CA1122737A - Binder compositions containing phenolic resins and organic phosphate and/or carbonate solvents - Google Patents

Abstract

Abstract of the Disclosure There are provided binder compositions particularly useful in the foundry art which are rapid curing and which comprise (A) a phenolic resin component including at least one resole or novolak resin, solvent comprising a mixture of (1) hy-drocarbon solvent and (2) polar organic solvent containing at least sufficient organic phosphate and/or carbonate ester to increase the curing speed and solubility of the phenolic resin component, (B) an isocyanate component having a functionality of two or more and (C) sufficient catalyst to catalyze substantially completely the reaction between components (A) and (B). There is also provided a moldable composition comprising aggregate material, such as foundry sand, and such binder com-positions and foundry cores or molds made therefrom and including a process for their manufacture from the moldable compositions by either "cold box" or "no-bake" procedures.

Description

112Z'~37 ~ . I
., .
,1 . . ", ,, ., .,. I

1 This invention relates to binder compositions, moldable-

2 compositions including the same and aggregate material, cores

3` or molds made therefrom and a process for making the same.

4 More particularly, the invention relates to foundry binder

5 1I compositions, moldable compositions including the same and

6!iaggregate material and foundry cores or molds made therefrom

7 ,including a process for their manufacture.
9 ~I Background of the Invention Binders o~ binder systems for foundry cores and molds are 11 known. Generally, such binders should exhibit good thermal and 12 ,Idimensional stability in order to result in. good dimensionally 13,~accurate metal castings. In addition, such binder syste~,sshould 14 ,have rapid curin~ times and exhibit uniform curing properties, that is, the centers of cores or molds made therewith should be 16 as well cured and as strong as their surfaces in order to mini- i 17 Imize breakage or warpage.
18~, In the foundry art, cores or mold$ for making metal cast-19 lings are normally prepared from a mixtur~ of an aggregate material, 20 ~,such as sand, and a binding amount of a binder or binder system.
21l,Typically, a~ter the aggregate material and binder have been 22 Ilmixed, the resulting mixture is rammed, blown or otherwise formed 23 ,to the desired shape or patterns and then cured with the use of 24 catalysts and/or heat to a solid, cured state.
25 ~ hile many of the known binders or binder systems prepared 26 ;with aggregate material, such as sand, and a binding amount of a 27 ,binder, such as polymerizable or curable material, possess the 28 required properties mentioned above and are suitable for use in 29 the foundry industry, even further improvements in such materials are required so that they exhibit even better properties and *

112273~

readily lend themselves to suitable core or mold making processes.
In this respect, there have been developed in the foundry industry, a variety of different processes for forming molds or cores, the particular process employed being dependent upon the binder or binder system being utilized. For example, many liquid binder systems require that curing and hardening be accomplished in a holding pattern or core box while subjected to heat. An example of this type of process is the commonly known "hot box" process. An exemplary process of this type is disclosed in U.S. Patent 3,306,864 issued February 28, 1967 to Lang et al.
On the other hand, some binder systems, such as for example the phenol-formaldehyde benzylic ether resin systems, do not require heating. Such systems are utilized in processes, commonly referred to as "cold box" processes which are accom-plished by passing gaseous catalyst through molded resin coated sand at ambient temperatures in order to achieve curing. In such systems, the resinous material is generally dissolved in a solvent and the type of solvent used affects curing speed and tensile strength. "Cold box" binders and processes as well as solvents employed therein are disclosed in U.S. Patents 3,905,934 issued'September 16, 1975 to Gardikes and 3,409,579 issued November 5, 1968 to Robins.
Still other types of binder systems do not require gassing or heating in order to bring about curing or hardening.
Such systems are known as "no bake" binders. Typical "no-bake" polyurethane binding systems of this type are disclosed in U.S. Patents 3,499,861, issued March 10, 1970 to Kujawa et al, 3,676,392, issued July 11, 1972 to Robins, and 3,686,106, issued August 22, 1972 to Tideswell et al. While these types of systems do not require gassing, many exemPlary "no-, . ~

l~Z~37 Il il . . i l ibake" resinous systems, on the other hand, still require 2 relatively long time periods to accomplish substantially 3 l complete curing at ambient temperatures or even under some 4,lheat.
5 1I Furthermore, although developments in resinous binder -6'1systems which can be processed according to the "cold box"
7 l¦ process have resulted in the provision of useful systems based : 8 ¦1 on pheno`l-formaldehyde benzylic ether resins and isocyanates 9,~which are employed wi~h various solvents, the selection of which solvents materially affects curing speed and tensile ll!istrength, as disclosed in the above-mentioned U.S. Patents 12'l,3,905,934 and 3,409,579, such systems still exhibit 13jlcertain disadvantages. For example, while such systems are 14llparticularly useful in the foundry art in making cores or molds, I
lS ,they are somewhat deficient in that the molds or cores made there-¦
16 !jwith exhibit relatively low hot strength which often results 17 ! in casting defects such as, "burn in" and erosion during use.
18ll There still exists, therefore, a need for the development of 19 ii resinous systems which exhibit even more improved curing speeds, 20 j', thus resulting in decreased production time per unit and, 21 1¦ conseauently, increased productivity, as well as providing 22 1i molds therewith which have increased hot strength and, as 23 'I well, elimination of casting defects, such as "burn in" and 24'l erosion. Moreover, there also exists a need for binder systems which readily lend themselves to processing to a molded, cured 26 ' state by either "cold box" or "no-bake" processes. The present 27 1 invention fulfills such needs.

_4_ l .

- 1~2Z737 _ief Statement of the Invention In accordance with this invention there is provided a binder composition comprising (A) a phenolic resin component including at least one phenolic resin selected from the group consisting of phenolic resole resins and phenolic novolak resins, sufficient solvent to reduce the viscosity of the phenolic resin component to below about 1000 centipoises comprising a mixture of (1) hydrocarbon solvent and (2) polar organic solvent containing at least sufficient organic ester selected from the group consisting of organic phosphate and organic carbonate esters and mixtures thereof to increase curing speed and solubility of the phenolic resin component, (B) an isocyanate component having a functionality of two or more and (C) sufficient catalyst to catalyze substan-tially completely the reaction between the phenolic resin and the isocyanate.

22'737 Description of the Preferred Embodiments 1 Component (A) the phenolic resin component employed - 2 in the practice of this invention can vary widely. It may be 3 any phenolic resin which is substanti~lly free of water, that is, :

CPC-25 11 .
!
, l! contains less than about 5 percent and preferably less than 2 " about 1 percent water, based on the weight of the resin, and whichj 3 Ii, is soluble in the solvents employed,such as phenolic resole or 4 ll phenolic novolak resins formed by reacting phenolic compo~ds 5¦¦with aldehydes. Resole or A-stage resins, as well as resitole 6¦¦or B-stage resins may be made by reacting a molar excess of 7¦~aldehyde, such as formaldehyde, with a phenolic compound, ¦ such as phenol, in the presence of an alkaline catalyst or metal 9 ion catalysts; while the novolak resins may be formed by reacting ,la molar excess of phenolic component with an aldehyde in the ~ presence of an acid catalyst.
12 ¦¦ The phenols employed in the formation o~ the phenolic 13 ¦¦ resin component of this invention are generally any of the 14 ¦I phenols which may be utilized in the formation of phenolic 15 1l resins and include substituted phenols as well as unsub-16 ,! stituted phenol per se. T'ne nature of the substituent 17 il can vary widely and exemplary substituted phenols include alkyl-18 ¦ substituted phenols, aryl-substituted phenols, cycloalkyl-substi- ¦
19 , tuted phenols, alkenyl-substituted phenols, alkoxy-substituted 20 ¦i phenols, aryloxy-substituted phenols, and halogen-substituted 21¦~phenols, the substituent groups containing from 1 to 26 or more 22 !I carbon a~oms and preferably from 1 to 6 carbon atoms. Specific 23 I~suitable exemplary phenols include, in addition to phenol 24 1l per se, o-cresol, m-cresol, p-cresol, 3,5-xylenol, 3,4-xylenol, 25 ,¦3,4,5-trimethyl phenol, 3-ethyl phenol, 3,5-diethyl phenol, 26 lp-butyl phenol, 3,5-dibutyl phenol, p-amyl phenol, p-cyclohexyl 27 ¦phenol, p-octyl phenol, 3,5-dicyclohexyl phenol, p-phenyl phenol 28 ll p-crotyl phenol, 3,5-dimethoxy phenol, 3,4,5-trimethoxy phenol, 29 ~l p-ethoxy phenol, p-butoxy phenol, 3-methyl-4-methoxy phenol, and p-phenoxy phenol. Such specific suitable exemplary phenols .

i ~22 737 can be described by the general formula: - j 2 ~ R(x) g¦¦wherein R is hydrogen, a hydrocarbon radical, or oxyhydro-g,lcarbon radical or halogen, x is an integer from 0 to 3 and , R may be the same or different. The preferred phenolic com-ll,~pounds are o-cresol and phenol.
12 li The aldehyde employed in formations of the phenolic resin 13 I¦ component employed in this invention can also vary widely. In 14 ll general, suitable aldehydes include any of the aldehydes hereto-lsllfore employed in the formation of phenolic resinssuch as for-16 'll maldehyde, acetaldehyde, propionaldehyde, furfuraldehyde, and ,benzaldehyde. In general, the aldehydes employed have the lg,iformula R'CXO wherein R' is a hydrogen or a hydrocarbon radical 19 lof 1 to 8 carbon atoms. The most preferred aldehyde is 20 liformaldehyde~
21 ! The preferred phenolic resin components employed in the 22 111 practice of this invention are resole resins made from o-cresol 23 ~ and formaldehyde at a mole ratio of formaldehyde to o-cresol 24 'in a range Oc from about 0.9 to about 2Ø Such phenolic 25 , resin components exhibit particularly good solubility in the 26 ,,solvents used in the practice of this invention which are 27 ~described more particularly hereinbelo~, cure rapidly, and, in 28 addit on, exhibit both high tensile strengths and high hot 29 strengths. It is to be understood, however, that in general mixtures of suitable phenolic resin components can also be used ..

~12~737 CPC-25 `I
-,'i . ,., . , .

. ~

1'l in the practice of this invention.
2,' Component (B), the isocyanate component which can be 3 employed in a binder according to this invention may likewise 4 'vary widely and has a functionality of 2 or more. Exempletive 5,1of the useful isocyanates are organic polyisocyanates such as 6~l2,4-tolylene diisocyanatel 2,6-tolylene, diisocyanate, and 7 Imixtures thereof, and particularly the crude mixtures thereof

8 ~¦ that are commercially available. Other typical polylsocyanates

9 include methylene-bis-(4-phenyl isocyanate), n-hexyl diisocyanate, 1,5-naphthalene diisocyanate, 1,3-cyclopentylene diisocyanate, 11 p-phenylene diisocyanate, 2,4,6-tolylene triisocyanate, 4,4',4"-12 Itriphenylmethane triisocyanate. Higher isocyanates are provided 13 ~by the liquid reaction products of (1) diisocyanates and (2) 14 ¦polyols o~r polyamines and the like. In addition, isothiocyanates ¦
15 ,~and mixtures of isocyanates can be èmployed. Also contemplated 16 are the many impure or crude polyisocyanates that are commer- 'I
17 ,cially available. Especially preferred for use in the invention 18 'lare the polyaryl polyisocyanates having the following general 19 ~Iformula ~ ~X2~X2~6 27 wherein Rbis selected from the group consisting of hydrogen, 28 chlorine, bromine, alkyl groups having 1 to S carbon atoms, and 29 ,alkoxy groups having 1 to 5 carbon atoms; X is selected from the group consisting of hydrogen, alkyl groups having 1 to 10 carbon _9_ ., 2Z~37 CPC-25 ;

ll ,, 1,, atoms and phenyl; and n has an average value of at least about l 2,l and generally about 1 to about 3. A typical commercially avail- I
3 iable isoc~anate is polymethylene polyphenylisocyanate such as t; 4 iPAPI-135/sold by Upjohn Co. and having a Brookfield viscosity 5 jlof about 1`77 centipoises at 25C., and an isocyanate equivalent 6i'.of 134.
7 i Generally, the amounts of the phenolic resin component (A) 8 and the isocyanate component (B) employed in a binder composi-9 i, tion of the invention are not critical and can vary widely.

10 I However, there should at least be enough of the isocyanate com-ll lponent present to react substantially completely with the 12 l¦ phenolic resin component so that there is no significant 13 li unreacted excess of either component present when reactio~
14 ji is complete. In this regard, the isocyanate component is gene-15 1l rally employed in a range of ~rom about 15 percent to about 400 16 i¦percent by weight, based on the weight of the phenolic resin 17 iI component and is preferably employed in a range of from about 18 1l 20 to 200 percent. Moreover, while liquid isocyanates can be 19 , used in undiluted form, so long as there is a sufficient amount 20 , of organic ester present in a composition according to this 21 , invention, in the solvent employed with the phenolic resin 22 ,¦ component to affect increased curing speed and solubility thereof ¦
23 ! and provide a composition having high tensile strength and high j 24 !, hot strength when cured, solid or viscous isocyanates, can 25 ~ also be utilized and when employed are generally used with an 26 ~, organic solvent such as those described more fully hereinafter.
27 In this respect, it is to be noted that component (B) the 28 isocyanate component may inc].ude up to 80 percent by weight 29 of solvent.

Furthermore, it is to be understood that in accordance ., , ~ --1 0--~ ~r ~ ~ ~ 7~ ~

~22737 ~ I
.... ~ . I
CPC-25 l ~ ~

'I i l'l¦with the invention both components (A) and (B) are, as a 2~',practical matter, dissolved in the described solvents in order 3 I to provide components-solvents mixtures of desirable viscosity 4,land thus facilitate the use of the same, such as in coating 5 !¦ aggre~ate material with the components. In this respect, 6ll sufficient solvents are employed to provide a Broo~field -7 i¦ viscosity of solutions of components (A) and (B) in suitable 8 ¦~solvents which is below about 1,000 centipoises and preferably 9 ¦, less than about 250 centipoises. More specifically, while the 10 , total amotint of solvent can vary widely, it is generally present ~ in a composition of this invention in a range of from about 12 11 5 percent to about 70 percent by weight, based on total weight I -13 1! Of the phenolic component, and is preferably present in a 14 I range of from about 20 percent to about 60 percent by weight.
15 ff¦ The solvents which can be employed in the practice of 16 fi this invention can vary widely so long as they contain, as 17 l¦ previously mentioned, sufficient organic phosphate and/or 18 ¦¦ carbonate ester to increase curing speed and solubility of the 19 ~I,phenolic resin component. In this respect, generally from 20 ji about 2 percent or more by weight, based on the weight of the 21 1l phenolic resin component, of organic phosphate and/or organic 22 ¦¦ carbonate solvents should be present as part of the solvent 23 !! mixture and preferably from about 4 percent to about 30 percent 2~ thereof should be present in a composition of this invention.
25 , The solvents e~lployed in the practice of this invention 26 i1 are generally mixtures of (1) hydrocarbon solvents and (2) polar 27 ''organic solvents containing organic ester selected from the group 28 ~'consisting of organic phosphate and/or organic carbonate esters.
29 ~l Suitable exemplary hydrocarbon solvents include aromatic 30 'Ihydrocarbons such as benzene, toluene, xylene, ethyl benzene, ., .

' f " .

~2;~737 CPC-25 ~l .
!

1 l,high boiling aromatic hydrocarbon mixtures, heavy aromatic 2 naphthas and the like, all of which are particularly useful 3 solvents.
4 The preferred polar solvents of this invention are organic phosphate esters. They provide good solubility for 6 - the phenolic resins, increase the cure speed and also increase ', 7 , hot strengths of the cured foundry cores. Examples of useful 8 i phosphates include alkyl phosphates, and ~he like. Specific 9 examples include trimethyl phosphate, triethyl phosphate, tripropyl phosphate,tributyl phosphate, trihexyl p'nosphate,

11 Tris (2-ethylhexyl) phosphate, t~ioctyl phosphate, dodecyl

12 diphenyl phosphate, octyl diphenyl phosphate, tricresyl

13 phosphates, triphenyl phosp'ilate, trixylenyl phosphate, cresyl

14 ,'diphenyl phosphate, tributoxyethyl phosphate, triethoxyethyl phosphate and the like. A particularly useful organic phosphate 16 1 ester is isodecyldiphenyl phosp~te.
17 " In general, the useful organic phosphate esters have the 18 l l following formula:
19 1 R ' O~
20 11 R" O -P = 0 21 l,, R''' ~ j 22 1I wherein R', R" and R''' may be any combination of alkyl, aryl, 23 l,aryloxyalkyl, alkoxyalkyl, and substituted aryl groups wherein 24 ; the radicals contain from 1 to 20 carbon atoms and the substi-tuents on the aryl groups are selected from alkyl, alkoxy and 26 aryl.
27 Another group of preferred polar solvents are organic 2~ carbonates. They provide good solvent solubility characteristics 29 for pnenolic resins and increase the curing speeds of phenolic ,urethane binders. Dialkyl and cyclic carbonates are particularly 22~37 ` I

`., 1 ~ useful. Alkyl, aryl and diaryl carbonates may also be used..
2 i Examples of useful carbonates are propylene carbonate, diethyl 3 carbonate, dipropyl carbonate, dibutyl carbonate, and the like.
4 Mixtures of hydrocarbon, phosphate and carbonate I solvents may be used. Also other polar solvents such as those 6 ,, disclosed in U. S. Patent No. 3,ao5,934 may be used in 7 1, combination with the solvents of this invention.
8 ii When such other polar solvents are employed, however, g the organic phosphate and organic carbonate esters should still ; be present in the solvent combination in the amounts mentioned 11 " above, it being understood that the total amount of polar 12 ,I solvent and hydrocarbon solvent can vary within all proportions 13 ,j with respect to each other so long as the required amount of the 14 '¦ mentioned phosphate and carbonate esters are present and the combination of solvents results in forming solutions with the 16 ' phenolic resin component and isocyanate component which permit 17 il substantially uniform and complete coating of aggregate material, ¦
18 ~, such as sand.
19 As previously indicated hereinabove, the compositions 20 ll of this invention can be cured by both the "cold box" and 21 ~11 "no-bake" processes. In this connection, the compositions 22 l include a suitable catalyst (C). While any suitable catalyst for 23 catalyzing the reaction between the phenolic resin component 24 ! and isocyanate component may be used, it is to be understood that when employing the "cold box" process the catalyst em-26 ployed is generally a volatile catalyst. On the other hand, 27 where the "no-bake" process is employed, a liquid catalyst 28 ; is generally utilized. Moreover, no matter which process is 29 utilized, that is, the "cold box" or the "no-bake" process, 1~ ` . 1122737 - CPC-25 li , ., ,` !
1 'l at least enough catalyst is employed to cause substantially 2 ~l complete reaction of components (A) and (B).
3 Preferred exemplary catalysts employed when curlng the 4 li compositions of this invention by the "cold box" process are ll volatile tertiary amine gases which are passed through a core 6 ~1 or mold generally along with an inert carrier, such as air 7 ¦i In this respect, it is to be noted that the flow rate may 8 1I vary widely. In general, the flow rate should be at least 9 sufficient so that substantially complete reaction takes , place between components (A) and (B). Exemplary volatile 11 , tertiary amine catalysts which result in a rapid cure at 12 ,l ambient temperature that may be employed in the practice of 13 l¦ the present invention include trimethyl amine, triethyl amine 14 , and dimethyl ethyl amine and the like.
On the other hand, when utilizing the compositions of 16 , this invention in the "no-bakel' process, liquid tertiary 17 amine catalysts are generally and preferably employed.
18 Exemplary liquid tertiary amines which are basic in nature 19 ! include those ha-ving a PKb value in a range of from about 4 ,~ to about 11. The PKb value is the negative logarithm of the 21 ,~ dissociation constant of the base and is a well known measure of i 22 !, the basicity of a basic material. The higher this number is, I
23 the weaker the base. Bases falling within the mentioned range , 24 are generally organic compounds containing one or more nitrogen atoms. Preferred among such materials are heterocyclic 26 compounds containing at least one nitrogen atom in the ring 27 structure. Specific examples of bases which have a PKb value 28 ~lithin the range mentioned include 4-alkyl pyridines wherein 29 the alkyl group has from 1 to 4 carbon atoms, isoquinoline, aryl-pyridines, such as phenyl pyridine, pyridine, acridine, :~2~737 l l 2-methoxy pyridine, pyridazines, 3-chloro pyridine, quinoline, 2 I N-methyl imidazole, 4,4-dipyridine, phenyl-propyl pyridine, 3 l-methyl benzimidazole and 1,4-thiazine. Additional exemplary, 4 , suitable preferred catalysts include but are not limited to il tertiary amine catalysts such as ~,N-dimethylbenzyl amine, 6 Il triethylamine, tribenzyl amine, N,N-dimethyl-1,3-propane 7 ',, diamine, N,N-dimethylethanol amine and triethanolamine. It 8 ll iS to be understood that various metal organic compounds 9 l,l can also be utilized alone as catalysts or in combination with the previously mentioned catalysts. Examples of useful ', 11 metal organic compounds which rnay be employed as added 12 : catalytic materials are cobalt naphthenate, cobalt octoate, 13 ~ dibutyl tri-dilaurate, stannous;octoate and lead naphthenate 14 l' and the like. When used in combinations, such catalytic 1, !I materials, that is the metal organic compounds, the nitrogen 16 ' containing catal~Jsts and amine catalysts, may be employed 17 , in all proportions with each other.
18 , It is to be further understood that when utilizing the 19 compositions of this invention in the "no-bake" process, ~, the amine catalysts, if desired, can be dissolved in suitable 21 ¦! solvents such as, for example, the hydrocarbon solvents -22 ¦, meneioned hereinabove. The liquid amine catalysts are generally 23 , employed in a range of from about 0. 5 percent to about 15 percen~
24 I, by weight, based on the weight of the phenolic resin component 25 present in a composition in accordance with the invention.
26 ; When employing a binder composition of this invention 27 in the "no-bake" process, the curing time can be controlled 28 ' by varylng the amount of catalyst added. In general, as the

-15-C~C-25 ' ~ ~2~737 . I

1 l, amount of catalyst is increased the cure time decreases. Further-2 ` more, curing takes place at ambient temperature without the 3 ' need for subjecting the compositions to heat, or gassing or the 4 ll like. In this regard, however, in usual foundry practice ,I pre-heating of the sand is often employed to raise the temper- ¦
6 ~1 ature of the sand to from about 30F up to as high as 120F., 7 1 and preferably up to about 75F. to 100F. in order to 8 !l accelerate the reactions and control temperature and thus 9 I provide a substantially uniform operating temperature on a day to day basis. However, it is to be understood that such pre-11 heating is neither critical nor necessary in carrying out the 12 , practice of this invention.
13 While the binder compositions of this invention may be 14 ' employed by admixing the same with a wide variety of particulate materials, such as limestone, calcium silicate and gravel

16 and the like, in order to bind the same, and the admixture

17 , then manipulated in suitable fashion to form coherent shaped

18 ; structures, they are particularly useful in the foundry art

19 as binding compositions for foundry~sand. When so employed, 1 the amount of binder and sand can vary widely and is not 21 , critical. ~n the other hand at least a binding amount f 22 , the binding composition should be present in order to coat 23 substantially completely and uniformly all of the sand 24 particles and to provide a uniform admixture of the sand and binder and, so that when the admixture is conveniently shaped 26 as desired and cured, there is provided a strong, uniform, ', 27 ' shaped article which is substantially uniformly cured throughout, CPC-25 l ~Z27~7 ! ' 1i 1 thus minimizing breakage and warpage during handling of the 2 1I shaped article, such as, for example, sand molds or cores, 3 so made. In this regard, the binder may be present in a 4 'I moldable composition in accordance with this invention in a 1! range of from about 0.7 percent to about 4.0 percent-by weight 6 i based on the total weight of the composition.
7 1, Other commonly employed additives can be optionally 8 !! used in the binder compositions of this inven~ion. Such 9 i~ additives include, for example, organo silanes which are ~ known coupling agents. The use of such materials may enhance ll ; the adhesion of the binder to the aggregate material. Examples 12 1 of useful coupling agents of this type include amino silanes, 13 li, epoxy silanes, mercapto silanes, hydroxy silanes and ureido 14 ,'l silanes such as, for example, gamma-aminopropyl trimethoxy i~ silane, gamma-hydroxy propyl-trimethoxy silane, 3-ureidopropyl 16 i triethoxysilane, gamma-mercaptopropyl-trimethoxy-silane, 17 gamma-glycidoxypropyltrimethoxy-silane, beta-(3,4-epoxycylo-18 ~, hexyl)- trimethoxysilane, ~-beta-(amino-ethyl)-gamma-amino-19 ' propyltrimethoxy-silane and the like.
,' In the practice of this invention additives normally 21 ' utilized in foundry manufacturing processes can also be added 22 1l to the compositions during the sand coating procedure. Such 23 1 additives include materials such as iron oxide, clay, carbo-24 1 hydrates, potassium fluoroborates, wood flour and the like.
In general the process for making a moldable composition 26 ,' in accordance with this invention comprises admixing aggregate 27 material with at least a binding amount of (A) a phenolic 28 resin component including at least one phenolic resin selected 29 from the group consisting of phenolic resole resins and , CPC-25 ~ Z~737 . ' .

1 I' phenolic novolak resins dissolved in sufficient solvent to 2 ,' reduce the viscosity of the phenolic resinous component to 3 ; below about 1000 centipoises, the solvent comprising a mixture 4 of (1) hydrocarbon solvent and (2) polar organic solvent 'I containing at least sufficient organic ester selected from the 6 i! group consisting of organic phosphate and organic carbonate 7 ~ esters and mixtures thereof to increase curing speed and 8 ll solubility of the phenolLc resin component and (B) an isocy-g ',~ anate component having a functionality of two or more, agitating ,j the admixture and substantlally completely and uniformly 11 coating the aggregate material with components (A) and (B), 12 '' suitably manipulating the admixture conveniently, as for 13 ~l example, by distributing the same in a suitable core box or 14 !1i pattern adding to the admixture at least a sufficient amount ,i of catalyst to substantially completely catalyze the reaction 16 ll between components (A) and (B), curing the admixture and i 17 ~ forming a shaped product.
18 ',ii It is to be understood that there is no criticality in 19 the order of mixing the constituents with the aggregate material.
;i On the other hand, the catalyst should generally be added to 21 1! the mixture as the last constituent of the composition so that 22 j, premature reaction between components (A) and (B) does not take 23 I place. It is to be further understood that as a practical 24 matter, the phenolic resin component (A) can be stored separately and mixed with solvent just prior to use or, if desirable, 26 l mixed with solvent and stored until ready to use. Such is 27 also true with component (~), the isocyanate component. On the 28 other hand, components (A) and (B), as a practical matter, 29 , `
; 30 .' ' !

~ -18-.~,'' .

c~c~ Z2'`737 1 should not be brought into contact with each other until ready 2 1' to use in order to prevent any possible premature reaction 3 w'nich might take place and in this regard components (A) and ` I
4 i, (B) may be mixed with the aggregate material either simultan- ¦
' eously or one after the other in suitable mixing devices, 6 ~, such as mullers, continuous mixers, ribbon blenders and the 7 ' like, while continuously stirring the admixture to insure : 8 1¦ uniform coating of aggregate particles.
: g ! More specifically, however, when the admixture is to be ~; cured according to "cold box" procedures, the admixture after 11 i; shaping as desired, is subjected to gassing with an amine 12 l; catalyst in air and the flow rate of catalyst through the 13 li, shaped admixture should:~e~.sufficient to provide sufficient 14 ~I catalyst to substantially complete reaction between components ' (A) and (B), the flow rate being dependent, of course, on the 16 l, size of the shaped admixture as well as the amount of phenolic j~ I
17 1 resin therein. In this respect, the cure time of cores 2 inches 18 , in diameter by 2 inches in length and having a weight of about 19 170 grams when subjected to gassing with triethyl amine in air , at a flow rate in a range from about 3 liters per minute to ~1 ~' about 6 liters per minute exhibit curing time less than about 22 ! 40 seconds.
23 i In contrast, however, when the admixture is to be cured 24 according to "no-bake" procedures, the catalyst is added to the aggregate material simultaneously or preferably after 26 1I coating the aggregate material with components (A) and (B), 27 , the admixture then being shaped and simply permitted to cure 28 until reaction between components (A) and (B) is substantially 29 complete and thus forming a shaped product such as a foundry core or mold.On the other hand it is to be understood that the 31 catalyst may also be admixed with either one of the components 32 j (A) or (B) prior to coating of the aggregate material with the ~~ ^ 3~ c-ompanents.

` 1122737 CP c--2 5 ~ ¦ ?
l l l .. . .

1 ' Consequently, by so proceeding, as indicated with an .
2 I~ admixture of foundry sand and a binding amount of components 3 (A) and (B) there is formed a foundry core or mold comprising foundry sand and a binding amount of a binder composition I' comprising the reaction product of components (A? and (B) and 6 ,~I~ polar organic solvent containing at least sufficient organic 7 ,l esters selected from the group consisting of organic phosphate 8 ¦1 and organic carbonate esters and mixtures thereof. -g i ~

'.

17 i 22 'I

-~n-1' llZ2737 . C~C-25 il THE EX~LES

l ~I The following specific examples of the present invention 2 l~ are set forth in order to illustrate the same. It is to be 3 ~l' understood that the examples are illustrative only and are not 4 '1¦ intended to limit the invention in any way. In the examples 5 1i all parts and percents are by weight, the temperatures are de-6 l, grees centigrade and the viscosity values are in centipoises, 7 ji unless otherwise indicated.

9 Il Examples I - VII
10 1 These examples illustrate the preparation of an o-cresol 11 , resole resin component (A) and solutions thereof with various 12 'lj solvent as well as an isocyanate solution component (B) and use ¦
13 l,l of the same inthe practice of the present invention by "cold bo~' 1' 14 Ij procedures to make foundry cores. The examples further illus-' trate that the cure times at various catalyst rates are con-16 '' sistently shorter where the compositions contain phosphate or 17 ll carbonate esters in comparison to compositions containing other 18 j polar solvents.

20 IT An o-cresol resole is prepared from 2160 grams of a com-Zl l' mërcially available mixture consisting of approximately 80%
22 ¦1, o-cresol and 20% phenol and 1200 grams of 50% formaldehyde 23 I solution, using 21.6 grams of lime as the catalyst. The reac-24 ~I tants are stirred at 70C.until the free formaldehyde dropped to 0.15%. After cooling to 45C., the pH is adjusted to 6.4 by 26 'I the addition of 26 grams of sulfuric acid, diluted with 124 27 ,~ grams of water. The resin is dehydrated under vacuum to a 28 l refractive index of 1.570 at about 25C. The resole is then 29 heated at 110C. for two hours and dehydrated under vacuum untill 30 the water content is 0.4%. The resin formed is then diluted with

-21-i' '.

11;ZZ7~7 "
-25 li , , .

ll, the s~lvent combinations listed in Table 1 to provide solutions 2l having viscosities in a range of from about 150 to 500 centipoises`.
3 The isocyanate solution listed in Table 1 is prepared by 4 dissolving 75% polymethylene polyphenylisocyanate in 25% of ; 5 11 Aromatic lO~ hydrocarbon solvent, having a boiling point of 6l 1~5-170C. sold by Exxon Company, the solution having a viscosity¦
711 in a range of about 38 centipoises.
8 ¦¦ In order to provide moldable compositions suitable for 9 foundry cores, admixtures of foundry sand are made with the .
!
variolls solutions of the o-cresol resole and the isocyanate !!
ll , solution and tested for cure speeds, the results being set forth 1 12 in Table 1. The foundry sand mixes are prepared as follows: ¦
13,i First, 25 grams of resin solution listed in Table 1 are mixed j, 14~ with 2500 grams Lake sand for one minute using a K-45 Kitchen 15' Aid ~!ixer. The polymeric isocyanate solution, 25 grams, is 16 added and mixing continued for two minutes. The resulting found-¦
17 ; ry sand mix is tested for cure speed, defined as the time re-18" quired to cure through a 2" diameter x 2" high core. The test 19 ; specimen is prepared from 170 grams of the foundry sand mix by standard AFS procedures, using a Dietert No. 315 sand rammer and 21 l a Dietert No. 315-9 specimen tube. Gassing is accomplished at ,l

22'' ambient temperatures by setting the air flow at the desired

23' rate, pæsing it over liquid triethylamine, and through a Dietert

24 ~ gassing att~chment. The core is retained in the specimen tube, which is placed on top of the gassing attachment and a timer 26 started. Whiie the tertiary amine gas is passing up through the ' 27 bottom of the core, the top surface of the core is probed until 28 it hardens and the required time is noted. The cure times at 29 I various catalyst flow rates are consistently shorter for the 30 , phosp~ate ester or carbonate containing resins, than for resins 31 containing other polar solvents as maq be seen in Table 1.

~lZ2~737 !

II III IV V VI VII

O-Cresol-formaldehyde55.055.055.0 55.0 55.0 55.0 55.0 resin Aromatic solvent 40.540.5 40.5 40.5 40.5 40 5 40,5 Release agent 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Silane A-186 (trade 0.2 0.2 0.2 0.2 0.2 0.2 0.2 mark) 2-butoxy-ethanol acetate 4.5 Di-iso-butyl phthalate - 4.5 Triethyl phosphate - - 4.5 _ _ _ - !
Tributyl phosphate - _ _ 4 5 _ _ _ ¦
Tricresyl phosphate - - _ - 4.5 - _ Propylene carbonate - - - - - 4.5 _ Dibutyl carbonate ~ - - - - - 4.5 , ,~
,., 'A~ Sand Tests Lake sand 100 100 100 100 100 100 100 Polyisocyanate solution 1 1 1 1 1 1 1 Resin solution 1 1 1 1 1 1 1 Cure time of 2" dia. x 2" core (170g) in sec.
Flow rate 3 l/min. 51 72 36 33 41 37 46 I~
6 1/min. 27 29 24 21 27 24 26 9 1/min. 21 24 15 lS 18 14 20 ~, Z2737 ` I
. CPC-25 ~~l Example VIII

l;l This example illustrates the making of an o-cresol resin , with a different reaction catalyst than used in Examples I - VII.j 3 Zinc acetate is used in place of lime. It also illustrates using ! combinations of solvents.

5 1! An o-cresol resole is prepared from 2940 parts of commer-6 11l cial ~0% o-cresol and 2450 parts of 50% aqueous formaldehyde 7ll using 88 parts of zinc acetate as a catalyst. The mixture is i 81' reacted at 95~C. until the free formaldehyde is between 4.2 - g li and 4.8%. The batch reaction mixture is then heated under vacuum to 110C. and stirred for 14 hours. Then 720 parts of Isodecyl 11 diphenyl phosphate, 1440 parts or heavy aromatic solvent having 12'l' a boiling point of 160-293C. and 1440 parts SC-150 aromatic sol- ¦
13 ~ vent boiling point 183-210C. are added thereto. Both aromatic 14'l solvents are available commercially rom Central Solven~ts &
15l' Chemicals, Chicago, Illinois. Then 14.5 parts of A-186 silane 16 j sold by Union Carbide Corporation and`14.5 parts of silicone fluid release agent are added and stirred into the reaction mixture.
18'l The resin solution has a viscosity of 140 centipoises at 25C.
! This o-cresol resole resin is coated onto sand along with 20 i1 a 75~/O polymPthylene polyphenyl isocyanate solution in Aromatic 21il 100 hydrocarbon soLvent as describ~d in Examples I - ~II. Cure 22 1I time tests are run as described in those Examples. At gassing 23'i flow rates of 3 liters per minute and 6 liters per minute,~the 24 cure times are 26.5 seconds and 16.0 seconds, respectively. One inch dog bone tensile test specimens are prepared using a Dietert 26 ~ No. 694 core box and cartrid~e. Sand is blo~ into the box at 27 ! 90 pounds per square inch pressure. Tensile specimens are gassed', 28 i with triethyl amine in air flowing 9 liters per minute and ten-29 i siles measured immediately after gassing, one hour and 24 hours j after ga~ing using a Detroit Testing Machine Co., Model CST ten-31, sile tester. Tensil~s are 133, 265 and 338 pounds per square ,i -24-CPC-25 ~l 1, .
I` . . I
1 ! inch, respective y. These data show that the resin compositions 2 , of this invention cure rapidly to give strong foundry cores.

4 l¦ E amples IX_ XII
5 ¦I To a 1 liter flask there is charged 259.5 grams (2.09 6 ! moles) of 2-methoxyphenol, 188.0 grams (3.13 moles) of 50%
7 ¦ formalin, and 7.8 grams of zinc acetate dihydrate. The reaction 8 ! mixture is heated at reflux for 18 hours. The resin is dehydrated i g s, under 28 inches vacuum and heated until an internal temperature ~ lO I of 110 is reached. These conditions are maintained for 14 hours ; 11 'I to give a base resin used to prepare the examples described in 12 li Table 2 by the procedures used in the previous Examples, the s .13 i¦ resin solvents mixtures having a viscosity in a range of 105 to 14 l, 360 centipoises at 25C. .
15 ~I TABLE 2 16 ! IX X XI XII
17 ¦¦ Base resin from Example IX 50 50 50 50 18 ! Propylene carbonate 25 !l 19 ll Isodecyldiphenyl phosphate -- 25 20 ,l I8Ophorone __ __ 25 _ 21 1l Dibutyl phthalate __ __ __ 25 22 1l Aromatic solvent 25 25 25 25 23 ¦I Silicone fluid 0.2 0.2 0.2 0.2 24 ,~ Silane 0.2 0.~ 0.2 0.2

25 ~I Sand Tests i,

26 ,i Lake Sand 100 100 100 100

27 , Polyisocyanate solution

28 ,l Resin solution

29 ' Cure time of 2" dia. x 2" core 'l (170g) in sec.*
Flow rate ; 3 l/min. 20 sec. 26 sec. 34 sec. 38 sec.
j 6 l/min. 12 sec. 16 sec. 23 sec. 23 sec.
*Samples gassed ~ith triethyl amine in air.

ll ~122737 C~C-25 li I
I' I

l l These Examples clearly illustrate the unexpectedly im-2 Il, proved curing time attained with the organic phosphate and car-3~l bonate esters in comparison with other polar solvents.
4',~
5 1¦ Examples XIII - XVII
6¦¦ To a 5 liter flask there is charged 1880 grams (20 moles) 71i of phenol, 1800 grams (30 moles) of 50% formalin, and 56.4 grams 8 l¦ zinc acetate dihydrate. The reactants are heated at reflux g~l (100C.) for 3 hours. After this period, vacuum is applied to the vessel and the resin is cooled to 50C. by dehydration. The pH is 11 , adjusted to 4.5 by the addition of phosphoric acid and dehydration 12!l is resumed. The temperature is increased to 90C. at 28 inches 13~i vacuum. Thé resin is stirred four (4) hours under these condition 14 ll to give a base resin which is used to prepare the Examples des-15~j cribed in Table 3 by the procedures used in the previous Examples, 16,. the resin solvents mixtures having a viscosity in a range of 280 17 to510 centipoises at 25C.

20 1 ;

22 j~
23'i 27';

CPC-25 jj llZ2737 ~ TABLE 3 2 ,, XIII XIV XV XVI XVII
3 ` Base resin from Example XIII 50 50 50 50 50 4 i, Propylene carbonate 33.5 -- -- -- -- j 5 ¦I Tricresyl phosphate -- 33.5 -- -- --6 !! Isodecyldiphenyl phosphate -- -- 33.5 -~
7 ¦l Isophorone -- -- -- 33.5 --8 ¦¦ Dibutyl phthalate -- -- -- -- 33.5 9 !l Aromatic solvent 16.5 16.5 16.5 16.516. 5 10 ~, Silicone fluid 0.2 0.2 0.2 0.2 0.2 i 11 Silane 0.2 0.2 0.2 0.2 0;2 12 i Sand Test 13 ii Lake Sand 100 100 100 100 100 ~; 14 ll Resin solution 15 !I Polyisocyanate solution 16 ii Cure time of 2" dia. x 2" core ; ¦i (170g) in sec-*
~! Flow rate 18 ,l 3 l/min. 25.0 33. 5 33.5 35.036. 5 19 ', *Samples gassed with triethylamine in air.
20 j 21 l! These Examples clearly show that the organic phosphate 22 1,i, and carbonate esters employed in the compositions of this 23 Ij invention result in faster curing times than do the previously 24 ii employed isophorone and dibutyl phthalate polar solvents.
25 , 26 ' 29 ',

30 1 ., i Il 1122~737 CPC-25 ~l !!
Il Example XVIII

1 ~This Example.demonstrates that resin compositions of 2 ll this invention are also useful for making foundry cores by the 3 ,1 "no-bake" process. A liquid tertiary amine catalyst is used in 4 li this case.
5 l, ` To a Hobart A-120 mixer there is added 2500 grams of ~6 ll Wedron 7020 washed and dried silica sand. The mixer is started 7 ji and 17.5 grams of the o-cresol resin of Example VIII, 17.5 grams 8 l¦ of polyisocyanate solution of Example VIII and 0.175 grams of 9 ll N,N dimethyl ethanol amine are added and mixing continued for , one (1) minute, and the sand discharged. Part of the sand is 11 , immediately used to form 12 standard American Foundry Society 1 12 il inch dog bone tensile briquets using a Dietert No. 696, 12 gang 13 i! core box. Cores are cured at room temperature and broken after 14 ll 1 hour and 24 hour cure times. Tensile strengths are determined , using a Detroit Testing Machine Co., Model CST tester. One hour 16 i, tensile is 60 pounds per square inch and 24 hour tensile is 180 17 j! pounds per square inch. The rest of the sand is used to make a 18 1I pyramid core. A thermometer is inserted into the core. The 19 '! stripping time thereo~ is determined as the time at which the 20 l~ core is so hard that the thermometer ca~ no longer be pushed into 21 Ill the core. The strip time is 12 minutes.
22 Il Foundry cores or molds made from the moldable composi-23 tions of this invention in accordance with the preceding Examples 24 l' exhibit, in addition to rapid curing times, good thermal and 25 , dimensional stability. I~hen used in casting procedures, such 26 ,I molds or cores exhibit good hot strength and result in reduced 27 l, casting defects such as "burn in" and erosion during use. More-28 l~ over, when other phenolic resins, as well as other isocyanates, 29 , and polar solvents such as the additional phosphate and carbonate ' esters such as those disclosed hereinbeore are employed in the ~ 28 -l ~z~737 CPC-25 1 .

1 ,, Examples as replacements for like materials used tl~erein, I
2 ll similar results are obtained. 1, 3 The present invention also presents many advantages in 4 I addition to those already mentioned above. For example the 5 1I materials employed in carrying out the invention are generally 6 ¦I readily available and can be used on existing equipment presently 7 l¦ employed in industry for the fabrication of cores or molds, and 8 Ii in particular in the foundry industry. Moreover, the process of 9 !I this invention readily lends itself to either "cold box" or "no-bake" procedures currently in use, thus obviating the need 11 for elaborate equipment changes and training of personnel, whïle I
12 l'i at the same time permitting flexibility of choice with respect to¦
13 1l utilization of the most convenient and beneficial procedure as 14 1I desired. Numerous other advantages of the invention will be 15 !I readily apparent to those skilled in the art.
16 While the invention has been described in connection 17 ,I with specific embodiments thereof, it is to be understood that 18 jl it is capable of further modification, and it is intended to.
19 I cover any variations, uses or adaptations thereof following, in 20 i~ general, the principles of the invention and including such 21 i¦ departures from the embodiments disclosed herein as come within 22 ~I the known or customary practice in the art to which the invention 23 ,I pertains and as may be applied to the essential features herein-24 before set forth, and as fall within the scope of the invention.

29 Il.

30 .
., .

.

Claims (27)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A binder composition comprising (A) a phenolic resin component including at least one phenolic resin selected from the group consisting of phenolic resole resins and phenolic novolak resins, sufficient solvent to reduce the viscosity of said phenolic resin component to below about 1000 centipoises comprising a mixture of (1) hydrocarbon solvent and (2) polar organic solvent containing at least sufficient organic ester selected from the group consisting of organic phosphate and organic carbonate esters and mixtures thereof to increase curing speed and solubility of said phenolic resin component, (B) an isocyanate component having a functionality of two or more and (C) sufficient catalyst to catalyze substantially completely the reaction between the phenolic resin and the isocyanate.

2. A binder composition according to claim 1 wherein the phenolic resin component includes a phenolic resole resin.

3. A binder composition according to claim 2 wherein the phenolic resole resin is an ortho-cresol resole resin.

4. A binder composition according to claim 2 wherein the phenolic resole resin is a phenol resole resin.

5. A binder composition according to claim 1 wherein the polar organic solvent is an organic phosphate ester having the formula:

wherein R', R", and R''' are organic radicals selected from the group consisting of alkyl, aryl, aryloxyalkyl, alkoxy-alkyl and substituted aryl radicals and combinations thereof.

6. A binder composition according to claim 1 wherein the polar organic solvent is isodecyldiphenyl phosphate.

7. A binder composition according to claim 1 wherein the polar organic solvent is an organic carbonate ester selected from the group consisting of dialkyl carbonates, arylalkyl carbonates, diaryl carbonates and cyclic carbonates and mixtures thereof.

8. A binder composition according to claim 1 wherein the hydrocarbon solvent is selected from the group consisting of aromatic hydrocarbons, high boiling aromatic hydrocarbon mixtures and heavy aromatic napthas.

9. A binder composition according to claim 8 wherein the hydrocarbon solvent is an aromatic hydrocarbon.

10. A binder composition according to claim 1 wherein the isocyanate component is a polyisocyanate having the general formula:

wherein R6 is selected from the group consisting of hydrogen, chlorine, bromine, aklyl groups having 1 to 5 carbon atoms and alkoxy groups having 1 to 5 carbon atoms, X is selected from the group consisting of hydrocarbon, alkyl groups having 1 to 10 carbon atoms and phenyl; and n has an average value of up to about 3.

11. A binder composition according to claim 10 wherein the isocyanate component is polymethylene polyphenyl-isocyanate.

12. A binder composition according to claim 1 wherein the isocyanate component is employed in a range of about 15% to about 400% by weight, based on the total weight of the phenolic resin component.

13. A binder composition according to claim 1 including polar organic solvent other than polar organic phosphate and polar organic carbonate esters.

14. A binder composition according to claim 1 wherein the organic ester is present in a range of from about at least 2% by weight, based on the total weight of the phen-olic resin component.

15. A binder composition according to claim 1 wherein the solvent is employed in a range of from about 5% to about 70% by weight, based on the total weight of the phenolic resin component.

16. A binder composition according to claim 1 wherein the catalyst is a tertiary amine.

17. A binder composition according to claim 16 wherein the catalyst is triethyl amine.

18. A binder composition according to claim 16 wherein the catalyst is dimethylethyl amine.

19. A binder composition according to claim 1 where-in the catalyst is employed in a range of from about 0.5% to about 15% by weight, based on the total weight of the phenolic resin component.

20. A binder composition according to claim 1 in-cluding a silane coupling agent.

21. A moldable composition comprising aggregate material and a binder comprising the binder composition of claim 1.

22. A process for making foundry cores or molds comprising admixing aggregate material and a binding amount of the binding composition of claim 1 and forming a shaped foundry core or mold.

23. A process according to claim 22 wherein the catalyst is added to the shaped, coated aggregate material by gassing, said catalyst being passed through the shaped, coated aggregate material.

24. A process according to claim 22 wherein the catalyst is admixed with the aggregate material simultaneous-ly with components (A) and (B).

25. A process according to claim 22 wherein the catalyst is added to the aggregate material subsequent to coating said aggregate material with components (A) and (B).

26. A process according to claim 22 wherein the catalyst is admixed with one of components (A) and (B) prior to coating of the aggregate material with said com-ponents.

27. A shaped foundry core or mold comprising foundry sand and a binding amount of the binder composition of claim 1.