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
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
  • C08G18/72—Polyisocyanates or polyisothiocyanates
  • C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
  • C08G18/76—Polyisocyanates or polyisothiocyanates cyclic aromatic
  • C08G18/7657—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings
  • C08G18/7664—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings containing alkylene polyphenyl groups
• • 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
  • B22C1/2273—Polyurethanes; Polyisocyanates
• • 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
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/2805—Compounds having only one group containing active hydrogen
  • C08G18/2815—Monohydroxy compounds
  • C08G18/282—Alkanols, cycloalkanols or arylalkanols including terpenealcohols
• • 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
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/54—Polycondensates of aldehydes
  • C08G18/542—Polycondensates of aldehydes with phenols
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
  • C09J175/04—Polyurethanes

Definitions

• This invention relates to a polyurethane-based binder system for use in the cold-box or no-bake process.
• an alcohol is used to replace, at least partially, an aromatic solvent.
• the alcohol selected is an alkyl alcohol with between 2 and 5 carbon atoms.
• the alcohol selected is ethanol.
• the alcohol is used in a polyol-containing component of a two component polyurethane-based binder system.
• polyurethane-based binder systems are used in large amounts, in particular for mold and core production using the cold-box or polyurethane no-bake process. These systems require solvents and it is an on-going need to reduce emissions from these systems when used.
• a two component system is provided for the user.
• the first component contains a polyol component that comprises a compound with at least two -OH groups per molecule.
• the second component is a polyisocyanate component that comprises a compound having at least two isocyanate groups per molecule. It is considered almost axiomatic that a solvent is included in at least one of the components, and in many cases, both components contain a solvent. Once the solvents are included with the respective components, they are usually packaged and sold in separate containers, only to be combined at the time of use.
• the solvent (or solvents) selected are not intended to participate in any relevant manner in the catalyzed reaction between the polyisocyanate and polyol compounds, but they may very well influence the reaction.
• the two binder components have substantially different polarities. This limits the number of solvents that may be used. If the solvents are not compatible with both binder components, complete reaction and curing of a binder system is very unlikely.
• polar solvents of the protic and aprotic type are usually good solvents for the polyol compound, they are not very suitable for the polyisocyanate compound.
• Aromatic solvents in turn are compatible with polyisocyanates but are not wholly suitable for polyol resins.
• the common aromatic solvents include the so-called "BTX" solvents - benzene, toluene and xylene.
• BTX so-called "BTX" solvents
• a given solvent needs to meet a number of criteria, including the cost of the solvent, its ecological implications and its health and safety implications.
• the combination of these may, in some circumstances, mandate a polyurethane based binder system in which the amount of aromatic solvents, and particularly, the BTX solvents, is reduced or eliminated to meet these criteria.
• a binder system for a molding material mixture is used when low emissions of aromatic solvents are required.
• the binder system has two components that are packaged separately, for combination at use.
• the first component has a polyol base resin with at least two -OH groups per molecule and an alkyl alcohol, having from two to five carbon atoms, as a solvent.
• the second component has a polyisocyanate with at least two -NCO groups per molecule.
• the alkyl alcohol may be anhydrous ethanol and the first component is substantially devoid of aromatic hydrocarbon solvents.
• the second component will typically consist essentially of diphenylmethane diisocyanate (MDI) with less than 0.1 % of a bench life extender.
• the first component may contain at least one fatty acid methyl ester and at least one dibasic ester.
• the binder system may be used for practicing either a "cold-box” or a "no-bake” method.
• the respective first and second components are present in a weight ratio such that the first component weighs less than the second component. More particularly, preferred embodiments will have about 48 parts by weight of the first component used with about 52 parts by weight of the second component.
• the first component contains about 58.8% by weight of the polyol resin, 23.9% by weight of the at least one dibasic ester, and 16.9% by weight of the alkyl alcohol, with the balance being the at least one fatty acid methyl ester.
• an amount of refractory mold base material is mixed with the binder system components.
• Preferred refractory mold base materials will include: quartz ore sand, zirconium ore sand, chromium ore sand, olivine, chamotte, bauxite, aluminum silicate hollow spheres, glass beads, glass granules, spherical ceramic molding materials and combinations thereof.
• the binder system is present in an amount of between 0.2 to 5%, by weight, based on the weight of the refractory mold base material, preferably in the range of between 0.3 and 4% by weight, and most preferably in the range of between 0.4 and 3% by weight.
• the method of producing a mold or core for casting of a molten metal can be either a polyurethane "cold-box” method or a polyurethane "no-bake” method, depending upon how a curing agent is applied to the binder system.
• the known method for producing cores referred to as the "cold-box method” has attained great importance in the foundry industry.
• two-component polyurethane systems are used for binding a basic refractory molding material.
• the polyol component consists of a polyol having at least two OH groups per molecule
• the isocyanate component consists of a polyisocyanate having at least two NCO groups per molecule.
• the binder system is cured by conducting gaseous tertiary amines through the molding material/binder system mixture upon injection of the latter into the shaped cavity (US 3,409,579). In the no-bake process liquid amines are added to the binder system prior to molding, to bring the two components to reaction (US 3,676,392).
• phenolic resins are used as polyols, which are obtained by condensation of phenol with aldehydes, preferably formaldehyde, in liquid phase at temperatures up to approximately 130°C in the presence of catalytic quantities of metal ions.
• aldehydes preferably formaldehyde
• US 3,485,797 describes the production of such phenolic resins in detail.
• substituted phenols preferably o-cresol and p-nonylphenol, can be used (see, e.g., US 4,590,229).
• phenolic resins modified with aliphatic monoalcohol groups having one to eight carbon atoms can be used.
• the binder systems should have increased thermal stability.
• As a solvent for the polyol component predominantly mixtures of high-boiling polar solvents (e.g., esters and ketones) and high-boiling aromatic hydrocarbons are used.
• the polyisocyanates are preferably dissolved in high-boiling aromatic hydrocarbons.
• EP 0771599 A1 and WO 00/25957 A1 describe formulations in which aromatic solvents can be entirely or at least largely replaced by using fatty acid esters.
• polyurethane systems are known in which epoxy resins, polyester resins or aqueous phenol formaldehyde resins are reacted with diisocyanates in the presence of a solvent such as dibutoxymethane, dipropoxymethane, diisobutoxymethane, dipentyloxymethane, dihexyloxymethane,
• diacetals specifically conversion products of C2 to Ce dialdehydes and C2 to C12 alcohols, in polyurethane systems is disclosed in WO 2006/09271 6 A1 .
• diacetals are 1 ,1 ,2,2-tetramethoxyethane, 1 ,1 ,2,2-tetraethoxyethane, 1 ,1 ,2,2- tetrapropoxyethane, 1 ,1 ,3,3-tetramethoxypropane, and 1 ,1 ,3,3-tetraethoxypropane. It was determined that the diacetals enable an extension of the processing time of the molding material mixtures. However, this has a substantially disadvantageous effect on the stability of the fresh mixtures ("shoot immediate"). The loss in stability in relation to the unmodified binder is approximately 1 5% to approximately 20%.
• the object of the invention is to provide a binder for molding material mixtures, containing at least one polyol component having a polyol with at least two -OH groups per molecule and at least one isocyanate component having a polyisocyanate with at least two -NCO groups per molecule.
• the polyol component further comprises at least at least one alkyi alcohol, especially an alkyi alcohol with from two to five carbon atoms. Most especially, the alkyi alcohol is anhydrous ethanol.
• the invention further relates to molding material mixtures which comprise basic refractory molding materials and up to 5 wt%, preferably up to 4 wt%, particularly preferably up to 3 wt% of the binder system according to the invention, referred to the weight of the basic refractory molding materials.
• Suitable refractory materials include quartz ore sand, zirconium ore sand, or chromium ore sand, olivine, chamotte and bauxite, for example.
• Synthetically produced molding materials can also be used, such as aluminum silicate hollow spheres (so-called microspheres), glass beads, glass granules, or the spherical ceramic molding materials known as "cerabeads" or
• the invention also relates to a method for producing a casting mold piece or a core. This is achieved by mixing refractory materials with the inventive binder system in a binding quantity of 0.2 to 5 wt%, preferably 0.3 to 4 wt%, particularly preferably 0.4 to 3 wt%, referred to the quantity of refractory materials, to obtain a molding mixture.
• This molding mixture is placed in to a mold and hardened in the pattern to obtain a self- supporting casting mold piece.
• the hardened molding mixture is separated from the pattern and hardened further, if necessary, to obtain a hard, solid, cured casting mold piece. At this point, molten metal may be poured into the casting mold.
• the use of an alkyi alcohol, ethanol in particular, as part of the binder formulation readily delivers on the economical, ecological and practical performance criteria of the binder.
• the alkyi alcohol improves the low-temperature resistance of the binder component.
• a solution to the emission problems has apparently been found in a binder composition that uses a two-component approach to provide a polyurethane cold-box (PUCB) or a polyurethane no-bake (PUNB) binder system.
• the Part I component comprises a polyol base resin, a set of suitable complements and an alky! alcohol
• the Part II component comprises a polyisocyanate accompanied by a set of suitable complements.
• the phenolic resin and the polyisocyanate can be selected from the group consisting of the compounds conventionally known to be used in the cold-box process or the no-bake process, as the inventive concept is not believed to inhere in these portions of the composition.
• the phenolic resin is generally selected from a condensation product of a phenol with an aldehyde, especially an aldehyde of the formula RCHO, where R is hydrogen or an alkyl moiety having from 1 to 8 carbon atoms.
• the condensation reaction is carried out in the liquid phase, typically at a temperature below 130 Q C.
• a number of such phenolic resins are commercially available and will be readily known.
• a preferred phenolic resin component would comprise a phenol resin of the benzyl ether type. It can be expedient in individual cases to use an alkylphenol, such as o-cresol, p-nonylphenol or p-tert-butylphenol, in the mixture, in particular with phenol, for the preparation of the phenol resin.
• these resins can feature alkoxylated end groups which are obtained by capping hydroxymethylene groups with alkyl groups like methyl, ethyl, propyl and butyl groups.
• polymeric isocyanate it may be preferred to use a polyisocyanate component that comprises diphenylmethane diisocyanate (MDI), although a number of commercially available polymeric isocyanates are directed for this specific market.
• MDI diphenylmethane diisocyanate
• the isocyanate component (second component) of the two-component binder system for the polyurethane cold-box or no-bake process usually comprises an aliphatic, cycloaliphatic or aromatic polyisocyanate having preferably between two and five isocyanate groups; mixtures of such polyisocyanates may also be used.
• Particularly suitable isocyanate component that comprises diphenylmethane diisocyanate (MDI), although a number of commercially available polymeric isocyanates are directed for this specific market.
• the isocyanate component (second component) of the two-component binder system for the polyurethane cold-box or no-bake process usually comprises an aliphatic, cycl
• polyisocyanates among the aliphatic polyisocyanates are, for example, hexamethylene diisocyanate, particularly suitable ones among the alicyclic polyisocyanates are, for example, 4,4'-dicyclohexylmethane diisocyanate and particularly suitable ones among the aromatic polyisocyanates are, for example, 2,4'- and 2,6'-toluene diisocyanate, diphenylmethane diisocyanate and their dimethyl derivatives.
• suitable polyisocyanates are 1 ,5-naphthalene diisocyanate, triphenylmethane
• polymethylenepolyphenyl isocyanates (polymeric MDI), etc.
• diphenylmethane diisocyanate (MDI), triphenylmethane triisocyanate, polymethylene polyphenyl isocyanates (polymeric MDI) and mixtures thereof are particularly preferred.
• the polyisocyanate is used in concentrations which are sufficient to effect curing of the phenol resin. In general, 10-500% by weight, preferably 20-300% by weight, based on the mass of (undiluted) phenol resin used, of polyisocyanate are employed.
• the polyisocyanate is used in liquid form; liquid polyisocyanate can be used in undiluted form, and solid or viscous polyisocyanates are used in the form of a solution in an organic solvent, it being possible for the solvent to account for up to 80% by weight of the polyisocyanate solution.
• AROMATIC SOLVENT 100 AROMATIC SOLVENT 150
• AROMATIC SOLVENT 200 AROMATIC SOLVENT 200
• SOLVESSO 100 SOLVESSO 150
• SOLVESSO 200 SOLVESSO 200
• Performance additives are also included in the respective parts of the formulation.
• an especially preferred performance additive is hydrofluoric acid (which is commonly used as a 49% aqueous solution, but it may be used in different dilution or with a different diluent). Coupling agents and additives based on fatty acids can also be used.
• the preferred performance additives would include modified fatty oils and bench life extenders, which would include phosphoroxytrichloride (POC ), phenyl dichlorophosphate and benzyl phosphoroxy dichloride.
• a recently developed binder system uses an alkyl alcohol, especially ethanol, as a solvent instead of the aromatic solvent as used conventionally.
• the binder is provided in two parts, with the two parts preferably being packaged separately and combined only upon use.
• the Part I component contains the base polyol resin, dibasic ester (“DBE"), a fatty acid alkyl ester like rapeseed methyl ester or soybean methyl ester, and ethanol.
• the Part II component is substantially diphenylmethane diisocyanate (MDI), although it would be common to include a small but effective amount (approximately 0.05% by weight) of a conventional bench-life extender.
• MDI substantially diphenylmethane diisocyanate
• This formulation will immediately be notable as being devoid of the aromatic solvents benzene, toluene and xylene (generally referred to collectively as "BTX").
• a binder system having this composition would be useful in markets where BTX emissions are tightly limited, although the flash point of the system could be disadvantageous in markets where flash point limitations are in effect.
• economics of ethanol and its "green" nature may provide an advantage in selected markets.
• Ethanol differs from the BTX family of solvents because it is a reactive diluent in the binder system.
• Other reactive diluents are used in, for illustrative purposes only, furan, epoxy, and urethane resin formulations. Some of these include, again for illustrative purposes only, triethylene glycol, resorcinol, and various mono- or di- functional glycidyl ethers.
• a reactive solvent or diluent can polymerize during the curing process, and be dispersed within the polymer matrix.
• VOC volatile organic compounds
• the Index should be within about 15% of 100.
• a binder composition containing ethanol and a polyol resin with an equivalent weight of 1 15 g/eq, and Parts I and II in a 60/40 ratio an Index of 58 obtains.
• Part II being 99.95% MDI
• the system lacks enough isocyanate for full reaction.
• the Index improves to 94, which is within the ideal range. This calculation assumes no ethanol loss from evaporation during mixing. Therefore, some further refinement of the ratio may yield improved performance.
• Ethanol as a primary alcohol, is more reactive than diacetone alcohol (CAS Reg. Nr. 123-42-2), which has been used as a solvent in binder systems.
• This increased reactivity is apparent in real work time results, as well as elsewhere.
• the addition of bench-life extenders can solve some of the reactivity issues, but cause other issues.
• the binder can require additional catalyst to achieve comparable reactivity of standard systems when ethanol is used.
• the no-bake binder system has trouble accelerating faster than a work time of 2.5 minutes, even with very strong catalysts.
• the mixed sand is observed to have less flowability, due to either the lower amount of total solvents, or ethanol reacting prematurely.
• bench-life extenders decrease the overall strength performance of cured cores and molds.
• the polyol resin is a benzylic ether phenolic resin, CAS Reg. Nr. 9003-35-4 with a hydroxyl equivalent weight of 1 15 g/eq.
• the dibasic ester used is a blend of dimethyl glutarate, dimethyl succinate and dimethyl adipate.
• INNOVATI 170 is a commercially-available methyl ester of fatty acids of soybean oil, CAS Reg. Nr. 67784-80-9.
• Isocyanate Type 1 is a polymeric diphenylmethane diisocyanate with an NCO content of 31 -33%.
• 4-PPP is 4-(3-phenylpropyl)pyridine, CAS Reg. Nr. 2057-49-0.
• NMI is N-methyl imidazole, CAS Reg. Nr. 616-47-7.
• references to ethanol are to anhydrous ethanol.
• composition A Composition A
• Composition A had the following Part I component:
• Part II component for Composition A was:
• Composition A may be generally characterized as a binder system in which the BTX solvents have been completely replaced by ethanol in the Part I component. Such a system may have commercial application in a market where ethanol is readily available and BTX emissions are strictly limited. Such a market may be found in Brazil, as an example.
• Composition B had the following Part I component:
• the Part I component of Composition B modifies Part I of Composition A by replacing DBE and INNOVATI 170 solvents with aromatic hydrocarbon solvents ("BTX solvents").
• Composition B also has a Part II component that is identical to Part II of Composition A.
• Composition C had the following Part I component:
• Part II component for Composition C was:
• Composition C is characterized as a conventional phenolic-binder system as used in the United States, and is presented as phenolic-urethane no-bake binder baseline comparison for that market.
• Part II has a lower percentage of Isocyanate Type I than Compositions A and B, due to the absence of ethanol in the Part I component it is used with.
• composition C a conventional phenolic-urethane no- bake binder formulation
• Compositions A and B binders with ethanol- containing Parts I
• the ethanol-containing systems required more catalyst to achieve comparable work time and strip time and failed to develop tensile strength over time, due to insufficient isocyanate, as the -NCO to -OH Index was only 58, compared to the higher Index of 88 for Composition C.
• Compositions A and B comprise a bench life extender in Part II to suppress premature reaction between ethanol and isocyanate, which led to higher catalyst demand.
• “work time” is the time elapsed for the foundry shape formed to reach a level of 60 on the Green Hardness "B” scale, using a gauge from sold by Harry W. Dietert Co., of Detroit, Ml. Details of the test are found many places, including in commonly-owned US Patent 6,602,931 .
• “Strip time” loosely defines the elapsed time from mixing the binder components with the sand until the formed foundry shape is able to be removed from the pattern.
• strip time is the time needed for the foundry shape formed to attain a level of 90 on the same Green Hardness "B” scale.
• the difference between strip time and work time is, therefore, an amount of dead time during which the mold being formed cannot be worked upon, but cannot yet be removed from the pattern.
• compositions C and A were tested again, using the "hotter" NMI catalyst to provide a faster work time.
• Composition A required a higher NMI content in a blended catalyst system to achieve the desired work time/strip time properties.
• Table 2 The results, as shown in Table 2 below, are consistent with the Table 1 results and are not unexpected.
• Composition A was initially tested at an Index well below the desired Index, which is between about 90 and 1 10. The latter can be obtained by adjusting the Part I to Part II ratio from 60/40 to 48/52. When this is done and the conditions of Table 1 are duplicated, the tensile strengths are again not able to match the conventional phenolic-urethane no-bake binder baseline (Composition C in Table 1 ), but the binder continues to develop strength over time.
• the binder was applied at a 1 .2% by weight in Table 1 .
• Composition A was determined to have a 1 hr tensile strength of 157, with tensile strengths of 302 and 309, respectively, at 3 and 24 hrs.
• Composition A (at 1 .48% binder) can approach the performance of the Composition C baseline case (at 1 .2% binder) through adjusting ratio and the amount of binder used.
• VOC Volatile organic carbon
• EPA Method 24 a sample, weighing from 0.3 to 0.5 g, is dissolved in 3 ml of acetone and placed in an oven at 1 10 °C for 1 hour. The percentage of VOC is based on weight lost.
• the test was conducted for the Part I components of Compositions C, A and B, that is, the phenolic-urethane no-bake binder baseline and the two ethanol-containing systems. The respective %VOC were 53.9, 51 .8 and 49.8%. These results are essentially equal and not distinguishable.
• Part II components were not actually tested according to EPA Method 24, it is believed that they would be less than 5% VOC for Compositions A and B, due to the higher isocyanate and the absence of the AROMATIC 1 00 constituent.
• a conventional Part II component has a VOC content according to EPA Method 24 in the range of 20% to 40%, so the ethanol-containing systems would be expected to reduce VOC content for the overall system.
• the second type of VOC test is the EPA Method 24 "Reacted” test.
• a sample, weighing about 0.3 g, of the multi-component binder i.e. including Part I, Part II and catalyst
• the baseline composition (C) had 30.2% VOC, respectively, in the EPA Method 24 "Reacted” test.
• ethanol-containing Composition A was measured with a Part I/Part II ratio of 60/40
• the EPA Method 24 "Reacted” was 14.4% VOC.
• EPA Method 24 "Reacted” VOC content dropped to 7.2%, a 50% reduction and an amount that is about 20% of the baseline composition.
• the third type of VOC test that is considered relevant by one or more regulatory authorities is the OCMA test (Ohio Cast Metals Association).
• OCMA test Ohio Cast Metals Association
• weight loss is measured for a mixed bowl of sand and binder over 24 hours. Because of the ability to vary the binder amount, the results can be reported as either pounds of VOC per ton of mixed sand or pounds of VOC per pound of binder.
• baseline Composition C was tested, using a 55/45 ratio and 1 .25% by weight BOB of 4-PPP, the pounds of VOC per ton of sand was measured at 1 .03 after 12 hours and at 1 .41 after 24 hours, which translates to 0.050 and 0.069 pounds of VOC per pound of binder, respectively. It was noted that the majority of weight loss in the ethanol-containing Composition A occurred during mixing, which is not unexpected.
• ethanol may be uniquely situated for this application.
• Methanol has a lower flashpoint and higher toxicity. It also is less likely to be available from a renewable "green” source.
• Propanol, in either of its isomers, and the higher molecular weight alcohols, are not typically available through fermentation of renewable resources, although all have higher flash points than ethanol.

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