US 3632844 A
Description (OCR text may contain errors)
United States Patent 0 3,632,844 NON-STICKIN G SAND MIX FOR FOUNDRY CORES Janis Robins, St. Paul, Minn., assignor to Ashlaud Oil, Inc., Houston, Tex.
No Drawing. Filed Mar. 10, 1969, Ser. No. 805,800 The portion of the term of the patent subsequent to Nov. 4, 1985, has been disclaimed Int. Cl. B22c 1/22 US. Cl. 260-18 TN 13 Claims ABSTRACT OF THE DISCLOSURE Shaped foundry products, e.g., cores, which are made from sand and a phenolic resin-isocyanate binder are rendered non-sticking by adding fatty acid to the sandbinder mix.
This invention relates to a method of making sand cores which do not stick to metal patterns in which they are cured. In one aspect, this invention related to a foundry process for making sand cores using organic binders containing a phenolic resin and an isocyanate, which process includes the incorporation into said cores of fatty acids to reduce the tendency of the cores to stick to metal patterns in which they are cured.
In the foundry art, cores for use in making metal castings are normally prepared from mixture of an aggregate material, such as sand, which has been combined with a binding amount of a polymerizable or curable binder. Frequently, minor amounts of other materials are also included in these mixtures, e.g., iron oxide, ground flax fibers, and the like. The binder permits such a foundry mix to be molded or shaped into the desired form and thereafter cured to form a self-supporting structure.
Typically, sand is used as the aggregate material. After the sand and binder have been mixed, the resulting foundry sand mix is rammed, blown, or otherwise introduced into a pattern, thereby assuming the shape defined by the adjacent surfaces of the pattern. Then by use of catalysts, e.g., chlorine and carbon dioxide, and/or the use of heat, the polymerizable binder is caused to polymerize, thereby converting the formed, uncured foundry sand mix into a hard, solid, cured state. This hardening can be accomplished in the original pattern, in a gassing chamber, or in the holding pattern.
In recent years, the foundry art has been provided with so-called cold-box binders containing phenolic resins and polyisocyanates. By use of the term cold-box, these binders are contrasted from binders requiring the introduction of heat to the pattern in order to cure the core. In the cold-box system, the binder cures at room temperature with the use of a suitable catalyst, e.g., a gaseous tertiary amine. See, for example, US. Pat. No. 3,409,579 to Robins which issued on Nov. 5, 1968. An alternative to the cold-box process which still requires the use of a phenolic resin-isocyanate binder is disclosed in US. Ser. No. 652,669 filed Aug. 12, 1967 now US. Pat. No. 3,432,- 457 issued to Robins on Mar. 11, 1969. In this process, a benzylic ether-type phenolic resin and isocyanate are cured by use of a metal ion The advantages of the cold-box process and of the alternative metal-ion cured system are many. The cold-box process olfers the following advantages:
(1) high tensile strength (2) instant cure (3) cured cores ready for immediate use (4) highly flowable mix (5) high degree of dimensional accuracy (6) good abrasion resistance (7) high density (8) exceptional collapsibility "ice (9) low gas evolution, and (10) superior surface finish.
Cores and molds made using the phenolic resin-isocyanate possess one inherent disadvantage, however. These shaped foundry products have a tendency to stick to metallic patterns in which they are cured. One possibility of correcting this problem is by use of non-metallic patterns, e.g., urethane or epoxy-lined patterns. Still another possibility lies in the use of ejector pins, i.e., pins which retract while the foundry mix is introduced into the pattern and the mix is cured but which eject forcing the cured core or mold out of the pattern after cure.
It has now been discovered that the tendency of cores and molds made using a phenolic resin-isocyanate binder to stick to the metallic patterns in which they are cured can be substantially reduced by adding to the foundry mix a fatty acid. The inclusion of a fatty acid in the foundry mix (i.e., the mixture of aggregate and binder) before the mix is introduced into a metallic (e.g., iron) pattern wherein the mix is cured performs a two-fold function. First, the adhesive strength between the cured core or mold and the metallic pattern is reduced; second, the cores and/ or molds are released from the pattern more cleanly.
Most existing foundry core-making processes have required that metallic patterns be used. Usually, the pattern is constructed of cast iron, aluminum, magnesium or a combination of these metals. Cast iron is a preferred material since it is high in resistance to wear and more permanent than the other metals. Although the advent of the cold-box" process makes it possible to construct patterns from less costly and lighter materials, e.g., plastics, such as urethanes, the industry has many metal core box patterns and will continue to use them.
The inclusion of a fatty acid material in the mix has had a surprisingly modest effect on the tensile strengths of the resulting cores and/ or molds. It follows that, if an additive reduces the tendency of a binder to stick to a metal pattern, it would also reduce the tendency of the binder to bind the aggregate together. It has been found that a tensile strength reduction of less than five percent is experienced when one-half of one percent (a preferred amount) of fatty acid is included in the mix. This one-half of one percent of fatty acid reduces the adhesive strength of the cured core to iron patterns by more than ninety percent. The dramatic nature of this invention, therefore, can readily be seen.
Thus, in the ordinary practice of this invention, sand cores (or sand molds) for use in making metal castings will be prepared by the following steps:
(1) Forming a foundry mix containing sand as the predominant ingredient and a binder comprising phenolic resin and isocyanate;
(2) Simultaneously or separately mixing a fatty acid with the sand of step 1 (alternatively the fatty acid can be mixed with the phenolic resin or with the isocyanate prior to mixing with sand);
(3) Introducing the resulting foundry mix of step 2 into a metallic mold or pattern to thereby shape said mix; and
(4) Thereafter curing the shaped foundry mix to thereby form a sand core (or sand mold).
Step 4 can be accomplished by the inclusion of a metal ion catalyst or a base having a pk of from 4 to 13 in the mix or, preferably, by contacting the shaped mix while in the metallic pattern with a tertiary amine gas.
The fatty acids used in this invention are saturated or unsaturated monocarboxylic acids having from 4 to 26 carbon atoms. Polymerized fatty acids can also be used, e.g., dimers and trimers of unsaturated fatty acids. More usually, the fatty acids have from 12 to 20 carbon atoms (preferably 16 to 18) and are represented by the following formula:
RCOOH wherein R is saturated or unsaturated aliphatic hydrocarbon radical having from 7 to 12 carbon atoms, preferably from 15 to 17 carbon atoms. A particularly preferred class of fatty acid additives are the dimer acids which result from polymerizing monoand polyunsaturated fatty acids by the processes disclosed in US. Pats. Nos. 2,793,219, 2,793,220 and 2,955,121 (all assigned to Emery Industries, Inc.). These polymerized fatty acids result from heating fatty acids in the presence of crystalline clay mineral and water at, e.g., 180 to 260 C. for several hours. The product generally contains some unpolymerized acid and some trimer acids and is useful in this invention as is. However, we have found that the dimer acids are preferred. Examples of suitable fatty acids are stearic, iso-stearic, lauric, oleic, palmitic, myristic, pelargonic, iso-decanoic, arachidic, behenic, palmitoleic, ricinoleic, petroselinic, vaccenic, linoleic, linolenic, eleostearic, licanic, parinaric, godeleic, arachidonic, cetoleic, erucic, capric, caprylic, caproic, isovaleric, butyric, dodecylenic, stillingic, decylenic, and the like, including mixtures thereof. Surprisingly, derivatives of the fatty acids, such as esters, amides, amines and alcohols, etc., are not useful in this invention. Examples of polymerized fatty acids are polymerized monoand polyusaturated fatty acids such as dimers and trimers of oleic acid, erucic acid, cetoleic acid, linoleic acid, linolenic acid, elaeostearic acid, arachidonic acid, tallow fatty acids, rapeseed oil fatty acids, cottonseed oil fatty acids, linseed oil fatty acids, corn oil fatty acids, soybean oil fatty acids and fish oil fatty acids.
The amount of fatty acid included in the foundry mix will be an effective amount of up to 5 percent based on the weight of sand. Frequently, the amount will be within the range of 0.05 to 2.5 percent based on the weight of sand, e.g., from about 0.20 to about 2.0 percent. An especially preferred amount is from 0 .5 to 1.0 percent by weight of sand.
The binder compositions which can be benefited by use of this invention are known to the art and are those which contain a phenolic resin and a polyisocyanate. Such phenolic/isocyanate binder systems are coreacted at or about the time of use in the presence of sand. Typically, the reactive ingredients of such binder compositions are sold, shipped and stored in separate packages (i.e., a mul tiple package core binder) to avoid undesirable deterioration due to premature reaction between the components. Solvents, catalysts, various additives and other known binders can optionally be used in conjunction with these essential ingredients, i.e., used with the phenolic resin and the isocyanate.
Any phenolic resin which is substantially free of water is soluble in an organic solvent can be employed. The term phenolic resin as employed herein is meant to define any polymeric condensation product obtained by the reaction of a phenol with an aldehyde. The phenols employed in the formation of the phenolic resin are generally all phenols which have heretofore been employed in the formation of phenolic resins and which are not substituted at either the tWo ortho-positions or at one orthoand the para-position, such unsubstituted positions being necessary for the polymerization reaction. Any one, all, or none of the remaining carbon atoms of the phenol ring can be substituted. The nature of the substituent can vary widely and it is only necessary that the substituent not interfere in the polymerization of the aldehyde with the phenol at the ortho-position. Substituted phenols employed in the formation of the phenolic resins include: alkyl-substituted phenols, aryl-substituted phenols, cycloalkyl-substituted phenols, alkenyl-substituted phenols, alkoxy-substituted phenols, aryloxy-substituted phenols, and halogen-substituted phenols, the foregoing substituents containing from 1 to 26 and preferably from 1 to 6 carbon atoms. Specific examples of suitable phenols, aside from the preferred unsubstituted phenol, include: m-cresol, p-cresol, 3,5-Xylenol, 3,4-xylenol, 2,3,4-trimethyl phenol, 3-ethyl phenol, 3,5-diethyl phenol, p-butyl phenol, 3,5-dibutyl phenol, p-amyl phenol, pcyclohexyl phenol, p-octyl phenol, 3,5-dicyclohexyl phenol, p-phenyl phenol, p-crotyl phenol, 3,5-dimethoxy phenol, 3,4,5-trimethoxy phenol, p-ethoxy p-phenol, p-butoxy phenol, 3-methyl-4-methoxy phenol, and p-phenoxy phenol. Such phenols can be described by the general formula:
wherein A, B, and C are hydrogen, hydrocarbon radicals, oxyhydrocarbon radicals, or halogen. The preferred phenols are those which are unsubstituted in the para-position as well as in the ortho-positions. The most preferred phenol is the unsubstituted phenol, i.e., hydroxybenzene.
The aldehydes reacted with the phenol can include any of the aldehydes heretofore employed in the formation of phenolic resins such as formaldehyde, acetaldehyde, propionaldehyde, furfuraldehyde, and benzaldehyde. In general, the aldehydes employed have the formula RCHO wherein R is a hydrogen or a hydrocarbon radical of l to 8 carbon atoms. The most preferred aldehyde is formaldehyde.
The phenolic resins employed in the binder compositions can be either resole or A-stage resins or novolac resins. The resitole or B-stage resins, which are a more highly polymerized form of resole resins, are generally unsuitable. The phenolic resin employed must be liquid or organic solvent-soluble. Solubility in organic solvent is desirable to achieve uniform distribution of the binder on the aggregate. The substantial absence of water in the phenolic resin is desirable in view of the reactivity of the binder composition of the present invention with water. The term non-aqueous or substantially Water-free as employed herein is meant to define a phenolic resin which contains less than 5 percent of water and preferably less than 1 percent of water based on the weight of the resin.
Although both the resole resins and the novolac resins can be employed in the binder compositions of the present invention, and, when admixed with polyisocyanates and a foundry aggregate and cured by use of catalysts (e.g., tertiary amines) form cores of suflicient strength and other properties to be suitable in industrial applications, the novolac resins are preferred over the resole resins. Many resole resins, are difiiculty soluble in organic solvents and thus do not permit a uniform coating of the aggregate particles. Furthermore, resole resins are generally prepared in aqueous media and even on dehydration contain 10 or more percent of water. Novolac resins generally have a more linear structure and thus are more readily soluble in organic solvents. Because of their higher molecular weight and absence of methylol groups, novolac resins can, furthermore, be more completely dehydrated. The preferred novolac resins are those in which the phenol is prevailingly polymerized through the two ortho positions. The preparation of novolac resins is known in the art and for that reason not specifically referred to herein.
Particularly preferred phenolic resins are condensation products of a phenol having the general formula:
wherein A, B, and C are hydrogen, hydrocarbon radicals, oxyhydrocarbon radicals, or halogen, with an aldhehyde having the general formula R'CHO wherein R is a hydrogen or a hydrocarbon radicals of 1 to 8 carbon atoms, prepared in the liquid phase under substantially anhydrous conditions at temperatures below about C. in the R m R 1,
wherein R is a hydrogen or a phenolic substituent meta to the phenolic hydroxyl group, the sum of m and n is at least 2 and the ratio of m-to-n is at least 1, and X is an end-group from the group consisting of hydrogen and methylol, the molar ratio of said methylol-to-hydrogen end-groups being at least 1.
The phenolic resin component of the binder composition is, as indicated above, generally employed as a solution in an organic solvent. The nature and the effect of the solvent will be more specifically described below. The amount of solvent used should be sutficient to result in a binder composition permitting uniform coating thereof on the aggregate and uniform reaction of the mixture. The specific solvent concentrations for the phenolic resins will vary depending on the type of phenolic resins employed and its molecular weight. In general, the solvent concentration will be in the range of up to 80 percent by weight of the resin solution and preferably in the range of 20 to 80 percent. It is preferred to keep the viscosity of the first component at less than X-l on the Gardner- Holt Scale.
The second component or package of the binder composition comprises an aliphatic, cycloaliphatic, or aromatic polyisocyanate having preferably from 2 to 5 isocyanate groups. If desired, mixtures of organic polyisocyanates can be employed. Less preferably, isocyanate prepolymers formed by reacting excess polyisocyanate with a polyhydric alcohol, e.g., a prepolymer of toluene diisocyanate and ethylene glycol, can be employed. Suitable polyisocyanates include the aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as 4,4'-dicyclohexylmethane diisocyanate, and aromatic polyisocyanates such as 2,4- and 2,6-toluene diisocyanate, diphenylmethyl diisocyanate, and the dimethyl derivatives thereof. Further examples of suitable polyisocyanates are 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, xylylene diisocyanate, and the methyl derivatives thereof, polymethylenepolyphenol isocyanates, chlorophenylene-2,4-diisocyanate, and the like. Although all polyisocyanates react with the phenolic resin to form a cross-linked polymer structure, the preferred polyisocyanates are aromatic polyisocyanates and particularly diphenylmethane diisocyanate, triphenylmethane triisocyanate, and mixtures thereof.
The polyisocyanate is employed in sufficient concentrations to cause the curing of the phenolic resin. In general, the polyisocyanate will be employed in a range of to 500 Weight percent of polyisocyanate based on the weight of the phenolic resin. Preferably, from to 300* weight percent of polyisocyanate on the same basis is employed. The polyisocyanate is employed in liquid form. Liquid polyisocyanates can be employed in undiluted form. Solid or viscous polyisocyanates are employed in the form of organic solvent solutions, the solvent being present in a range of up to 80 percent by weight of the solution.
Although the solvent employed in combination with either the phenolic resin or the polyisocyanate or for both components does not enter to any significant degree into the reaction between the isocyanate and the phenolic resin in the presence of the curing agent, it can affect the reaction. Thus the ditference in the polarity between the polyisocyanate and the phenolic resins restricts the choice of solvents in which both components are compatible. Such compatibility is necessary to achieve complete reaction and curing of the binder compositions of the present invention. Polar solvents of either the protic or aprotic type are good solvents for the phenolic resin, but have limited compatibility with the polyisocyanates. Aromatic solvents, although compatible with the polyisocyanates, are less compatible with the phenolic resins. It is therefore preferred to employ combinations of solvents and particularly combination of aromatic and polar solvents. Suitable aromatic solvents are benzene, toluene, xylene, ethylbenzene, and mixtures thereof. Preferred aromatic solvents are mixed solvents that have an aromatic content of at least percent and a boiling point range within a range within a range of 280 to 450 F. The polar solvents should not be extremely polar such as to become incompatible with the aromatic solvent. Suitable polar solvents are generally those which have been classified in the art as coupling solvents and include furfural, furfuryl alcohol. Cellosolve acetate, butyl Cellosolve, butyl Carbitol, diacetone alcohol, and Texanol. Furfuryl alcohol is particularly preferred.
The binder components are combined and then admixed with sand or a similar foundry aggregate to form the foundry mix or the foundry mix can also be formed by sequentially admixing the components with the aggregate. Methods of distributing the binder on the aggregate particles are well-known to those skilled in the art. The foundry mix can, optionally, contain other ingredients such as iron oxide, ground flax fibers, wood cereals, pitch, refractory flours, and the like.
The aggregate, e.g. sand, is usually the major constituent and the binder portion constitutes a relatively minor amount, generally less than percent, frequently within the range of 0.25 to about 5 percent, these figures being based on the Weight of the aggregate. Although the sand employed is preferably dry sand, moisture of up to about 1 weight percent based on the weight of the sand can be tolerated. This is particularly true if the solvent employed is non-water-miscible or if an excess of the polyisocyanate necessary for curing is employed, since such excess polyisocyanate will react with the water.
In an especially preferred aspect of this invention, i.e., its use in the cold-box process, the resulting foundry mix is then molded into the desired core or shape, whereupon it can be cured rapidly by contacting with the tertiary amine. The actual curing step can be accomplished by suspending a tertiary amine, in an inert gas stream and passing the gas stream containing the tertiary amine under suflicient pressure to penetrate the molded shape, through the mold until the resin has been cured. The binder compositions of the present invention require exceedingly short curing times to achieve acceptable tensile strengths, an attribute of extreme commercial importance. Optimum curing times are readily established experimentally. Since only catalytic concentrations of the tertiary amine are necessary to cause curing, a very dilute stream is generally sufficient to accomplish the curing. However excess concentrations of the tertiary amine beyond that necessary to cause curing are not deleterious to the resulting cured product. Inert gas streams, e.g., air or nitrogen, containing from 0.01 to 5 percent by volume of tertiary amine can be employed. Normally gaseous tertiary amines can be passed through the mold as such or in dilute form. Suitable tertiary amines are gaseous tertiary amines such as trimethyl amine. However, normally liquid tertiary amines such as triethyl amine are equally suitable in volatile form or if suspended in a gaseous medium and then passed through the mold. Although ammonia, primary amines and secondary amines exhibit some activity in causing a room temperature reaction, they are considerably inferior to the tertiary amines. Functionally, substituted amines such as dimethyl ethanol amine are included within the scope of tertiary amines and can be employed as curing agents. Functional groups which do not interfere in the action of the tertiary amine are hydroxyl groups, alkoxy groups, amino and alkyl amino groups, ketoxy groups, thio groups, and the like.
In mixing the fatty acid, phenolic resin and isocyanate with sand, it is advantageous to first mix the fatty acid with the phenolic resin. Then, the fatty acid-phenolic resin mixture is mixed with the sand (and other optional ingredients such as catalyst when incorporated in the mix) and, finally, the polyisocyanate is added and mixed with the other ingredients. The fatty acid can, however, be premixed with any of the ingredients, or it can be mixed with the sand initially. Because some reaction occurs when the fatty acid is mixed with the polyisocyanate and because pre-coating the sand with fatty is ineflicient, the fatty acid is usually incorporated in the phenolic resin package. In this package, the fatty acid-phenolic resin mixture is stable and can be shipped and stored. Further, and quite surprisingly, the cloud point of the resulting phenolic resin solution is lowered by the addition of fatty acid. This makes the resin more stable from a visual standpoint. The resulting foundry mix will typically remain workable or plastic at room temperature for from 20 to 100 minutes.
The foundry mix is then molded or shaped into the desired form in a metallic pattern box or mold, and thereafter cured to form a sand core. Depending upon the type of results desired and equipment available, the curing will be accomplished by simply allowing the binder to react at room temperature or by contacting the shaped mix with a gaseous tertiary amine to cure the core or mold instantaneously.
The present invention will be further understood by reference to the following specific examples which include the best mode known to the inventor for practicing the invention. Unless otherwise indicated, all parts and percentages are by weight.
EXAMPLES I-XIII These examples illustrate the marked decrease in sticking when various fatty acids are added to a conventional cold-box binder and the resulting binder is used to make cores by the method of US. Pat No. 3,409,579.
A foundry mix was prepared containing (1) 100 parts Port Crescent lake sand; (2) 1 part of a mixture containing 47% phenolic resin, 20% furfuryl alcohol and 33% aromatic hydrocarbon solvent (HiSol lB.P. 320 to 350 F.); and (3) 1 part of a mixture containing 65% diphenyl methane diisocyanate (Mondur MR) and 35% aromatic hydrocarbon solvent (same as in (2)). The phenolic resin is a benzylic ether type phenol-form aldehyde resin prepared from phenol and paraformaldehyde by the method of copending application Ser. No. 536,180 filed Mar. 14, 1966 now US. Pat. No. 3,485,797 issued to Robins on Dec. 23, 1969. This multiple-package core binder was a commercially available binder (Isocure, a product of the Ashland Chemical Company). Twelve additional mixes were prepared using the same ingredients and amounts except that 0.5 percent of an acid was added to the phenolic resin portion. The mixes were then used to make cores by the method of US. Pat. No. 3,409,579.
Each mix was introduced into a Redford core blower from which the mix was blown into a grey iron pattern at a pressure of 100 p.s.i. to form core test samples. As soon as the samples were formed, they were gassed by passing nitrogen at a pressure of about 81 psi. through liquid triethyl amine and thereafter charging it to the core samples in the iron pattern at a pressure of about 20 to 40 p.s.i. through the blow holes (through which the mix entered). The samples were gassed for seconds and permitted to remain in the machine for an additional one minute before removal.
The adhesive strength of the cured core to the iron pattern was measured by determining the force required to pull the core away from the pattern. The area of the pattern covered with sand after removal of the core was also measured. The latter measurement is indeed important since it is desirable to keep the pattern clean and any sand deposited on the pattern represents an imperfection in the core surface.
The acids which were added and the results are shown below in Table I.
TABLE I Adhesive Percent Amount strength area Example Additive (percent) (p.s.i.) covered I None 240 50 II... CF3COOI-I. 0.5 260 60 III Iso-nonioc acid 0.5 210 40 IV Iso-octoic acid. 0. 5 175 40 V Iso-decanoic acid 0. 5 130 20 VI Pelargonic acid 0. 5 125 20 Capric acid 0.5 120 10 Caprylic acid 0. 5 5 Iso-stearic acid 0.5 60 2 Laurie acid. 0.5 40 1 Stearic acid 0.5 40 1 Oleic acid 0.5 20 1 Sylfat 96 0. 5 20 0 1 A commercial blend of unsaturated fatty acids (e.g., oleic and linoleie) gaving an average chain length of C and available from the Glidden EXAMPLES XIV TO XX These examples illustrate the effect of this invention on non-metal patterns i.e., epoxy.
The foundry mixes of Examples I. IV, VIII, X, XI, XII and XIII were used to make cores in the manner disclosed above except that the iron pattern was replaced with an epoxy-lined pattern. The tendency of the resulting cores to stick to the pattern is illustrated in Table II.
TABLE II Adhesive Percent Amount strength area Example Additive (percent) (p.s.i.) covered XIV None 280 60 Iso-oetoic acid... 0. 5 270 50 Caprylie aeid.. 0.5 280 60 VII Laurie acid 0. 5 250 45 XVIII Stearlc acid... 0.5 230 50 XIX Oleic acid 0.5 260 40 XX Syliat 96 1 O. 5 260 40 1 See Footnote to Table I.
EXAMPLES XXI TO XXV These examples illustrate the slight reduction in tensile strength due to the addition of a fatty acid (in this case Sylfat 96) to the phenolic resin portion of the binder. The addition is also noted to lower the cloud point of the phenolic resin solution.
Five sand mixes were prepared. The first mix was identical to the mix of Example I. The other mixes contained 0.25, 0.5, 1.0 and 1.5 percent Sylfat 96, respectively in the phenolic resin package. The cloud point of the resulting phenolic resin packages were measured and are recorded in Table III.
The resulting mixes were then formed into standard AFS tensile test samples using the standard procedure. The resulting samples were then cured by contact with triethyl amine (TEA). In contacting the samples with TEA, an air stream was bubbled through liquid TEA and then passed through the test samples for a period of 60 seconds.
The results are shown in Table III.
XXII Sy1tat96. XXIII do- XXIV... do.-- XXV ..do
1 Average of 12-25 specimens.
9 EXAMPLES XXVI AND XXVII This example illustrates the improved release properties of the present invention in aluminum patterns as compared to iron patterns.
The foundry mix of Example XII is again tested, once in an iron pattern and once in an aluminum pattern. With the iron pattern, the adhesive strength was p.s.i. and the area of the pattern covered by sand after the core was removed was 1 percent. With the aluminum pattern, the adhesive strength was 90 p.s.i. and the area covered with sand after removal was 1 percent. Since the adhesive strength is not too important if sand does not remain in the pattern after removal, the results in aluminum patterns are seen to be comparable to those in iron.
EXAMPLES XXVIII AND XXIX These examples illustrate that fatty derivatives, i.e., fatty amines and fatty alcohols, do not work in this invention.
Two foundry mixes identical to that in Example I were prepared. To the first mix was added 1 percent oleyl amine in the phenolic resin component. To the second was added 1 percent tridecyl alcohol in the phenolic resin component.
Cores were made as in Examples I to XIII in iron patterns and the cores were tested for release properties. The first mix (Example XXVIII) yielded an adhesive strength of 230 p.s.i. and left 80 percent of the pattern covered with sand after the core was removed. The second mix (Example XXIX) yielded an adhesive strength of 260 p.s.i. and left 50 percent of the pattern covered with sand.
EXAMPLES XXX TO XXXVI These examples illustrate the eifectiveness of various fatty acids, both monomeric and polymeric, in reducing the stickiness of the foundry mix of Example I to grey iron and aluminum.
Seven foundry mixes were prepared as in Example I. To six of the mixes were added 0.5% fatty acid. The mixes were then used to make cores according to the method of US. Pat. No. 3,409,579. For an explanation of the method, see Example I.
Cores were made from each of the mixes by using a grey iron pattern and an aluminum pattern. The adhesive strength and the area covered with sand after removal of the core were measured.
The acids which were added and the results are shown below in Table IV.
TABLE IV the foundry mix to reduce the tendency of the cured, shaped mix to stick to the mold.
2. The process of claim 1 wherein the fatty acid is added to the phenolic resin package of the binder.
3. The process of claim 1 wherein the shaped foundry mix is cured by contact with a gaseous tertiary amine.
4. The process of claim 1 wherein a metal ion catalyst is added to the foundry and causes the shaped foundry mix to cure while in the mold.
5. The process of claim 1 wherein the fatty acid is a saturated or unsaturated monocarboxylic acid having from 4 to 26 carbon atoms.
6. The process of claim 3 wherein the fatty acid is a saturated or unsaturated monocarboxylic acid having from 12 to 20 carbon atoms.
7. The process of claim 1 wherein the fatty acid is a polymerized unsaturated monocarboxylic acid having from 4 to '26 carbon atoms in each fatty chain.
8. The process of claim 3 wherein the fatty acid is a polymerized unsaturated monocarboxylic acid having from 12 to 20 carbon atoms in each fatty chain.
9. The process of claim 6 wherein the binder comprises a benzylic ether resin and an aromatic polyisocyanate, and the fatty acid is a monocarboxylic acid having the formula:
RCOOH wherein R is hydrogen or a phenolic substituent meta to the hydroxyl group of the phenol, m and n are numbers the sum of which is at least 2, and the ratio of m-to-n is at least 1, and X is a hydrogen or a methylol group, the
Grey iron pattern Aluminum pattern Tensile Adhesive Percent Adhesive Percent Amount strength strength area strength area Example Addltive (percent) (p.s.i.) (p.s.i.) covered (p.s.i.) covered XXVI Azelic Acid 0. 5 250 260 70 260 70 1 Blend of acids having average chain length of C available from the Glidden Company.
6 Mixture of 25% dimer, 25% monomer fatty acids having C13 chain length and 50% polymerized rosin available from Emery Industries.
5 Fatty acid having chain length of Cr.
What is claimed is:
molar ratio of said methylol group-to-hydrogen being at 1. In a process for preparing shaped foundry products 70 least 1; said hardener component comprising liquid orwherein a foundry aggregate is mixed with a binder comprising a phenolic resin package and an organic polyisocyanate package, the resulting foundry mix is shaped in a mold and the shaped mix is cured while in the mold;
ganic polyisocyanate containing at least two isocyanate groups; and said curing agent comprising a tertiary amine.
12. The composition of claim 11 wherein the fatty acid is saturated or unsaturated monocarboxylic acid havthe improvement which comprises adding a fatty acid to 75 ing from 12 to 20 carbon atoms.
1 1 1 2 13. The composition of claim 11 wherein the fatty acid 2,735,814 2/ 1956 Hodson 10638.24 is a polymerized unsaturated monocarboxylic acid 11av- 2,683,296 7/1954 Drumm 1 64-43 ing from 12 to 20 carbon atoms in each fatty chain. 2,358,002 9/1944 Dearing 106--38.24
References Cited 5 UNITED STATES PATENTS DONALD E. CZAJA, Primary Examiner E. C. RZUCIDLO, Assistant Examiner Robins 26052 Robins 260-304 U S CL X R Yost 260-18 Tobler 106-3824 10 10638.24; 16443; 26019 A, 30.4 N, Digest 40