SEMI-AQUEOUS CLEANING PROCESS AND SOLVENT COMPOSITIONS

Abstract: A semi-aqueous cleaning composition and process comprising certain glycol ethers, particularly dipropylene glycol n-butyl ether; a hydrocarbon; and optionally, a surfactant and inhibitors are disclosed.

Description: SEMI-AQUEOUS CLEANING PROCESS AND SOLVENT COMPOSITIONS The present invention is related to semi-aqueous cleaning processes and compositions useful therein. Cleaning is required in the metal working and electronics industries to remove oils, greases, coolants, fluxes and various particuiates such as metal fines and shop soils. Typically, chlorocarbon and chlorofluorocarbon solvents have been used m vapor αegreasmg equipment to provide the needed cleaning. However, environmental concerns and regulations nave been directed toward the jse of these solvents in recent years. One alternative to the jse of chlorocarDon ana chiorofluorocarbon solvents .s the use of a semi-aqueous cleaning process and ceaner. Seτ.ι-aαueous cleane r s are hyσrocarDon formulations containing emu'Sifying agents to ennance their ami ity to D 'insed Generally the formulations are not bulk liquid flammable, out nave vapors tnat can ignite under certa, '- conditions whicn results in potential problems n processing and equioment design. Semi- aqueous cleaners typically use their affinity to organic contaminants to solvate the contaminants from the surface of the item to be cleaned and take them .nto solution Tne solution must be rinsed off the cleaneα surface witn water resu ting in an effl uent containing the hyαrocarbon contaminants ana wate'. Comoo "as ur r enc y * auart to oe se- ' c.: *-> semi-aαueous orocesses -"ci αe various compounds sucn as .erDenes -owever .nere remains a neeα *or aacitionai serr.- aαueous ceaπng methods arα comoo..t.ons _,se"_' '.^e ς , r. Summary of the invention In one aspect, the present invention is a cleaning composition consisting essentially of 0) 30 to 70 voiume percent of a giycol ether selected from tne group consisting of diproDvleπe glycoi n-outyl ether, tπOropyiene glycoi n-buty! ether, and propylene giycol phenyl ether and mixtures thereof; (2) 30 to 70 volume percent of one or more 2-13 nydrocarbons having a flash point greaterthan about 200°F, a viscosity of less than 3.0 cP at 25°C and a surface tension of less than 30.0 dynes cm at 25°C; and (3) zero to 10 volume percent of one or more surfactants with a hydro- Dhiie/fipophiie balance (HLB) of from 1 to 8.5 or from 12 to 16; and (4) zero to 5 volume percent of one or more innibitors, perfumes or dyes The various comDoneπτs of tne composition are selecteα so that tne comoositior has a ooiiing point greater tnan 200°C ana a freezing point less than 5°C; a flash DOint greater tnan 95'C, ana water solubility of less tnan 1 g/1 OOg ■ n a second aspect, the present invention is a semi-aqueous ciea ng process using the above described composition. Detailed Description of the illustrative E.mboαimeπts in the semi-aqueous cleanmg.process of the Dresent invention, the part :o be cleaned is typically P) subjecτeα to a solvent wash; (2) bιown ιth air to control soivent carr y ¬ over; (3) πnsed witn water: and (4) driec ; n a modification of this system, an emulsion stage s used, n tne rr-oαifieo system, the Dart rs suDiected to a solvent wasn and then mmerseσ - a- emuision of soiver.t and water prior to σeing blown with a:r, πnsed ana dried. Solvents are kept at a minimum in tne emulsion stage and tne water ; s continuously recycled by recirculating the emulsion througn a static tanK or coalesce*-. The emulsion must readily separate - the static tan< to Dermit the recycling of the water and/or solvent. The cleaning Drocess may oe conducted at room temperature or at elevated temDθ'-atures to accelerate leaning ano separation of emuiSion. One skilled in tne art wi.. recognize that eievateύ * emperatαres wiii be maintaineα _eιow - _ e rasn oom -or safety pu'ooses ~ ne sen- ' i-aαueous c eane r oτ ve Drese n t rv "' en ~c: jαes *π e Givcoi etner. one or -!θ'= ~vαroca'_oπ5. ootionaiivo-a o r mor -"-.rectaπts <_ c co * . ona- . ■ oπe c πo r e -- rv- '-. oer -imes. dve oOtn ' onve _ ".O"a- aαsit ves ~->e ς , z ' e r r .s ore÷eraD , g yco- r.-o xv! etne r crtr-Dropv e-e givco- r-D-_../ι et-er anc s mo r e orefe r adι , ΠIDΓOD J e~e g-yce r, -Di-tvϊ ethe' A hydrocarbon or a blend of hydrocarbons may be used i n the practice of the invention. The hydrocarbon may be l i near, branched or cyclic with li near being preferred. Typically, the hydrocarbon wil l have from from 12 to 18 carbon atoms, with C l4 li near paraffins being preferred The cycl ic hydrocarbons may contain i nert substituents such as alkyi groups. Surfactants useful in the composition of the present invention are non-ionic surfactants having an HLB of 1 to 8.5 or 12 to 16. The surfactants will typically comprise a Cβ-i . linear, branched or cyclic aliphatic hydrophilic chain and a hydrophobic chain containing between 2 and 10 mole percent degree of alkoxylation. Preferred surfactants are Cs-i 5 alkyoxylated alcohols having from 1 to 8 al kylene oxide units wherei n the alkylene oxide 15 ethylene oxide, propylene oxide or.butylene oxide with ethylene oxide being preferred ore preferred surfactants are C9.11 alkyoxylated alcohol ' s having 5-7 ethyiene oxioe units. The semi-aqueouS'Cleaner may also include i nhibitors to orevent corrosion of metals such as steel. Examples of useful inhibitors inciude amines, phosphates, polyphosphates, nitrides, molybdates, suifonates and quarternary ammonium salts Antioxidants such as butylated hydroxy toi uene are also useful in some applications, it may also be necessary or desirable to aαd perfumes, dyes or other additives. The relative amounts of the various components of the cleani ng formulation are any which results i n a composition having tne desired orooerties. Tne glycol etner comprises from 30 to 70 volume oercent of the comoosition, preferably from 30 to 60 vol ume percert, more Dreferao'y from 40 to 50 ana most Dreferaoiy 40 to 45 vol ume Dβrcent. The hyarocarDo*- compπses from 30 to 70 volume percent of the composition, preferably from 40 to 70 vol ume percent, more preferably from 50 to 65 and most Dreferably 50-55 volume Dercent. The surfactant comprises from 0 to 10 volume oercent of the composition, preferably from 1 to 5 volume percent. An inhibitor or inhibitors, perfumes, dyes or other additives comprises from 0 to 5 volume percent of the composition, preferably from 0 1 to 1 .5 vol ume oercent Of course, tne totai volume of components in the composition totals 100. The semi-aαueous cleaner 's oreoared oy m-yng the components > r. a suitable vessel typical, used oy those amr iar witn the art Orαer of mixi ng s not critical ~ne c.'eane r ^o oos. tion s tormuiated to nave a flasn poi nt of 95 C C o r grea'.e r . _ oonτg DO _ T. o* 20C ; C O Γ greater and a ~reezι~g pe nt at or oeiow 5°C; a a to nave wate r so.JD'i i y 'ess man '. g. l OGg τ ne cieaner composition also nas certai n soi l oaσi ng capac.ty . * πe ao> ι -Ty τo orea an e^ s.o- . "nsaDiiitv _nα cleari ng capaoi 'ity The cleaning composition has soil loading capacity of at least 15 weignt percent at 60°C. This soil loading capacity is the weight percent of soil , i.e. grease or oii, wmcn when present in the cleaning composition causes the cleaning performance of the formuiation to decrease below 90 percent. Aprocedure foUowec to measure soil loading capacity is to soil a series of 2" x l/2" x 1/16" 1010 steel coupons with grease or oil (soil) . The oil is applied by dipping the coupons ;n the oil, and then allowing the excess oil drip off before weighing the ■ coupons. These coupons are placed in 1 -ounce bottles containing solutions of the αeaner containing various weight percentages of grease or oil, i. e. soil loading. The bottles are placed in an Eberbach shaker for 5 minutes at 25°C and 180 oscillations per minute Tne couponsare then removed from the bottles, hung from hooks in a support assembly, and rinsed under tao water at 25°C for 10 minutes at 110°C and allowed to cool in a open atmospnere for 20 minutes. Atthis point the coupons are reweigned, and cleaning performance is determined DV the oercent soil removed by each formulation The percentage of grease or oil oreser.t -.r. tne composition whicn causes cleaning performance to oe lowerthan ninety percent Another important characteristic of the compositions ;s their ao ty to form and breaK emulsions The compos.ttons of this invention, when emulsified with water, .vill preferably separate from water :n five, more preferably three, minutes or less at temperatures of 60 c Corabove. x he ability to separate from water is determined bymixing, at room temperature, thirty ml of the cleaning composition and 70 mi of deionizeα wate r n a graαuated cylinder. Location of the mitial meniscus is noted and the cyϋnαer <s mverteα severa: timesto msure mixing The cylinder s 'eft undisturbed for a se peπoα of time " hen the appearance of each layer and the location of the meniscus are noted. The same tests are repeated at 6C°C. :n this instance, the cylinders were p laced n a 60°C water oatn fo r 30 minutes before shaking and then allowed to stand tn the oath. Similar tests are conαucted with constant observation to establish the actual time reαuired for tne emulsion to separate 'nto two distinct 'ayers. Theaoiiity o σuickly πnse from items to be cleaned is also an imponart characterstic o the cleaning com p osition 't is oreferreα tnat cieaπmg compositions wni r nse n one mmuτe or less. Rinsing capabit ties are determined by mmersinc a COU DO^ ■- a ! eane r "o wnich nas been addeα a aye ana tne - ■ m ers "g the coupon ; π.o a container of αe-on-zeo water wnich is then mi'di agitateα ~-e t : .me -! n e'apses τo~ tr<e r rore": tnecojno r ; πtroαuceα m tne wate r unt t no mo r e αve can oe seen o^ . ts s._'÷ace 'S coπsιαe r eα t ~ e to to The following examples are provided to more ful ly illustrate the invention anc should not be considered as limiting it in any way. 5 Example 1 -- Semi-aqueous Cleaning with No Emuision Stage Six commercial greases were used to evaluate the cleaning compositions of this invention. These were Conoco HD Calcium Grease from Conoco Incorporated, Prestige 741 Lithium Grease from Witco, Alemite CD-2 White Lithium Grease from Stewart- Warner and three greases from Sta-Lube Inc. identified as Sta-Lube Aluminum High Temperature Bearing 10 Grease, Sta-Lube Fibrous Sodium Heavy Duty Grease and Sta-Lube Molybdenum Disulfide- Lithium Extreme Pressure Grease. Using a wooden applicator, approximately 100 mg _+_ 0 1 mg of grease was applied on 2 inch x θ.5 inch x 0.063 inch 1010 steel coupons which had been previously vapor degreased with inhibited 1 ,1 , 1 -trichloroethane and weighed. The COUDOΠS were neid in a grooved metal holder which facilitated the application of an even film of grease 15 The greased coupons were weighed and then Diaced in 2-ounce pottles containing 50 mi of tne test composition. The bottles were placed in a shaker bath at 25 = C and snaken for 1 5 minutes at 160 oscillations per minute. The coupons were then removed from the Dottles, hung from hooks in a support assembly and rinsed at 25 c C for 10 minutes and then reweigned The percent grease removed by each composition provided an indication of cleaning performance. 20 All tests were αone in triplicate and the results averaged The results of these tests are summarized in Table 1. TABLE I Formulation 4 ! 1 00. 0 99 . 9 99 . 9 ?9 . 9 99 . 9 1 00 r ormulation 1 50 /40 ( v / v ) di propyiene giycol n-Dutyl ether /branched C 1 _i— " r.ydrocarbor r ormulation 2 - 50/40 triDroDVier.e εivco_ xεtnv ether.'branched C1___ 1 _ hyάrccarocn ormula ion 45/55 (v.v) dipropyiene glycol r.-v ether .. - • • linear 3ra?51r. r ormuia ior. - 40/55 -5 "v v • v ) ::rc_y .er.e z_ycc. .-Du: ethe 'C • . •>>-. linea caraff. i sϊ orimarv alcohol ethovxiate Example 2 — Semi-aqueous Cleaning with Emuision Stage The 1010 steel coupons were greased as αescπbed in Example 1 with Prestige 74' athium Grease and placed in 1 -ounce flint bottles containing 15 mi of an emuision made by mixing 4.5 ml of the formulation with 10.5 mi αeiontzeα water (30/70 ratio). Each formulation contained dipropyiene giycol n-butyl ether (DPnB), a C,. _.. iinear hydrocaroon and the various surfactants shown in the amounts listed in Table 2 The bottles were placed in an EDeroac snakerand shaken at 180 oscillations per minute. The shaker was stopped every 1 minute so that the coupons could be visually inspected for cleanliness. The test was discontmueα wnen grease could no ionger be seen on the coupon. Each formulation was tested in triDiicate and the results averaged. Another test was conducteα to esτabiisn the time reαuired for tne emuision to separate into two distinct layers. Three ml of solvent or blend and 7 mi αeionized water were oiDetted into a small giass vial. The viai was snaken vigorously for 15 seconαs anc tnen allowed to stand until the emuision separated to a maximum of 10 minutes. Tne same test was repeated at 6C°C. ! n tnis case, tne viais were praceα in a 60 C C water oath -or lϋ mi.-ute. Deτore snafcmg ana tnen allowed to stanα the oatn Results from the cleaning arα separation tests are su maπzeα in Taσie 2 I 'l TABLE 2 (Cont. ) in I ©o \ ■ No! an embodiment of the invention, .Ml Example 3 Using a wooden applicator, approximately 0.1000 g of either a lithium or caicium based grease was applied on 1 inch x 0.5 inch x 0.063 men 1010 steel couDons whi n nao been 5 previously vapor degreased with inhibited 1 , 1 , 1 -tπchloroethane and weigned. The ouDons were held in a grooved metal holder which facilitated the application of an even film of grease The greased coupons were weighed and then piaced in 1 -ounce bottles containing 15 mi of the test composition. The test composition was 55 volume percent of a C.. .. cydoaliphatic hydrocarbon; five volume percent of a linear primary alcohol ethoxylate C .. with an average 10 of 6 moles ethylene oxide per mole of alcohol ; and 40 volume percent of either dipropyiene glycol h-butyl ether or tripropylene glycol n-butyl ether. The bottles were Placed m an Eberbach shaker at 25°C and shaken for 5 minutes at 180 oscillations per minute τ he coupons were then removed from the bottles, hung from hooks in a support assembly ana rinsed under coid tap water for 5 minutes and then dried in an oven at 100 c C for en minutes. All tests were 15 done m triplicate and tne results averaged. When the dipropyiene giyco /.-as _, sea. 38 77 percent of the lithium and 99 47 percent bf the calcium grease was removed. When tne tπpropyiene glycol ' was used, 90.64 percent of the lithium and 99.04 percent of tne caicium grease was removed. 20 Example 4 The procedure in Example 3 was followed with the exception tnat the test composition was varied as shown in Table 3 beiow TABLE 3 -_- Examoie 5 In this example, the coupons were greased as descπbeα previously with each of the commercial greases and olaceα in 1-ounce flint bottles containing 20 ml of an emulsion made by mixing 6 ml of neat solvent or formulation with 14 ml deionized water (30/70 ratio) The Dottles were Dtaced in an Eberbach shaker for 10 minutes at 25°C and 180 oscillations per minute. The coupons were then πnsed. dried, and cooled as previously described. The coupons were reweighed, and cleaning performance was determined by tne percent grease removed 0 each solvent or formulation. Results obtained are shown in Table 4 below. TABLE 4 -70-

Claims: WHAT IS CLAIMED IS: 1. A composition consisting essentially of (1 ) 30 to 70 volume Dercent of a glycol ether selected from the group consisting of dipropyiene glycol n-putyi eτner, tπoropyiene giycol n-outy; ether, propylene glycol pnenyl ether and mixtures thereof; (2) . 30 to 70 volume percent of one or more C.. linear, branched or cyclic aliphatic hydrocarbons having a flash point of greater than 200°F, a viscosity of less than 3.0 cP at 25°C, and a surface tension of less than 30.0 dynes/cm at 25°C; (3) zero to 10 volume percent of at least one -surfactant with a nydro- phile/lipophile balance (HLB) of from 1 to 8.5 or from 12 to 16; ana (4) zero to five volume percent of at least one mhioitor, perfume or aye, said composition having a boiling point greater than or equal to 200°C and a freezing point less than or equal to 5°C; a flash point greaterthan 95°C; and water solubility of iess tnan lg/ 100g. 2. The composition of Claim 1 wherein the glycol ether is dipropyiene glycol n-Dutyl ether. 3. The composition of Cain " ' nere>n a surfactant :s present 4 The composition of Claim 3 wnerem the s_ract_nt <i a C ^ _ etnoxyiatec aicohol having from ' to 8 etr,y:ene oxide units. 5. Tne composition of Claim 1 wherein tne giycoi ether .s present in tne composition in from 40 to 50 volume percent and the hyαrocaroon is present .n the composition in from 50 to 65 volume percent. 6. The composition of Claim 5 wherein the surfactant is a Cg.ιβ aikyoxylateα alcohol having from 1 to 8 alkylene oxide units and is present in the composition in from 2 to 6 volume percent. 7 The composition of Claim 1 which is 40 to 45 volume percent dipropyiene glycoi n-butyl ether 50 to 55 volume percent Cι_,-,6 hydrocarbon and 1 to 5 volume percent C9- 11 alcohol ethoxylate having 6 ethylene oxide units. 8. A process for cleaning metal parts comprising (a) subjecting the parts to a solvent wash; (b) blowing the wasned parts with air to control solvent carry over; (c) rinsing it with water; and (d) drying it wherein the solvent is a composition consisting essentially of (1) 30 to 70 volume percent of a glycol ether selected from the group consisting of dipropyiene giycpl n-butyi ether, triDropyiene giycoi n-Dutyl ether, and propylene glycoi Dhenyi ether and mixtures thereof; (2) 30 to 70 volume percent of one or more C IS linear, branched or cyclic aliphatic hydrocarbons having a flash point of greater than 200°F, a viscosity of less than 3.0 cP at25°C, and a surface tension of less than 30.0 αynes/cm at25°C; (3) ootionally, zero to 10 volume Dercent of at least one surfactant with a nvαropniie/iipopnne Daiance f^-LB) θ" ÷ rom " to 8.5 or -rom 2 to '-6: anc (.4) ODtionaΛy, zero to ve votume per ent o÷ at least one nnioitor, perfume o r dve, -ttr said composition having a boiling point greater than or equal to 200°C and a freezing point iess than or equal to 5°C; a flash point greater than 95°C; and water solubility of less than 1g/100g. 9. The process of Claim 8 further comprising immersing the part in an emulsion of solvent and water prior to step (b). 10. The process of Claim 8 wherein the solvent is 40 to 45 volume percent dipropyiene glycol n-butyl ether 50 to 55 volume percent Ci 4 .1 6 ydrocarbon and 1 to 5 volume percent Cg_ι 1 alcohol ethoxylate having 6 ethylene oxide units.

Inventors: DONATE FELIPE A, FARELLA JOANNA M, LEE LAURENCE W, MORRIS NANCY H, PAPAJESK JAMES G, DONATE, FELIPE, A., FARELLA, JOANNA, M., LEE, LAURENCE, W., MORRIS, NANCY, H., PAPAJESK, JAMES, G.
Applicants: DOW CHEMICAL CO, THE DOW CHEMICAL COMPANY
Application year: 1992
Main classification: C11D3
IPC codes: C11D3, C11D7, C23G5