|WO/2003/089551||ENVIRONMENTALLY COMPATIBLE ADDITIVES FOR AQUEOUS LUBRICANTS|
Elliott, David L. (45 Forest Glenn, Imperial, PA, 15126, US)
Castaing, Denis R. (105 School Street, McDonald, PA, 15057, US)
Elliott, David L. (45 Forest Glenn, Imperial, PA, 15126, US)
|1.||A metal working composition comprising 1) a soap, 2) a nonvolatile ester, and 3) a particulate component.|
|2.||The composition according to claim 1 wherein the soap of 1) is an metal, or amine salt of a 10 to 30 carbon fatty acid; the nonvolatile ester of 2) is either polymeric or nonpolymeric and is water dispersible; and the particulate component of 3) is a finely divided particulate substance.|
|3.||The composition according to claim 1 wherein the soap of 1) is present in a concentration between about 3 and about 25 weight percent; the nonvolatile ester of 2) is present in a concentration between about 2 and about 20 weight percent; and the particulate component of 3) is present in a concentration between about 5 and about 40 weight percent; all in an aqueous base.|
|4.||The composition according to claim 1 wherein the soap of 1) is a salt selected from the group consisting of stearic acid, oleic acid, linoleic acid, isostearic acid, tall oil fatty acid, and neodecanoic acid.|
|5.||The composition according to claim 1 wherein the particulate component of 3) is selected from the group consisting of swelling clays, a non swelling clays, and organically modified clays.|
|6.||The composition according to claim 5 wherein the particulate component of 3) is a nonswelling clay.|
|7.||The composition according to claim 6 wherein the particulate component of 3) is kaolin.|
|8.||The composition according to claim 1 further comprising at least one more additive selected from the group consisting of corrosion inhibitors, yellow metal protection additives, biocides, dyes, viscosity modifiers, buffering agents, alkalinity control agents, fragrances, odor masking agents, extreme pressure additives, supplemental lubricity agents, surfactants, wetting agents, dispersants, emulsifiers, coupling agents, oils, and solvents.|
|9.||The composition according to claim 8 wherein said extreme pressure additives are selected from the group consisting of active sulfur containing agents, phosphate esters, and organic chlorinecontaining agents.|
|10.||A metal working process comprising a) applying the composition of claim 1 to a metal surface of a workpiece, thereby forming a coated metal surface, b) contacting said coated metal surface with a metal working tool, and c) working said workpiece.|
|11.||The metal working process according to claim 10 wherein the working process using said composition is a metal forming process selected from the group consisting of forging; extrusion; rod, wire or tube drawing; rolling; and sheet forming.|
BACKGROUND OF THE INVENTION In metal forming operations, the presence of a metal working lubricant is a necessity. Without a suitable lubricant, the friction between the die and the workpiece is so great as to cause galling, scoring, and even tearing of metal.
These problems are exacerbated in operations involving the formation of deep sections, for example two-piece metal beverage cans, vehicle oil pans and particularly products of thick sections such as spark plug bases.
Metal forming and metal working are disclosed in these books: "Metalworking Fluids", J. P. Byers, Marcel Dekker, New York, 1994.
"Metal Forming : Mechanics and Metallurgy", by W. Hosford and R. Caddell, 1983 (or 1993).
The following patents disclose metal working compositions and processes: 4,559,153; 4,765,917; 4,983,229; 5,531,912; 5,783,530; and 5,837,658, the disclosures of which are incorporated herein by reference in their entirety.
In addition to being lubricious under extreme operating conditions, a suitable metal forming lubricant must also possess other characteristics in order that it may be successfully used in a commercial setting. For example, the lubricant must not build up on the die, otherwise"break through"or striations may be formed. In some cases, the lubricant has formed a residue of sufficient size
such that the fully formed workpiece contains hollows corresponding to the built up residue, and thus produces a part that is not the mirror image of the die.
Lubricants, usually liquid lubricants, are used in metal working operations to reduce friction between the surface of metal being worked and a surface of the apparatus carrying out the operation. A liquid lubricant reduces friction by separating the two surfaces with a thin fluid film having little resistance to shear.
In many metal working operations the pressure between a surface of the metal being worked and a surface of the apparatus is so great that the fluid film of a liquid lubricant may be squeezed out so allowing actual metal-to-metal contact with the result that excessive damage to the surfaces may occur. Solid film lubricants have been developed to provide much greater load bearing properties and thus greater performance, avoiding some of these problems. However, solid lubricants have their own disadvantages. Solid lubricants are harder to manufacture, are more difficult to apply to the metal surfaces, and are more difficult to remove after the metal has been worked, than liquid lubricants.
In addition to its lubrication characteristics, a lubricant may be expected to fulfill certain other requirements if it is to be useful industrially. For instance, it should be easy to apply and easy to remove it should afford some protection to the metal surface during handling and storage, it should present no health hazard to persons coming into contact with it and, obviously, should be inert to the surfaces with which it comes into contact. Many lubricants produce severe stains on the surface of the metal during annealing thereof. It is, therefore, highly desirable to avoid such staining by using a lubricant having the properties demanded by the particular conditions under which the lubricated metal is to be worked and which is also non-staining.
It would be desirable to provide a lubricant that has the high performance characteristics of solid lubricants but yet has the handling advantages of a liquid lubricant, particularly an aqueous lubricant. It would be further desirable to
provide a low viscosity water based lubricant with the performance characteristics of solid lubricants that is environmentally friendly.
SUMMARY OF THE INVENTION The composition of the present invention comprises 1) a soap, 2) a non- volatile ester, and 3) a particulate component. These main components of the composition according to the present invention are in an aqueous base.
The metal working process according to the present invention comprises a) applying the composition above to a metal surface of a workpiece, thereby forming a coated metal surface, b) contacting said coated metal surface with a metal working tool, and c) working said workpiece.
DETAILED DESCRIPTION OF THE INVENTION The inventors have unexpectedly discovered a metal forming composition that has high performance characteristics and is easily handled in metal forming processes. This composition can be a low viscosity water based lubricant that is environmentally friendly and has high performance characteristics, even under great pressures.
The product is in the form of a thick but flowing liquid mulsion. Its unique technical attribute or advantage is a novel combination of lubricity additives (soap) and barrier additives (non-volatile ester and particulate), giving the composition superior performance without the use of traditional extreme pressure additives that contain undesirable components such as sulfur compounds, halogenated organics (i. e. chlorinated compounds), or phosphates. These can be added to give even greater performance if desired if there are no environmental concerns.
This invention is designed for cold-working or cold-forming processes of metals. Examples of metals are ferrous types such as steel, stainless steel, leaded steel, galvanized iron or steel, and other ferrous alloys; and non-ferrous types such as aluminum, brass, zinc, lead, copper, titanium, silver, and the like.
By metal forming is meant any process that is designed to alter the shape of metal without producing chips (metal fragments). These processes include but are not limited to forging; extrusion; rod, wire or tube drawing; rolling ; and sheet forming. Examples of forging are such operations as open-die forging, cogging, closed die forging, coining, nosing, upsetting, heading, piercing, hobbing, roll forging, orbital forging, ring rolling, rotary swaging of bars and tubes, and radial forging. Examples of rolling are flat rolling or shape rolling. Examples of sheet forming are blanking, piercing, press bending, deep drawing, stamping, stretch forming, spinning, hydroforming, rubber-pad forming, shallow recessing, explosive forming, dimpling, roll forming, or flanging.
The composition form can be either a solid, a paste, or a liquid. Preferred is a liquid of pourable viscosity. The soap component can be present at concentrations between 3 and 25%, with 10-20% preferred, and 12-18% most preferred. The ester can be present at concentrations between 2 and 20%, with 6-16% preferred and 10-15% most preferred. The particulate component can be present at concentrations from 5 to 40%, with 10-30% preferred and 15-30% most preferred. The preferred particulate material is a ground kaolin having particle size from 0.1 to 10 microns, with 0.5 to 5 more preferred and 1 to 2 most preferred. Other particulate materials which are useful in this invention are bentonite clays and calcium carbonate.
The pH of the composition can be from 6.5 to 11.5, with 8 to 10.5 preferred and 8.5 to 10 most preferred. The significance of pH is that the preferred compositions need to have pH greater than about 8.5 to have suitable
corrosion resistance for commercial applications, but pH lower than about 10 to avoid causing skin irritation or other health or environmental problems.
Preferably, the composition should contain customary additives such as corrosion inhibitors, yellow-metal protection additives, biocides, and dyes. The composition may further contain other additives such as viscosity modifiers, buffering agents, alkalinity control agents, fragrances, odor masking agents, extreme pressure additives such as active sulfur containing agents, phosphate esters, or organic chlorine-containing agents, supplemental lubricity agents, surfactants, wetting agents, dispersants, emulsifiers, coupling agents, and solvents or oils.
The metal lubricant composition according to the present invention is an aqueous system and preferably contains low to no organic solvents and therefore would be a composition that did not have volatile organics (VOCs) and would be a low VOCs composition.
The extreme pressure additives, if employed in the water-base lubricant composition of the present invention can be at a level of 0.01 to about 35%, preferably about 0.01 to about 22%, and highly preferred at about 1 to about 16% by weight. The extreme pressure additives enhance the metal forming process under extremely high pressure conditions. The extreme pressure additives are selected from the group consisting of phosphate esters, sulfurized fatty acids, phosphosulfurized vegetable oils, and mixtures thereof.
The biocides employed in the water-base lubricant composition of the present invention are at a level from 0 to about 5%, preferably about 0.01 to about 2%, and highly preferred at about 0.05 to about 1 % by weight. The biocide or preservative agents of the present invention are preferably selected from the group consisting of polyamino derivatives, triazine derivatives,
benzisothiazolinone derivatives, and mixtures thereof. A specific preferred example inclues 1,2-benzisothiazolin-3-one.
Aqueous lubricating compositions of the present invention are usually supplied in a concentrated form. The lubricant composition may be employed in concentrated form for difficult metal forming operations. In other somewhat less difficult metal forming operations, the concentrate lubricant can be diluted with water to fit the particular metal working needs. The amount of dilution can be determined by actual operation of the metal working machinery on a particular workpiece. Satisfactory metal working applications have used dilution ratios of 1: 1 to 1: 50 (volume ratio of the concentrated lubricant composition of the present invention to water).
The preferred method of application of the lubricant composition of the present invention is by spraying the composition on the surface of the dies or directly upon the workpiece, however, swabbing, dipping, or the like may also be employed.
1) Soap Component The soap component according to the present invention is preferably metal, or amine salt of a 10 to 30 carbon fatty acid. Preferred metals of the metal salt are alkali metal and alkaline earth metals, with alkali metals being more preferred. Examples of more preferred soaps include the salts of the following: Stearic Acid (18 carbons, fully saturated) Oleic Acid (18 carbons, with 9-unsaturation) Linoleic Acid (18 carbons, with 9,12-unsaturation) Isostearic Acid (18 carbons, fully saturated, branched) Tall Oil Fatty Acid (mixture of oleic, linoleic, and rosin acids, significant unsaturation) Neo-decanoic Acid (10 carbons, fully saturated)
2) Non-Volatile Ester Component The non-volatile ester component of the composition of the present invention is designed to provide lubricity and can be either polymeric or non- polymeric. This non-volatile ester component is preferably water dispersible.
Water dispersible means that this non-volatile ester component is not completely soluble an aqueous media, however, it is somewhat hydrophilic and can be at least partially hydrated in an aqueous medium. This non-volatile ester component more preferably can be solubilized with an emulsifier. This non-volatile ester component also provides for tackiness of the composition as well as a chemical barrier and provides separation from the tool and the workpiece. Preferred examples of this non-volatile ester component include : Syn-Ester GY-10 (Gateway Additives Co.) Polymeric ester, high iodine value.
Doverlube B-902 (Dover Chemicals) Non-polymeric ester, low iodine value.
Methyl Tallate (Rhodia) Non-polymeric ester, high iodine value Syn-Ester GY-25 (Gateway Additives Co.) Polymeric ester, low iodine value 3) Particulate Component The particulate component of the present invention is preferably a swelling clay, a non-swelling clay, or organically modified clay; more preferably a non- swelling clay. This particulate component provides a barrier layer between the tool and the workpiece. The swelling clay or swellable clay component of the structuring system can be a clay mineral of the smectite type. The clay can be naturally occurring or synthetic and of the dioctahedral or trioctahedral type.
Examples of the natural clays that may be used in this invention are montmorillonites, hectorites, nontronites, beidillites, saponites, and sauconites.
Materials of this type are available under the names of Gelwhite GP and Thixagel (trade names of Southern Clay). Synthetic swelling clays such as Laponite (trade name of Laporte Industries) may also be used. The smectite type clay should preferably be in an alkali or alkaline earth metal exchange form.
Peptizing agents, such as hexametaphosphate, pyrophosphate, or other polyelectrolytes known to the art can be used. Additionally, organically modified swellable clays, such as CLAYTONE from Southern Clay Products Inc. can be used. Examples of non-swelling clays include attapulgite (Attagel) and kaolin (Astra-Glaze). The clay may be present at about 0.1 to 30%, preferably about 1 to 25%, and most preferably about 5 to 20% by weight of the final products. The use of excessive amounts of clay within the formulas that contain high levels of other solids can lead to viscosities considerably above the preferred range.
Other examples of the particulate component of the present invention, but less preferred, include molybdenum disulfide, graphite, boron nitride, talc, calcium carbonate, mica, and magnesium oxide.
Examples of more preferred particulate additives according to the present invention include the following clay or particulate additives: Astra-Glaze (ECC, Inc.) Kaolin, fine particle size.
Claytone 2000 (Southern Clay Products, Inc.) Organically-modified clay.
Calcium Carbonate Flour (ECC, Inc.) Particulate calcium carbonate.
4) Kaolin Kaolin is the most preferred inorganic particulate component used in composition of the present invention, due in part to its cost, the resulting viscosity of the composition, and good performance in metal working.
Kaolin is a clay, consisting substantially of kaolin minerals, that is naturally white or nearly white, or can be beneficiated to white or nearly white.
Kaolin clay pigments are obtained from kaolin. Kaolin is a type of rock formed through weathering or hydrothermal alteration of feldspar or mica minerals to kaolin minerals, or a sedimentary rock containing a high concentration of kaolinite particles or grains. Sedimentary kaolin rocks contain mostly clay or silt sized particles of kaolin minerals and fine and coarse particle size impurities. Some of the impurities (e. g. fine ferruginous or titaniferous impurities) impart undesirable color to the clay. Other impurities have an undesirable effect on the rheology of the kaolin, and still other impurities are coarse particles called"grit"that are generally above 45 microns which may cause scratching and/or abrasion if used in most applications.
The most common kaolin mineral is a naturally occurring hydrated aluminate silicate known as kaolinite (Al2Si205 (OH) 4). Kaolinite is the primary mineral in the kaolin clay widely used in the paper industry as fillers and/or coating pigments. Kaolin is also called china clay or hydrous kaolin. Its particles occur over a range of sizes and aspect ratios. Aspect ratio can be defined as the diameter of a kaolin particle divided by its thickness. Thus, a kaolin crude will not contain particles of a single size, such as, for example, particles all of which are 2 microns. Typically, a degritted (where 45 micron particles are removed) kaolin crude will contain particles ranging in size from submicron or colloidal to particles 20 micrometers or larger.
Kaolins from different deposits, or even from different parts of the same deposit, can vary widely in the content of impurities, particle size distribution, as well as shape of the kaolin particles. In general, kaolin particles finer than about 1 micrometer are composed of individual platelets, and particles larger than about 1 micrometer are composed of stacks or booklets of several platelets mixed with discrete platelets. Particle sizes of kaolins are conventionally determined by sedimentation using Stokes Law to convert settling rates to particle size distribution, and assume a spherical particle shape for the kaolin
particles, hence, the use of the conventional term"equivalent spherical diameter (e. s. d.)" to designate particle size.
In addition to the main components used in the composition according to the present invention other standard additives can be used. Preferably, the composition should contain customary additives such as corrosion inhibitors, yellow-metal protection additives, biocides, and dyes. The composition may further contain other additives such as viscosity modifiers, buffering agents, alkalinity control agents, fragrances, odor masking agents, extreme pressure additives such as active sulfur containing agents, phosphate esters, or organic chlorine-containing agents, supplemental lubricity agents, surfactants, wetting agents, dispersants, emulsifiers, coupling agents, and solvents or oils.
These include for example: Ingredient Purpose Caustic Soda, 50% Alkalinity, pH control Addco CP-B-2 (an amine borate from Gateway Additives Co.) Corrosion protection Sodium Tolytriazole (COBRATEC TT-50-S) Yellow metal protection Proxel GXL (1,2-benzisothiazolin-3-one from Zeneca, Inc.) Biocide Tall Oil Fatty Acid (Acintol FA-2, Arizona Chemicals) Lubricity Syn-Ester GY-25 (a high MW polyester from Gateway Additives Co.) Lubricity Addco DF-1 (Alkanolamide, Gateway Additives Co.) Emulsifier Surfonic POA L-44 (an ethylene oxide/propylene oxide block copolymer from Huntsman Corp.) Lubricity, Wetting
Examples Example 1. A Typical Formulation with Performance Comparison COMPOSITION 1 Ingredient % in Formula Zeolite-softened Water 45.9% Sodium Hydroxide, 50% 4.0% Tall Oil Fatty Acid 14.3% Syn-Ester GY-25 5.0% Addco DF-1 Alkanolamide 3.0% Surfonic POA L-44 3.0% Addco CP-B-2 2.0% Sodium Tolytriazole, 50% 0.8% Proxel GXL Biocide 0.5% Astra-Glaze kaolin 21.5% Composition 1 was tested for lubricity using a Draw Bead Simulator. This instrument tests the lubricating characteristics of various metal forming compositions and their relative value in drawing and stamping operations. The test entails coating the dies and a standardized test strip (2 x 18 x 0.03") with the candidate composition, clamping the strip in the dies (with a specific drawing load), and pulling the strip through the dies for a distance of approximately 5 inches. The loads experienced while pulling the strip through the dies are recorded. The SLT number relates the candidate composition performance to a 1200 second viscosity oil standard. The SLT number will thus be lower as the drawing (metal forming) efficiency of the composition improves.
Composition 1 was compared via Draw Bead Simulation to a standard composition (Composition 2) consisting of 20% chlorinated paraffin in a 100- second oil. This type of composition would have excellent drawing/stamping performance in the metal forming industry, as the chlorinated paraffin is a common extreme pressure additive used in many commercial or industrial operations. The results of draw bead testing are as follows: Sample ID SLT Number Composition 1 196 Composition 2 211 No composition (blank) > 400 Example 2. Performance of Compositions Having Varying Combinations of Ingredients The following tests were conducted to demonstrate the importance of the three key components of this invention. Alternate compositions were prepared having zero, one, two, and three of the key components. These were tested via Draw Bead Simulation as described above.
The soap component is a tall oil fatty acid. The ester component is Syn- Ester GY-25 (Gateway Additives). The particulate is Astra-Glaze (ECC) kaolin.
Customary additives included caustic soda, alkanolamide emulsifier, Surfonic POA L-44 lubricity agent, Addco-CP-B-2 corrosion inhibitor, sodium tolytriazole yellow metal corrosion inhibitor, and Proxel GXL biocide.
% in Formulation Ingredient 1 2 3 4 5 6 7 8 Water 38.4 38.4 38.4 38.4 38.4 38.4 38.4 38.4 Customary Additives 12.3 12.3 12.3 12.3 10.3 10.3 10.3 10.3 Soap 18.3 18.3 18.3 18.3 Ester 6.0 6.0 6.0 6.0 Particulate 25.0 25.0 25.0 25.0 Total % of Formulation * 100 75 69 94 54.7 79.7 48.7 73.7 Comments all no soap no ester no none clay three clay only ester only soap only SLT Number 196 213 252 266 304 385 414 424 * In this Example, if the component was removed, it was not further diluted with water. Had this dilution been done, the SLT Number would have been much higher for numbers 2-8.
As evidenced by the low SLT Number, the composition according to the present invention containing all three components (#1) has superior drawing performance over non-inventive compositions.
Example 3. Soap Substitutions The following tests were performed to determine the effect of different soap components. The formula in Example 1 was modified with the substitution of the following soaps in the exact same amount of 18.3 weight percent, all other factors were equal:
Soap SLT Number Stearic Acid 157 Isostearic Acid 139 Linoleic Acid 140 Tall Oil Fatty Acid 196 Although these three substitute soaps had lower SLT Numbers there were other drawbacks with these that are not present with preferred soap, tall oil fatty acid. The resulting compositions for the first two were too viscous and had viscosities well over 35,000 cP. Stearic Acid is also a wax and hard to process.
Linoleic acid, although it provides a composition with a low SLT Number, is expensive and prone to oxidation.
Example 4. Ester Substitutions The formula in Example 1 was modified with the substitution of the following esters: Ester SLT Number Methyl Tallate 179 Doverlube B-902 206 Syn-Ester GY-10 177 Syn-Ester GY-25 196 Although these three substitute non-volatile esters had equal or lower SLT Numbers than the preferred Syn-Ester GY-25, these substitutes are more expensive.
Example 5. Particulate Substitutions The formula in Example 1 was modified with the substitution of the following particulate components: Particulate SLT Number Claytone 2000 96 Calcium Carbonate 153 Kaolin (Astra-Glaze) 196 Although the two substitute particulate components had lower SLT Numbers than the preferred (kaolin) the resulting compositions had very high viscosities (above 35,000 cP) and were very hard to work with. Additionally, Claytone 2000 is more expensive.
Example 6. A Preferred Formulation The formulation below is a more preferred formulation that provides good results in practice.
Ingredient % in Formula Purposes Zeolite Softened Water 38.4%--- Sodium Hydroxide, 50% 4.0% pH adjustment Addco CP-B-2 2.0% Rust protection Sodium Tolytriazole, 50% 0.8% Yellow metal protection Proxel GXL 0.5% Biocide Tall Oil Fatty Acid 16.3% Lubricity Syn-Ester GY-25 6.0% Lubricity
Addco DF-1 4.0% Emulsifier Surfonic POA L-44 3.0% Lubricity, Wetting Kaolin (Astra-Glaze) 25.0% Barrier protection The above examples are intended to illustrate the present invention but are not intended to be a limitation upon the reasonable scope thereof.