US2825693A - Metal working lubricant - Google Patents

Description

ivmrxr wonmu LUBRICANT Stewart J. Beaubien, flakland, Thomas E. Reamer, El Cerrito, and Paul H. Williams, Orintla, Califi, assignors to Shell Development Company, New York, N. Y., a corporation of Delaware No Drawing. Application February 3, 1955 Serial No. 486,032

3 Claims. (Cl. 252-325) This invention relates to improved lubricating compositions, and more particularly to aqueous lubricating compositions adapted for various metal cutting and fabrieating operations.

The class of water-soluble non-ionic surface active agents available commercially under the trade name Pluromcs, marketed by the Wyandotte Chemical Corporation and of the class of polyoxyalkylene diols described in U. S. Patents 2,674,619 and 2,677,700, have been suggested as suitable lubricants for water-base metal working lubricants. Although cutting fluids containing these surface active agents are excellent as far as cutting and load carrying properties are concerned, it has been found that they cause sticking of machine tool ways, resulting in a slow down, or under aggravated conditions, even in stoppage of production. The reason for this phenomenon is not understood but it appears that it may be attributable to the presence of the hydrophobic homopolymeric polyoxyalkylene unit representing essentially a substantial portion of the molecule. Increasing the water-solubility by incorporating a larger proportion of water-soluble alkylene oxide groups in compounds of this type does not obviate the above undesirable properties which compounds of the above type possess.

The principal object of this invention is to provide an improved aqueous metal-working lubricant. A further object is to provide an aqueous base concentrate suitable as a metal-working lubricant and adapted to be diluted with water to an improved metal working lubricant.

It has now been discovered that the objects of the present invention are attained by a substantially aqueous medium containing a minor amount of (I) a water-soluble heteric copolymeric alkylene glycol, ether or ester thereof, wherein the diiferent oxyalkylene units are substantially randomly distributed throughout the entire polyoxyalkylene chain, and (II) a minor proportion of a water-soluble polyoxyalkylene compound containing a hydrophobic homopolyoxyalkylene unit, of the type described in the above mentioned U. S. Patents 2,674,619 and 2,677,700. These polymeric agents are block copolymers or cogeneric mixtures of conjugated polyoxyalkylene compounds containing at least one hydrophobic homopolyoxyalkylene unit of a unit weight of at least 800, and preferably 900, and one or two other hydrophilic polymeric unit(s) which comprise about to about 90% of the total polymeric compound.

The heteric copolymeric compounds (I) are available commercially under the trade name of Ucons and sold by Carbide and Carbon Chemical Company and are fully described in U. S. Patent 2,425,845. The manner in which these compounds (1) function in overcoming the sticking properties of the other type of polymer (II) is not clearly imderstood. Both polymeric materials (I) and (II) have been suggested in publications and prior patents as additives for metal working compositions. However, polymers of type (I) lack load carrying properties and are therefore relatively useless! States Patent where extreme pressures, wear and loads are encountered and are also excessively corrosive. However, applicants have discovered that the combination of the difierent types of polymeric compounds (I) and (H) in an aqueous base, provides a lubricant in which the shortcomings of each additive are overcome by the presence of the other; the desirable properties of each are accentuated and the result is an aqueous metal working lubricant which is stable, non-corrosive, does not cause sticking and is capable of carrying loads far in excess of similar compositions but in which either type of additive is omitted.

The heteric copolymeric compounds (I) are watersoluble relatively high molecular weight copolymers containing no substantially hydrophobic polyoxyalkylene units or chains, the polymer being composed of randomly distributed (heteric) oxyethylene and oxy 1,2-propylene groups in the molecule. Polymers of this type are suitably prepared by the methods described in U. S. Patent 2,425,845, as by reacting aliphatic diols or glycols simultaneously with ethylene oxide and 1,2-propylene oxide. The term heteric is used to designate an internal configuration of random distribution of the units making up the copolymer, as distinguished from a group ing of such oxyethylene and oxypropylene units, in homopolymeric units, with those of oxypropylene being of sufiicient degree of polymerization to exhibit a substantially hydrophobic character, as in the case of type II polymers.

A suitable method of preparing these heteric copolymers is to charge about 25 to parts of 1,2- propylene glycol and from about 10 to parts ethylene oxide into a suitable reactor and react the mixture in the presence of a caustic catalyst, such as sodium hydroxide. To the mixture a diol such as diethylene glycol is added and the mix is heated to about C. to C. at from 5 to 75 p. s. i. After the reaction is (completed, the reaction mixture is neutralized with carbon dioxide and hot water washed. The diol composition phase is dissolved in dichloro diethyl ether and its lowboiling constituents removed by stripping.

EXAMPLE I A polymeric product of type (I) is prepared by reacting a mixture of 75 parts of ethylene oxide, 25 parts of 1,2-oxypropylene, 20 parts of diethylene glycol and 1 part of sodium hydroxide. The mixture was heated for 2-4 hours at a temperature of ll0-l25 C. and a pressure of 6-40 p. s. i. The product was purified by distillation to remove volatile fraction and filtration to remove sodium hydroxide and had the following properties: average molecularweight 1,108; specific viscosity at 18 0., 0.1811; density, 210 R, 1.0296; refractive index 20 C./D 1.4671; flash temperature, 446 F; viscosity, centistokes at 210 F., 17.5; and is water-soluble in all proportions.

The second of the polymeric compounds (H) is a block copolymer or cogeneric mixture containing substantially a hydrophobic polyoxyalkylene unit such as polyoxypropylene unit of at least 800 and preferably 900 unit weight and the balance, which comprises from 15 to 90% of the total molecule, being hydrophilic polyoxyalkylene unit or units such as polyoxyethylene units. Copolymers of this type can be prepared by the methods described in U. S. Patents 2,674,619 and 2,677,700. Essentially, these polymeric compounds can be prepared by first condensing an alkylene oxide having from 3 to 8 carbon atoms such as propylene oxide with an organic base compound containing a single or plurality of reactive hydrogen atoms to form a hydrophobic polyoxyalkylene polymer such as polyoxypropylene polymer of at least 800 and preferably 900 molecular weight and thereafter condensing said polymer with ethylene oxide so as to form thereon hydrophilic 3 nelye ye hylene nitts), which comprise from about o a u f he total polymer- In preparing the polyoxypropylene polymer, the condensation of propylene oxide with the reactive hydrogen organic compound is normally carried out at elevated temperatures and pressures in the presence of an alkaline catalyst such as sodium alkoxide, a quaternary ammonium base, or sodium hydroxide. Similarly, the condensation reaction may be carried .out in the'presence of acid catalysts as set forth in U. S. Patent No. 2,510,540.

Although the reaction may be carried out by simply heating a mixture of the reactants under pressure at a suf ficientlyhigh temperature this procedure is not ordinarly used as the temperatures and pressures required are excessive and control of the exothermic reaction is diificult.

The preferred method of carrying out the reaction is to add the propylene oxide to a stirred, heated mixture of the desired reactive hydrogen compound and alkaline catalyst in a sealed reaction vessel. By adding the propylene oxide to the reaction vessel at such a .rate that it reacts as rapidly as added, an excess of propylene oxide is avoided and control of the reaction is simplified.

The temperature at which the reaction is run will depend upon the particular system in question and especially upon the catalyst concentration used. Generally, at higher catalyst concentrations the reaction can be run at lower temperatures and correspondingly lower pressures. The temperatures and pressures required for any given reaction will vary with the reactive-hydrogen compound, and the type and concentration of catalyst used.

The condensation of ethylene oxide with the polyoxypropylene polymer is carried out in an analogous manner.

The preparation of the type II block polymeric polyoxyalkylene compound is illustrated in Example II.

EXAMPLE II.PART A In a one-liter 3-neck round bottom flask equipped with a mechanical stirrer, reflux condenser, thermometer and propylene oxide feed inlet, there were placed 57 grams (0.75 mol) of propylene glycol and 7.5 grams of anhydrous sodium hydroxide. The flask was purged with nitrogen to remove air and heated to 120 C. with stirring, and until the sodium hydroxide was dissolved. Then sufficient propylene oxide was introduced into the mixture as fast as it would react until the product possessed a calculated molecular weight of 2380. The product was cooled under nitrogen, the NaOl-I catalyst neutralized with sulfuric acid and the product filtered to remove inorganic solids. The final product was a water-insoluble polyoxypropylene glycol having an average molecular weight of 1620 as determined by hydroxyl number or acetylation analytical test procedure.

EXAMPLE II.PART B The foregoing polyoxypropylene glycol, having an average molecular weight of 1620, was placed in the same apparatus as described in Part A of this example, in the amount of 500 grams (0.308 mol), to which there was added 5 grams of anhydrous sodium hydroxide. One hundred and five grams of ethylene oxide was added to an average temperature of 120 C., using the same'technique as employed in Part A. The amount of added ethylene oxide corresponded to 17.4% of the total weight of the polyoxypropylene glycol base plus the weight of added ethylene oxide.

Polyoxypropylene is prepared by condensing propylene oxide with a relatively low molecular weight organic compound containing a plurality of reactive hydrogen atoms. The function of this base compound is to furnish reaction hydrogen atoms which initiate the polymerization of the propylene oxide'and since the base compound constitutes only a small proportion of the resulting high molecular weight polyoxyalkylene compounds, it ordinarilydoes not have an influence onthe properties thereof. In other words,-the particular base compound'employed in preparing the polyoxyalkylene compounds is not critical so long as it furnishes at least one reactive hydrogen atom, and operable polyoxyalkylene compounds are obtained regardless of the particular base compound employed in the preparation of the polyoxypropylene polymer. Ordinarily it is preferred to employ relatively low molecular weight base compounds, e. g., less than 200 molecular weight, preferably polyhydric alcohols, such as ethylene glycol, propylene glycol, butylene glycol, trimethylene glycol, glycerol, and the like, usually a monomeric substance, although dimers, such as diethylene glycol and dipropylene glycol are suitable.

EXAMPLE III positions of the resulting compounds are set forth in Table I.

Table I l Moleoulm- Polycry- Weight ethylene Polyoxy- Content, Base Compound propylene Percent of Polymer Compound (water- (wateriusoluble) soluble) Acetamide, 974 i 36 1,5-pentanediol l, 372 50 Glyeerine 2, 060 48 Sucrose, 5, 060 4-9 Ethylene diamine 1, 850 50 Ben'zenesulfonamide 1, 179 50 In many cases the addition of solubilizing or coupling agents to compositions of this invention is desirable. Suitable agents of this type include: glycol-ethers, such as diethylene glycol momomethyl, ethyl, n and isopropyl ethers, diethylene glycol mono-butyl ether, diethylene glycol mono-.decyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-isopropyl ether, dipropylene glycolmonodsoamyl ether, diisobutylene glycol-mono isopropylether, etc. Instead ofthe glycol-ethers, various alcohols may be used, such as diols having 6 or more carbon atoms in the molecule, e. g., hexylene .glycol, decylene glycols,- cetylene glycols, etc.; diglycols such as dipropylene glycols,-dibutylene glycol, diamylene glycol, ether alcohols andparticularly the glycol monalkyl ethers, "eg., Carbon and Carbide Chemical Corp. Carbitols and el osol s su h a t y glycol monohyl ther. ethylene glycol mono-propyl ether, ethylene glycol monon-bu y et er, e h e eg y o mo yl h r, ethylene glycol mono-.tert-butylether, ethylene glycol mono? hexyl-butyl ether, propylene glycol mono-isoamyl ether,

etc.

When necessary, corrosion inhibitors can be used in compositions of this invention of which appreciably watersoluble inorganic or organic nitrites and/or aminessuch as alkyl or alkylolamines, and mixtures thereof are particularly preferred.

' The nitrites include the metal nitrites such as sodium, potassium,lithium, calcium and barium nitrites, of which the alkali metal nitrites are preferred; also, the organic base nitrites maybe used, preferably the organic nitrogen base nitrites, such as benzyl-trimethylammonium nitrite, morpholiniu n nitrite, dibenzylammonium nitrite, 3,3,5- trimethylcyclohexylammonium nitrite, cyclo-hexylam noiutn n ite, b a-phenyl t y m ni nitr t 2,4,5- tetramethyl tetrahydro 1,3-oxazonium nitrite, methyl isobutyl carbammonium nitrite, piperidinium nitrite, dicyclohexylammonium nitrite, dicyclohexyl isopropylammonium nitrite, and their homologues and analogues, as well as mixtures containing these and other corrosion inhibitors.

The amines include alkyl and alkyloamines such as mono-, diand triethyl-, propyl-, butylamine; mono, diand tri-ethanolamines, dimethyl-ethanolamines, diethylethanolamines, aminoethyl-ethanolamiue, mono-, diand tri-isopropylamine, methyl-diethanolamine, N-acetyl ethanolamine, phenylethanolamine, phenyl-diethanolamine and mixtures thereof.

If desired, oiliness or specific types of anti-wear agents can be added in minor amount to compositions of this invention of which fatty acids and particularly unsaturated fatty acids are most suitable. Among such acids are included saturated acids, e. g., capric, lauric, myristic, palmitic, stearic acids; unsaturated acids such as palmoleic, oleic, ricinoleic, erucic, linoleic, linolenic acids and mixtures thereof. These acids are stabily dispersed in the water base apparently by the aid of the block polymers 1!.

Minor amounts of anti-foaming, masking, bactericidal and anti-corrosive agents for copper and copper alloys, and/r perfuming agents, may be added to improve the composition. Among such materials may be included: anti-foaming agents, e. g., organic silicone compounds illustrated by dimethyl silicone polymer; phosphates, e. g., tributyl phosphate, alkali metal polyphosphates illustrated by sodium alkyl polyphosphates; polyglycidiisopropyl other (mol. wt. 500-1200, preferably 600-800); masking agents, e. g., low molecular weight aldehydes (acetaldehyde); oil of pines, oil of mirbane; bactericides, e. g., alkyl phenols and phenates such as sodium o-phenyl phenate; and copper anti-corrosion agents, e. g., mercaptobenzothiazoles (sodium mercaptobenzothiazole), and the like.

Efiective metal working lubricant concentrates, in accordance with the present invention, are preparable according to the following formulations:

Broad Pre- Range, fer-red percent Range, wt. percent Essential Additives:

Ablock polymer comprising a mixture of a polymeric compound (II) containing a hydrophobic polyoxyalkylene unit; of at least 800 mol wt. made by polymeric alkylene oxides of from 3 to 8 carbon atoms and polyoxyethylene units comprising 15-90% of the total polymer 5-20 6-10 A randomly distributed water-soluble polyoxypropylene-polyoxyethylene copolymer (1) having substantially no hydrophob units 5-2O 6-15 Preferred Additives:

1. Corrosion inhibitors e. g., inorganic nitrites,

alkylolamiucs and mixtures 1-12 5-10 2. Anti-wear agents, fatty acids, e. g., oleic acid. 0. 01-5 0. 5-3 Optional Additives: Anti-foaming agents, coupling agents, germicidal agents, etc 0. 01-20 0.1-12 Base:

Water Balance Balance Illustrative examples of metal working concentrates of this invention comprise:

Composition A: Ferceut Additive of Example I Addition of Example II 3 Sodium nitrite 8 Triethanolamine 8 Hexylene glycol 10 Oleic acid 1 Sodium mercaptobenzothiazole (in 50% water)- 0.5 Sodium o-phenylphenate 1 Sodium alkyl polyphosphate 1 Water Balance Composition B:

Additive of Example I 10 Additive of Example H 8 Sodium nitrite 8 Trisodium phosphate 8 Water Balance Composition C:

Additive of Example I 8 Additive of Example II 8 Sodium nitrite 8 Ethanolamine 8 Water Balance Composition D:

Additive of Example I 10 Additive of Example H 10 Sodium nitrite 8 Sodium borate 8 Oleic acid l Dimethylethanolamine 8 Water Balance Composition E:

Additive of Example I l0 Additive of Example II 10 Sodium nitrite 8 Linoleic acid 2 Triethanolamine 8 Sodium mercaptobenzothiazole (in 50% water)- 0.5 Water Balance Generally the concentrates can be used neutral or diluted with from 1 to parts of Water depending upon the use to which it is put. For cutting of steel, dilutions of 1:20-1:40 are recommended. For cutting of cast iron 1:10-1:20, while for grinding operations dilutions with water of 1:40-1:50, can be used.

Compositions of this invention are outstanding metal working lubricants. For example, composition A (at 1:20 dilution with water) was compared by test to a similar composition but in which additive Example 11 was omitted (composition X). Composition A showed an increase of 54% in drill life over composition X, and a decrease in sliding friction of from 500 g. to g. over composition X. Also, composition A, when used as a coolant on a lathe in a commercial plant caused no corrosion of metal parts with which it came in contact and the lathe was clean and its working parts were in excellent condition even after weeks of use. However, when a similar composition was used, but in which additive of Example I was omitted (composition Y) in the same machine and operation, the sliding parts of the lathe became sticky and after a day the machine had to be stopped and cleaned.

Compositions of this invention can be applied with ex cellent results to general cutting operations where cooling and lubrication of the tool and work piece under adverse conditions are encountered. Metals machined with the aid of fluids of this invention have good surface finish, are free from rust and stain, and the total life of machine tools and fluid is excellent.

We claim as our invention:

1. A metal Working lubricating concentrate comprising a Water base composition containing from about 5% to about 20% each of (1) a block copolymer of polyoxypropylene polyoxyethylene compounds containing in their structure hydrophobic oxypropylene groups, hydrophilic oxyethylene groups and an organic radical derived from an organic compound containing a reactive hydrogen atom; the compounds being characterized in that all of the oxypropylene groups are present in polyoxypropylene chains that are attached to the organic radical at the site of a reactive hydrogen atom thereby constituting a hydrophobic polyoxypropylene polymer, the oxyethylene groups being attached to the polyoxypropylene polymer. in polyoxyethylene chains, the average molecular Weight of the hydrophobic .polyoxypropylene polymers in the mixture being at least 900, as determined by hydroxyl number, and the oxyethylene groups present constituting -90% by weight, of total block .copolymers, and (2) a mixture of heteric oxyethylene-oxy 1,2-propylene diols in which ethylene oxide and 1,2-propylene oxide are combined therein as oxyethylene and oxy 1,2-propylene groups in a ratio which is at least one-third part of 1,2-propylene oxide for each part of ethylene oxide, by weight, said diols containing in a single molecule both the oxyethylene and the .oxy 1,2-propylene groups and said'mixture having an average molecular Weight of at least 300 attributable to said groups, from about 1% to 12% each of (3) sodium nitrite and an ethanolamine and from about 0.01% to about 5% of (4) an unsaturated high molecular Weight fatty acid.

2. A metal working lubricating concentrate comprising a water base composition containing from about 5% to about each of (1) a block copolymer of polyoxypropylene-polyoxyethylene containing in their structure oxypropylene groups, oxyethylene groups and an organic radical derived from an organic compound containing a plurality of reactive hydrogen atoms; the cornpounds being characterized in that allot the oxypropylene groups are present in polyoxypropylene chains that are attached to the organic radical at the site of a reactive hydrogen atom thereby constituting a hydrophobic polyoxypropylene polymer; the oxyethylene groups being ati tached to the polyoxypropylene polymer in hydrophilic polyoxyethylene chains; the average molecular weight of the hydrophobic polyoxypropylene polymers in the mixture being at least 1600, as determined by hydroxyl number, and the oxyethylene groups present constituting I t -60% by Weight, of the mixture, and (2) a mixture of heteric oxyethylene-oxy 1,2-propylene diols in which ethylene oxide and 1,2-propylene oxide are combined therein as oxyethylene and oxy 1,2-propylene groups in a ratio which is at least one-third part of 1,2-propylene oxide for each part of ethylene oxide, by weight; said diols containing in a single molecule both the oxyethylene and the oxy 1,2-propy1ene groups and said mixture having an average molecular weight of at least 300 attributable to said groups; from about 1% to 12% each of (3) sodium nitrite, (4) triethanolamine, (5) hexylene glycol, and from about 0.01% to about 5% each of (6) oleic acid, (7) sodium o-phenylphenate, (8) sodium alkyl polyphosphate and (9) sodium mercaptobenzothiazole.

3. A metal working lubricating concentrate consisting essentially of a water .base composition containing: 1) 10% of a block copolymer of polyoxypropylene-polyoxye'thylene containing in its structure oxypropylene groups, oxyethylene groups and 'an organic radical derived from an organic compound containing a-plurality of reactive hydrogen atoms, the copolymer being characterized in that all of the oxypropylene groups are present in polyoxypropylene chains that are attached to the organic radical at the site of a reactive hydrogen atom thereby constituting a hydrophobic polyoxypropylene polymer structure, the oxyethylene groups being attached to the polyoxypropylene polymer "structure in hydr0- philic polyoxyethylene chains, the average molecular weight of the hydrophobic polyoxypropylene polymer structure inthe copolymer being at least 1600, as determined by hydroxyl number, and the oxyethylene groups present constituting BO-% by weight of the copolymer, (2) 8% of a mixture of heteric oxyethylene-oxy-1,2- propylene diols in which oxyethylene and oxy-1,2-propylene groups are present in a ratio which is at least onethird part by weight of oxy-1,2-propylene groups for each part by weight of oxyethylene groups, said diols containing in a single molecule both the oxyethylene and the oxy-1,2-propylene groups and having an average molecular weight of at least 300 attributable to said groups, (3) 8% sodium nitrite, (4) 8% tn'ethanolamine, (5) 10% hexylene glycol, (6) 1% oleic acid, (7) 1% sodium o-phenylphenate, (8) 1% sodium alkyl polyphosphate and (9) /z% sodium mercaptobenzothiazole.

References Cited in the file of this patent UNITED STATES PATENTS 2,425,845 Toussaint Aug. 19, 1947 2,692,859 Talley Oct. 26, 1954 FOREIGN PATENTS 716,354 Great Britain Oct. 6, 1954 721,526 Great Britain Jan. 5, 1955

Claims (1)

1. A METAL WORKING LUBRICATING CONCENTRATE COMPRISING A WATER BASE COMPOSITION CONTAINING FROM ABOUT 5% TO ABOUT 20% EACH OF (1) A BLOCK COPOLYMER OF POLYOXYPROPYLENE POLYOXYETHYLENE COMPOUNDS CONTAINING IN THEIR STRUCTURE HYDROPHOBIC OXYPROPYLENE GROUPS, HYDROPHILIC OXYETHYLENE GROUPS AND AN ORGANIC RADICAL DERIVED FROM AN ORGANIC COMPOUND CONTAINING A REACTIVE HYDROGEN ATOM; THE COMPOUNDS BEING CHARACTERISED IN THAT ALL OF THE OXYPROPYLENE GROUPS ARE PRESENT IN POLYOXYPROPYLENE CHAINS THAT ARE ATTACHED TO THE ORGANIC RADICAL AT THE SITE OF A REACTIVE HYDROGEN ATOM THEREBY CONSTITUTING A HYDROPHOBIC POLYOXYPROPYLENE POLYMER, THE OXYETHYLENE GROUPS BEING ATTACHED TO THE POLYOXYPROPYLENE POLYMER IN POLYOXYETHYLENE CHAINS, THE AVERAGE MOLECULAR WEIGHT OF THE HYDROPHOBIC POLYOXYPROPYLENE POLYMERS IN THE MIXTURE BEING AT LEAST 900, AS DETERMINED BY HYDROXYL NUMBER, AND THE OXYETHYLENE GROUPS PRESENT CONSTITUTING 15-90% BY WEIGHT, OF TOTAL BLOCK COPOLYMERS, AND (2) A MIXTURE OF HETERIC OXYETHYLENE-OXY 1,2-PROPYLENE DIOLS IN WHICH ETHYLENE OXIDE AND 1,2-PROPYLENE OXIDE ARE COMBINED THEREIN AS OXYETHYLENE AND OXY 1,2-PROPYLENE GROUPS IN A RATION WHICH IS AT LEAST ONE-THIRD PART OF 1,2-PROPYLENE OXIDE FOR EACH PART OF ETHYLENE OXIDE, BY WEIGHT, SAID DIOLS CONTAINING IN A SINGLE MOLECULE BOTH THE OXYETHYLENE AND THE OXY 1,2-PROPYLENE GROUPS AND SAID MIXTURE HAVING AN AVERAGE MOLECULAR WEIGHT OF AT LEAST 300 ATTRIBUTABLE TO SAID GROUPS, FROM ABOUT 1% TO 12% EACH OF (3) SODIUM NITRITE AND AS ETHANOLAMINE AND FROM ABOUT 0.01% TO ABOUT 5% OF (4) AN UNSATURATED HIGH MOLECULAR WEIGHT FATTY ACID.