CA2142830C - Foundry mixes containing a polyether polyol and their use - Google Patents

Abstract

This invention relates to foundry mixes which comprise a dry: foundry aggregate and a polyurethane-forming foundry binder. The binder components include a polyether polyol component and an organic polyisocyanate component which is cured with a liquid tertiary amine catalyst. The foundry mixes are used to prepare foundry shapes made from foundry mixes by a no-bake process. The resulting foundry shapes are used to cast metal parts from ferrous and non ferrous metals.

Description

PCT/L;~S93108299 wo 9~/0s~; ~ 14 2 g 3 0 ' w..r.v l n ~'v r.
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pL,~'ET HE~ POLL.., ~i~D '='HEIt"Z USE .
'='ECHNIC~L WELD~
'''his _nvention =elates _.. foundry .;,fixes whicz corar ise a dr ~- f oundr'. aggr agate , a polyure thane-i orming foundry 'nder, and a'liquid amine curing catalyst. The binder comprises -a poiyether polyol comoonen~ and an organic polyisocyanate component. ~'he foundry mixes are used to prepare roundry shapes made from foundry mixes by a no-bake proeess. '"he binders do not contain any free fcrnaidehyde cr pneno~, and are preTerably,soiventless and odor less , whic'.~. resul is in less s tress to the environment.
__ The resu -1 =~ ~~_ f ound=°: snaoes are used to cas t metal marts r or" f e= r ous and non f err ous metals .
BACKGROUND Or THE Tr7V~NTION
20 In the zoundry industry; one cf the processes used fo= making metal parts is sand casting. In sand casting, di.sm_osable foundry shapes (usually characterized as molds and cores) are made by shaping and curing a foundry mix whic:: is a mixture cf send and an organic or inorganic .... binder . The binge= is used to s 'r engthen the molds and cones.
One c' the processes used ~~ sand casting fcr making molds and cores is the no-bake process. T_n this process, j, a foundry aggregate, binder, and liquid curing catalyst E
:30 are mixed and compacted to p:oduce a cured mold and/or core. In the no-bake process, '_' is imaorta.~.= to E
formulate a foundry mix which wi'_1 provide su:~icient war?: time to allow shaping . Wor~aime is the time between when mixinc begins and when the mixture can no longer be ~ eff ec tiveiy shaped t:. f i' 1 a mold cr care .
A binder common:.., toed _.. the no-bake process is ~.
r i~.'1 moivuretnane binder derived ~_° _,.-~~~ a poiyurethave-fo~-m;ng :,finder wit'.~. a liquid te_-tia=y amine catalyst.
Sucpoiyuretnane-f~'~-ina binders usec _.. the no-pake :,z ocess . Nave p-oven sa t~ s::ac tea _: -_ __ cas ty:.g sucz metals re ..rw.,..ni ~ .'~.~~ ~e~~e~~~~~~G
~g _~ ~~ .._ Ste°. nr.:.~: a_ ...._...__ WO 94/05447 ~ 1 ~ ~ ~ 3 ~ PCT/L'S93/08299 exceedinc about ?500 degrees :ahrenheit. They are also useful =:: the casting c° '_ight-weight metals, such as aluminum, which have melting points of less than 1500 , degrees Fahrenheit.
The polyurethane-for:r,ing binder usually consists of a ohenolic resin component and polyisocyanate component which are mixed with sand prior to compacting and curing.
Both the phenolic resin component and polyisocyanate component generally contain a substantial amount of organic solvent which can be opnoxious to smell and can create stress for the environment. Because of this, there is an interest in _developing binders which do not reauire the use of organic solvents.
British Patent Specification l 203 943 discloses a 25 foundry binder which purports to be solventless, yet effective. The foundry molds and/or cores disclosed in this patent are prepared from a foundry mix consisting of a (1) a wet foundry aggregate and (2) a, polyurethane forming foundry binder comprising (a) a poiyether polyol having a hydroxyl value above 200 milligrams of potassium hydroxide per gram of polyether polyol and a functionality of at least 2.5 (b) an organic polyisocyanate, and (c) an orQano-metallic or amine catalyst. The foundry mix is comD_acted into a mold and allowed to harden until the mix has sufficient dimensional stability so that it can be removed from the mold.
- 'The patent states that the amount of the water in the foundry aggregate is from 2 to 7% by weight based upon the weight of the foundry aggregate. The patent suggests that the water in the aggregate may contribute advantageously to' an earlier attainment cf dimensional stability in the foundry shape. wt also s;:ates that excess polyisocyanate .
is desirable to compensate for the presence of water. The examo_les show an isocyanate index of 130.
The patent is otherwise rather indeffinite. For instance the amount of the catalyst level is not given in any cf the examples.

' ~" -' ~:'Vr.Ni IOPd S LTM~IAR f ,. . _ .. r, _ , This ~.:,ven t=on r elates :.o a ~oundrv :~i}: comnr ising as a miktur a ~ a j a dr ~: . oundr-: aggregate ;
;b) a pcivurethane binder comnr~smg:
~;) a oolvether polyol component; and (2j 2n organic palydsocyanate component;
y0 and ~~) a catal.:ticallv effective amount ef a liauid t'rtiarv amine catalyst wherein components (1) and (2) are compatible w f t:: eac~ c then .
15 '~'he invention also relates t~ the use of these foundry mixes in a no-bake process for, preparing ~oundr,: shapes, and the use of these foundry shapes to cast metal parts.
The binders of the foundry mixes.do not contain any free formaldehyde ar phenol and preferably do not use 20 solvents and thus are odorless, which creates less stress to the environment khan conventional polyurethane-forming binders . The f oundry shapes prepared with the binders also show good shakeout -when used to make metal castings.
~inall~.v, 'he metal castings do not exhibit as :;such ... ?.ustrous carbon as taose made with many other commercial binders. This is signi=icant because lower lustrous carbon results in reduced casting defects:
BEST MODE AND OTHER MODES OF PRACTICING THE INVENTTON
The polyether polyois which are used in the polyurethane-forming Foundry binders are liquid polyether polyols or blends c. w quid polvether polyols having a hydroxyl number of '=om about 200 to about 600, preferably about 300 to about 500 r,.illigrams of KOH based upon one gram of polyether poiyol. The viscosity cy the polyether polyol is from 100 t~ 1,000 centipoise, preferably _rom 200 to 700 centipo:.se, :post ~rererabiy 300 ..,. 500 centicoise _. '"he poiv a then ~olv~ois may have pr ir.~ar~.: and! or WO 94/D~:l..t ~ ~ 1 ~ ~ ~ ~ O PCT/L~543/08299 -a-sect.~.aar ~ . _ _. _ _= ouos .
~Ji~ "_c G~.~e ....~,.~.:ISIe=~...G~~.. 31'G.'..~.?r~'J~.e ~'G.iC: ~ile.lr met..~.oa c= ~epar~.._c>. and deter.-.:~:~:.- their nvdrok~.1 :value ~.s we:.! ::sown. =!:e ~c ~yetner ~oiyols ere ~re~red by .=_ac~~,r,c a;. zlk;.~'_ene c~:iae kit:. ~ poiv~~~cric a~~cohOi .n ~h= rc=_sence _: _.. ~oc.:c _ vase c::~aivs~ sucas sodium .'.?et,~.X.lQe 2~.~.~r~_. . ~_. Tle,'.I:O.~'~.5 W~._ :::la'vJi. _.. Li?o ?=v.
:W.y su_tabi.e alt:-, 1=ne o>:ide cr -i~:tures oa'_~:vlene c}:ides may be = ea~=tea h i t~:-:e co ~:.~ :~vc= '_.. a'~ cohcl ~o ~r eoare the _,. oolve they c ~ vo?.s . "_'~e a ~~}:vlena ..:~;ides used __ tr mare the aolvetne~ c:vo~_s tical~~~: Zave _r o~ two to six carboy, atoms. ~earesentative examaies include athvlene oxide , . _-c~ylene oxide , ~;: tylene oxide , amyiene cx~de, s . v r enE: c};ide , .._ .-..=ya~.:r es : hereof . The tclvhvdr is alc~hois t:~~zcsll~,~ uses =~ nreoare the ~oivether aolvols genera~.ly :nave ~ =urctiona':.ic~; greater khan pre=erably _rom 2.5 to 5.0, :,lost preferably from 2.5 to Exaraoies i.~.ciude ethylene aiycol, diethylene glyco3, nropvls:ne glycol, _rimethvlol propane, and glycerine.
20 Although not preferred, ~ainor amounts of phenolic rasi.:~ and/or amine-based palyals car, be added ~to the polyether aolyo":.. 9y minor amounts, a is meant that less that ~a weicht aercent c= phenolic res_.~. and/or amine-oasec poi~. c_ _s added ~asec upo;, the weiC.-.t .,_ the _.. aoiyether poiycl, usually: 'Hess r.han :5 weight percent and preferabl_~ less t:an 5 weiw:.t pence..~.t, said weigh t percent based upon Lhe weight c' :.he polyether polyol component.
_T_' a phenol=c resin is added to tze nolyether polyoi, the preferred ahenalic resins used are benzylic ether phenolic resins which are specificall! dese=ibed in U.S. Patent ;~485,7~7.
:.:Lthouch not preferred, organic solvents may be added :,w. =he polyether polycl car..ponen:, pa=t:cuiar_y _t a __ benzyl _c ether pheno~.:ic resin .s used ~,~i=:: the poiyether oolvoi. The axount of solvent ~aec is aenerallw '_ess =ha.~. =~ weich ~ Mercer.-., usu~ll_ less Khan _., weigh t WO 94I054~7 ~ ~ ~ 2 ~ 3 0. PCT/C.~S93/08299 percent, rreferablv Hess t:.an ~ wezar.t aercent based ::pon whe ~o~al weight c~ she poiyether polyol component.
Other optional =ngredients ::hic;z .:~ay be added to the aolyether include release agants and adhesion p:o~oters, _ such as silanes described ~n '~.~. Paten. x,540,°a:.
Organic polyisocvanates used in the organic polyisocyanate component, ;which act as a hardener, are icuid oolvisocvanates having a iunctionalitv cf two cr more, preferably _ to ... They zay be aliphatic, cycloaliphatiy, aroz~atic, or a hybrid polyisocyanate.
:~:ixtures c: suc;: 5olyisocyanates nay be used. The polyisocyanates s:~~ouid have a ~~:.scosit_; cf about :,00 to _., about =,000, preferacly aoout 200 to about 600:
Representative examples o~ polyisocyanates which can be used are aliphatic palyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as ~,4'-dicyclohexylmethane diisocyanate, and aromatic 20 polyisocyanates such as 2,4- and 2,6-toluene diisocyanate, diphenylmethane diisocyanate, and dimethyl derivates thereof. Other examples of suitable polyisocyanates are 1,5-naphthalene diisocyanate, triphenylnethane _~ iisocyanate , xylylene ~iisacyanate , and ~:~e "e t::yl derivaces thereof, polymethylenepclyphenyl isoc_~~anates, chlorophenylene-2,4-diisocyanate, arid the like.
The polyisocyanates are used in sufficient concentrations to cause the cu:ing of the palyether p~lyol when cured with the liquid amine curing catalyst. In 30 general the isocyanate ratio of the polyisocyanate to the hydroxyl of the polyether polyol resin .s from y.2~:1.0 to 0.75:1.0, preferably about 0.~:~,.o to 1.1:1.0, an3 ~ost preferably about 1.0:1:0.
The polyisocyanate preferably contains a natural cil 35 ~ahich may include unmodified natural oils as yell as :hei_ various i~nown modifications, e.g., the heat bodied ai=
blown, or oxygen-blown oils suc:~ as blown linseed c__ and WO 9~/OS=14 ~ , PCT/L~S93/08299 X14283(1 cio~,~n sowean .._~. =:~e:' ar°- generally ciassiyied as esters .._ ethvie~~cali~.~ ~.:nsaturated 'att.: acids.
~re~eraby~: ;.he viscosm_: .._ ~:~.e natural oil is from A to ~.~.de~: :yore preferably on t:~e ~:ar finer ?-?o~ t . ~scos~ t_: _ , , .. _r cm .. to ~ , and ;,ios t _ : e~eraDlV' r to 5. ar efer ably the acid value c: the natural ci'_ ;s ficm about 0 to about IO, rare prererably about 0 to about -~ , and most preferably about 0 to about ~ as neasured by the number c~ milligrams c~ potassiu:.l h~:dr~i::.de needed .... neutral ize a ~ gram :0 samnie o~ tze natura'~ cll.
The natural oils are used _.. an effective amaunt sufficient to ~ ;,prove 'he tensila strength of the foundry shapes _maae wi t the c:.nder s . =:~is amount w ill generally range from about . percent by weight to about IS percent 1 J w y we igh t , :cos t prey erably about 2 per cent to about IO
percent by weight, based upon the weight of the organic polyisocyanate. Repzesentative examples of naZUral oils which are used in the isocyanate component are linseed'oil including refined ;inseed oil, epoxidized'linseed oil, 20 alkali refined linseed oil; soybean oil, cottonseed oil, RBD Canola oil, =efined sunflower oil, rung oil, and dehydrated castor cll.
Pr ef er ably used as the ha tur al c l 1 are pur e. f crms of natural o;is which are -seated to remove fatty: acids and azher impurities. These purer forms of natural oils typically consist cy trigiycerides~and less. than l weight percent cy impurities such as fatty acids and other impurities. Speciyic exampie~ cf these purer natural oils are purified linseed oils, such as Supreme Linseed 30 Oil manufactured by Cargill Corporation, having an acid value of aDOUt 0.30 maximum and a viscosity of ~. and pure=led soybean cils such as refined soybean oil having an acid value of less than 0.1 and viseasity~ of ~ to 8.
Drying oils, ~c~ example those ~isciosed ..~. ~.S.
__ Patent :~,260.~25, may also be ~,aed i.~. the poiyisocyanate component. Drying ells may be synthetic o= natural W IWV~'~in~ a~4 r.~1W 1~? Va~~eTi~e~ .re al~W.nl.y aI~~Lj YYn~V~

WO 94/0a44.
~;.:,ta~:: .-.;o == ..,crc :J::..:~we coeds ~.:nerebv ~:;vgen on JYposure ~_ a~- ca:~ --c G.:sCrDed to give pert}:ides whit::
catalv~= ~:e poivmer~~a-~on c~ t~e unsaturated portions.
~~ct~onai :..~red~.ents suc:: as ~eiease agents and solvents -a~' a~;so ce used ;.. the organic ~olyisacyanate ~;,ma_ onen t .
l t:.oucn ~ct _ re~err°d. solvents ",ay be used .:: the organic :,oiv;soc~_ anate co:.~.ponent andlo~ poiyether polyol.
__ solvents are ~~sed _., ether , t:ZOSe sf:illed in the ar~
'.;ill r:noc; now _.. select then.:. ~.ypical organic solvents whit:. are used _~:clude aromatic solvents, esters, or a ther s , ~-e ~ era~c 1 ~ .::' %: ;.ores ,: ~ these so l vents . ~ener a l iv , =::ese s:~ive.~.ts e''° t=SeC ... a:~ounts '.Hess trap about ercent cased uDOn the weight cL t:Ze organic weigi:,.
_5 poiyisocyanate component, ~,rezerably less than :. weight percent.
The binder .s preferably made available as a three package system with the nolvether polyol component in one package, ~he organic aolyisocyanate component in the 20 second package, and the catalyst in the Third package.
when making foundry mixes, usually the binaer components are combined and then nixed with sand or a similar acc_ rotate t.. f cr:~ the f oundr :~ix cr the :,~,ix. can be ~ crmed by sequent~ali.: .-,;fixing the ccr,:ponents wit:: he aggregate.
- Droferably the poiyether poivol and catalyst are first GJ
.~"ixed~ wi t:: t:.e sand bef cr = :~i}:ing the isocyanate component w i th the sand . !r!ethods of ::is tr ibuting the binder on the aacreaate par titles are well-'mown tc those 'skilled in the art. The r,.ix can; optionally contain other ingredients 30 such as iron oxide, Ground flax fibers, wood cereals, D_ itc::, refractory f lour s , and the like .
The ' ~~uid a:,,ine cataiys~ is a base having a phi value general 1y ~ ; the range c f abou t '' ~ o abou t _ _ . 'r'he ter ~:
"'_icuid amine" is meant tc i~~'ode amines which are :.'_quid :.'-, at ambient ~e:~p°_r=Lure ~_. t:.ose in solid farm, whit : are ;:issolved _.. app~opristo solvents. '"he et;:. ~-aiue .s th°-neca t~ ~: a _ far _ _.-.: .. _ _::e _isscci:: tic., cons ta.~.. .._ =:=°_ 214~83C~ ,.._ WO 94/05.x=i. PCT/L~S93/08299 base and is a we:L:.-known raeas,ure of ;.he basiciw.~ c: a basic material. fhf: s~igher this number is, the weal~:er the base. The bases fa.ll.ng witain this range are generally organic r_ompounds containing one or more ni.tragen atoms.
Pref erred bases are :~~eterocyclic compounds containing at least one nitroge:a atom in the ping structure.
Specific examples of bases which have pKb values within t:he necessary range include 4-alkyl pyridines wherein t:he alkyl g:rou~o has :rom one to four carbc:. atoms, isoauino:line, ar~rlpyridines such as phenyl pyridine, pyridine, acridine, ~-methoxypyridine, pyridazine, 3-chloro pyridine, guinoline, N-methyl imicazole, N-ethyl imidazole, =,,~'-dipyridine, 4-pheny'propylpyridine, methylbenzir.:idazoie, and 1,4--thiazine. Preferably used 1~ are bicyclic ter t.iary amines such as DABCC~~3 LV and DBU
sold by ~~ir Produca;s Company, and diethylenetriamine. The amines have boi,..ing points of at least 100'C, most preferably at least 200'C.
In view of the varying catalytic activity and varying catalytic effect desired, catalyst concentrations will vary widely. In general, the lower the pI~ value is, the shorter will be the worktime of the compasition and the faster, more comple:te will be the cure. solvents and any acidity present in added ingredients su~h as sa:.d may 2., affect the catae..ytic act~.vity . In general, however, catalyst concentrations will be a catalytically effective amount which generally will range from about 0.5 to about 5.0 percent by weight of the polyether polyol, preferably 1.0 percent by weight to 3.0 percent by weight, most preferably 1.0 percent by weight to 2.5 percent by weight based upon the weight of the polyether polyol.
In a preferred embodiment of the inventio~, the "
catalyst. level i. adjusted to provide a worktime for the foundry mix of minutes to 1o minutes, preferably 3 ~ minutes to about 10 minutes , and a striptime o f abou ~ -:
minutes to 12 minutes , pref erably 9 minutes to aboL ~ 10 minutes. Wori:time is defined as the time inteesa".: alts=

WO 9.~/05:~:1. PCT/L'S93/t18299 _g_ ~ixinc t:-:e p:,~~.'.':.socvanate, poivrether , and catalyst and the time when the =oundr~,~ shape reaches a level cf 60 on the Green Hardness "n" Scale Gauge sold by.Harry W. Dietert Co. , Detroit, '.~'.ichigan. Striptime is time interval after ~ixing ~he poll-i socyanate, polyether , and catalyst"and the time when the foundry shape reaches a level of 90 on the Green Hardness "3" Scale Gauge.
In this preferred embodiment, the ratio of the socyanate gr ouDS cf the pol}~isocyanate to hydroxyl groups l0 of the polyether polyol is preferably about 0.9:1.0 to about 1.1:1.0, post preferably about 1.0:1:0, the hydroxyl number cf the polyether polyel is from about 200 to about 500, and the weight ratio of polyisocyanate to polyether ~olyol is from about 55:45 to about 45:55, preferably 1~ about 50:50. These parameters provide optimum worktime, striptime; and tensile properties.
Various t~~pes cf aggregate and amounts of binder are used to prepare foundry mixes by methods well known in the art. ordinary shapes, shapes nor precision casting, and 20 refractory shapes can be prepared by using the, binder systems and paoper aggregate. The amount of binder and the type of aggregate used is known to those skilled in the art. The preferred aggregate employed for preparing foundry nixes is sand wherein at least about 70 weight 25 percent, and preferably at least about 85 weight percent, of the sand is silica. Other suitable aggregate materials for ordinary Foundry shapes include zircon, olivine, aluminosilicate, chromite sand, and the like.
In ordinary sand type foundry applications, the 30 amount of binder is generally no greater than about 10% by weight and ~reauently within the range of about o.5% to about 7% by weig'.~.t based upon the weight c' the aggregate.
Mos t often , the binder conten ~ f o~ c~ dinary sand f oundrlr shaaes ranges 'rpm about 0.6% to about 5o by weight based :;:. upon the weig::- of the aggreaa~e .n ordinar:~ sand-type foundry shapes.
The aggregate employed w~~.. the catalyzed binder in vt~p g,~lp~; PCT/L~S93108299 _ y~,_ _"..~_.~. ..::°_ _..::~~-, .-..:.:~. s:,cu:.e ce s:::__..~er.:,_. ,. _ so .-::at ? handleabie _csnar; s.~.ape =esults ef:.er a wcrJ:time to ... n~nutes ana 2. st=_p time o~ f t.o 1~ ::inures.
N
~~ene=gi_v the a~.ou.~,~.s ~_ ...~zst:.re _:, to aacreaate is less _ =::a:, . -about ~.5 per cant , ~.~mc:.t, pYeferabl~~ '.ess than abou= ~.~ fierce~t ~y weight. and roost p=eferablv 'Hess than about o.: percent ~y weic:.t cased on t::e weig::t cf the sand.
_ n L~:.~MP LLS
The examples uhic:. _cllow wii= _llustrate specific emboi::ents .o' the _nve.~.ticn. '"hens examples a:ong ~:ith _a u,r_..:.e:~ descr:-_i;,.~. ~::_1 enable one sr::.l'_ed ~_. :he art __ to -practice the invention. '_. is contemplated that many other embodiments of the _nvention will be operable besides those spec:.'~.caly- cisc;osed.
:n all cf the examples, ~he test specimens, unless otherwise indicated, were produced by the no-bake process 2~ using DABC0~3 L~ , a bicycl:.c te: nary amine sold by Air ?roducts Company, as a ~3 percent solution in dipropylene glyco 1. All parts are by weight and all temperatures are in °C unless otherwise specified.
Unless c~herwise .: cic~ted. -he faundrw :.-axes were ..., p= spared ~.y . :.r s t ~ixin~ ~ fiDRO ;~ 5C 0 sane . w f t:: the ooiyether ~lyoi anC catalyst for about ~ minutes. Then the MONDlJR ?fit was nixea -with the ~ixzure c' sand, poiyether, and catalyst fcr about 2 minutes. The amount of polyether polyol and polyisocyanate was such that the ;;: ratio of hydroxyl Groups cs the polyether polyol to isacyanato Groups cf the pelyisocyanate was about .:1 and the weight r grip of poiyether polyol to polyisocyanate was ' abou4 ~0:.'-.~. ':he binder :.evel and amounts of poly~socyanate arid p:,lyethe=, pl~.a any other components __ are given :..~. the rabies wnic~ _cllow.
Meant... _ ' ''se aog bone shapes the ~e.~.Sl:.e 5 ~~ en~..~. C.
enables one .:. Drec~c_ '.;o;; the ~ixt;:re cf sand ana finder ~.:or:: a ::.ua~ -......d'.. :.perat:.:.rs. Lows= ters_~.e ::.__ _..

~~4283U
w0 9aio5aa; PC?/L~S93/08299 _"_ .. _r e:~g-::s _ ~_ Y~:e . :ape= _...._ca ~.e _ a t the ~~ls~eLher oolvc'; Gad c.._._sccvanate ~e~cteh ~ore eia ensivelv during ~axina :: l ~_.._ sane p. _.._ cc y.,_.-"mg . ounarv snapes, ana =':us wer n ::..,. _ __ ~a~~e . __ _ __..._. _ _ sundry shapes _ ;'e _-..:::.~-_ shapes were s4ored :. :.our , ~ hours and 2.:, haur s :..~. ~ ..cps tar. t -°_I(tDe="'c.. tur a = oom at a relative humicit.: c. ~;;~ and,a cems~erature c~ _~°C before -measuring their tensile ==rengths. :;nless otherwise specified, the Tensile st~en~~.~.s were also measured C:1 SllabeS S;.ored 24 hours a' a re~_a_:.ve ::unidit. ;nri) c~ :.000.
m::e ~ cl'_o:; inc ter~s 'were used _., the e~:ar:ales:
'~iOt:D'~ '~a - an _=canic coivisocvanate commercially available _rom MILES. T_NC. paving .5 a t::nctionalitv o~ 3.5 to 2...
?LL'~raCO:. :OLYGL '_'?-440 - a polyether polyol, sold commercially by BASF, having an OH value of 398, prepared by reacting propylene oxide with t: iraethyo loronane .
20 RF'. - relative humidity.
SLO = Supreme i.inseed Oil Sm - stri:.ti:ne.
tc'?~ - wor:r: ti:aa .
0/W = on weig~~ ~_.
:.5 BOS = based on sand.
at~s~T ~ . ansl y"~Mpsri,.a=.~iIT~~ F~L.T~s~i~ h:~L' Examples :. and 2 are w l t::in the scoae of the subj ect invention and were prepared with dry sand. Comparative 30 Examples h-F are t,.he same as Example 1 except varying amounts cr:ois;.ure were added to the sand as indicated in Table I. :.dcit:.onally, :.n Co:,iparative Examales B and D, the isocvanate :.nde>; was varied _ror" .: ~ to 1. 3 : ~ to cor r esDOnd w l t' whe .ade~; shown _.. B, :, fish aten t _~ ~ .. spe=_.__ examai~ _, anon.~.er t=.-,~sterc_a:'_ ava:'~a~ie ~5?ve=~mr . ....__.. -s e'~e~~_~:e _,. u_:.=Rn::C~ .___ ~oiye::~gr . ..~:,'. sc'_~ , ~:.~_es. _..,..

~1~2830 WO 94/OS:i4 ~ . PCT/L~S93/08299 -1?-Soec~ficatic:~ ~ 303 943.
The data _.. Table _ _::dicate t:~at the foundr;~ .;,fixes :,renared with ~~v sand and soiventless binders perform effectiveiv. ;hev furt:~er indicate that these same ~cinciers do not pe_form effectively on wet sand which is surtrisina '~ view c' the teachinas as shown in Brwtish Patent Speci~ication 1 203 943. This indicates that there ;s a difference between the subject invention and the _nvention described i.~. the B.~itish patent.

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..A._ _~ and In Example ~, the procedure of ~'xample 1 was repeated. Example 3 ~.s a repeat of Example 2 except five weight percent cf t:~e MONDLR MR organic polyisocyanate ~ , was replaced with SLC, Supreme Linseed Oil. Obviously the weight ratio of polyisocyanate to polyether was affected by this addition. The weight ratio of polyether to polyisocyanate for Example 2 was 51.6/48.4 while the weight ratio for Example 3, the formulation containing the SLO, was 50.3/49.7. The results of yhe experiment are show in TABLE I.I. '"he experiments indicate that the tensile strengths of the test specimens are improved with the addi tion of the SLO.
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Table _TII indicates that, in order to obtain adequate worktime and striptime, the catalyst level must be from about 0.75 weight percent to about 2.25 weight percent based upon the total weight of the polyether polyol.

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Comparative Examples J-L illustrate the effect of using polyether polyols with hydroxyl numbers outside the claimed range. VORANOL 230-660 polyether polyol, used in f' :.
Comparative Examples J and h, is a trifunctional polyether ~s polyol having a hydroxyl number of 660 and a viscosity of 850 cps. PLURACOL 726 pol ether y poiyol, used in Comparative Example L, is a trifunctional polyether polyol t having hydroxyl number of 55 and a viscosity of 420 cps. E
The data in Table IV which follows indicates that these polyols are not effective in achieving the results ,.:
demonstrated by the subject invention.
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Claims (13)

We claim:

1. A no-bake foundry mix consisting essentially of in admixture:
(a) a foundry aggregate containing less than 0.2 percent by weight of moisture, said weight based upon the total weight of the foundry aggregate;
(b) as the binder:
(1) a polyether polyol having (i) a functionality greater than 2.0;
(ii) a hydroxyl number of from 200 to 600;
and (iii) a viscosity of from 100 centipoise to 1000 centipoise at 25°C;
provided that said polyether polyol component contains less than 5 weight percent of hydroxyl containing materials selected from the group consisting of phenolic resins, amine-based polyols, and mixtures thereof, and further provided that said polyether polyol contains less than 5 weight percent of organic solvent, and (2) an organic polyisocyanate, provided that said organic polyisocyanate contains less than 5 weight percent of organic solvent, wherein (1) and (2) are compatible with each other; and (c) from 0.75 weight percent to 2.25 weight percent, based upon the total weight of the polyether polyol, of a liquid tertiary amine catalyst, such that said foundry mix has a worktime from 3 to 20 minutes and a striptime from 4 to 12 minutes.

2. The foundry mix of claim 1 which is free of formaldehyde and phenol and wherein the polyether polyol has a hydroxyl number of 200 to 500, a functionality of from 2.5 to 4.0, and a viscosity of from 300 centipoise to 500 centipoise at 25° C.

3. The foundry mix of claim 2 wherein the tertiary amine catalyst is a bicyclic tertiary amine.

4. The foundry mix of claim 3 which is solvent free and wherein the amount of moisture in the aggregate is less than 0.1 weight percent based upon the total weight of the aggregate.

5. The foundry mix of claim 4 wherein the polyisocyanate is mixed with a natural oil.

6. The foundry mix of claim 5 wherein the tertiary amine catalyst is triethylenediamine.

7. The foundry mix of claim 6 wherein the natural oil is Supreme Linseed Oil.

8. A no-bake process for the fabrication of foundry shapes comprising the steps of:
(a) mixing a dry foundry aggregate with a bonding amount of up to loo by weight, based upon the weight of the aggregate, of a binder composition consisting essentially of:
(1) a polyether polyol having (i) a functionality greater than 2.0;
(ii) a hydroxyl number of from 200 to 600;
and (iii) a viscosity of from 100 centipoise to 1000 centipoise at 25° C;
provided that said polyether polyol component contains less than 5 weight percent of a hydroxyl containing material selected from the group consisting of phenolic resins, no more than 5 weight percent amine-based polyols, and mixtures thereof and further provided that said polyether polyol contains less than 5 weight percent of organic solvent is used in the polyether polyol component of the binder, and (2) an organic polyisocyanate, provided that said organic polyisocyanate contains less than 5 weight percent of organic solvent, wherein components (1) and (2) are compatible with each other; and (3) from 0.75 weight percent to 2.25 weight percent, based upon the total weight of the polyether polyol, of a liquid tertiary amine catalyst, whereby said foundry mix has a worktime from 3 to 10 minutes and a striptime from 4 to 12 minutes, (b) introducing the foundry mix obtained from step (a) into a pattern;

(c) allowing the foundry mix to harden in the pattern until it becomes self-supporting; and (d) thereafter removing the shaped foundry mix of step (c) from the pattern and allowing it to further cure, thereby obtaining a hard, solid, cured foundry shape.

9. The process of claim 8 which is free of formaldehyde and phenol wherein the polyether polyol has a hydroxyl number of 200 to 500, a functionality of from 2.5 to 4.0, and a viscosity of from 300 centipoise to 500 centipoise at 25° C.

10. The process of claim 9 wherein the catalyst is a bicyclic tertiary amine.

11. The process of claim 10 wherein the binder is solvent free and the amount of moisture in the aggregate is less than 0.1 weight percent based upon the total weight of the aggregate.

12. The process of claim 11 wherein the polyisocyanate is mixed with a natural oil.

13. The process of claim 12 wherein the bicyclic tertiary amine catalyst is triethylenediamine.