KR19990029090A - Improved Water Soluble Metalworking Fluids - Google Patents

Abstract

Improved water-soluble metalworking containing basic additives having sufficient basicity and buffering power to maintain polyaspartic acid, amides thereof and salts thereof, corrosion inhibitor (s) and compositions at a pH of at least about 8.5, preferably at least about 9. Fluids are disclosed. Such compositions are useful as lubricants in the process of cutting, bending, grinding and shaping ferrous and nonferrous metals, and tend to maintain larger pH values by incorporation of basic additives. In practice, polyaspartic acid and its salts are advantageous because they are readily biodegradable, so that the fluid can be easily processed after use without special handling.

Description

Improved Water Soluble Metalworking Fluids

Because of the importance of environmental factors, known oil-containing metalworking fluids require regeneration or need to be treated by a method different from that which flows into a conventional sewage treatment system. In some cases, the processing cost is close to the initial cost of the fluid, so the processing cost is the main cost.

Metalworking fluids perform many functions in various metalworking applications. Typically, these functions include removal of heat from the work piece and the tool (for cooling), reduction of friction between chips, tools and the process product (lubrication), removal of metal debris produced by the work, reduction or suppression of corrosion. And preventing or reducing build-up on the edges such as occur between work debris and the tool. Combinations of these functions generally require the preparation or combination of components in the fluid to achieve the best properties required for a particular metal working operation.

Recently it has been proposed to replace various fluids with oil-containing metalworking fluids such as primary amides, ethylenediamine tetraacetic acid, fatty acid esters and alkanolamine salts. The compounds can be replenished during use by dissolving the tablets containing these compounds during the life of the fluid. See Sato, US Pat. No. 4,144,188.

Amine has also been found to be useful as an antimicrobial agent in cutting oils. Such amines include arylalkylamines such as anilinoamine and p-benzylaminophenol. See EPO No. 90-400732 to Noda et al.

As mentioned above, one of the problems encountered in the industry is the proper treatment of metalworking fluids. The amines as described above are removed from the fluid by biodegradation methods, requiring equipment such as sedimentation tanks, treatment tanks and sludge treatment tanks. Such a system is disclosed in Japanese Patent No. 03181395. Other waste disposal methods and oil removal systems are used to comply with environmental standards.

Public health of workers has always been the focus of problems with the oil-containing water-soluble metalworking fluids currently in use. It is inevitable that such fluids will contact workers who use the fluids in cutting, bending, threading, and other metalworking applications. These oil-containing fluids create cloudy mist on the part of the process product that is being processed, and this mist travels through the air in the vicinity of the machine and its operator. Several attempts to alleviate the fog problem are disclosed in British Patent No. 2,252,103. There is disclosed a polymeric thickener containing a copolymer of acrylamide, sodium acrylate and N-n-octylacrylamide. Copolymers are formulated with monomers that are soluble in water and monomers that are insoluble in water.

Due to the fog in the workplace using conventional water soluble metalworking fluids and drifts in such mists, such workplaces are generally associated with a unique odor that spreads to all areas. Usually this peculiar smell is tolerated as an unpleasant and inevitable state.

There is a need for water soluble metal working fluids that are highly biodegradable, odorless and fog free, particularly useful for cutting operations. Such fluids will not require treatment costs and will provide a more hygienic and desirable workplace.

Various methods have been found to accelerate the polymerization of anhydrous mixtures of aspartic acid to form polysuccinimides. Preferred catalysts for performing in anhydrous conditions are phosphoric acid. It has been known for many years that phosphoric acid is an excellent catalyst for the thermal condensation reaction of aspartic acid, but traditionally phosphoric acid has been used in large amounts to form mixtures such as liquid mixtures or doughs. However, methods of using relatively small amounts to maintain substantially flowable powders are also known. For example, US Pat. No. 5,142,062 to Knebel et al. Discloses that the weight ratio of aspartic acid / catalyst can be used in the range of 1: 0.1 to 1: 2. Fox and Harada also describe a process for thermocondensation of α-amino acids in a publication entitled "Analysis of Protein Chemistry," which uses a molar ratio of aspartic acid / catalyst of 1: 0.07. Fox and Harada also disclose the use of polyphosphoric acid as a very effective catalyst for polycondensation reactions of amino acids and describe that temperatures below the temperature required when o-phosphoric acid are used.

US Pat. No. 5,401,428 to Carlotta et al. Discloses the utility of polyaspartic acid, salts thereof and amides thereof in metal processing. Surprisingly, even though these salts are known to be useful as corrosion inhibitors of ferrous metals in aqueous systems, Carlotta et al., US Pat. No. 4,971,724, surprisingly, the metalworking fluids disclosed in US Pat. Turned out to be necessary. Exposing the liquid to the air for an excessive amount of time results in the inclusion of a corrosion inhibitor, since the fluid will corrode the metal. Although corrosion inhibitors are present, some fluid degradation is observed due to the breathability that occurs through normal use in the application of metalworking. There is a need for compositions of metalworking fluids, such as Carlotta, that resist corrosion due to continued exposure to air.

Brief description of the invention

Stable amount having sufficient basicity and buffering capacity to maintain the pH of polyaspartic acid, its salts and their amides and compositions of at least about 8.5, preferably at least about 9, highly biodegradable, odorless and fog-free. A novel metalworking fluid composition containing a stabilizing amount of basic additive has been found. Such compositions have been found to resist degradation due to aeration during the metalworking function and to remain non-corrosive for extended periods of time.

When diluted in water, these compositions are suitable for cutting, threading, bending, grinding, broaching, tapping and planning of various ferrous and nonferrous metals. ), Gear forming, drilling, deep hole drilling / gundrilling, drilling, boring, hobbing, milling, turning It provides a highly preferred water based metalworking fluid useful for operations such as turning, sawing and forming. After reading this specification, those skilled in the art will recognize that these various metalworking operations and materials will optimally require different dilution of the metalworking fluid and various concentration ratios of the various compositional components.

The present invention relates to a novel water soluble metalworking fluid which is biodegradable and does not require regeneration. More specifically, the present invention provides an improved composition containing polyamino acids, salts thereof and amides thereof useful for cutting, grinding, forming and other metalworking operations requiring metalworking fluids. (formulation). The disclosed polyamino acid compounds have improved antiseptic properties and are more environmentally satisfactory than conventional oils containing fluids.

1 is a graph showing data obtained in an experiment showing the pH effect of carbon dioxide on an aqueous sodium polyaspartate solution containing a small amount of sodium phosphate and benzotriazole.

Typically, the metalworking fluid of the present invention contains a compound that provides an effective amount of an effective amount of polyaspartic acid or a salt thereof or an amide or solution thereof, with a concentration ranging from about 0.5% to 70% by weight of water. Such very wide concentration ranges include the concentrations of the compositions used in metalworking applications (processing fluids) and the concentrations of commercially packaged compositions as diluent concentrates prior to their actual use as processing fluids. It has been found that it is convenient to provide a processing fluid by dilution of a commercial composition of about 10: 1 although other ratios may apply. Other concentration ratios and dilution ratios will be apparent to those skilled in the art.

Preferred compositions of the present invention contain, as concentrates, about 3% to about 25% polyaspartic acid in water and preferably about 5% to about 20% salts or amides. At dilution the processing fluid contains from about 0.15% to about 20% of the polymer, but more or less than that may be used.

Any number of basic compounds can be used as additives to produce polyaspart compositions with improved stability according to the present invention. The basic additive is preferably at least somewhat water soluble. Since substantially small amounts are required in solution to impart stability, the basic compound only needs to be dissolved to a relatively small degree in order to have an effect. The basic additive must have a high basicity and buffering capacity sufficient to effectively maintain the pH of the polymer solution (measured in an aqueous solution of 10% or less at room temperature) from about 8.5 to about 11, more preferably from about 9 to about 10.5. do. However, since the use of fluids is more dangerous, especially for machine operators, it is desirable that the pH of the polymer solution at an effective level not be greater than about 11.

Examples of suitable basic additives include alkali metal carbonates, alkali metal orthophosphates, alkali metal polyphosphates, alkali metal silicates, alkali metal borates and the like and mixtures thereof. Alkali metal carbonates are preferred in that they are inexpensive and have adequate basicity, solubility and usability. The term "alkali metal" as used herein means lithium, sodium, potassium, rubidium and cesium and mixtures thereof.

Preferably, the alkali metal used in the present invention is potassium. Potassium salts used in the present invention increase the solubility of water in metalworking fluids and, more importantly, result in lowering the freezing point of the composition below the freezing point of other alkali metals, such as commonly used and inexpensive sodium. It became. Therefore, it is preferable to use potassium ions in all the steps applied to prepare the compositions of the present invention. That is, the hydrolysis reaction of the polysuccinimide intermediate, which is a hydrolysis reaction known in the art, is preferably performed with potassium hydroxide rather than general sodium hydroxide. Alkali metal basic additives are preferably potassium salts, in particular potassium carbonate. However, using potassium as at least part of the alkali metal and the other alkali metals such as sodium provides some benefits. For example, when the hydrolysis reaction of polysuccinimide is carried out with sodium hydroxide, which is commonly used, the basic additive may be a potassium salt such as potassium carbonate.

The amount of basic additive used to form a stabilized polyaspart metalworking fluid can vary widely depending on good results, with the minimum effective level being considered with the preferred pH ranges described above for the selected additives. It can be determined by periodic experiments considered. In the use of sodium carbonate, the preferred range is from about 0.02% to more by weight in the processing fluid, the sodium carbonate in the concentrate is in an amount up to about 7% by weight, from about 0.02% to about 4% by weight, more preferably. Preferably about 1% to about 3% by weight sodium carbonate is a particularly preferred amount in the concentrate.

The basic additives of the present invention are mixed with the polyaspart solution by typical and suitable mixing or blending methods. In the typical preparation of polyaspart metalworking fluids, the solid material polysuccinimide is generally produced first. This material is generally hydrolyzed by an aqueous solution of base, which is a typical known method, which makes the solid material in liquid form. Basic additives are typically added to the liquid phase during the preparation step. Since only a small amount is used, the blending of the basic additives can be performed during the final stages of the preparation and packaging of the fluid. No special processing means are required as long as proper mixing is achieved to obtain a uniformly composed composition.

For sodium carbonate, which is a basic additive, up to solubility limits can be used. Since the solubility of the potassium salt is higher in the aqueous solution described above, a slightly more than the amount of sodium salt can be used, for example 9% by weight in a concentrated solution of polyamide. However, the polyaspart metalworking fluids of the present invention are typically prepared as concentrates containing polyaspartic acid, salts thereof or amides thereof in an amount ranging from about 2% to about 70% by weight or solubility limit. When added to the concentrate of the present invention, the content of sodium carbonate may be from about 0.2% to about 7% by weight of the total mixture. In diluted form for use in conventional metalworking equipment, concentrates of the present invention are typically diluted to about 0.7% for polyaspartate polymers, and sodium carbonate has a solubility higher than about 0.02% to about 7%. Limit or about 0.03% to about 10%, and potassium carbonate is preferably diluted to about 0.08% to about 0.8%.

Various other additives may be used in the compositions of the present invention to enhance or contribute to properties that may broaden the functionality associated with the use of the composition in metalworking applications. Types of additives include boundary lubricants, corrosion inhibitors, oxidation inhibitors, detergents and dispersants, viscosity index enhancers, emulsion modifiers, antiwear and antifriction and antifoaming agents.

For example, additives may be used to enhance boundary lubrication, such as wear inhibitors, lubricants, pressure resistant agents, friction modifiers, and the like. Typical examples of such additives include metal dialkyl dithiophosphates, metal diaryl dithiophosphates, alkyl phosphates, alkali metal phosphates, tricresyl phosphate, 2-alkyl-4-mercapto-1,3,4-thiadiazole , Metal dialkyldithiocarbonates, metal dialkyl phosphorodithioates, where the metals are typically zinc, molybdenum, tungsten or other metals, phosphorylated fats and olefins, sulfated fats or chlorinated fats and olefins and paraffins, Fatty acids, carboxylic acids and salts thereof, esters of fatty acids, organic molybdenum compounds, molybdenum disulfides, graphite and boric acid dispersants. Such limit lubricity additives are well known in the art. Other additives useful herein include detergents and dispersants that provide a cleaning function.

The polyaspartic acid compounds of the present invention are corrosion inhibitors that function as corrosion inhibitors in certain pH ranges, but the corrosion inhibitors function as corrosion inhibitors in a pH range in which polyaspartic acid, its salts or amides cannot function as corrosion inhibitors. It can be used for the composition. Typical but non-limiting examples of corrosion inhibitors known in the art useful in the present invention are zinc chromate, dithiophosphates such as zinc dithiophosphate, metal sulfonates, where the metal is an alkali metal, such as ethanolamine Alkanolamines and substituted alkanolamines, wherein the backbone of the alkyl groups are substituted to provide various properties, boron compounds such as alkylamines such as hexylamine and triethanol amines, sodium borate, mixtures of amines and boron, high pH ( Carboxylic acids including polyaspartic acid and boric acid esters such as boric acid having alkyl amino carboxylic acids, sodium molybdate, monobenzyl borate and various ethanol amines (also acts as biostates) which are particularly useful in hard water , Benzoic acid, nitro derivatives of benzoic acid, ammonium benzoate, high Triethanol amine salts of carboxylic acids with carboxymethyl tin groups, such as hydroxybenzoic acid, sodium benzoate, 1-1- (carboxymethylthio) undecanoic acid triethanol amine salt, benzotriazole, tolyltriazole and others Other C_One-C₄ Alkylbenzotriazoles.

Publication 1993, entitled "Chromate Substitutes For Corrosion Inhibitors in Cooling Water Systems," incorporated herein by reference (Corrosive Reviews, 11 (1-2)) 105-. On page 122, Aruna Bahader made a more thorough review of corrosion inhibitors.

In particular, it is preferred and advantageous that alkali metal phosphates, preferably potassium orthophosphate or sodium orthophosphate, are contained in the compositions of the present invention to supplement corrosion inhibitors. Therefore, the composition of the present invention comprises a corrosion inhibitor and a supplemental corrosion inhibitor containing alkali metal orthophosphate in a preferred embodiment. Supplementary alkali metal orthophosphates are used in amounts based on metalworking operations in the range of about 0.1% to about 10% by weight of the processing fluid. Other ranges of concentrations will be apparent to those skilled in the art because the polyamino polymer is applied to concentrates as well as processing fluids.

As used herein, the term "corrosion inhibitor" includes chemicals that exhibit corrosion inhibitive properties when used in combination with other ingredients of the compositions of the present invention.

Typical concentrate compositions of the present invention that are diluted to produce a processing fluid are shown in Table 1 below. In Table I the compositions are shown in parts by weight.

Typical concentrate compositions of the present invention comprise from about 3% to about 30% by weight of a salt of polyaspartic acid or poly with about 1% to about 10% by weight corrosion inhibitor and about 200 ppm to about 5% by weight of a basic additive solution. It is an aqueous solution containing the amide of aspartic acid.

Table I

ingredient Sodium salt Mixed Na / Ka Salts Potassium salt Sodium Polyaspartate 10 10 10 7.5 0 0 Potassium polyaspartate 0 0 0 0 11.2 8.37 Divalent basic sodium phosphate 2.24 0.97 0 0 0 0 Divalent basic potassium phosphate 0 1.56 1.5 4.58 2.75 9.17 Potassium carbonate 0 1.30 1.3 1.3 1.30 1.3 Sodium carbonate 1.00 0 0 0 0 0 Benzotriazole 0.95 0.95 0 0 0 0 Tolyltriazole acid 0.55 0.55 0.99 1.6 0.99 1.37 water 85.26 84.67 86.21 85.02 83.76 79.39 Caprylic acid 0 0 0 0 0 0.4

The composition of the present invention may also contain a small amount of catalyst used in the thermal condensation reaction of L-aspartic acid from which the polymer is produced. Typically, such catalysts are acids, such as phosphoric acid, which are converted into the salts of pyrophosphate by-products and the corresponding salts during hydrolysis of the succinimide polymer.

Typical oxidation inhibitors may also be incorporated into the compositions of the present invention, for example zinc and other metal dithiophosphates, hindered phenols, metal phenol sulfides, metal free phenol sulfides, aromatic amines and mixtures thereof It includes.

Because many operations in which the composition of the present invention is used produce fine particles that must be removed from the metal surface, detergents and dispersants are applied to the composition of the present invention. Typical dispersant (s) include polyamine succinimides, alkaline oxides, hydroxy benzyl polyamines, polyhydroxy succinic esters and polyamine amide imidazolines and mixtures thereof. Typical detergents include metal sulfonates, overbased metal sulfonates, metal phenate sulfides, overbase metal phenate sulfides, metal salicylates and metal thiophosphonates and mixtures thereof.

Thus, the compositions of the present invention may also include surfactants, pressure resistant agents, buffers, precipitation devices, antibacterial agents and other auxiliaries commonly used in these compositions and mixtures thereof.

The concentrated compositions of the present invention are most conveniently used commercially, and the concentrated compositions of the present invention, which are diluted prior to use, preferably contain potassium salts of the various components in a range of concentrations, but typically about 0.5 weight. Potassium polyaspartate up to the solubility limit, or up to solubility limit, from about 0.1% to about 10% by weight of divalent basic potassium orthophosphate as supplementary corrosion inhibitor, from about 0.02% to about 9.5% by weight of potassium carbonate having a solubility limit and from about 200 ppm to About 3% by weight of a corrosion inhibitor. Preferred corrosion inhibitors as described above contain from about 40% to about 0% by weight of 4-methyl-1H-benzotriazole and from about 60% to about 100% by weight of 5-methyl-1H-benzotriazole. Tolyltriazole. Those skilled in the art will appreciate that the solubility limit of the components is affected by the pressure of the other components. Other useful corrosion inhibitors include alkylbenzotriazoles such as C ₁ -C ₄ alkylbenzotriazoles and butylbenzotriazoles.

The polyaspartic acid of the present invention is preferably provided by the thermal condensation reaction of aspartic acid. Polyaspartic acid can also be prepared by the polymerization of other monomers such as mono- or diammonium maleate, mono- or diammonium fumarate and maleic acid. Many other processes are known for achieving this purpose. For example, a continuous process has recently been discovered using tray driers, in which aspartic acid is the highest level that moves periodically in a horizontal plane to transport reactants to adjacent lower level trays. Is introduced into the tray. The residence time in the dryer is controlled by the number of tray levels, the tray rotation speed, and the circulation and temperature of the heated gas, such as the air passing through the dryer. The temperature of such a device is usually from about 180 ° C. to about 350 ° C. for a residence time of about 0.5 hour to about 6 hours. A typical tray dryer is commercially available from Fort Lee's Wymont Company, Inc. in New Jersey.

Another tray dryer that may be used in the above process is a tray dryer commercially produced by Krause Mapei of Florence, Kentucky. In the Krause Mapei tray dryer, the heated tray is stationary and the reactants are moved across each plate by flows or shovels that rotate in the axial direction. The reactants are selectively dropped from one tray level to the next at the inner or outer edge of the tray. The reactants are heated directly by the tray.

There are some isomers of aspartic acid that can be used to prepare polyaspartic acid, such as D-, L- or DL-aspartic acid, but it is preferable to use L-aspartic acid here.

If a catalyst is used in the reaction, the residence time in the tray may be shorter than about 30 minutes to about 2 hours, depending on other factors as described above. Carbon dioxide in the circulating gas will promote the thermal condensation reaction when present in an amount of at least about 5% by volume. The amount of carbon dioxide in the circulating gas is usually about 10% by volume.

Various other reactors may be used to produce the polyaspartic acid of the present invention. Typical reactors are A. Swiss. Rat. List reactors commercially available from Ernis, Ogst; Littleford Bros., Kentucky; Littleford reactors such as Model FM 130 laboratory mixers and mass production models available from Inc. It includes.

Littleford mixers provide sufficient agitation to provide fluid bed conditions, and choppers that break down lumps or clumps of developing particles and provide additional shear force to the fluid bed. Can be equipped. Stirring by the mixer is sufficient to keep the particles substantially free of flow throughout the reaction time. Typically, the Littleford mixer is operated at least about 180 ° C. and can maintain the heated bed at a temperature of about 180 ° C. to 250 ° C. or higher for a time sufficient to polymerize aspartic acid. The mixer is preferably equipped to provide a purge gas stream through the reactor. According to the present invention the gas stream is preferably provided with a sufficient amount of carbon dioxide to promote the condensation reaction, thus significantly reducing the time required for the aspartic acid to fully polymerize.

Common thermal condensation reactions of aspartic acid produce polysuccinimide intermediates. This intermediate is easily hydrolyzed to the polyaspartic acid salt by alkaline solution. Examples of alkaline solutions include alkali metal hydroxides, triethanolamine (TEA), ammonium hydroxide, and the like.

Salts of water-soluble polyaspartic acid, including compounds that can be produced by thermal condensation of L-aspartic acid, can be used in the metalworking compositions of the present invention. Typical water soluble salts include alkali metal salts, ammonium salts, organic ammonium salts and mixtures thereof. The term "alkali metal" includes lithium, sodium, potassium, cesium and rubidium and mixtures thereof. Organic ammonium salts useful herein include salts prepared from organic amines having a low molecular weight, i.e., a molecular weight of about 270 or less. Organic amines useful herein include alkyl amines, alkylene amines, alkanol amines. Typical organic amines are propylamine, isopropylamine, ethylamine, isobutylamine, n-amylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, hexadecylamine, Basic amino acids such as heptadecylamine, octadecylamine, and lysine.

Regardless of which reactor is used, polyaspartic acid or salts thereof prepared by thermal condensation of L-aspartic acid are useful in the present invention. Such polymers have been found to provide sufficient lubricity to allow metal processing on ferrous and nonferrous metals.

Polyaspartic acid of any molecular weight may be usefully employed here.

Polyaspartic acids derived from other sources are also useful in the compositions and methods of the present invention. For example, using maleic acid or derivatives thereof such as those disclosed in US Pat. No. 3,846,380 to Fujimoto et al., US Pat. No. 4,839,461 to Boemke, and US Pat. No. 4,696,981 to Harada et al. Polyaspartic acid may be derived from the polycondensation process. Although not preferred, copolymers of amino acids such as copolymers prepared according to US Pat. No. 4,590,260 to Harada et al. May also be used in the process of the present invention.

The metalworking fluids based on water of the present invention are practically advantageous in that they are essentially odorless with respect to aqueous solutions consisting of polyaspartic acid or salts thereof or amines thereof. In addition, the fluids of the present invention have been observed to significantly reduce fog generation around work tools, a common phenomenon in oil-based fluids based on water. Since the generation of fog is substantially reduced, the work area remains substantially free of deflected fluids leaving the machine, and workers are substantially free from contamination by metalworking fluids that render the invention infeasible. The metalworking fluids based on water of the present invention are most advantageous in that the active ingredient, polyaspartic acid or salts thereof have a fast biodegradation rate. The biodegradability of the metalworking fluids of the present invention allows for treatment via conventional methods, such as the release to sewage treatment systems. This cost benefit of the fluids of the present invention is evident from an environmental point of view, which ultimately provides an alternative treatment means.

Testing with non-ferrous metals such as brass and copper has shown that the workplace is relatively unpolluted and there are no discoloration deposits left in the process product. In fact, it has been observed that aqueous solutions of polyaspartic acid salts are corrosion inhibitors as disclosed in US Pat. No. 4,971,724 to Carlotta et al. Therefore, metals, in particular ferrous metals, are virtually protected from corrosion by the metalworking fluid of the present invention and no harmful deposits are formed. However, the corrosion inhibitory effect of the polyaspartic acid aqueous solution is applied to a solution having a pH of about 8.5 or more. If the composition using the polyaspartic acid or derivative thereof of the present invention is an aqueous solution having a pH of about 10 or less, it is advisable to incorporate additional anti-corrosion inhibitors into the composition of the metalworking fluid of the present invention. However, it is shown in FIG. 1 that while the fluid is actually used, the pH of the polyaspart composition of the present invention tends to decrease due to contact with acidifying agents such as carbon dioxide in the atmosphere. Therefore, it is common practice to include additional corrosion inhibitor (s) in the compositions of the present invention. The amount of corrosion inhibitor used may vary widely depending on the specific inhibitor and the environment in which the fluid is used. For example, if zinc chromate is a corrosion inhibitor, the effective amount in the processing fluid will be at least 50 ppm.

The metalworking fluids of the present invention are useful in a variety of metalworking applications as described above using all types of metals. In particular, the fluids of the present invention are useful in the processing of ferrous metals and alloys such as iron, steel (carbon steel and low alloy carbon steel), cast iron, stainless steel, nickel base alloys and cobalt-containing alloys and the like. Non-ferrous metals and alloys that can be processed into the fluids of the present invention are copper, brass, titanium, aluminum, bronze, magnesium and the like. These metals are safely processed by the lubricity supplied by the water based fluid of the present invention.

A practically important function of the metalworking fluid of the present invention in cutting operations is the function of cooling to keep the tool temperature low as well as the processing temperature. This control helps to minimize tool wear and process warpage. Another function of the metalworking fluid of the present invention is to reduce the friction between the tool and the process product, as well as to act as a lubricant to reduce the friction between the tool and the chip generated during the cutting operation. For various types of cutting operations, small metal chips are typically produced that are advantageously removed from the process product as soon as possible so as not to be entangled in the cutting tool.

Example 1

In the following examples, a laboratory model of a tray dryer was used, which had two trays for passing reactants from one side to the other, simulating the conditions of the commercially available tray dryer mentioned above. . The reactants were passed from one tray to the other tray to be equal to the tray level number of the desired commercial model. A tray dryer simulating the Weyssmont Turbo Dryer, available from Weissmont, Fort, NJ, was operated by adding 1 kg of L-aspartic acid per tray level to 2.5 cm deep on the tray. In total, 28 tray levels were used. The temperature of the circulating air passing through the 305 ° C. dryer was maintained at 305 ° C. throughout the experiment. The air speed was maintained at 114.3 m / min and the tray rotation was fixed at 3 min / rotation. Carbon dioxide was supplied such that the total amount of carbon dioxide in the air in contact with the reactants on the tray was provided at 10% by volume. Samples were taken from the trays at various reaction times and analyzed for amount, pH, color (APHA) and molecular weight converted to polymer. The data obtained here are shown in Table II below.

Table II

Sample number Minutes Molar weight color pH % Polymer conversion One 30 9402 112 9.17 53.66 2 64 9333 471 9.82 99.00 3 70 9263 565 9.26 99.06 4 90 8792 1069 10.01 99.16

Example 2

Experiments were performed to show the effect of carbon dioxide on the pH of the polyaspart metalworking fluid of the present invention. A 1% aqueous solution of sodium polyaspartate containing residual sodium phosphate (1500 ppm as PO ₄ ) was subjected to aeration with a gas mixture of 2.5% by volume of carbon dioxide in nitrogen as well as pure nitrogen. The data is shown in Figure 1, where curve A is the data obtained by treatment with pure nitrogen, curve B is the data obtained by treatment with a blend of carbon dioxide and nitrogen. Rapid slope of pH, as shown by curve B, shows the effect of carbon dioxide on the pH of the solution. As shown in FIG. 1, the pH of the solution rapidly aerated with a gas containing carbon dioxide indicates about 7, while the pH of the solution aerated with nitrogen alone remained essentially unchanged.

Example 3

Subsequent tests were performed to show the effect of basic additives on the pH stability of the metalworking cousins and the tendency of fluids to be corrosive to metals. Polysuccinimide samples prepared by various methods were prepared for hydrolysis and use as metal covalent carriers. One set of samples was made with aspartic acid without catalyst (Sample A) and the other set of samples was made with polyaspartic acid prepared in the presence of phosphoric acid at 7.5% by weight of aspartic acid (Sample B). Samples were prepared to have the following composition and pH was adjusted equally by addition of acid or base as needed.

Sodium Polyaspartate 1% by weight

Benzotriazole 950ppm

1500 ppm disodium phosphate (as PO ₄ )

pH 9.60

693 g of water

Tap water (Sample C), the third sample of which pH was adjusted to 9.6 with sodium hydroxide, was used as a control. Ambient air, typically containing 0.033% CO ₂ , was injected into the liquid samples at a constant rate greater than 200 cc / min at ambient room temperature and pressure. The pH of each solution was measured once a day for 6 days. An amount of sodium carbonate ranging from 250 ppm to 1000 ppm was added to each sample at the beginning of the test. The test results are shown in Table III below.

Table III

Sample A A A B B B C Na ₂ CO ₃ 250 500 1000 250 500 1000 - 3.5 hours 9.32 9.43 9.43 9.37 9.31 9.34 7.94 1 day 8.89 9.17 9.24 9.00 9.08 9.07 8.05 2 days 8.84 9.01 9.11 8.88 8.87 9.04 7.92 3 days 8.84 8.97 9.08 8.87 8.87 9.04 7.92 4 days 8.80 8.94 9.04 8.80 8.84 9.03 7.84 5 days 8.80 8.92 9.04 8.81 8.85 9.00 8.03 6 days 8.83 8.95 9.05 8.80 8.86 9.03 8.02

From the data it can be seen that sodium carbonate is effective at all levels to maintain a pH level higher than the pH level found in tap water. In addition, the pH reached 9 or more after 2 days at the 1000 ppm level. Above pH 9, it can be seen that the corrosion level is reduced to a slight level. The addition of basic additives stabilizes the processing fluid to an acceptable level of pH in subsequent tests, demonstrating that it does not degrade even if normally used for a relatively long time.

Example 4

Polyaspartic acid, sodium salts were prepared by a Wysmont turbo dryer in the presence of 7.5% phosphoric acid catalyst. The acid polymer was hydrolyzed with sodium hydroxide and diluted with 1% by weight aqueous solution. Two polyaspartic acid polymer batches were formulated with benzotriazole, which had a pKa value of 8.3.

Since the pKa value is below the pH of the test solution, no effect on pH in this test is affected by benzotriazole. No sodium carbonate was added to one batch containing 200 ppm of benzotriazole, and sodium carbonate was added at a concentration of 1000 ppm to another batch containing 950 ppm of benzotriazole. The cutting fluid of each batch was used as the cutting fluid of the Okuma LB10 cutter. The pH of each cutting fluid batch was measured initially, after one day and after five days. Each batch was used to cut 300 pieces of 1018 steel from 2.54 cm to 0.934 cm using a Mitsubishi DMN G 432MA insert. This splitter was the Manchester M50. The pH test results obtained by periodic pH measurement of polyaspart polymer cutting fluids are shown in Table IV below.

Table IV

No carbonate 1000 ppm carbonate Start 1 day 5 days 9.88.918.16 10.39.919.78

The results show that 1000 ppm sodium carbonate stabilizes the pH of the polyaspart polymer cutting fluid, while cutting fluid without basic additives drops to 9-9.5 below the desired pH level.

Example 5

Typically, preferred compositions of the present invention are polymerized with L-aspartic acid as described in Example 4, followed by hydrolysis of the resulting polysuccinimide by filling it in a suitable container at the weights set forth in Table V below. It can manufacture.

Table Ⅴ

Filling content Polysuccinimide 106 water 1072 50% KOH 133

21 parts by weight of dipotassium phosphate, 17.7 parts by weight of potassium carbonate and 13.5 parts by weight of tolyltriazole were added to the potassium polyaspartate prepared by the hydrolysis process described above. Tolyltriazole consists of a mixture comprising 40% 4-methyl-1H-benzotriazole and 60% 5-methyl-1H-benzotriazole. When using tolyltriazole, it is desirable to maintain tolyltriazole at a level of about 900 ppm or more in the processing fluid for best results.

Example 6

To illustrate the point drop in the composition of the present invention consisting of the incorporation of potassium ions instead of sodium ions, the three compositions shown in Table I above were tested by cooling while visually observing the composition with respect to homogeneity and point. It was. The results are described in Table VI below.

Table VI

Composition Freezing point- ℃ Precipitation amount Sodium salt -1 ℃ +10 Potassium salt -6 ℃ No precipitation Mixed salt -3 ℃ Very little @ -0 °

From the data above, it was found to be very advantageous in that the potassium salt significantly reduced the freezing point. An important point associated with the reduction of freezing point is the fact that no precipitate is observed even at freezing point, indicating that no phase separation of the solution occurs. Thus, the freezing effect of the potassium salt mixture is not as detrimental as in the case of sodium or mixed salt compositions which require further mixing to redistribute the separated phases of the composition due to the freezing temperature.

While the invention has been described in terms of specific embodiments described in detail, it is merely illustrative of the effective amounts of effective compositions and components, and as the optional embodiments and techniques of operation will become apparent to those skilled in the art, It is to be understood that the invention is not limited thereto. Accordingly, modifications are expected without departing from the spirit and scope of the invention described above.

Claims (50)

A metal processing method provided with a lubricant, comprising the steps of: providing an aqueous solution consisting of a polyaspartic polymer selected from the group consisting of polyaspartic acid, salts thereof or amides thereof, corrosion inhibitors and stable amounts of basic additives, the basic additives Is a metal processing method, characterized in that it has sufficient basicity and buffering capacity to maintain the pH of the composition at about 8.5 or more. The method of claim 1, wherein the pH is maintained at about 9 or greater. The method of claim 1 wherein the polyaspart polymer is potassium polyaspartate, the basic additive is an alkali metal salt or an amine salt or an ammonium salt, and the corrosion inhibitor is tolyltriazole or benzotriazole or alkylbenzotriazole. The method of claim 3, wherein the alkali metal salt is a potassium salt, and the corrosion inhibitor is tolyltriazole. 4. The process according to claim 3, wherein the tolyltriazole or benzotriazole is present in an amount of at least about 100 ppm, preferably about 900 ppm. 6. The tolyltriazole or benzotriazole of claim 5 contains from about 0% to 40% of 4-methyl-1H-benzotriazole and from about 60% to 100% of 5-methyl-1H-benzotriazole. Characterized in that it is present as a mixture. The method of claim 1 wherein the solution contains from about 0.05% to about 70% by weight, preferably from about 0.5% to about 2% by weight of the polymer, and the corrosion inhibitor is tolyltriazole or benzotriazole or alkylbenzo Triazole, and the basic additive is potassium carbonate. 8. The method of claim 7, wherein the solution contains from about 0.05% to about 70% by weight of the polymer, and the basic additive is present from 0.02% to about 8% by weight of the solution. The method of claim 1, wherein the metal working is a cutting operation selected from the group consisting of dressing, grinding, forming, turning, milling or drilling. The method of claim 1 wherein the metal working is bending. The method of claim 1, wherein the metal is an iron metal or alloy selected from the group consisting of iron, steel (carbon steel and low alloy steel), cast iron stainless steel, nickel base alloys, cobalt containing alloys, and the like. The method of claim 1 wherein the metal is a non-ferrous metal or alloy selected from the group consisting of copper, bronze, brass, titanium, aluminum, magnesium, and the like. A polyaspartic polymer selected from the group consisting of polyaspartic acid, salts thereof, or amides thereof, comprising from about 0.05% to about 70% of an aqueous solution of a corrosion inhibitor (s) and a stable amount of basic additive, wherein the basic additive comprises A metalworking composition comprising sufficient basicity and buffering capacity to maintain a pH of about 8.5 or greater. The composition of claim 13, wherein said pH is maintained at about 9 or greater. The composition of claim 13, wherein the corrosion inhibitor (s) is present in the range of about 50 ppm to about 15 weight percent and the basic additive maintains the pH at about 8.5 to about 11. 15. The composition of claim 15 wherein the basic additive is potassium carbonate and the corrosion inhibitor is tolyltriazole. The method of claim 16 wherein tolyltriazole is a mixture containing from about 0% to about 40% 4-methyl-1H-benzotriazole and from about 100% to about 60% 5-methyl-1H-benzotriazole. Composition, which is present. 17. The composition of claim 16, wherein the tolyltriazole is present as a mixture containing about 100% 5-methyl-1H-benzotriazole. The method of claim 13, wherein the concentration of the polyaspart polymer is at least about 0.05% by weight of the solution, the corrosion inhibitor is tolyltriazole and is present in about 0.01% to about 2% by weight, and the water-soluble alkali metal phosphate or ammonium phosphate is about 0.1%. A composition comprising a supplemental corrosion inhibitor containing from about 10% by weight to about 10% by weight. 20. The composition of claim 19, wherein the alkali metal phosphate is selected from the group consisting of sodium orthophosphate or potassium orthophosphate. The composition of claim 20 wherein the polymer is an alkali metal salt. The composition of claim 21 wherein the salt is a potassium salt. The composition of claim 22 wherein the polymer is an amide. An aqueous solution consisting of potassium polyaspartate, a basic additive having sufficient basicity and buffering capacity to maintain the pH of the composition above about 8.5, a corrosion inhibitor, and a supplemental corrosion inhibitor containing about 1% to about 10% potassium orthophosphate A dilution metal working composition for producing a processing fluid, characterized in that it comprises. 25. The composition of claim 24, wherein the pH is maintained at about 9 or greater and the basic additive is potassium carbonate. 25. The method of claim 24, wherein the potassium polyaspartate is present in a range from about 0.5% to its solubility limit, wherein the corrosion inhibitor is from about 0% to about 40% by weight of 4-methyl-1H-benzotriazole and about A tolyltriazole containing from 100% by weight to about 60% by weight of 5-methyl-1H-benzotriazole. 27. The composition of claim 26, wherein the tolyltriazole is present in the range of about 0.1% to about 2% by weight. 25. The composition of claim 24, wherein the corrosion inhibitor is a salt of benzoic acid. 25. The composition of claim 24, wherein the corrosion inhibitor is selected from the group consisting of sodium benzoate and ammonium benzoate. About 0.5 wt% to about solubility limit of potassium polyaspartate, about 0.2 wt% to about 9 wt% potassium carbonate, about 0.3 wt% to about 2 wt% corrosion inhibitor, and about 1 wt% to about 10 wt% A dilution metal processing concentrate composition comprising a supplemental corrosion inhibitor containing potassium orthophosphate. 31. The composition of claim 30, wherein the corrosion inhibitor is tolyltriazole. 32. The method of claim 31 wherein the tolyltriazole is about 0% to about 40% by weight of 4-methyl-1H-benzotriazole and about 100% to about 60% by weight of 5-methyl-1H-benzotriazole A composition comprising a. 33. The method of claim 32, wherein the solution contains from about 0.5% to about 70% by weight of the polymer, the corrosion inhibitor is alkylbenzotriazole or tolyltriazole or benzotriazole, and the basic additive is sodium carbonate. Way. The method of claim 33, wherein the solution contains about 0.5% by weight or the solubility limit of the polymer, and sodium carbonate is present in an amount up to about 7% by weight of the solution. 34. The method of claim 33, wherein the metal working is a cutting operation selected from the group consisting of dressing, grinding, forming, turning, drilling and milling. 34. The method of claim 33, wherein the metal working is a bending operation. 34. The method of claim 33, wherein the metal is an iron metal or alloy selected from the group consisting of iron, steel (carbon steel and low alloy steel), cast iron, stainless steel, nickel based alloys, cobalt containing alloys. 34. The method of claim 33, wherein the metal is a non-ferrous metal or alloy selected from the group consisting of copper, bronze, brass, titanium, aluminum and magnesium. 34. The composition of claim 33, wherein the basic additive is a mixture of sodium carbonate and potassium carbonate, and the corrosion inhibitor is benzotriazole or tolyltriazole or alkylbenzotriazole. 40. The composition of claim 39, wherein the concentration of corrosion inhibitor is from about 50 ppm to about 15 weight percent. The composition of claim 1, further comprising a small amount of sodium orthophosphate retained from the polymerization process to obtain the polyaspart polymer. The composition of claim 1 wherein the polymer is an alkali metal salt. The composition of claim 1 wherein the polymer is an ammonium salt or an amine salt. The composition of claim 1 wherein the polymer is an amide. Sodium polyaspartate, metal processing comprising a basic additive having sufficient basicity and buffering capacity to maintain the pH of the composition above about 8.5, a small amount of aqueous solution of sodium orthophosphate and corrosion inhibitor and potassium orthophosphate Composition. 46. The composition of claim 45, wherein the sodium polyaspartate is present in the range of about 0.5% to its solubility limit, and the corrosion inhibitor is benzotriazole or alkylbenzotriazole or tolyltriazole. 46. The composition of claim 45, wherein the corrosion inhibitor additives are present in the range of about 50 ppm to 15% by weight. The method of claim 1 wherein the solution contains from about 0.5% to about 70% by weight of the polymer, the corrosion inhibitor is benzotriazole and the basic additive is sodium carbonate. The method of claim 2 wherein the solution contains from about 5% to about 15% by weight of the polymer and sodium carbonate is present in an amount up to about 7% by weight of the solution. 3. The method of claim 2 wherein the metal working is a cutting operation selected from the group consisting of dressing, grinding and forming.