US20080125517A1 - Accelerated furanic aggregate binders from bio-derived components

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Abstract

Description

Claims

US20080125517A1

Publication number: US20080125517A1
Application number: US11/904,723
Authority: US
Inventors: Michael C. Clingerman; Alex W. Kawczak; James T. Schneider
Original assignee: Individual
Current assignee: Battelle Memorial Institute Inc
Priority date: 2006-09-29
Filing date: 2007-09-28
Publication date: 2008-05-29

Broadly, the invention provides for newly available bio-derived formaldehyde-free furanic materials for aggregate binding. A specific example is aggregate binding for forms used in the metal casting process. The inventive binder formulations involve the use of 2,5-furan dimethanol and other “filler” components for high productivity and fast tensile development without formaldehyde, urea, urea-formaldehyde or formaldehyde containing compositions.

This application claims the benefits of U.S. Provisional Application 60/848,329, filed Sep. 29, 2006. The entire disclosure of the provisional application is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention provides bio-derived binder materials as a partial replacement or addition to furfuryl alcohol along with a synergistic “filler” material for use in applications such as acid-cured aggregate binders like those used in the metal casting industry for making self-hardenable forms for shaping cast metal parts. These forms are made by coating an aggregate (for example, sand) with a binder comprising an add-curable resin and an add-based curing agent, charging the mixture into a pattern, and allowing the binder to cure. This invention includes components and formulation compositions typically based on plant-derived materials as binder components. In the Furan No-Bake process, the aggregate is coated sequentially by the acid catalyst, then the acid hardenable binder, and the mixture is then charged into a pattern. The binder cures over a period of time at ambient conditions and the hardened forms are removed from the pattern.
Furanic acid-cured binders can also cure in the presence of heat in which case the process is referred to as a Furan Hot Box or Furan Warm Box process depending on the amount of heat and the type of catalyst. Furanic acid-cured binders can also be cured by means of an acidic gas or vapor, such as SO₂(sulfur dioxide) instead of a liquid acid catalyst, in which case the process is referred to as a Furan Cold-Box process.
Furanic acid-cured binders can furthermore be used as “blown” sand/binder mixture that is rapidly cured by composite acid catalysts (i.e.; ABC Process), a hybrid core making process. The invention includes components and formulations for use in aggregate binding that are based on plant-derived materials and a synergistic “filler” material.
Alternative energy sources for binder cure can include microwave, warm air, electromagnetic radiation, ultrasound, ultraviolet radiation, electron beam, and others can be used for curing formulations containing the newly available bio-derived materials and chosen “filler” materials.

BACKGROUND OF THE INVENTION

Briefly, there is an increasing need for greater productivity in metal-casting operations, wherein aggregates are bonded into solidified forms that can serve various functions. One example of such a function is the use of binders in metal-casting form manufacture known as sand cores and sand molds. One of the processes used for making metal parts in the metal casting industry is aggregate casting, in which single-use metal casting forms are made by shaping and curing a resin-coated (resinous) aggregate mix. This mix includes aggregate (typically sand), an organic or inorganic binder and a particular acidic catalyst chosen depending on the process. The binder is used to strengthen the forms and can be heat cured (Hot-Box or Warm-Box process), catalytically cured at ambient temperatures (No-Bake process), acid-cured my means of an acidic gas or vapor (Cold-Box process), Catalytically cured at ambient temperatures, then “blow” or “shot” into a core shape (ABC process) or cured with a combination of heat and a catalyst.
Furanic acid-cured binders for metal casting applications are comprised primarily of furfuryl alcohol, a bio-derived material. However, furfuryl alcohol is mostly an imported raw material in North America and therefore subject to trade and economic issues. Fillers, both organic and inorganic, are commonly used in furan binder formulations to decrease the use of furfuryl alcohol (see, for example, U.S. Pat. No. 5,856,375) and to impart additional properties (see, for example, U.S. Pat. No. 5,856,375). A recent patent application discusses the use of alternate bio-derived furanic materials to displace furfuryl alcohol in whole or in part from these formulations.
It was believed that certain combinations of furanic materials and other formulation elements would demonstrate unusually fast cure times either by itself, or synergistically with a known “filler” material. The present invention addresses specific formulation combinations that are unusually reactive and therefore has additional value in creating unique faster-reacting binder systems leading to improved productivity while maintaining or creating a more environmentally-friendly binder process.
The examples in this invention focus upon the use of newly available materials in furan acid-cured binder systems, but the potential applicability of the examples as a replacement for a portion in phenolic acid-cured, phenolic and furanic thermally cured processes, gas-cured furanic formulations, unique high-production “blown” No-Bake cores, or alternate energy source is obvious to one practiced in the art.
The invention also lends itself well to processes other than those foundry related. Examples may include but are not limited to, resin/binder applications for reinforcing materials, such as impregnates (fibers, alternative aggregates, mats, woven mesh), coatings, adhesives, sealants, electronics and for use in polymer concretes and mortars.
The perception among those practiced in the art is that formaldehyde, urea and/or phenol is essential to the development of strength in metal casting forms, particularly the overall speed of cure and the through-cure (cure in the interior of the metal casting form) and the bonding strength. Efforts have been made to reduce the formaldehyde, urea and phenol used in the formulation of these binders, such as the effort described in EP 0698432. The present inventive approach to these formulations is to eliminate the formaldehyde, urea and the phenols from the formulations while maintaining acceptable strength development and cure speed in a surprisingly short time.
The present inventive approach to these formulations can also be used with existing formaldehyde, urea and/or phenolic modified phenolic or furan resins to reduce the amounts of those ingredients, therefore reducing any environmental impact without greatly affecting, and in some cases, improving their overall performance.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates specifically to the use of a combination of materials as components of ambient fast-curing binders for aggregates. In particular, the invention relates to the use of formaldehyde-free, urea-free and phenol-free materials in a fast ambient-curing organic binder process.
The application in whole or in part relates to the inventive formulations of other binders; such as furanic and phenolic acid-cured, acidic gas or vapor-cured, thermally cured, composite hybrids or “blown” binder processes.
The present invention provides for the acceleration of aggregate binder cure by the use of materials capable of formulating synergistic reactivity, leading to very fast setting aggregate binders. A “furanic acid-cured binder” as used herein is meant in the sense of an organic chemical solution, comprised in part of furfuryl alcohol, that is mixed onto aggregates, such as metal casting aggregate (sand), which has already been treated with an acid catalyst solution. Typically, acid-cured furan or phenolic binders may incorporate formaldehyde, phenol, alternate “fillers” and amine-containing ingredients such as ureas. Each of these components can have negative effects in terms of environment, health, waste removal (spent sand disposal), core/mold-making or casting performance. The materials of this invention can produce effective formulations without these materials. Optionally, for no-bake applications, the binder components and the catalyst components should be mixed onto the sand separately, typically the catalyst first, followed by the binder, and then mixed together. The mixed resinous aggregates then cure at ambient conditions to harden the metal-casting form (cores and molds). The advantage of the catalyst chosen is that the resins of the various embodiments cure faster. This is important in making production more efficient in consideration of the ambient conditions at the time of core/mold production.
The typical acid catalysts used for no-bake processes are sulfonic acids such as toluene sulfonic acid, benzene sulfonic acid, xylene sulfonic acid and others. The problems with sulfur containing catalysts are the release of potentially harmful aromatic species into the work environment (EP 1531018), corrosive action on the pattern and related tooling, corrosion of catalyst storage tanks or transfer pipes and valves, handling safety, and sulfur contamination of sensitive metal alloys (Gieniec). In some instances phosphoric acid and other weaker acids can also be utilized either separately, or in combination with the stronger sulfonic acids (JP 19970478840). Lewis acids, such as zinc chloride, are also reported to be useful as third part cure boosters (U.S. Pat. No. 4,543,374; U.S. Pat. No. 4,543,373; WO 0181024). Furanic formulations can also be cured with gaseous Lewis acids, such as sulfur dioxide in processes termed “cold-box”. Cold-box processes are highly productive, but require the use of highly specialized equipment, and in the case of furanic cold-box processes, can be highly corrosive to foundry equipment. In the acid-cured process, the acid catalyst triggers the cure of the furanic acid-cured binders at ambient mixture temperatures. The aggregate forms (cores and molds) are then utilized in the metal casting process.
Furanic materials can also be used in hot box processes, where the binder is cured with a heat-activated catalyst at 200-250° C., and warm box processes, where the binder is cured with heat-activated latent catalysts that are triggered at 130-225° C.
A broad embodiment of the invention includes a furanic binder composition made up of a a mixture of
a. a furfuryl alcohol;
b. about 1 to about 90 wt % 2,5-furan dimethanol, wherein the 2,5-furan dimethanol is derived from the reduction of 5-hydroxymethyl furfural;
c. about 0 to about 15 wt % resorcinol;
wherein the total of mixture a, b, and c comprises 100 wt %.
Another broad embodiment includes a furanic binder composition made up of a mixture of

- a. a furfuryl alcohol;
- b. about 1 to about 90 wt % 2,5-furan dimethanol,
- c. about 1 to about 30 wt % aromatic polyester polyol; and
- d. about 0 to about 15 wt % resorcinol;
- wherein the total of mixture a, b, c, and d comprises 100 wt %; and wherein the substantially no formaldehyde is present. Typically the 2,5-furan dimethanol is derived from the reduction of 5-hydroxymethyl furfural.

In some embodiments the materials, in addition to being substantially free of formaldehyde, may also be substantially free of nitrogen atoms.
Typically the amount of 2,5-furan dimethanol comprises about 5 to about 60 wt %. In some embodiments a catalyst is used. The catalyst in some embodiments is a weak acid having a pk_abetween about 2 and about 4. One typical acid is phosphoric acid.
Another embodiment of the invention includes a method for making an aggregate casting by using a composition according to the invention to coat one aggregate material; using a weak acid to coat another aggregate material; and mixing the coated aggregates and blowing the mix together in a mold.
Another embodiment of the invention provides for compositions without formaldehyde, urea, urea-formaldehyde or formaldehyde.

DETAILED DESCRIPTION OF THE INVENTION AND BEST MODE

The present invention provides for formulations which function as acid-cured binders for sand-based cores and molds used within the metal casting industry and are partly comprised of components derived from agricultural waste streams. These materials are the result of acid catalyzed digestion of hexoses, such as fructose, and include 2,5 furan dimethanol (FDM), (see the Formula below) as a major product (U.S. Pat. No. 4,740,605 and Lewkowski). A good general discussion of possible uses of furanic materials from cellulosic feedstocks is found in the Gandini reference.
2,5 furan dimethanol is known as an accelerator for furanic acid-cured binder processes (JP 2000246391; JP 2000225437; JP 09047840; WO 9605925) in the metal casting industry. 2,5 furan dimethanol in the published art, however, is typically obtained in an altogether different manner. FDM typically is synthesized by the treatment of furfuryl alcohol or furan with formaldehyde (See EP 1531018 and U.S. Pat. No. 6,479,567). FDM, oligomers of FDM, and varying amounts of free formaldehyde are present in a resin that is utilized as a furanic acid-cured binder formulation. Even in a case where FDM was used as a commercial product (EP 0698432), the formulation included both FDM and formaldehyde-containing resins. It is commonly believed among those practiced in the art that some formaldehyde is needed for rapid through-cure and deep-set properties. It is an intent of this invention to achieve acceptable foundry core/mold properties without the use of formaldehyde.
The FDM in this invention is derived from the reduction of 5-(hydroxymethyl)-2-furfuraldehyde (5-hydroxymethyl furfural or HMF) to FDM (Lewkowski). The elimination of formaldehyde from the production improves process safety of these formulations by decreasing potential worker exposure to formaldehyde. Surprisingly, the rate of cure with the FDM thus derived is apparently at least as fast as the “reactive resin” using co-polymers such as urea-formaldehyde. This enables either higher productivity using the typical sulfur-based strong acid catalysts or typical productivity using a weaker phosphorous-based catalysts when compared to currently known furan acid-cured formulations. In some specific operations the use of urea is known to cause nitrogen defects in the castings. Since the majority of furan no-bakes binders having a high rate of reactivity with the known acid catalysts contain a reacted “base resin”, the base resin usually contains formaldehyde with urea added to scavenge “free” formaldehyde. The presence of this urea adds nitrogen to the equation when molten metal is poured into the core/mold shapes made using these binders.
The use of the phosphorous catalyst is preferred for some alloys and when using warm sands. Some castings from certain alloys are negatively impacted by the incorporation of sulfur from the conventional sulfur based catalysts. Warm sands can cause early cure, leading to forms that are weak and/or resinous sand mixes that are un-useable.
Advantages of the present invention are the replacement of petrochemical-based materials in some metal casting applications, partial replacement of furfuryl alcohol in furanic acid-cured type binders, replacement of reacted base resins, very fast cure response, elimination of formaldehyde and urea from the process, reduced cost in binder manufacturing time, reduction or removal of formaldehyde or phenol, reduction in the amounts and/or type of acid catalyst used, and formulations of making metal casting binders that may include the exclusive use of a inorganic acid catalyst while utilizing a cold-blended resin composite.
On embodiment of the invention provides for a high-productivity acid-cured process using an inorganic acid catalyst such as phosphoric acid. Such a process may react so quickly that there will be essentially zero strip time—the catalyst and binder would need to be mixed separately on the aggregate using separate mixers or blenders, then the two pre-mixed composite aggregates mixed together using a common high-speed mixer and then this mixture “blown” together into a mold with a compressed gas, air, piston, ram or some other means of rapid integration or injection and mixing. Once the sands are mixed and compressed, the cure would proceed rapidly allowing for, in effect, a high-productivity no-bake core molding process.
The data shows that in many inventive formulations, the speed or rate of the reaction is increased by the use of the bio-derived materials. The speed of reaction increases in some cases to the point that weaker catalysts such as, for example, phosphoric acid can be utilized in place of the sulfonic acids while maintaining acceptable cure speeds. Some references (for example JP 09047840 and EP 0698432) teach the use of FDM being used with a blend of sulfonic and phosphoric acids. The inventive formulations have sufficient speed of cure that the added sulfonic acids are not required.
As used herein the term weak acid refers to an acid having a pK_abetween about 2 to about 6, and preferably between about 2 and about 4. Typical weak acids useful in the invention include weak organic acids such as phosphoric acid, hydrofluoric acid, nitrous acid, formic acid, and the like, alone or in combination.
The use of 100% phosphoric acid would be preferred in foundries that cannot tolerate sulfur pickup in the metal being cast through the mold/metal interface or cannot use a sulfonic acid due to environmental considerations. The use of the relatively inexpensive phosphoric acid use may also save cost of the mixed sand in the metal casting operation. The build-up of phosphorus materials in recycled sand would obviously have to be monitored, as is standard practice in shops utilizing a phosphoric acid catalyst. Typically, an increase in the amount of new, clean sand to the recycled (reclaimed) sand is used to reduce or dilute the effects of phosphorus buildup over time.
In addition to furanic materials, these formulations may include phenolic resins, phenolic resoles, urea resins, urea-formaldehyde resins, urea-formaldehyde/furfuryl alcohol resins as cure-enhancing ingredients. Incorporation of these materials is not necessarily preferred, however, especially in those cases that free formaldehyde and nitrogen (if urea is included) is added to the binder formulation due to their inclusion.
It is important to formulate a metal casting mix which will provide sufficient time to shape the metal casting mix in the pattern. “Work-time” is defined as the time interval after mixing the binder and acid catalyst components onto the sand and the sand mixture placed into a pattern, and the time when the metal casting form (core/mold) reaches a level of 60 on the “Green Hardness B-Scale Gauge” sold by Harry W. Dietert Co., Detroit, Mich. “Strip-time” is the time interval after mixing the binder and acid catalyst components onto the sand and the sand mixture placed into a pattern, and the time when the metal casting form reaches a level of 90 on the Green Hardness B-Scale Gauge (American Foundry Society (AFS) Method 3180-03-S). Depending on the size and configuration of the core/mold, the type of aggregate and the pattern used, the required work time/strip time may vary from those values.
The strip-time for removing the form from the pattern should be minimized for higher productivity aggregate forms. A typically desired work-time may range from 1 minute to 1.5 hours and typically desired strip-times range from 3 minutes to 8 hours. The forms produced must be strong enough so that the forms can be handled after the strip-time has elapsed. The forms should also be easily removable from the pattern. The forms must also produce useful castings, i.e., castings that do not have or have allowable levels of defects such as veining, porosity, lustrous carbon, penetration, and erosion defects and still maintain other desirable characteristics; such as, for example, shake-out or surface finish.
Acid-cured furan binders are attractive alternatives to phenolic-based acid-cured binders because the acid cured furan binders, preferably, do not contain free phenol, free formaldehyde, urea (therefore nitrogen) high levels of VOC emission, result in unpleasant odors, and generate lower smoke during the form-making and casting processes. It is also desirable to have no free formaldehyde in the process to make such binders an in the binders themselves. Typically, faster-reacting higher productivity furan acid-cured binders are comprised in part of “reactive furan resins” made from the reaction of furfuryl alcohol or furan with formaldehyde or urea-formaldehyde, thus introducing formaldehyde into the process and into the binder. Faster-reacting furan acid-cured binders may also typically contain higher levels of monomeric furfuryl alcohol, increasing their cost and lowering emissions, but requiring stronger sulfonic acids or higher amounts of those acids to cure the binders. Furan binders are also modified to increase their reactivity by incorporating other polymer or reactive monomers into the furan binder, e.g. urea formaldehyde resins, phenol formaldehyde resins, resole resins, resorcinol, bisphenol A tar, polyols, etc. Nevertheless, these modifications may or may not provide the cure speed and/or immediate tensile strengths that are needed for true high productivity. The inventive formulations can lead to formaldehyde free, VOC free, nitrogen free and phenol free formulations. Fillers are used in binder formulations to replace furfuryl alcohol and to enhance mechanical or physical properties and typically lower resin cost.
It has been discovered that the two components of this invention, the inventive reactive filler aromatic polyester polyol, exemplified by FDM and well known fillers such as, for example, Phenrez® 178 (from Invista, USA), can be used in combination with each other to allow for the reduction of furfuryl alcohol and other reactive ingredients while maintaining a highly-reactive furan no-bake binder system. In accordance with the invention, a first ingredient for replacement of furfuryl alcohol is FMD and a second ingredient is an aromatic polyester polyol that is not FMD.
In addition to increasing the cure rate of the binder, it is desirable to identify additives that impart improved mechanical or physical properties to the forms. These additives are also desirable for improved humidity and temperature resistance in the core and mold making process. Additionally, additives which lower free formaldehyde by reacting with it are desirable unless they increase unwanted properties.
Conventional furan acid-cured formulations rely on furfuryl alcohol and often on additional resinous materials to enhance certain properties. These resinous materials include phenolic polymers with formaldehyde and/or urea formaldehyde, such as resoles (see U.S. Pat. No. 3,676,392 for PEP, or polyether phenol, resole resins), used at 0-50 wt-% levels, and furfuryl alcohol polymers with formaldehyde and/or urea formaldehyde (for example Beetle® 65 resin from Cytec) copolymers at 0-95 wt-% levels. Other candidate constituents include resorcinol or bis-phenol A (between about 0 and 15 wt-%) which are used to increase the rate of cure, an alcohol such as methanol (between about 0 and 10 wt-%), silanes (between about 0 and 4 wt-%), and other fillers (between about 0 and 75 wt-%).
Fillers are used to replace furfuryl alcohol and to enhance mechanical and physical properties and typically lower resin cost. For example, some fillers are used to plasticize the binder improving the toughness, but retaining a slightly pliable nature as the cores or molds are released from the patterns when compared to the relatively brittle furanic binder. High furfuryl alcohol containing binders without plasticizers are well known to cause core/mold breakage when being released from certain patterns. If these cores/molds cannot be repaired by standard foundry practice (examples; bolting, core/mold adhesives, nails), the affected cores/molds must be remade resulting in excessive “down time”, lost production, increased man-hours and added cost.
Typical filler/plasticizers are resorcinol pitch and bis-phenol A tar (by-products from the manufacture of resorcinol and bis-phenol A; residues or bottoms from the production of azelaic acid by the ozone oxidation process (Henkel Corporation, Emery Group); by-products (mixed esters) from the production of terephthalic acid and its esters; lignins and lignosulfonates from the paper industry; various rosins from the forest industry, and the like. Purified commercial products may also be used as fillers, such as Terol® 250 and 256, Terate® 203 (Oxid), and Phenrez® 178 (Invista). These all may be utilized as fillers by themselves or even mixtures thereof. Such fillers need be compatible with the acid-cured furan formulations and are used to reduce the amount of furfuryl alcohol, adding plasticity to the formulation and reducing the formula cost.
Such conventional fillers and/or plasticizers are at least partially, if not fully, compatible and can be replaced by or blended with FDM in accordance with the present invention. Further, furfuryl alcohol can be replaced with these fillers in formulations with little loss in performance properties.
Silanes can be used with various embodiments of the invention for improved strength, adhesion, and humidity resistance. Examples of some commercially available silanes are γ-aminopropyl-methyldiethoxy silane (Dow Corning D1505®); 3-(diethoxymethylsilyl)propylamine (Aldrich); γ-glycidoxy propyltrimethoxy silane (Dow Corning Z6040® and Union Carbide A-1879); γ-aminopropyltriethoxy silane (Union Carbide A-1100); N-beta(aminoethyl)-γ-amino-propyltrimethoxy silane (Union Carbide A 1120®); γ-ureidopropyltriethoxy silane (Union Carbide A-1160®); and others.
Further information on these formulations can be found by reference to Langer, et al., “Foundry Resins”, Encyclopedia of Polymer Science and Engineering, Vol. 7, Second Edition, pages 290-298, John Wiley & Sons, Inc. (1987). See also Solomon, The Chemistry of Organic Film Formers, Second Edition, pages 253 et seq., Robert E. Krieger Publishing Company, Huntington, N.Y. (1977). The disclosures of these references are expressly incorporated herein by reference.
The FDM can be utilized as a partial replacement for furfuryl alcohol or for fillers and plasticizers in accordance with the teachings of the present invention. The FDM can also enhance the reactivity of formulations in which it is utilized. The amount of FDM can range from about 1 wt % up to about 90 wt % and advantageously it ranges from about 1 wt % to about 75 wt %, and more preferably about 5 to 60 wt %. Caution needs to be exercised above 30 wt % FDM, however, as the typical sulfonic catalyzed reaction becomes extremely fast. For typical metal casting applications, switching to weaker acid catalysis—such as phosphoric acid, or lower levels of the existing sulfonic acids—should be considered when higher loadings of FDM are utilized.
Unexpectedly, it was determined that with the use of non-formaldehyde containing FDM in a furanic acid-cured metal casting binder formulation, faster strip times were realized than in conventional formulations despite the absence of formaldehyde-derived resins and free formaldehyde. Faster strip-times can translate into higher productivity and/or lower catalyst usage in the production of metal casting forms. At 30 wt % replacement of the furfuryl alcohol with FDM in a standard formulation and elimination of the expensive accelerator resin resorcinol (Example 1), the performance is equivalent to the control formulation. Further, the use of resorcinol enhances the reactivity of the FDM synergistically, permitting very high reactivity's across the FDM loadings tested.
Higher loadings of FDM also show faster strip times, but also show high mold strengths initially and, unexpectedly, after 24 hours aging compared to a conventional formulation. In the past, high strip times and initial tensile strengths were also seen with the use of bis-phenol A tar filler compared to conventional filler (U.S. Pat. No. 5,856,375), but aged strengths were conventional, tending to level off or decrease somewhat as time progressed. The inventive FDM based formulations tend to continue increasing in strength through at least 24 hours.
These results also imply that a high-productivity acid-cure process is technically possible. Such a process may react so quickly that there will be essentially zero strip time—the catalyst and binder would need to be mixed on separate portions of the aggregate, the two premixes are then either “blown” together through a common high-speed mixer into a mold with a compressed gas, plunger, ram, or some other means of rapid integration and mixing. Once the aggregates are mixed and compressed, the cure would proceed rapidly.
This offers the metal caster the possibility of using a furanic no-bake resin system as a replacement to the commonly employed high-production phenolic-urethane resin system, which contains phenol, formaldehyde, urea, liquid amine catalysts and isocyanates for a zero formaldehyde, zero phenol and zero amine high-speed furan core-making process.
Improved early strengths translate into less breakage and waste in the core/mold process and later in the metal casting operation. Alternatively, the metal caster may choose to use less acid catalyst or a less expensive catalyst, saving money and achieving equal performance. Lower binder levels are also a possibility, likewise saving cost.
The examples contained herein were tested on conventional silica sand. Other aggregate materials also can be used with suitable adjustments for the nature of the aggregate. The bound forms or shapes need no be limited to the metal casting application. Other potential applications include filters, catalyst surfaces, mortars, cements, coatings, impregnates and other bound aggregate or fiber applications.
Additives can be added to the aggregate for improvement of various core/mold making operations, handling and casting properties. These include, for example, iron oxides (red and black), Lewis acids, ground flax fibers, flour, cellulosics, and the like.
The following examples show how the invention has been practiced, but should not be construed as limiting. All percentages and proportions herein are by weight and all citations are expressly incorporated herein by reference.
A description of the acid-cured laboratory test procedures (a sub-set of binders generally referred to as “no-bake”) used to determine the cure rate and final properties of cured aggregate metal casting forms can be found in the American Foundry Society Mold and Core Test Handbook Third Edition.
The following examples are provided to illustrate several aspects of the invention and are not intended to limit the scope of the invention in any way.
The formulations disclosed in Examples 1 through 3 were used to evaluate FDM and synergistic fillers in furanic acid-cured binder formulations.

EXAMPLE 1

Example 1 illustrates the use of FDM in a furanic a cid-cured binder formulation.
Table 1 shows formulations with FDM as a binder element.

TABLE 1

FDM as an Additive in a Furanic No Bake (FNB) Binder

Test No.

Ingredients	Control	1	2	3	4	5	6

Furfuryl Alcohol	96.0	91.0	86.0	76.0	66.0	69.8	56.0
(pph*)
Resorcinol	3.85	3.85	3.85	3.85	3.85	0	3.85
(pph*)
Silane**	0.15	0.15	0.15	0.15	0.15	0.15	0.15
(pph*)
FDM	0	5.0	10.0	20.0	30.0	30	40.0
(pph*)

*pph = parts per hundred (weight)

Table 1 lists six formulations and a control for FDM as an additive in an FNB binder. The ingredients in each of the formulations were added to an 8 oz jar and shaken until dissolved to a clear amber solution.
The catalyst solution was comprised of 38 (weight percent) wt % Columbus, Ohio tap water, 2 wt % methanol, and 60 wt % para-toluene sulfonic acid (Aldrich).
To 4000 grams of Wedron 540® sand (Fairmont Minerals), 20 grams (40% on binder weight) of this aromatic sulfonic acid catalyst solution was added and mixed for one minute in a Hobart N50® mixer. This aggregate mixture then was manually “flipped”, placed back on the Hobart N-50 Mixer and mixed for another minute. For each separate sand test, or evaluation, one chosen formulation (50 grams) was added to the aggregate mix and the mix procedure repeated. This final mix was immediately placed into a fifteen cavity core making box, the cavities structured to make standard American Foundry Society “dog-bone” test forms and pressed firmly (hand tucked and rammed) into place and excess sand “struck off”.
The time recorded for the “work time/strip time” measurement began after the mix was complete. “Work time” is defined as the time it takes for these furanic sand mixtures to reach 60 hardness on a Model #473® Green Hardness “B” Scale Tester (Dietert Co., Detroit, Mich.) and is a measure of cure speed. “Strip time” is the time at which the molds are hard-enough to remove and handle, for these furanic sand mixtures, as measured by the time it takes the mix to reach 90 on the same scale, and is a measure of processing speed.
Upon reaching a mold hardness of 90, the dog bones from the Table 2 tests were removed “stripped” from the pattern (core box), placed pattern-side up allowing them the air-cure further and timing for the tensile testing begun. Tensile strengths were run on a Thwing-Albert QC-3A® tensile tester equipped with a 454 kg load cell at 5.1 cm/minute.
These were mixed and tested as described and the results are shown on Table 2.

TABLE 2

FDM as an Additive in an FNB Binder - Test Results

Test No.

	Control	1	2	3	4	5*	6

Work time	29	22	22	19	15	19	12
(minutes)
Strip time	45	38	33	25	19	30	16
(minutes)

Kg/cm²(average of 3 runs)

1 Hour	6.0	6.4	7.9	8.3	7.9	6.3	17.8
3 hours	8.3	19.8	23.5	21.8	23.1	9.0	24.5
24 hours	23.8	25.8	24.8	25.0	25.0	25.1	22.7

Ambient conditions: 18° C., 44% RH, Sand at 17° C.
Notebook reference: 51231-19 except for 5.
*data for 5 is extrapolated

The data from Tables 1 and 2 show a decrease in the strip time and an increase in the initial strengths and the ultimate strengths as the FDM is increased. FDM at 30% (Test No. 5) is roughly equivalent to the control in terms of tensile development (Formulation 5, Table 1), replacing both some of the furfuryl alcohol and all of the resorcinol. The strip time remains faster, so higher productivity, or lower catalyst usage is also possible. The formulations with both resorcinol and FDM have much faster tensile strength development as well as faster strip time, indicating a synergistic relationship. These results show that FDM could increase both productivity and strength in aggregate binding applications and that the resin manufacturer can either reduce cost by eliminating resorcinol, or a “reacted” base resin, or increase productivity by using a resorcinol/FDM blend. Unlike the literature examples, no formaldehyde, phenol, or urea was utilized in these formulations.

EXAMPLE 2

The Use of Phosphoric Acid

This example illustrates the use of phosphoric acid instead of para-toluene sulfonic acid. The use of phosphoric acid is advantageous for those alloys negatively impacted by sulfur contamination and by the elimination of benzene-like molecules into the work environment after pouring the metal. Typically, phosphoric acid is not acceptable for use with “cold-blended” furan binder systems due the slow reactivity and lack of tensile development, especially on colder aggregates. The Control was run at 50% of 85% phosphoric based on binder weight. The test formulations were tested at 50 and 40% of phosphoric acid as shown on Table 3. The Table 3 series also shows the tests for several typical polyester fillers in combination with the FDM.
The formulations on Table 3 were made in the laboratory as described and tested in example one, except for the use of two different levels of the catalyst.

TABLE 3

FDM-containing FNB Binder Formulations
Cured with 85% Phosphoric Acid

Test No.

Ingredients (pph*)	Control	1	2	3	4	5

Furfuryl Alcohol	96.0	78.5	78.5	78.5	78.5	78.5
Resorcinol	3.85	3.85	3.85	3.85	3.85	3.85
Silane	0.15	0.15	0.15	0.15	0.15	0.15
FDM	—	10.0	10.0	10.0	10.0	10.0
Phenrez ® 178	—	7.5	7.5	—	—	—
Terol ® 250	—	—	—	7.5	—	—
Terol ® 256	—	—	—	—	7.5	—
Terate ® 203	—	—	—	—	—	7.5

wt % of Phosphoric Acid Catalyst on Binder

85% Phosphoric	50	50	40	40	40	40

all ingredients in *pph = Parts per hundred (weight)

The test results for Table 3 formulations are shown in Table 4.

TABLE 4

FDM containing FNB Binders Cured with
85% Phosphoric Acid - Test Results

Test No.

	Control	1	2	3	4	5

Minutes

Kg/cm²(average of 3 runs)

1 Hour	3.6	4.6	5.7	6.6	6.4	6.8
3 hours	5.2	6.0	9.0	10.4	10.6	11.1
24 hours	6.6	6.4	15.0	15.5	17.4	17.3
Scratch Hardness	34	36	42	24	52	32
(at 24 hours,
average of three)

Ambient conditions: 18° C., 32% RH. Sand at 17° C.

The work time/strip times were all relatively fast for these formulations, indicating rapid surface cure with the phosphoric acid although the formulation without any fillers did utilize a higher phosphoric acid level. The tensile strength development was significantly greater for the FDM-containing formulations. The scratch hardness values were better for the FDM containing formulations 1, 2 (Phenrez® polyester filler) and 4 (Terol® 256 polyester filler). Thus, significantly improved tensiles and scratch hardness values are obtained when employing the inventive FDM-containing formulations.

EXAMPLE 3

This example illustrates FDM formulation performance on warm and cold aggregates.
The performance of furan no-bake binders can be severely affected by the temperature of the aggregates as well as ambient temperatures and humidity. A faster curing binder formulation should perform better on cold sands. Ideally, such a binder formulation should still perform acceptably on warm sand as well. A typical-means of achieving fast cure on cold sand is the use of reacted base formulations, the reacted base being, for example, a urea-formaldehyde resin. Such resins increase the reactivity, but also introduce free formaldehyde into the formulations. Another means of achieving faster cure on cold sands is to use either higher levels of an acid catalyst, use a higher reactivity sulfonic acid, or one containing an inorganic acid “kicker”, such as straight sulfuric acid or hydrochloric acid. Other means of increasing reactivity on cold sands include the addition of alcohols, such as methanol, to either the resin or the catalyst.
For warm sands or aggregates, the trend is typically reversed using lower amounts of acid, lower reactivity catalysts, ad lower amounts or the reduction in alcohols.
Table 5 show three formulations for comparison testing; a reacted base formulation, an FDM-containing formulation, and a typical FNB formulation (control).

TABLE 5

Formulations for Comparison on Warm and Cold Aggregate

	1	2
	Reacted	FDM-	3
Ingredients	resin	containing	Control

Furfuryl Alcohol (wt %)	67.85	66.0	96.0
Resorcinol (wt %)	2.0	3.85	3.85
Silane	.15	0.15	.15
FDM	—	20.0	—
Beetle 65 ® urea	25.0	—	—
formaldehyde resin (Cytec)
Phenrez ® 178	—	10.0	—
Terol ® 250	5.0	—	—

The ingredients were mixed together as in Example 1 and tested under two different sets of conditions. Two different catalysts were used: sulfonic acid based (Example 1) and phosphoric acid based (as in Example 2). All catalyst solutions were utilized at 40% by weight on binder weight. Two different temperature conditions were used: warm (32.3° C.) and cool (10° C.) at a typical lab RH of 35-40%.
The test results for the warm temperature/sulfonic acid experiments are shown on Table 6.

TABLE 6

FDM-containing FNB Binder Vs Controls Cured
para-toluene sulfonic acid on Warm Aggregate

Test

	1	2	3

Work time	19	6	8
(minute)
Strip time	25	9	12
(minute)

Kg/cm²(average of 3 runs)

1 Hour	11.9	12.2	12.8
3 hours	16.1	21.4	24.6
24 hours	18.3	24.9	27.8
Scratch Hardness	36	62	47
(at 24 hours,
average of three)

The FDM-containing binder and the control binder had faster strip times and greater tensile development than the reacted-resin formulation. The FDM-containing formulation had the highest hardness of these three under these test conditions.

TABLE 7

FDM-containing FNB Binder Vs Controls Cured with
para-toluene sulfonic acid on Cool Aggregate

Test

	1	2	3

Work time	65	30	26
(minute)
Strip time	90	40	41
(minute)

Kg/cm²(average of 3 runs)

1 hour	12.2	13.9	16.1
3 hours	16.4	25.1	26.7
24 hours	17.9	27.7	30.9
Scratch Hardness	61	58	45
(at 24 hours,
average of three)

The FDM-containing binder and the control binder had faster strip times and greater tensile development than the reacted-resin formulation. The FDM-containing and the reacted-resin formulations had the highest hardness of these three under these test conditions.

TABLE 8

FDM-containing FNB Binder Vs Controls Cured
with Phosphoric Acid on Warm Aggregate

Test

	1	2	3

Work time	14	2	3
(minute)
Strip time	20	4	5
(minute)

Kg/cm²(average of 3 runs)

1 Hour	13.9	9.0	3.2
3 hours.	21.6	12.2	5.7
24 hours	22.7	14.6	7.4
Scratch Hardness	41	50	17
(at 24 hours,
average of three)

The reacted-resin binder had the greatest tensile development, but longer strip time than the FDM containing and the control formulations. The FDM-containing formulation had the highest hardness. The control binder was the weakest performer of these three under these test conditions.

TABLE 9

FDM-containing FNB Binder Vs Controls Cured
with Phosphoric Acid on Cool Aggregate

Test

	1	2	3

Work time	50	9	7
(minute)
Strip time	60	13	12
(minute)

Kg/cm²(average of 3 runs)

1 Hour	22.6	12.4	8.7
3 hours	27.3	18.5	15.0
24 hours	28.4	22.5	20.2
Scratch Hardness	60	65	61
(at 24 hours,
average of three)

The reacted-resin binder had the greatest tensile development, but longer strip time than the FDM containing and the control formulations. The FDM-containing formulation had the highest scratch hardness. The control binder was the weakest performer of these three under these test conditions.
Under each condition, the FDM-containing binder demonstrated good productivity and tensile strength development. The inventive FDM-containing binder has an advantageously wide range of performance capability with respect to ambient conditions. Based on these results it appears that this performance flexibility will extend to other acidic catalysts and other typical ambient conditions likely to be seen in foundry operations.
While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all of the possible equivalent forms or ramifications of the invention. It is to be understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit of the scope of the invention.

Strip time

1. A furanic binder composition comprising:

a mixture of

a. a furfuryl alcohol;

b. about 1 to about 90 wt % 2,5-furan dimethanol, wherein the 2,5-furan dimethanol is derived from the reduction of 5-hydroxymethyl furfural;

c. about 0 to about 15 wt % resorcinol;

wherein the total of mixture a, b, and c comprises 100 wt %.

2. The composition according to claim 1, wherein 2,5-furan dimethanol comprises about 5 to about 60 wt %.

3. The composition according to claim 1, comprising a catalyst.

4. The composition according to claim 3, wherein the catalyst comprises a weak acid having a pk_abetween about 2 and about 4.

5. The composition according to claim 4, wherein the catalyst comprises phosphoric acid.

6. The composition according to claim 1, comprising an additive selected from the group consisting of iron oxide (red), iron oxide (black), Lewis acid, ground flax fiber, flour, and cellulosics.

7. A method for making an aggregate casting comprising:

a. using the composition of claim 1, to coat one aggregate material;

b. using a weak acid to coat another aggregate material;

c. mixing the coated aggregates from step a and step b above and blowing the mix together in a mold.

8. The method according to claim 7, wherein the blowing is by compressed gas, air, or with a piston or ram.

9. A furanic binder composition comprising:

a mixture of

a. a furfuryl alcohol;

b. about 1 to about 90 wt % 2,5-furan dimethanol,

c. about 1 to about 30 wt % aromatic polyester polyol; and

d. about 0 to about 15 wt % resorcinol;

wherein the total of mixture a, b, c, and d comprises 100 wt %; and

wherein the substantially no formaldehyde is present.

10. The composition according to claim 9, wherein the 2,5-furan dimethanol is derived from the reduction of 5-hydroxymethyl furfural.

11. The composition according to claim 9, wherein 2,5-furan dimethanol comprises about 5 to about 60 wt %.

12. The composition according to claim 9, comprising a catalyst.

13. The composition according to claim 12, wherein the catalyst comprises a weak acid having a pk_abetween about 2 and about 4.

14. The composition according to claim 13, wherein the catalyst comprises phosphoric acid.

15. The composition according to claim 9, comprising an additive selected from the group consisting of iron oxide (red), iron oxide (black), Lewis acid, ground flax fiber, flour, and cellulosics.

16. A method for making an aggregate casting comprising:

a. using the composition of claim 9, to coat one aggregate material;

b. using a weak acid to coat another aggregate material;

17. The method according to claim 16, wherein the blowing is by compressed gas, air, or with a piston or ram.