous composition which, if applied without remixing, can lead to poor results or cause damage to treated vegetation. Furthermore, inherent tackiness or particle fines generated through attrition can result in compaction and/or caking before the end user applies the dry adjuvant and fertilizer.
Liquid adjuvants and fertilizers overcome the disadvantages of long dissolving times and particle separation. But, due to solubility limitations, liquid adjuvants and fertilizers are limited in the number and amount of components present in the liquid composition. In addition, incompatibilities between different composition components makes several liquid fertilizer compositions impossible to manufacture or store for extended time periods.
The inability to solubilize high percentages of active components in a liquid adjuvant or fertilizer is a major disadvantage. In particular, concentrated liquid adjuvants and fertilizers are required to avoid the high cost of shipping large amounts of water. Concentrated liquid adjuvants and fertilizers also have the problem of phase stability because solid components tend to precipitate or settle from the composition, or liquid components tend to form separate liquid phases.
For both dry and liquid adjuvants and fertilizers, it is desirable to incorporate several different ingredients, in a high concentration (if needed), into a single composition. For example, it is desirable to incorporate a fertilizer component, an adjuvant, a spreader-sticker (i.e., a deposition aid), a drift control agent, an antifoaming agent, and a pesticide (if desirable) into a single product. A single, multipurpose composition eliminates a need for the end user to inventory a large number of different chemicals. In addition, application of the chemicals is made easier and less hazardous, with a reduced chance of misapplication, because only one product is measured, dissolved, and applied. Combination adjuvants and fertilizers also are more environmental friendly because fewer empty containers are generated, and fewer chemical containers are stored for long periods.
When an adjuvant is used in conjunction with an herbicide, a barrier to maximizing herbicide performance, especially at the lowest possible labeled use rates, is the application technique itself. In an effort to ensure the herbicide is applied within intended boundaries (i.e., does not drift), conventional sprayers utilize nozzle tips that produce large spray droplets. Research has shown that these large droplets are not retained by many species of vegetation, and, consequently, herbicide efficacy is reduced.
Attempts have been made to include various polymers with the fertilizer in a liquid formulation to improve the solubility and dispersibility of the fertilizer in water of a wide quality range. Unfortunately, commonly used polyacrylamide-based polymers and other organic polymers, such as xanthan gum, have not been successful in solubilizing or dispersing efficacious concentrations of fertilizers in an aqueous solution.
Accordingly, investigators have continually sought concentrated liquid adjuvants and fertilizers that can perform more than one function. This has proven difficult because as the concentration fertilizers and adjuvants in a liquid product increases, the phase stability of the liquid product decreases. The present invention, therefore, is directed to a concentrated liquid adjuvants and fertilizer, further containing a drift control agent/deposition aid, that is phase stable over extended storage periods.
The present invention is directed to liquid adjuvants and fertilizer compositions containing a high concentration of a nitrogen compound and a drift control agent/deposition aid. The compositions are phase stable liquids that can be stored for extended periods without observing solid-liquid or liquid-solid phase separation.
More particularly, the present invention is directed to a concentrated adjuvant and fertilizer composition containing (a) about 25% to about 35%, by weight of the composition, of a nitrogen compound in the form of an ammonium salt, (b) about 0.1% to about 5%, by weight of the composition, of an ampholytic surfactant, (c) about 0.1% to about 2.5%, by weight of the composition, of a drift control agent/deposition aid, typically a gum, like guar gum, and (d) about 55% to about 75% of a carrier comprising predominantly water.
Accordingly, one aspect of the present invention is to provide a phase stable, concentrated liquid adjuvant and fertilizer for the agricultural and nonagricultural markets.
Another aspect of the present invention is to provide a readily dispersible or soluble liquid adjuvant and fertilizer composition, that can be rapidly diluted in the field, and, after dilution, applied as a low drift spray that remains on sprayed vegetation.
Another aspect of the present invention is to provide an adjuvant that can be blended with an herbicide, like glyphosate, and water to provide a herbicidal blend for application to vegetation.
These and other aspects and advantages of the present invention will become apparent from the following, nonlimiting detailed description of the preferred embodiments.
The present concentrated liquid adjuvant and fertilizer composition comprises, by weight of the composition:
(a) about 25% to about 35% of a nitrogen compound in the form of an ammonium salt;
(b) about 0.1% to about 5% of an ampholytic surfactant,
(c) about 0.1% to about 2.5% of a drift control agent/deposition aid, and
(d) about 55% to about 75% of a carrier.
The composition can further contain optional ingredients, like pH adjusters and preservatives, in an amount sufficient to perform their intended function.
The present compositions can be used as an adjuvant, a fertilizer, or both. The end use varies depending upon the identity of the nitrogen compound and the compatibility of the composition with a pesticide, like an herbicide. As used in this application, the term xe2x80x9cadjuvantxe2x80x9d is defined as a composition that is blended with a pesticide to improve the efficacy of the applied pesticide.
The present compositions can be used as adjuvants when compatible with the pesticide of interest. The advantages of using an adjuvant with various herbicides, like glyphosate, is well known in the art. For example, Gednalske et al. U.S. Pat. No. Re. 36,149, incorporated herein by reference, summarizes the advantages of applying glyphosate and a fertilizer, in combination, to increase the efficacy of the glyphosate. One advantage is that a combination of fertilizer and herbicide accelerates the uptake of the herbicide by leaves of the vegetation, thereby substantially increasing the efficacy of the herbicide. In addition to use as an adjuvant, the present compositions can be used as a nitrogen fertilizer due to the high concentration of nitrogen compound in the compositions.
The present compositions are phase stable liquids. The compositions typically are applied at a rate of about 2.5 to about 5 gallons of the composition diluted with sufficient water and/or other ingredients, e.g., an herbicide, to provide 100 gallons of a spray solution. The composition is readily dispersible in water, and the spray solution exhibits minimal to no drift when properly applied.
The present concentrated liquid adjuvant and fertilizer compositions contain about 25% to about 35%, and preferably about 30% to about 35%, by weight of a nitrogen compound in the form of an ammonium salt. It is preferred that the ammonium salt present in the composition is near, but below, the solubility limit of salt in 25xc2x0 C. water. However, for any ammonium salt that can provide an aqueous solution containing greater than about 35% by weight of the salt, the amount of ammonium salt in the present compositions should not exceed about 35% by weight, otherwise phase stability problems can occur.
The ammonium salt utilized as the nitrogen source is not limited, and can be any ammonium salt known to persons skilled in the art. Nonlimiting examples of ammonium salts that can be used in a present adjuvant and fertilizer composition include, but are not limited to, ammonium sulfate, ammonium chloride, ammonium metaphosphate, ammonium nitrate, diammonium phosphate, monoammonium phosphate, ammonium phosphate nitrate, ammonium phosphate sulfate, ammonium polyphosphate, ammonium sulfate nitrate, ammonium thiosulfate, ammonium polysulfide, and mixtures thereof. Preferred ammonium salts are ammonium sulfate, diammonium phosphate, and monoammonium phosphate. Ammonium sulfate is an especially preferred salt for use in an adjuvant, particularly in an adjuvant designed for use with the herbicide glyphosate.
In addition to the nitrogen compound, a present concentrated liquid adjuvant and fertilizer contains about 0.1% to about 5%, and, preferably about 0.25% to about 4%, by weight of the composition of an ampholytic surfactant. To achieve the full advantage of the present invention, the composition contains about 0.5% to about 3%, by weight of the composition, of an ampholytic surfactant.
The ampholytic surfactant present in the adjuvant and fertilizer composition is stable and water soluble at both alkaline and acidic pH values. It has been found that nonionic, cationic, and anionic surfactants cannot be used in the method of preparing a present composition, and do not impart sufficient phase stability to the concentrated liquid composition.
Ampholytic surfactants can be broadly described as derivatives of secondary and tertiary amines having aliphatic radicals that are straight chain or branched, and wherein one of the aliphatic substituents contains from about 8 to 18 carbon atoms and at least one of the aliphatic substituents contains an anionic water-solubilizing group, e.g., carboxy, sulfonate, sulfate. Examples of compounds falling within this description are sodium 3-(dodecylamino)propionate, sodium 3-(dodecylamino)propane-1-sulfonate, sodium 2-(dodecylamino)ethyl sulfate, sodium 2-(dimethylamino)octadecanoate, disodium 3-(N-carboxymethyl-dodecylamino)propane-1-sulfonate, disodium octadecyliminodiacetate, sodium 1-carboxymethyl-2-undecylimidazole, and sodium N,N-bis(2-hydroxyethyl)-2-sulfato-3-dodecoxypropylamine.
More particularly, one class of ampholytic surfactants include sarcosinates and taurates having the general structural formula:
wherein R1 is C11 through C21 alkyl, R2 is hydrogen or C1-C2 alkyl, Y is CO2M or SO3M, M is an alkali metal, and n is a number 1 through 3. In preferred embodiments, R1 is predominantly C12-C14, or predominantly C12-C18. The term xe2x80x9cpredominantlyxe2x80x9d is defined as at least 75% of the R1 groups are within the disclosed carbon chain length.
Another class of ampholytic surfactants is the amide sulfosuccinates having the structural formula:
The following classes of ampholytic surfactants also can be used:
Additional specific examples of ampholytic surfactants useful in the present invention are sodium coconut N-methyl taurate, sodium oleyl N-methyl taurate, sodium tall oil acid N-methyl taurate, sodium palmitoyl N-methyl taurate, cocodimethylcarboxymethylbetaine, lauryldimethylcarboxymethylbetaine, lauryldimethylcarboxyethylbetaine, cetyldimethylcarboxymethylbetaine, lauryl-bis-(2-hydroxyethyl)carboxymethylbetaine, oleyldimethylgammacarboxypropylbetaine, lauryl-bis-(2-hydroxypropyl)-carboxyethylbetaine, cocoamidodimethylpropylsultaine, stearylamidodimethylpropylsultaine, laurylamido-bis-(2-hydroxyethyl)propylsultaine, disodium oleamide PEG-2 sulfosuccinate, TEA oleamido PEG-2 sulfosuccinate, disodium oleamide MEA sulfosuccinate, disodium oleamide MIPA sulfosuccinate, disodium ricinoleamide MEA sulfosuccinate, disodium undecylenamide MEA sulfosuccinate, disodium what germamido MEA sulfosuccinate, disodium wheat germamido PEG-2 sulfosuccinate, disodium isostearamideo MEA sulfosuccinate, cocoamphoglycinate, cocoamphocarboxyglycinate, lauroamphoglycinate, lauroamphocarboxyglycinate, capryloamphocarboxyglycinate, cocoamphopropionate, cocoamphocarboxypropionate, lauroamphocarboxypropionate, capryloamphocarboxypropionate, dihydroxyethyl tallow glycinate, and mixtures thereof. Preferred surfactants are the taurates and sarcosinates. Most preferred surfactants are the taurates. Mixtures of surfactants, especially mixtures of taurates, are particularly preferred to provide maximum composition phase stability.
In addition to the ammonium salt and ampholytic surfactant, the present concentrated adjuvant and fertilizer compositions contain about 0.1% to about 2.5%, and preferably about 0.25% to about 1.75%, by weight of the composition, of a drift control agent/deposition aid. To achieve the full advantage of the present invention, the drift control agent/deposition aid is present at about 0.5% to about 1.5%, by weight of the composition.
In addition, the ampholytic surfactant and drift control agent/deposition aid are present in a weight ratio of about 3 to 1 to about 1 to 5, and preferably about 2 to 1 to about 1 to 4. To achieve the full advantage of the present invention, the weight ratio of ampholytic surfactant to drift control agent is about 1 to 1 to about 1 to 3.
A drift control agent/deposition aid helps eliminate small droplets (e.g., less than 150 microns) from a spray. The drift control agent/deposition aid helps provide a cohesive stream of spray, thereby preventing airborne spray droplets from contacting vegetation outside the intended point of application. The drift control agent/deposition aid also helps keep the spray droplets in contact with the sprayed vegetation.
The drift control agent/deposition aid typically is a polymeric compound, and more typically is a gum. Nonlimiting examples of gums, and related hydrophilic colloids, that can be used as the drift control agent/deposition aid in the present fertilizer composition include, but are not limited to, acacia, agar, algin, ammonium alginate, carboxymethyl hydroxyethylcellulose, carboxymethyl hydroxypropyl guar, carrageenan, cellulose gum, damar, dextran, dextrin, gelatin, guar gum, gum benzoin, hydroxybutyl methylcellulose, hydroxypropylcellulose, hydroxypropyl guar, hydroxypropyl methylcellulose, jalap resin, karaya gum, kelp, locust bean gum, maltodextrin, methylcellulose, olibanum, pectin, propylene glycol alginate, sandarac gum, sodium carboxymethyl dextran, tragacanth gum, xanthan gum, and mixtures thereof. A preferred drift control agent/deposition aid is guar gum. A preferred drift control agent/deposition aid is guar gum or a guar gum derivative. Various guar gum and guar gum derivatives are disclosed in Hazen U.S. Pat. Nos. 5,550,224; 5,705,173; and 5,874,096, incorporated herein by reference. Commercially available guar gums are Ag-RHO(copyright) DEP-775 and Ag-RHO(copyright) DR-2000, available from Rhodia, Cranbury, N.J.
The nitrogen compound, surfactant, and drift control agent/deposition aid are dissolved or dispersed in a carrier, typically water. The carrier is present in a concentrated liquid adjuvants and fertilizer compound in an amount of about 55% to about 75% by weight of the composition. The carrier can be water, or can be predominantly water together with a water miscible organic solvent. Nonlimiting examples of water-miscible organic solvents include C1-C4 alcohols, e.g., methanol, ethanol, isopropyl alcohol, and butanol, a glycol, e.g., ethylene glycol, diethylene glycol, or propylene glycol, a ketone, e.g., acetone or methyl ethyl ketone, a glycol ether, e.g., a C1-C4 ether of ethylene glycol or propylene glycol, and other similar water-miscible solvents.
The solvent, if present at all, comprises 0% to about 10%, and preferably 0% to about 5%, by weight of the composition. The solvent is used to help dissolve or disperse composition ingredients or to adjust composition viscosity.
The concentrated adjuvant and fertilizer composition of the present invention also can contain various optional ingredients. An optional ingredient is present in a sufficient amount to perform its intended function and not otherwise adversely affect the composition, usually 0% to about 1% by weight of the composition. The optional ingredients typically are present in a total amount of 0% to about 5%, by weight of the composition.
An example of an optional ingredient is a pH adjuster, either basic or acidic. The pH adjuster provides a proper pH range for a more facile manufacture of the composition, and a preferred final pH for the composition. A proper final pH also helps impart phase stability to the fertilizer composition. Proper pH adjustment also precludes the undesirable evolution of ammonia from the fertilizer composition.
Examples of preferred classes of basic pH adjusters are ammonia; mono-, di-, and tri-alkyl amines; mono-, di-, and tri-alkanolamines; alkali metal and alkaline earth metal hydroxides; and mixtures thereof. However, the identity of the basic pH adjuster is not limited, and any basic pH adjuster known in the art can be used. Specific, nonlimiting examples of basic pH adjusters are ammonia; sodium, potassium, and lithium hydroxide; monoethanolamine; triethylamine; isopropanolamine; diethanolamine; and triethanolamine.
Examples of preferred acidic pH adjusters are the mineral acids and polycarboxylic acids. Nonlimiting examples of mineral acids are hydrochloric acid, nitric acid, phosphoric acid, and sulfuric acid. Nonlimiting examples of polycarboxylic acids are citric acid, glycolic acid, and lactic acid. The identity of the acidic pH adjuster is not limited and any acidic pH adjuster known in the art, alone or in combination, can be used. The preferred acidic pH adjuster is a polycarboxylic acid, e.g., citric acid.
Another optional ingredient can be a preservative, which is added to the composition in a sufficient amount to prevent microbial growth in the fertilizer composition during storage of the composition. Nonlimiting examples of preservatives include formaldehyde, formaldehyde precursors, a paraben, DEDM hydantoin, diazolidinyl urea, DMDM hydantoin, glyoxal, imidazolidinyl urea, MDM hydantoin, methylchloroisothiazolinone, methyl isothiazolinone, benzoic acid, sodium benzoate, other preservatives that are well known in the art, and mixtures thereof. Additional optional ingredients include, for example, chelating agents, antifoam agents, viscosity modifiers, suspending agents, and dyes.
As previously stated, difficulties encountered in designing and manufacturing liquid adjuvants and fertilizers include incorporating a sufficiently high concentration of ingredients into the composition to render the composition cost effective and providing a phase stable composition. Providing a phase stable, concentrated composition is difficult because the active adjuvant and fertilizer components desirably are present near their saturation limit. In accordance with an important feature of the present invention, a method of manufacturing a concentrated liquid adjuvant and fertilizer is disclosed, wherein the resulting concentrated composition is phase stable over extended storage periods.
The term xe2x80x9cphase stablexe2x80x9d is defined as a composition that can be stored under normal storage conditions (i.e., about 10xc2x0 C. to about 50xc2x0 C.) for at least six months without a settling or precipitation of solid components from the composition, and without stratification of the composition into two or more liquid layers. Phase stability is an important property with respect to providing a homogeneous fertilizer composition. If phase stability is lacking, concentration differentials can result from the top to the bottom of the container. This concentration differential could result in applying an incorrect amount of fertilizer to the vegetation. To overcome such a problem, the end user would have to stir the container contents prior to each use to ensure a homogeneous solution. This is both a time-consuming and costly process.

Concentrated liquid adjuvant and fertilizer


Active compositions are deposited by means-of an impregnating process onto structured supports, where the impregnating medium has a surface tension of not more than 50 mN/m. Monoliths are made from the structured supports thus produced. The structured supports or the monoliths are used as catalysts in chemical processes.

The present invention relates to an impregnating process for the application of active composition to structured supports or monoliths. Furthermore it relates to catalytically active structured supports and monoliths which are produced by means of this process and to processes in which they are used as catalysts.
By structured supports we mean, within the scope of this invention, supports having a regular two-dimensional or three-dimensional structure, which thus differ from particulate supports used as a bulk bed. Examples of structured supports are supports composed of threads or wires, mostly in the form of supporting webs, such as woven fabrics, single-thread or multi-thread knit fabrics, or felts, or metal plates, which may exhibit recesses, such as perforated plates or expanded metal. Such substantially two-dimensional, structured supports can be converted to three-dimensional structures, so-called monoliths, having a shape appropriate to their end use, which structures can then be used as, say, catalyst packs or column packings. Packings may be composed of more than one monolith. Alternatively, monoliths need not be composed of two-dimensional supporting webs, but can be made directly, without inter-mediate stages, such as is the case with ceramic monoliths having flow channels, these being known to the person skilled in the art.
Active compositions can be applied to structured supports or monoliths so as to impart catalytic activity to the structured supports or monoliths. By active compositions we mean catalytically active substances or mixtures of substances containing at least one catalytically active ingredient. They can in addition contain further catalytically active ingredients, auxiliary substances and/or promoters for influencing the catalytic properties such as selectivity, activity and/or on-stream time. Catalytically active structured supports or catalytically active, monoliths are used eg in processes in which the use of a bulk catalyst bed is disadvantageous for example for fluid dynamic or reaction-kinetic reasons. Typical fields of application are their use for exhaust gas purification, primarily in automobiles, their use as catalyst packs in vapor-phase or liquid phase reactors or their use as column packings in reactive distillations.
Various techniques are known for application of active compositions to structured supports and for the production of catalytically active monoliths composed thereof, or for application of active compositions to monoliths.
Thus EP-A 198,435 discloses the vapor deposition of catalytically active substances and promoters onto net-like or woven supports. Catalyst packs for the detoxication of exhaust gas are prepared from these vacuum-metallized support materials. EP-A 564,830 teaches the production of catalyst packs, known as monoliths, by tempering a metallic support mate-rial in air, cooling, coating the support material with active components and promoters by vapor deposition in vacuo followed by cutting, shaping and processing to form monoliths. EP-A 412,415 teaches the vapor deposition of palladium and a metallic inhibitor to a structured support and also the use of the thus prepared catalysts for the hydrogenation of triple bonds to double bonds, eg hydrodehydrolinalool to hydrolinalool.
By the use of vapor deposition it is possible to apply the active composition to the support materials, very uniformly and normally without the formation of agglomerates of undesirable magnitude, in the form of firmly adhering fine particles, which method is, however, relatively time-consuming and technically elaborate, particularly when relatively large amounts of active composition are to be applied. The vapor deposition must be carried out in vacuo, which requires a batch process involving comparatively long set-up times, or high vacuum pump capacities in continuous plants. There has thus been no lack of attempts to prepare the active composition by the impregnating process well known to the person skilled in the art from the manufacture of catalysts on bulk supports in particulate form.
For this purpose a so-called xe2x80x9cwash coatxe2x80x9d is frequently applied to a pre-formed monolith, this being a coating composed of a finely divided oxidic catalyst-supporting powder, which is in turn coated with catalytically active substances. This mostly takes place by impregnation of the monolith with a suspension which contains the oxidic powders already provided with active composition, or the oxidic powders and precursors of the active composition, drying and, where applicable, conversion of the precursors to the active composition. Conventional processes for the application of wash coats are disclosed eg in DE-A 4,135,055 and DE-A 3,915,685. U.S. Pat. No. 4,746,537 discloses a process for coating a ceramic monolith with xcex3-aluminum oxide precipitated in situ from the vapor phase. The monolith thus coated with finely divided alumina is then impregnated with a solution of salts of catalytically active metals, dried and calcined.
Wash-coated monoliths however show unsatisfactory properties, usually due to the fact that when the coating is applied by impregnation under active flow conditions precipitation preferentially takes place at the upstream end of the monolith or when the monolith is lifted out of a non-flowing impregnation bath precipitation preferentially takes place at that end of the monolith which is last in contact with the liquor, and in addition, there is poor adhesion of such a coating. As a result, comparatively large amounts of catalytically active material can become detached and, eg in the case of an automobile, be removed through the exhaust or, in the case of a chemical plant, be deposited at some other site. Such deposits can consititute a considerable safety risk, particularly when they catalyze exothermal reactions at an uncooled site.
Thus the attempt has also been made to apply active material or a pulverulent support material for active material to structured support materials, using an impregnating process, prior to shaping of the latter to form monoliths.
EP-A 68,862 discloses the preparation of units comprising on the one hand hydrophilic woven, knitted or felted fabrics of textile material, and on the other hand, open-mesh hydrophobic material coated with catalytically active substances, the catalytically active substancesxe2x80x94ie platinum crystallites on a finely divided carbon supportxe2x80x94being applied as aqueous suspension to the hydrophobic material and fixed by drying and sintering at elevated temperature. EP-A 56,435 teaches a continuous process in which metallic webs are passed through a dip bath, in which they are coated with an adhesive resistant to high temperature, eg a ceramic adhesive, and are then coated with a granular support material for the catalytically active substances. The substances deposited in the dip bath are then dried and the metallic web is fabricated to form monoliths
These impregnating processes suffer from the drawback, however, that the applied substances are not deposited on the structured support uniformly and or in uniform particle size. The particles always agglomerate to form comparatively large lumps. Such agglomeration is accompanied by a loss of active surface, and the activity of such catalysts is therefore always unsatisfactory. Furthermore, such agglomerated material as occurs in wash coats readily detaches itself from the support, particularly when the structured supports provided with active composition are being processed to form the monoliths, but also during industrial use of the monoliths, which likewise leads to the drawbacks described above with respect to wash coats.
Thus the problem to be solved is to find an industrially simple process for the application of catalytically active substances to structured supports, which avoids the drawbacks of the known processes.
Accordingly, we have found an impregnating process for the application of catalytically active substances to structured supports or monoliths, which is characterized in that an impregnating medium having a surface tension of not more than 50 mN/m is used. Furthermore we have found monoliths produced by means of the impregnating process of the invention or composed of catalytically active structured supports prepared by means of the impregnating process of the invention, and also heterogeneously catalyzed processes in which these structured supports or these monoliths are used as catalyst.
The drawing illustrates a specific embodiment of the impregnating process of the invention.
The impregnating process of the invention is industrially simple to carry out and leads to a surprisingly homogenous deposition of very small and firmly adhering particles of active substance, without agglomeration occurring. Comparatively large amounts of active composition can be deposited in a simple manner. The catalytically active structured supports produced by the impregnating processes of the invention can be shaped to catalytically active monoliths without noticeable detachment of active composition, and these monoliths can be used as catalysts for chemical reactions without active composition being removed to any appreciable extent
The structured supports used are usually substantially two-dimensional structured supports, eg woven fabrics, single-thread or multi-thread knit fabrics, felts, films, plates, perforated plates or expanded metal. However, the process is equally suitable for applying active composition to three-dimensional structures such as monoliths.
The materials used for the supports are selected from metallic or ceramic materials or plastics depending on the conditions existing during preparation and processing thereof and, above all, during the use thereof. Examples of metallic materials are pure metals such as iron, copper, nickel, silver, aluminum, and titanium or alloys such as steels, for example nickel, chromium, and/or molybdenum steel, brass, phosphor bronze, monel and/or nickel silver. Examples of ceramic materials are alumina, silicon dioxide, zirconium(IV) oxide, cordierite, steatite and/or carbon. Examples of plastics materials are polyamides, polyethers, polyvinyls, polyethylene, polypropylene, polytetrafluoroethylene, polyketones, polyetherketones, polyethersulfones, epoxide resins, alkyd resins, urea resins and/or melamine aldehyde resins.
Preferably there are used metallic structured supports in the form of metallic wovens, knits or felts, carbon fiber wovens or felts or man-made wovens or knits.
Optionally the support is pretreated prior to application of the active composition. Pretreatment is advantageous, for example, when it is desirable to improved the adhesion of the active composition to the support. Examples of pretreatment are coating of the support with adhesion promoters or roughening by mechanical techniques (for example grinding, sandblasting) or thermal techniques such as heating, usually in air, plasma etching or cathodic etching.
In a particularly preferred embodiment metallic structured supports are used which are composed of wires, which in turn consist of high-grade steel, which exhibits a roughened surface when tempered in air and subsequently cooled. This property is particularly evident in high-grade steels in which one alloying ingredient accumulates at the surface above a specific de-mixing temperature and forms a tenacious rough oxidic surface layer in the presence of oxygen, due to oxidation. Such an alloying ingredient can be aluminum or chromium for example, from which there forms a corresponding surface layer of Al2O3 or Cr2O3. Examples of such steels are those having the material numbers 1.4767, 1.4401, 1.4301, 2.4610, 1.4765, 1.4847 and 1.4571 (as specified in German Standard DIN 17007). These steels are thermally roughened by known methods (cf eg EP-A 564,830) by tempering in air at from 400xc2x0 to 1100xc2x0 C. over a period of from one hour to 20 hours followed by cooling to ambient temperature.
The supports are impregnated with an impregnating medium which contains the active composition, its constituents, the precursors of the active composition and/or the precursors of said constituents. If the impregnating medium contains precursor compounds, these are converted during further processing to form the active composition. Normally, the active composition, its constituents, the precursors of the active composition and/or the precursors of said constituents are dissolved and/or suspended in a solvent or suspending agent, but it is equally possible to carry out the process without solvents or suspending agents, eg by using a liquid precursor of the active composition which has the required surface tension.
The impregnating medium has a surface tension of not more than 50 mN/m. In a preferred embodiment the impregnating medium has a surface tension of not more than 40 mN/m and in a particularly preferred embodiment, not more than 35 mN/m. Generally, no lower limit is imposed on the value of the surface tension. However in a preferred embodiment the impregnating medium has a surface tension of at least 10 mN/m, and in a particularly preferred embodiment it is at least 25 mN/m.
The surface tension is measured by the OECD ring method known to the person skilled in the art (ISO 304, cf The Official Journal of the European Communities No. L 383 of 29.12.1992, pages A/47 to A/53).
A solvent or suspending agent present in the impregnating medium is selected such that the active composition that is to be applied, its components and/or its/their precursors undergo no undesirable reactions in or with said solvent or suspending agent; further criteria for selection are cost and ease of handling. Suitable solvents or suspending agents are well-known and industrially commonly used solvents, eg aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cumene, pentane, hexane, heptane, hydrocarbon cuts such as benzin, ligroin, petroleum white oil, alcohols, diols, polyalcohols such as methanol, ethanol, the two propanol isomers, the four butanol isomers, glycol, glycerol, ethers such as diethyl ether, di-n-butyl ether, methyl-tert-butyl ether, ethyl-tert-butyl ether, methyl-tert-amyl ether, ethyl-tert-amyl ether, diphenyl ether, ethyleneglycoldimethyl ether, diethyleneglycoldimethyl ether, triethyleneglycoldimethyl ether, or water. The organic solvents or suspending agents used may be substituted, if desired, eg with halogens, as in chlorobenzene, or with nitro groups, as in nitrobenzene. The solvents or suspending agents are used individually or intermixed.
In a preferred embodiment the solvent or suspending agent used is water.
The active composition, its constituents, the precursors thereof and/or the constituents thereof are suspended and/or dissolved in the solvents or suspending agents. In the simplest case, the active composition or the constituents thereof is/are dissolved and/or suspended in a solvent or suspending agent. For example, soluble active compositions or the soluble components thereof are dissolved in a solvent, or finely powdered, insoluble active compositions or the individual components thereof are suspended in a suspending agent. Alternatively, precursors cursors of the active composition or the constituents thereof are dissolved and/or suspended in a solvent or suspending agent. Precursors are converted to the final active composition during further processing. It is equally possible to use, in the impregnating medium, part of the active composition in the form of precursors and part as finished components of the active composition.
The impregnating medium additionally contains, if necessary, auxiliary substances. For example, the impregnating medium contains acid-reacting or alkaline-reacting compounds or buffers, if they are necessary or advantageous for stabilizing or solubilizing the active composition or at least one of the components or precursors thereof or their precursors present in the medium.
Preferably soluble salts of the components of the active composition are completely dissolved in a solvent. Advantageously, there is used an aqueous solution of components of the active composition.
If the active composition consists of metals, it is particularly preferred to use either an aqueous nitric-acid solution of nitrates of the metals or an aqueous ammoniacal solution of amine complexes of the metals. If the active composition consists of amorphous metal oxides, use is preferably made of an aqueous sol of the oxide, which sol may be stabilized.
The active composition is selected according to its end use; suitable active compositions for the various areas of application are known to the person skilled in the art. For the removal of nitrogen oxides from burner gases there are used eg pulverulent active compositions containing titanium(IV) oxide and vanadium oxide. For hydrogenating reactions there are used mostly metals as the active composition, frequently Group 8b metals, eg iron, cobalt, nickel, ruthenium, rhodium, platinum, palladium and/or iridium, which are optionally doped with other metals acting as promoters, eg alkali metals and/or alkaline earth metals such as lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium and barium, coinage metals such as copper, silver and/or gold, zinc, tin, bismuth, antimony, molybdenum, tungsten, and/or contain other promoters such as sulfur and/or selenium.
If water is used as the solvent or suspending agent, the surface tension is usually only just below the value for pure water (72 mN/m). If the surface tension of the impregnating medium is above the upper limit of 50 mN/m set by the invention, at least one additive capable of reducing the surface tension is added to the impregnating medium in an amount which lowers the surface tension to the desired value. The surface tension-reducing additive is a surface-active substance. The surface-active substance added is usually at least one anionic or non-ionic surfactant. Preferably there are used non-ionic surfactants and more preferably low-foam non-ionic surfactants. The quantity of surfactant to be used is determined in each case by carrying out a few simple experiments. Usually additions of from 0.01 to 1 wt % of a surfactant factant or surfactant mixture, based on the total weight of the impregnating solution, suffice, and it is preferred to use from 0.05 to 0.2 wt % of surfactant.
Anionic, non-ionic and low-foam surfactants are widely used commercial substances well known to the person skilled in the art. Non-ionic surfactants are available eg under the trade name LUTENSOL(copyright) and low-foam non-ionic surfactants under the trade name PLURAFAC(copyright) sold by BASF Aktiengesellschaft, Ludwigshafen, or under other trade names of numerous other suppliers.
The structured support is impregnated with the impregnating medium in known manner. For this purpose the structured support is either dipped in the impregnating medium or washed or sprayed therewith.
The impregnated support is usually dried in known manner following impregnation, in order to free it from solvent or suspending agent. This is generally carried out by heating the impregnated support, in order to evaporate the solvent or suspending agent. Simultaneously or instead, a vacuum can be applied. In the case of impregnation with aqueous solutions and/or suspensions it is generally sufficient to heat the support to at least 100xc2x0 C. to approximately 120xc2x0 C.
Following drying, or concurrently with drying in a single step, precursor compounds which can be thermally decomposed to the active composition, are thermally decomposed to the active composition (xe2x80x9ccalcinedxe2x80x9d) in known manner. To this end, the impregnated and optionally dried support is heated to an adequate temperature. The temperature suitable for this purpose is determined by routine tests. Generally temperatures in the range of from 120xc2x0 C. to 650xc2x0 C. are sufficient, and usually temperatures in the range of from 120xc2x0 C. to 400xc2x0 C. are adequate.
The temperature may be attained in any type of oven or by using unenclosed radiators. It should in each case be set such that the material of the support remains stable at the temperature used. In the case of plastics materials there is therefore automatically an upper limit to the temperature which can be used, this being dependent on the plastics material itself, conforming to its maximum temperature resistance as given in data sheets or compiled tables for the plastics material concerned.
Precursor compounds which cannot be thermally decomposed to the active composition are, instead of thermal decomposition, converted to the active composition by suitable chemical treatment, concurrently with, or subsequently to, said heat treatment. For example, metal nitrates are decomposed during said heat treatment generally to oxides, which, normally following the heat treatment, undergo reduction by treatment with a reducing agent for the metal. The metal oxide in the finished monolith is reduced in simple manner to the metal with hydrogen or a hydrogen-containing gas mixture before the monolith is used as catalyst in the reactor.
During the drying procedure, the solvent or suspending agent used substantially evaporates, whilst during calcination and/or chemical after-treatment the final active composition is produced from precursors of the active composition, components thereof and/or precursors of said components.
A two-dimensional support substantially structured as a supporting web is shaped in known manner, usually following the heat treatment, to a three-dimensional entity appropriate to its end use. Shaping takes place eg in separate steps such as trimming, corrugation of the web, arranging and fixing the corrugated webs to form a monolith having parallel or crisscross channels. Shaping of the web to form a monolith may be carried out, if desired, prior to impregnation, drying, heat treatment or chemical treatment.
The impregnating process of the invention is carried out continuously or batchwise.
A continuous embodiment is illustrated diagrammatically by way of example in the drawing. A supporting web travels at a known velocity from roll R1 via a system of deflection and tension rolls through bath B containing the impregnating medium. The concentration of active composition, the components thereof, precursors or their components and also any auxiliary substances in the impregnating medium, is known. Bath B rests on balance W to enable measurement of the quantity of impregnating medium absorbed by the supporting web. Following impregnation, the supporting web passes successively through two heating zones in which radiant heaters H heat the supporting web first to a drying temperature T1 and then to a calcining temperature T2. On leaving the heating zones the supporting web coated with active composition cools down and is collected on roll R2 for further processing. The quantity of active composition deposited on the supporting web can be calculated from the known concentration of the active composition or its precursors in the impregnating medium and the weight measurements carried out via balance W. The deposited quantity of active composition is governed by the concentrations in the impregnating medium and the residence time of the supporting web in the impregnating medium, which is in turn governed by the velocity of the supporting web and/or the size of the vessel containing the impregnating medium. For entirely continuous operation, the impregnating medium is fed continuously to the impregnating vessel at a replenishment rate based on the weight of impregnating medium absorbed by the supporting web.
The monoliths of the invention are prepared as described above from the structured supports coated with active composition by the impregnating process of the invention. It is possible to make the monoliths from uncoated supporting webs or, in particular, to take ceramic monoliths, made by some other commonly used process, eg casting or extrusion, and then to coat said monoliths with active composition by means of the impregnating process of the invention. The monoliths usually have open channels which are, in use, parallel to the main direction of flow or at an angle thereto. The general forms of monoliths, their structures, processes for the preparation thereof and their installation as catalyst packs or column packings are known to the person skilled in the art.
The heterogeneously catalyzed processes of the invention are characterized in that at least one structured supporting web coated with active composition by means of the impregnating process of the invention or at least one monolith of the invention is used in said processes as the catalyst. Examples of heterogeneously catalyzed processes of the invention are hydrogenations of organic compounds or reactive distillations in which a monolith of the invention or a packing composed of monoliths of the invention is used. Generally a structured supporting web coated with active composition by the impregnating process of the invention or a monolith of the invention can be used in any process in which catalytically active structured supporting webs or monoliths are used. Specific processes are eg the hydrogenation of multiple bonds in organic molecules, such as the hydrogenation of 2-butyne-1,4-diol to 2-butene-1,4-diol and/or butane- 1,4-diol, the hydrogenation of vinyl oxirane to butylene oxide, of dihydrofuran to tetrahydrofuran, of reactive diolefins and olefins in C5+ streams such as pyrolysis gasoline, reformed gasoline or coke-oven benzene, of vinyl acetylene in C4 streams to 1,3-butadiene and/or butenes, of butadiene in C4 streams to butenes, of propyne and/or propadiene in C3 streams to propene. These processes can be carried out in a packed-bed reactor or in a packed reactive distillation column with simultaneous separation of substances (xe2x80x9ccatalytic distillationxe2x80x9d).

Impregnating process for the application of active composition to structured supports or monoliths


Prior art synthesizers often select a small interval d to detune. For example, if the nominal oscillator frequency was 1000 Hz, then applying a detune parameter of 10 cent would result in a detuned oscillator frequency of 1006 Hz. However, at the next octave, the nominal frequency would be 2000 Hz with the detuned oscillator frequency of 2012 Hz. Accordingly, a detuned oscillator has a frequency deviation which is proportional to its nominal frequency. Hence, when mixing detuned oscillators, the resulting signal has a beat frequency which varies with the pitch and doubles with each octave.

Music synthesizer generate audio tones. Many synthesizers generate their tones by using one or more oscillators. It is very common to use several oscillators in a single synthesizer voice but with at least one oscillator detuned. That is to say, that oscillator is oscillating at a slightly different frequency to at least one other oscillator. As a consequence of interference, this results in a periodically changing resulting signal due to the varying phase difference between them.
When there are two slightly detuned sine waves, the resulting signal is perceived as a single sine wave with a sinusoidal amplitude modulation varying with frequency. The frequency of this amplitude modulation is called the "beat frequency". This can be expressed as follows:
Oscillator A:a(t) = sin (2π fa t)Oscillator B:b(t) = sin (2π fb t)The resulting signal: s(t)= a(t) + b(t)= sin (2π fa t) + sin (2π fb t)= 2 sin (2π [fa + fb] t/2) cos (2π [fa − fb] t/2)
where fa is the frequency of oscillator A, fb is the frequency of oscillator B, a(t) is the output from oscillator A and b(t) is the output from oscillator B.
More often than not, there are two detuned oscillators producing more complex waveforms. Complex waveforms include waveforms in shapes which differ more or less from a perfect sine wave, e.g. a sawtooth or rectangular wave and can be decomposed into a sum of harmonic sine waves (the overtones or partial frequencies). The resulting interference from such complex waveforms is not a simple amplitude modulation but a complex timbre variation. This is because each pair of harmonic overtones has to be treated separately. However, the timbre variation when mixing two slightly detuned oscillators is still periodic with a beat frequency. Moreover, that beat frequency is equal to the difference between the two frequencies of the mixed detuned oscillators.
Synthesizer oscillators are usually tuned in a chromatic scale that consists of equal semitone intervals. An interval is defined by a certain frequency ratio between two tones. Twelve semitone interval steps result in an octave interval which is defined as a frequency ratio of 2:1. Hence, each semitone is the twelfth root of 2 or approximately 1.06. A semitone can be further divided into cents. A cent is one hundredth of a semitone. Thus, one cent is a 1200th root of 2 or approximately 1.0006.
In the prior art, synthesizer oscillators have been detuned by setting a certain detune interval which was usually measured in cents. Due to the fact that the detune interval defines the ratio between the detuned frequency and the nominal frequency, the frequency deviation itself is proportional to the nominal frequency. For example, if the nominal oscillator frequency was 1000 Hz, then applying a detune interval of 10 cent (approx. 1.006) would result in a detuned oscillator frequency of 1006 Hz and a beat frequency of 6 Hz. However, with the same detune interval of 10 cent at the next octave, the nominal frequency would be 2000 Hz with the detuned oscillator frequency of 2012 Hz and a beat frequency of 12 Hz. Accordingly, at a given detune interval the detuned oscillator has a frequency deviation which is proportional to its nominal frequency. Hence, when mixing detuned oscillators, the resulting signal has a beat frequency which varies with the pitch and doubles with each octave.
In order to accommodate for this beat frequency, a compromise is reached but often such audio tones have a beat frequency which is relatively too slow at lower tones and too high at higher tones.
An aim of the present invention is to provide a music synthesizer whereby sounds are generated with an optimum beat across a large range of tones.

Music synthesizer and a method of generating a synthesizer output with a constant beat

Abstract: An aim of the present invention is to provide a music synthesizer whereby sounds are generated with a constant optimum beat across a large range of tones.

Abstract: The present invention relates to a music synthesizer comprising a first and second oscillator and a signal generator which applies a constant beat parameter to a pitch signal to derive the input for said second oscillator, thereby enabling a synthesizer output to be generated at a substantially constant beat.


The present invention relates to a more easily recyclable enamel composition which includes at least one glass frit and includes, as pigment(s), at least one or more manganese compounds, this composition furthermore having a melting temperature below 750xc2x0 C.

The present invention relates to the deposition of enamel on a glass substrate, in particular on a glazing. It relates in particular to a novel enamel composition and to a novel process for the manufacture of an enamelled layer on a glass substrate, as well as to the enamelled products obtained.
Enamels are well known in the prior art and are used, in particular, for coating glass substrates, such as window panes, in the motor-vehicle industry or the building industry. They make it possible, inter alia, to form inscriptions or decorative layers, conductive layers, protective layers, in particular layers for protecting against ultraviolet radiation the adhesive layers or adhesive beads intended for fitting the window panes into bodywork openings, masks, in particular masks for concealing current-collecting strips of heater arrays or for concealing the adhesive beads mentioned above, etc.
The enamels used for coating glass substrates are generally formed (before they are applied to the substrate and fired) from a powder which includes a glass frit (which has to form the glassy matrix), and from pigments (in particular as colorants, it being possible for these pigments also to form part of the frit), the frit and the pigments being based on metal oxides, and from a medium or xe2x80x9cvehiclexe2x80x9d allowing application and temporary adhesion of the enamel to a substrate. The vehicle, chosen depending on the end-use of the enamel, must ensure that the particles of the frits and pigments used are properly in suspension and must be consumed at the latest during firing of the enamel. This vehicle may contain solvents, diluents, oils, resins, etc.
One problem with existing enamelled glass substrates is the difficulty of recycling such products, in particular in the manufacture of glass substrates in the form of sheets (glazings). Since glazings have to satisfy many requirements in terms of coloration, light and/or energy transmission, etc., it is indeed important for glass waste reintroduced in ground form (cullet) into the melting furnaces used for manufacturing glazings not to disturb the usually already present glass compositions and not to give products which do not meet the necessary requirements. Although non-enamelled glass cullet may thus be reintroduced into a furnace for manufacturing float glass, in amounts generally of about 20-30% by weight of the furnace charge, enamelled glass cullet, on the other hand, generally results in the appearance of undesirable residual colorations or non-melted islands in the glass sheets formed. The amount of enamelled glass cullet which can be reintroduced into these furnaces consequently does not exceed, in the most favorable cases, from 2 to 3% by weight of the charge of the furnaces (the enamel generally constituting from 0.1 to 0.5% by weight of this glass cullet).
The object of the present invention is to provide an improved enamel composition and an enamelling process making it possible to obtain improved enamelled glass substrates (especially glazings), in particular enamelled substrates which can be more easily recycled (in particular in the manufacture of glazings) than the existing enamelled substrates, the enamelled layers obtained furthermore preferably having the usually required characteristics (in particular, in terms of opacity and coloration) for the enamelled layers which have to coat window panes (glazings) for motor vehicles.
This object is achieved by the enamel composition according to the invention, this composition including at least one glass frit and including, as pigment(s), at least one or more manganese compounds, this composition furthermore having a melting temperature below 750xc2x0 C.
In one advantageous embodiment of the invention, the enamel composition furthermore includes less than 10% by weight (with respect to the composition) and, preferably, less than 5% by weight of silver particles.
Particularly preferably, it includes less than 10% and advantageously less than 5% by weight of silver particles and of any other silver-based compound and/or includes less than 10% and advantageously less than 5% by weight of silver particles and of any other conductive particle (i.e., in the latter case, it includes less than 10% and advantageously less than 5% of conductive particles). In particular, the compositions according to the invention containing no silver particles and/or no silver-based compounds and/or no other conductive particles and/or no certain undesirable heavy metals mentioned later (in particular, lead or lead oxides) have many advantages, as will be explained later.
The expression xe2x80x9cenamel compositionxe2x80x9d is understood to mean, according to the invention, the composition of the enamel considered before it is fired, the enamel after it has been fired being essentially in the form of a coloured glassy matrix. The expression xe2x80x9cmelting temperature of the enamel compositionxe2x80x9d is understood to mean, according to the invention, the melting temperature of the enamel in its form as deposited on the substrate to be coated. This xe2x80x9cmelting temperaturexe2x80x9d is also commonly called xe2x80x9cfiring temperaturexe2x80x9d or xe2x80x9cfusability temperaturexe2x80x9d. In the field of enamels, it corresponds to the minimum temperature at which xe2x80x9csufficientxe2x80x9d sintering of the composition is observed, this xe2x80x9csufficientxe2x80x9d sintering being manifested in particular by the disappearance of the capillary effect in the enamel during sintering. Those skilled in the art know how to measure this melting temperature, for example by passing an ink pen (i.e. more specifically a felt-tip pen) over the enamel (after the latter has been raised to a treatment temperature and then cooled) and by noting the lowest treatment temperature for which the trace, left through the cooled enamel by the solvents in the ink when they are absorbed by the enamel due to the capillary effect, disappears. During the production of an enamelled substrate, the temperature chosen for firing the enamel deposited on the substrate is then preferably chosen to be above or equal to its melting temperature. As a general rule, and preferably, the melting temperature of the enamel composition according to the invention is below 700xc2x0 C.
According to the invention, the enamel composition includes at least one or more manganese compounds (this is generally a single compound, but it may also be a mixture of various manganese compounds) as pigment(s). Preferably it includes the said manganese compound(s) as the main pigment(s), that is to say that the enamel composition may optionally include one or more other pigments but that, in this case, the amount of each other optional pigment remains less than the amount of manganese compound(s). Particularly advantageously (in particular, for reasons associated with recycling), the manganese compound(s) represents (represent) at least 50% by weight of the pigments present, preferably at least 75% by weight of the pigments present, and is (are) particularly preferably the only pigment(s) used in the composition according to the invention. In particular, the enamel composition according to the invention advantageously contains no chromium oxides, no copper oxides, no cobalt oxides or nickel oxides and also contains no other colorant compounds, such as copper chromates, cobalt chromates, etc. and/or no other colorant oxides, such as iron oxides, etc.
The manganese compound(s) is (are) preferably added in the form of manganese salt (or salts) and/or of manganese oxide(s) (for example, MnO2 and/or Mn2O3 and/or Mn3O4 and/or MnO) to the enamel composition according to the invention, particularly preferably in the form of manganese carbonate(s) and/or MnO2. Depending on the way in which the enamel composition is prepared, it (they) may also be provided or occur in another form (or other forms) in the composition (in particular, in the form of other manganese derivatives). As a general rule, it (they) gives (give) one or more manganese oxides (preferably, Mn3O4 optionally accompanied by Mn2O3, or even MnO) at the latest while the enamel on the coated substrate is being fired. It is generally advantageous, in particular if the manganese compound(s) used is (are) not already in crystallized form, to treat the manganese compound(s) so as to obtain a structural rearrangement, for example of the crystallization type, within this compound (or these compounds), for example by subjecting the enamel according to the invention to a heat treatment (it being sometimes possible for the rearrangement to occur while the enamel is being fired, but it generally being caused by an independent heat treatment prior to firing), this rearrangement promoting the formation of enamel layers having improved properties, in particular in terms of opacity, coloration and/or anti-adhesive properties.
The amount of pigment(s) (advantageously of the manganese compound (or compounds)) in the frit(s)/pigment(s) combination of the composition according to the invention is generally between 10 and 50% by weight, preferably between 15 and 40% by weight and particularly preferably between 20 and 35% by weight (with respect to the frit(s) and pigment(s) combination), in particular for reasons of opacity and of integrity of the enamel layer.
The glass frit according to the invention is a vitrifiable mixture which includes oxides chosen in particular from the oxides commonly employed in enamel frits, for example chosen from silicon oxides, zinc oxides, bismuth oxides, sodium oxides, boron oxides, lithium oxides, potassium oxides, calcium oxides, aluminum oxides, magnesium oxides, etc., or from barium oxides, strontium oxides, antimony oxides, etc. Preferably (in particular, for reasons associated with recycling), the glass frit is a frit which includes less than 1% (advantageously less than 0.1% and particularly advantageously less than 0.05%) by weight of lead oxides and, particularly preferably, is a frit containing no lead oxides. It also preferably contains no other undesirable elements, such as cadmium oxides, fluorine, etc.
Particularly advantageously, this is a frit which includes SiO2 as network-forming oxide. Also preferably, it includes Bi2O3 and/or ZnO as intermediate oxide(s) (particularly preferably as the main intermediate oxide(s)).
The terms xe2x80x9cnetwork-forming oxidexe2x80x9d, xe2x80x9cnetwork-modifying oxidexe2x80x9d and xe2x80x9cintermediate oxidexe2x80x9d are terms well known to those skilled in the art of glassmaking. The network-forming oxides are oxides such as silica SiO2, B2O3, etc., these forming the essential components of the glassy network; the network-modifying oxides are oxides such as CaO, K2O, Na2O, BaO, etc., these being capable of modifying the glassy network and of influencing properties such as the viscosity or the melting point; the intermediate oxides are oxides such as Al2O3, PbO, ZnO, Bi2O3; these acting, depending on their environment and the proportion in which they are present, as network-forming oxide and/or as network-modifying oxide.
The enamel composition according to the invention may include several glass frits mixed together and having different properties (in particular, different melting temperatures). According to a preferred embodiment, the enamel composition according to the invention includes, as the frit(s) (the pigments not being taken into consideration), the mixture of the following components in the proportions expressed in percentages by weight (with respect to this mixture):
with, preferably,
This composition makes it possible to obtain a particularly useful enamel which has, in particular, very good recyclability.
The enamel composition according to the invention may also include a vehicle making it possible to obtain the desired viscosity for applying the enamel to the substrate and allowing it to bond to the substrate. This vehicle may be any vehicle normally used in conventional enamel compositions and may, in particular, contain solvents, diluents, oils such as pine oils and other plant-based oils, resins such as acrylic resins, petroleum fractions, film-forming materials such as cellulosic materials, etc. The proportion of vehicle in the ready-to-be-deposited composition is preferably between 15 and 40% by weight of the said composition.
The enamel obtained after firing has good opacity allowing, in particular, its use as a mask (for example, for protecting adhesive beads in motor vehicles). The enamel is considered to have good opacity if it has an optical density of at least 2.8 and preferably at least 3. The optical density (OD) is measured using a densitometer, for example the GRETAG(copyright) D200 apparatus (in which a 550 nm filter is used) and is related to the light transmission factor TL through the relationship:
OD=log 1/TL
Moreover, whatever the initial color (before firing) of the enamel composition according to the invention, it generally gives, after firing (at temperatures generally lying between 550 and 750xc2x0 C.), an enamel whose color is appropriate for motor-vehicle applications. Preferably, the enamel composition according to the invention is chosen so as to give, after firing, a black enamel (this is generally the case with compositions according to the invention which include manganese salt (or salts), in particular manganese carbonate and/or manganese oxide (or oxides) such as MnO2, Mn2O3 and/or Mn3O4, and/or with compositions according to the invention containing none of the aforementioned undesirable compounds, and/or which include the abovementioned frit in the indicated percentages by weight, etc.) particularly sought-after in such applications. The expression xe2x80x9cblack enamelxe2x80x9d is understood to mean hereafter an enamel having a black color after firing.
Particularly preferably, the enamel composition according to the invention is chosen so as to obtain a black enamel having the following colorimetric coordinates, in absolute values:
L*xe2x89xa65; |a*|xe2x89xa62 and |b*|xe2x89xa62 (and, preferably, |a*|xe2x89xa61 and |b*|xe2x89xa61).
The colorimetric coordinates L*, a* and b* were defined and proposed in 1931 by the International Commission on Illumination [Commission Internationale de l""Eclairage (CIE)] and have formed the subject of a CIE official recommendation in 1976 (Commission Internationale de l""Eclairage, Colorimetryxe2x80x94Recommandations Officiellesxe2x80x94Publication CIE No. 151-2, Vienne, 1986). The calorimetric coordinates indicated above are measured in reflection, on a Minolta CM 2002 spectrocolorimeter, under D65 illuminant, for enamel which is on a non-tinted glass substrate having a light transmission factor of approximately 90% and a thickness of 4 mm.
Substrates coated with the enamel according to the invention also have superior recyclability because of the use of the manganese compound or compounds as all or some of the pigments. Thus, when the substrates coated with the enamel having the composition according to the invention are reintroduced, in cullet form, into a furnace for melting the batch materials for the production of glass sheets (at temperatures generally about 1350 to 1500xc2x0 C.), the coloration of the enamel generally disappears and does not interfere with the coloration of the glass resulting from the batch materials used. The recyclability of the composition according to the invention and its opacity and colour characteristics are particularly improved when the enamel composition includes less than 10% of silver particles or less than 10% of silver particles and any other silver-based compound, or less than 10% of conductive particles, as indicated previously, in particular when the composition contains none of the said silver particles and/or none of the said conductive particles and/or none of the said silver-based compounds (as silver may, in particular, cause problems when recycling and give the enamel a not very desirable chestnut-brown coloration). In the same way, the recyclability and/or the opacity and color characteristics of the enamel and/or possibly the mechanical properties of the enamelled glasses are further improved when the composition includes less than 1% of or does not contain one or more of the aforementioned undesirable components (such as lead, chromium, copper, cobalt, nickel, iron, cadmium, or compounds, for example metal oxides, containing at least one of these metals).
Apart from the advantages associated with recycling and with the satisfactory properties obtained in terms of opacity and coloration, it may be pointed out that the enamel composition according to the invention is also easy to employ and is more economic because of the use of the manganese compound(s), these compounds being less expensive than the compounds normally used as pigments in enamel compositions. Since the pigments represent from 10 to 50% by weight of the frit(s)/pigment(s) combination, the cost saving may be particularly great.
The enamel composition according to the invention may be obtained by adding, in particular, the manganese compound(s) (and optionally the other pigment or pigments) in the form of powder(s) to a powder of glass frit(s) (this frit or these frits possibly being already in suspension in a vehicle).
In this case, the particle size of the frit(s)/pigment(s) combination in powder form is preferably chosen so that at least 90% by weight of the particles forming the powder have a diameter of less than 40 xcexcm and particularly preferably less than 20 xcexcm, the choice of such a particle size enabling the opacity of the enamel obtained after firing to be further improved.
The frit(s)/pigment(s) combination of the composition according to the invention may also be obtained using the following process (called hereafter the xe2x80x9cdirect processxe2x80x9d): a mixture of raw materials suitable for obtaining the desired frit(s)/pigment(s) combination (for example, a mixture of bismuth oxide, silica, boric acid and/or borax, sodium carbonate and/or sodium nitrate, alumina, and manganese carbonate and/or MnO2, when it is desired to obtain a frit(s)/pigment(s) combination which includes the frit with the composition expressed hereinabove in percentages by weight and including MnO2 by way of pigment) is melted at temperatures of approximately 1000 to 1300xc2x0 C., this melting preferably being followed by a treatment, such as annealing, at temperatures below about 480-500xc2x0 C. in order to obtain a structural rearrangement within the mixture (in particular within the pigment(s)) and, possibly, to develop crystallization seeds. Next, the mixture is ground up in order to give a frit(s)/pigment(s) combination in the form of a powder. Preferably, the grinding carried out is a fine grinding so that at least 90% by weight of the particles forming the powder obtained have a diameter of less than 40 xcexcm, preferably less than 20 xcexcm and particularly less than 10 xcexcm (this fine grinding making it possible to obtain better results in terms of opacity of the enamel). Next, the powder is optionally heat treated, generally between 400 and 600xc2x0 C., so as to stabilize the mixture and to reinforce the coloration of the enamel obtained from this powder (for example, to give it a xe2x80x9cblackerxe2x80x9d coloration).
The direct process is particularly advantageous; in particular, it is more simple, rapid and economical than the conventional processes for producing enamel compositions. In general, it makes it possible to obtain enamels having a blacker coloration than those obtained by mixing a powder of glass frit(s) and a powder of manganese compound (or compounds), in particular it generally makes it possible to obtain enamels having the aforementioned colorimetric coordinates (i.e.: L*xe2x89xa65; |a*|xe2x89xa62 and |b*|xe2x89xa62).
The frit(s)/pigment(s) combination of the composition is generally put in suspension in a vehicle so as to obtain a composition capable of being deposited on a substrate. According to the enamelling process of the invention, at least part of a glass substrate is coated with an enamel composition according to the invention and the enamelled substrate is subjected to a heat treatment so as to fire the enamel and, where appropriate, so as to develop crystallization seeds or to obtain structural rearrangement within the pigments.
The substrate on which the enamel composition is deposited may be a bare glass substrate or a glass substrate already coated with one or more layers of enamel, preferably with one or more layers of enamel according to the invention. This substrate may consist of one or more glass sheets and may be toughened so as to have improved mechanical strength and thermal resistance properties. The substrate coated with enamel according to the invention thus includes at least one glass sheet coated on at least part of one of its sides with at least one layer of an enamel having a composition according to the invention. The enamel according to the invention may also be used to coat other types of substrate.
In the process for enamelling glass substrates, in particular glazings, according to the invention, the enamel composition is preferably deposited on the substrate by screen printing and then fired, the firing taking place, where appropriate, during the heat treatment associated with the bending and/or toughening of the substrates, the firing temperatures generally being approximately 550 to 750-800xc2x0 C. In this regard, it may be observed that the enamel according to the invention may advantageously be implemented with the aid of the devices and under the temperature and pressure conditions which are normally used for implementing conventional enamels, in particular in motor-vehicle applications.
The deposition of the enamel composition may also be carried out by spraying, by curtain coating or roller coating, etc., the deposition generally being followed by a drying step, for example using infrared, in order temporarily to fix the enamel, for example by removing the diluents from the vehicle serving for applying the enamel to the substrate. If several layers are deposited on the substrate, each layer is preferably dried before the next one is deposited, firing being carried out on all the layers.
The optional bending and toughening of the glass substrates are carried out using known methods. In particular, the bending may be carried out under gravity (in particular the bending of glass substrates in pairs for the purpose of producing laminated glasses) or with the aid of dies and, when the substrates are bent and toughened, the toughening operation may be carried out after the enamelled substrates have been bent, optionally within the same device.
If glass substrates have to undergo simultaneous bending for the purpose of producing panes of laminated glass, the enamel is deposited on at least one of the substrates and the substrates are joined together and then bent, the glass substrates being subsequently separated in order to insert at least one interlayer film of different material, and then the pane of laminated glass is obtained by joining together all these components with the application of heat and pressure.
It should be pointed out that some enamel compositions according to the invention have anti-adhesive (anti-stick) properties, these compositions not adhering to the other glass sheets or to the dies which come into contact with them during the bending operations.
The glass substrates, in particular glazings, coated with enamel according to the invention have improved recyclability, these substrates generally being recyclable, especially in the form of cullet in furnaces for manufacturing glass sheets, in particular in the furnaces, which are most widely used, for the manufacture of glass sheets using the float process, or xe2x80x9cfloatsxe2x80x9d, in amounts which may be as much as 15%, or even at least 50% by weight of the charge of the furnaces (the enamel generally constituting from 0.1 to 0.5% by weight of the glass cullet). The substrates coated with enamel according to the invention furthermore have mechanical properties which are sufficient for their use in motor-vehicle applications.
Other advantages and characteristics of the invention will emerge from the following examples which illustrate the present invention without, however, limiting it.

Process for enamelling glass substrates, enamel composition used and products obtained

Abstract: The invention also relates to an enamelling process using this composition, as well as to the enamelled products obtained.


A grass dethatcher includes a plurality of housings fixedly mounted on a rotatably shaft, with flexible nylon filaments secured to each housing. In operation, as the shaft is rotated, the centrifugal force extends each flexible nylon filament generally perpendicular to the horizontal shaft, and with the filaments in a radially disposed position to effect dethatching of the lawn.

This invention relates to apparatus for dethatching a lawn.
Thatch is a mat of undecomposed plant material, consisting mainly of grass clippings, accumulated next to the soil in a lawn. Excessive thatch is undesired, since it chokes the roots of the grass, restricts exposure of the soil to the atmosphere, and causes run-off of water away from the soil. At present, thatch is often removed by raking and collecting the raked material. However, thatch is typically well embedded in a lawn and requires a large, time-consuming effort to be raked. xe2x80x9cWalk behindxe2x80x9d gas-powered dethatchers have been developed in the prior art to case the dethatching process. The prior art dethatchers, however, suffer from several drawbacks. First, the dethatchers are built for professional landscapers who need to regularly dethatch lawns, and, therefore, require a fast and efficient tool to accomplish the task. As such, the prior art dethatchers are built to professional standards, having size and power much greater than that needed for a homeowner, and at a relatively high expense. The high cost of the prior art dethatchers cannot be justified by the typical homeowner who will dethatch his lawn once or twice a year. Second, the prior art dethatchers utilize a completely metallic structure for extracting the thatch from a lawn. In particular, metallic claws or coils extend from a cylindrical, rotating housing, which are systematically passed into the grass to xe2x80x9ckick upxe2x80x9d the thatch. The loosened thatch is collected either by raking or blowing and properly disposed of. Unfortunately, the claws and coils are often damaged by hidden rocks, roots, etc. or tangled up with thatch material to completely loose effectiveness. As such, the claws and coils must be removed and either replaced by substitute parts or cleaned. Such removal, however, requires tools, such as an Allen wrench, box wrench, a screwdriver, etc. and a time-consuming effort.
It is an object to the subject invention to provide a dethatcher which uses a flexible filament.
It is also an object to the subject invention to provide a dethatcher which allows for quick and easy replacement of the dethatching elements.
The aforementioned objects are met by a dethatcher which utilizes a flexible filament, such as a nylon trimmer line typically used which rotating trimmers and edgers. Additionally, the subject invention utilizes a clamping mechanism which allows for the attachment of flexible filament without additional tools.
The invention includes a horizontally disposed rotating shaft to which is mounted one or more cylindrical housing. At least one strand of flexible filament is mounted to the housing(s) to radially extend therefrom. A motor is coupled to the shaft to cause rotation thereof, with the flexible filament. As such, the rotating shaft can be guided to lower the end of the spinning filament into a lawn to forcibly lift embedded thatch.
The filaments are preferably circumferentially staggered along the length of the housing(s) so that the filaments engage the thatch sequentially rather than in unison. The shaft can be driven either by an electrical motor or a gas-powered motor. With either source of motive force, it is preferred that wheels be mounted to the dethatcher to ease operation thereof. The use of flexible filament allows for a light, electrically-powered apparatus to be formed in accordance with this invention, which is ideal for home use. Additionally, the invention can also be used in conjunction with a heavy-duty, gas-powered model intended for professional gardeners and landscapers. It is preferred that each of the flexible filaments be securely held in the housing(s) by the clamping mechanism disclosed in U.S. Pat. No. 5,758,424, which issued on Jun. 2, 1998 and of which the inventor herein is a co-inventor. The disclosure of U.S. Pat. No. 5,758,424 is incorporated by reference herein.