Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G16/00—Condensation polymers of aldehydes or ketones with monomers not provided for in the groups C08G4/00 - C08G14/00
  • C08G16/02—Condensation polymers of aldehydes or ketones with monomers not provided for in the groups C08G4/00 - C08G14/00 of aldehydes
  • C08G16/025—Condensation polymers of aldehydes or ketones with monomers not provided for in the groups C08G4/00 - C08G14/00 of aldehydes with heterocyclic organic compounds
  • C08G16/0256—Condensation polymers of aldehydes or ketones with monomers not provided for in the groups C08G4/00 - C08G14/00 of aldehydes with heterocyclic organic compounds containing oxygen in the ring
  • C08G16/0262—Furfuryl alcohol
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
  • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
  • B22C1/20—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents
  • B22C1/22—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins
  • B22C1/2233—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • B22C1/224—Furan polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G12/00—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
  • C08G12/02—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes
  • C08G12/04—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds
  • C08G12/10—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds with acyclic compounds having the moiety X=C(—N<)2 in which X is O, S or —N
  • C08G12/12—Ureas; Thioureas
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/0005—Separation of the coating from the substrate

Definitions

• a foundry core binder may be defined as that part of the foundry core which causes adhesion among the sand particles. To a large extent the properties of a foundry core are determined by the properties imparted to it by the particular binder employed. There are certain required properties for a foundry core.
• binders have been used in the foundries with varying degrees of success.
• One of the oldest known binders is the cereal-core oil binder.
• the main disadvantage of this system is the long curing time required. With the use of high speed automatic equipment a rapid curing binder is very desirable.
• Another type of core binder is made from phenolic resins. Because of the high cost of such resins, the binder is used to merely bond a shell instead of acting as a binder throughout the core.
• the use of phenolic resin type binders results in cores that have a tendency to resist shakeout after the metal casting has hardened, especially with the casting of low melting point non-ferrous alloys.
• Other disadvantages of the phenolic resin binders are extended curing times for the cores and less than satisfactory tensile strengths.
• a third type of core binder is the urea-formaldehyde cereal binder.
• the core made from this binder collapses too readily on contact with high temperature melting metals and loses strength in a high humidity atmosphere.
• a solvent is required in order to prevent crystallization or gelling. Water has been employed as this solvent, but its use incurs certain undesirable elfects, such as an extended curing time and excessive shrinkage of the foundry core upon curing.
• the water is not a reactive solvent, it does not in any way improve any of the inherent weaknesses of the urea-formaldehyde resin.
• Another object of this invention is to produce a foundry sand binder that imparts to the foundry core an improved tensile strength.
• Still another object of this invention is to produce a binder that when mixed with foundry sand cures rapidly so that the sand-binder mixture may be used with highspeed automatic machinery.
• a further object of this invention is to produce a liquid foundry core binder that when mixed with sand, cures at room temperature to form a foundry core which will produce a metal casting free from blowholes produced by the gas evolution from the core.
• a still further object of this invention is to produce a liquid binder that gives a foundry core that can withstand the heat from a high melting point metal and yet can be readily shaken out after the metal casting has hardened.
• Still another object of this invention is to produce a stable, liquid foundry binder from materials that are relatively inexpensive as compared to many presently used materials.
• a further object of this invention is to produce a foundry core binder which gives foundry cores that do not lose strength in a high humidity atmosphere.
• a still further object of this invention is to provide a liquid, resinous, foundry core binder that has sufficient stability for storage and shipment in commerce.
• the above objects are accomplished by a process in which urea, furfuryl alcohol, and a non-polymerized aqueous mixture of formaldehyde, urea, and equilibrium reaction products thereof about 15% by weight water.
• the resulting solution from the above components is adjusted to a pH in the range of 5.0 to 6.5; however, the preferred range is a pH of 5.5 to 6.0.
• the said solution is then refluxed at to C. until the solution has a viscosity in the range of 350 to 3000 centipoises if measured at 25 C.
• a preferred viscosity range for this end point is 400 to 1500 centipoises.
• the pH of the solution is adjusted to a range 6.5 to 8.5.
• Aqueous UP. mixtures (non-polymerized) are sold in commerce.
• One example is UP. Concentrate85.
• Another aqueous U.F. mixture is marketed as Urea-Formaldehyde 25-60.
• the formaldehyde, urea and equilibrium reaction products thereof, present in aqueous U.F. mixtures are believed to exist in equilibria. as follows:
• the total amount of urea and formaldehyde present in the aforementioned solution of this invention is stated in terms of a molar ratio.
• the amount of urea added separately (as opposed to that urea included in the aqueous UJF. mixture) will vary with the analysis of the particular aqueous U.F. mixture that is employed.
• the amount of urea to be added separately can be determined from the aforementioned molar ratio and the analysis of the particular aqueous U15. mixture that is employed.
• available urea refers to free urea as well as urea combined with the methylol group in the equilibria shown above.
• available formaldehyde refers to free formaldehyde as well as formaldehyde combined with urea in the equilibria shown above.
• the refluxing end point may be determined by either measuring the refractive index or by measuring the viscosity of the solution. However, measuring the viscosity is the preferred method to determine the refluxing end point. Both the refractive index and viscosity are indicators of the solutions stage of resinification. The stage of resinification is critical because if there is not sufficient resinification the binder solution will be unstable. If the stage of resinification becomes too advanced then the binder solutions high viscosity will prevent proper mixing of the binder with the sand at the foundry.
• the invention will be further illustrated but is not limited by the following examples in which the quantities stated in parts are parts by weight unless otherwise indicated.
• percent of binder is stated, it is percent by weight based on the weight of the foundry sand.
• percent of any of the components of the binder e.g., furfuryl alcohol, catalyst, water
• All tensile strengths are stated in pounds per square inch (p.s.i.).
• Example 1 Into 2710 parts of UP. Concentrate-85 were admixed 2025 parts of furfuryl alcohol and 654 parts of urea. The pH of the resulting solution was adjusted to 5.7 by the addition of 58% aqueous phosphoric acid. This solution was then charged into a 3-necked vessel equipped with a stirrer, thermometer and reflux condenser. The solution was heated to 100 C. over a period of one hour, and then refluxed at about that temperature for an additional two hours. The degree of rcsinification was observed by checking the viscosity at regular time intervals. When a withdrawn sample of the solution had a viscosity of 380 centipoises at 25 C.
• Example 2 The procedure of Example 1 was repeated except that only 983 parts furfuryl alcohol were admixed with the U.F. Concentrate-85, and the pH of the solution was adjusted to 5.9 by the addition of 50% aqueous phosphoric acid. The progress of the resiniiication during the refluxing was observed by determining the time required for a sample of the hot solution to drain from a standard consistency cup with a orifice. When there was sixty second draining time, the refluxing Was discontinned andthe solution was neutralized to a pH of 8 with 13 parts of NaOH in parts of water. Upon cooling the resulting binder composition was a slightly cloudy, light-amber liquid.
• Example 3 To show the importance of the addition of furfuryl alcohol to the aqueous UP. mixture, binders were prepared essentially as described in Example 1 but with varying amounts of furfuryl alcohol. Foundry cores were then produced employing these binders. To produce the foundry cores, the binders were mixed with sand and catalyst in the proportions shown below and the resulting mixtures rammed into 1% x 2" core boxes. The resulting cores were removed from the core boxes and cured in an oven at 425 F. for 5 minutes. The cured cores were then placed in a Dietert Thermolab Dilatometer at 1590 F. and 2500" F. for 5 minutes. A compressive load was applied. I-lot strength at failure in pounds per square inch was determined. The following results were obtained for three cores employing 1.5% binder:
• Example 4 The procedure of Example 3 was repeated except that the cores were A" x 2 and were cured on a hot plate at 237 C. At specified intervals while on the hot plate the foundry cores were tapped lightly with a spatula. The curing time was determined from the beginning of the baking period to that time when an indentation was no longer made by the spatula. The following results were obtained.
• the term solids refers to all ingredients other than water in the binder before resinification. All percentages given are by weight and based on the binder.
• Example 6 If there is excessive gas evolution from a foundry core While hot metal is being poured around the core, blow holes may result in the metal casting.
• the procedure of Example 3 was essentially repeated except that the cores were cured at room temperature. The cores were crushed and ten gram samples of the crushed material were placed in porcelain boats which were inserted in a combustion tube maintained at 1800 F. This test simulated the conditions obtained when hot molten metal is poured around a foundry core. The gas evolved was collected in a burette at 120 C. over silicone oil. The total volume of gas collected at 125 C. was measured in milliliters. The pressure was equalized to atmospheric pressure. From cores made with binders having 1.8% by weight solids (based on sand), 25% furfuryl alcohol, and with varying percentages of water (percent by weight of binder) the following results were obtained:
• Example 7 Room temperature curing and oven curing are two separate methods of curing foundry cores. Oven curing is desirable for some uses because the foundry cores moisture content is lowered during the heating. Foundry 0 fromthis invention. The procedure for determining gas evolution from the foundry cores was repeated as in Example 6. The total volume of gas (in milliliters and percent collected at 120 C.) evolved was measured at successive- Core mx Tensile sive time intervals from the time the core was initially Alcohol in Strength a Bi exposed to the 1800 F. temperature. The results were as follows:
• resinous, foundry core binder comprising the steps of,

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Metallurgy (AREA)
• Mold Materials And Core Materials (AREA)

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Cited By (6)

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  • NL NL265641D patent/NL265641A/xx unknown
  • IT IT649598D patent/IT649598A/it unknown
  • NL NL120181D patent/NL120181C/xx active
• 1960
  • 1960-07-11 US US41728A patent/US3168490A/en not_active Expired - Lifetime
• 1961
  • 1961-04-05 GB GB12113/61A patent/GB920236A/en not_active Expired
  • 1961-04-05 FR FR857802A patent/FR1285719A/fr not_active Expired
  • 1961-04-11 DE DEQ00651A patent/DE1215872B/de active Pending

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