US3403721A - Tensile strengths of certain sand cores - Google Patents
Tensile strengths of certain sand cores Download PDFInfo
- Publication number
- US3403721A US3403721A US556891A US55689166A US3403721A US 3403721 A US3403721 A US 3403721A US 556891 A US556891 A US 556891A US 55689166 A US55689166 A US 55689166A US 3403721 A US3403721 A US 3403721A
- Authority
- US
- United States
- Prior art keywords
- silane
- sand
- oil
- isocyanate
- binder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000000203 mixture Substances 0.000 description 39
- 239000011230 binding agent Substances 0.000 description 28
- 229920000180 alkyd Polymers 0.000 description 27
- 229920001228 polyisocyanate Polymers 0.000 description 27
- 239000005056 polyisocyanate Substances 0.000 description 27
- 239000012948 isocyanate Substances 0.000 description 22
- 150000002513 isocyanates Chemical class 0.000 description 21
- 239000004576 sand Substances 0.000 description 21
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 19
- 229910000077 silane Inorganic materials 0.000 description 19
- 239000003054 catalyst Substances 0.000 description 18
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 18
- 238000000034 method Methods 0.000 description 14
- 239000000376 reactant Substances 0.000 description 14
- 239000003921 oil Substances 0.000 description 9
- 235000019198 oils Nutrition 0.000 description 9
- QQVIHTHCMHWDBS-UHFFFAOYSA-N isophthalic acid Chemical compound OC(=O)C1=CC=CC(C(O)=O)=C1 QQVIHTHCMHWDBS-UHFFFAOYSA-N 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 6
- 125000004432 carbon atom Chemical group C* 0.000 description 6
- WXZMFSXDPGVJKK-UHFFFAOYSA-N pentaerythritol Chemical compound OCC(CO)(CO)CO WXZMFSXDPGVJKK-UHFFFAOYSA-N 0.000 description 6
- 150000005846 sugar alcohols Polymers 0.000 description 6
- WYTZZXDRDKSJID-UHFFFAOYSA-N (3-aminopropyl)triethoxysilane Chemical compound CCO[Si](OCC)(OCC)CCCN WYTZZXDRDKSJID-UHFFFAOYSA-N 0.000 description 5
- 239000004615 ingredient Substances 0.000 description 5
- IQPQWNKOIGAROB-UHFFFAOYSA-N isocyanate group Chemical group [N-]=C=O IQPQWNKOIGAROB-UHFFFAOYSA-N 0.000 description 5
- 239000000944 linseed oil Substances 0.000 description 5
- 235000021388 linseed oil Nutrition 0.000 description 5
- -1 sulfhydrylalkyl Chemical group 0.000 description 5
- UPMLOUAZCHDJJD-UHFFFAOYSA-N 4,4'-Diphenylmethane Diisocyanate Chemical compound C1=CC(N=C=O)=CC=C1CC1=CC=C(N=C=O)C=C1 UPMLOUAZCHDJJD-UHFFFAOYSA-N 0.000 description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- 125000003118 aryl group Chemical group 0.000 description 4
- 150000004756 silanes Chemical class 0.000 description 4
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 3
- QORUGOXNWQUALA-UHFFFAOYSA-N N=C=O.N=C=O.N=C=O.C1=CC=C(C(C2=CC=CC=C2)C2=CC=CC=C2)C=C1 Chemical compound N=C=O.N=C=O.N=C=O.C1=CC=C(C(C2=CC=CC=C2)C2=CC=CC=C2)C=C1 QORUGOXNWQUALA-UHFFFAOYSA-N 0.000 description 3
- 229920000538 Poly[(phenyl isocyanate)-co-formaldehyde] Polymers 0.000 description 3
- 125000001931 aliphatic group Chemical group 0.000 description 3
- 125000000217 alkyl group Chemical group 0.000 description 3
- 229920001577 copolymer Polymers 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 125000002768 hydroxyalkyl group Chemical group 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 229920000728 polyester Polymers 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- UUEWCQRISZBELL-UHFFFAOYSA-N 3-trimethoxysilylpropane-1-thiol Chemical compound CO[Si](OC)(OC)CCCS UUEWCQRISZBELL-UHFFFAOYSA-N 0.000 description 2
- RBVMDQYCJXEJCJ-UHFFFAOYSA-N 4-trimethoxysilylbutan-1-amine Chemical compound CO[Si](OC)(OC)CCCCN RBVMDQYCJXEJCJ-UHFFFAOYSA-N 0.000 description 2
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 2
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- 241000208202 Linaceae Species 0.000 description 2
- 235000004431 Linum usitatissimum Nutrition 0.000 description 2
- LGRFSURHDFAFJT-UHFFFAOYSA-N Phthalic anhydride Natural products C1=CC=C2C(=O)OC(=O)C2=C1 LGRFSURHDFAFJT-UHFFFAOYSA-N 0.000 description 2
- UKLDJPRMSDWDSL-UHFFFAOYSA-L [dibutyl(dodecanoyloxy)stannyl] dodecanoate Chemical compound CCCCCCCCCCCC(=O)O[Sn](CCCC)(CCCC)OC(=O)CCCCCCCCCCC UKLDJPRMSDWDSL-UHFFFAOYSA-L 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 125000004103 aminoalkyl group Chemical group 0.000 description 2
- JHIWVOJDXOSYLW-UHFFFAOYSA-N butyl 2,2-difluorocyclopropane-1-carboxylate Chemical compound CCCCOC(=O)C1CC1(F)F JHIWVOJDXOSYLW-UHFFFAOYSA-N 0.000 description 2
- 125000004181 carboxyalkyl group Chemical group 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 239000012975 dibutyltin dilaurate Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 238000009472 formulation Methods 0.000 description 2
- 150000002334 glycols Chemical class 0.000 description 2
- 238000005058 metal casting Methods 0.000 description 2
- GEMHFKXPOCTAIP-UHFFFAOYSA-N n,n-dimethyl-n'-phenylcarbamimidoyl chloride Chemical compound CN(C)C(Cl)=NC1=CC=CC=C1 GEMHFKXPOCTAIP-UHFFFAOYSA-N 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- XNGIFLGASWRNHJ-UHFFFAOYSA-N phthalic acid Chemical compound OC(=O)C1=CC=CC=C1C(O)=O XNGIFLGASWRNHJ-UHFFFAOYSA-N 0.000 description 2
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 2
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 2
- 235000021122 unsaturated fatty acids Nutrition 0.000 description 2
- DJKGDNKYTKCJKD-BPOCMEKLSA-N (1s,4r,5s,6r)-1,2,3,4,7,7-hexachlorobicyclo[2.2.1]hept-2-ene-5,6-dicarboxylic acid Chemical compound ClC1=C(Cl)[C@]2(Cl)[C@H](C(=O)O)[C@H](C(O)=O)[C@@]1(Cl)C2(Cl)Cl DJKGDNKYTKCJKD-BPOCMEKLSA-N 0.000 description 1
- FKTHNVSLHLHISI-UHFFFAOYSA-N 1,2-bis(isocyanatomethyl)benzene Chemical compound O=C=NCC1=CC=CC=C1CN=C=O FKTHNVSLHLHISI-UHFFFAOYSA-N 0.000 description 1
- SBJCUZQNHOLYMD-UHFFFAOYSA-N 1,5-Naphthalene diisocyanate Chemical compound C1=CC=C2C(N=C=O)=CC=CC2=C1N=C=O SBJCUZQNHOLYMD-UHFFFAOYSA-N 0.000 description 1
- SJECZPVISLOESU-UHFFFAOYSA-N 3-trimethoxysilylpropan-1-amine Chemical compound CO[Si](OC)(OC)CCCN SJECZPVISLOESU-UHFFFAOYSA-N 0.000 description 1
- YATIYDNBFHEOFA-UHFFFAOYSA-N 3-trimethoxysilylpropan-1-ol Chemical compound CO[Si](OC)(OC)CCCO YATIYDNBFHEOFA-UHFFFAOYSA-N 0.000 description 1
- NHIDUYBCYBGHAX-UHFFFAOYSA-N 4-(dimethoxymethylsilyl)butan-1-amine Chemical compound COC(OC)[SiH2]CCCCN NHIDUYBCYBGHAX-UHFFFAOYSA-N 0.000 description 1
- MLTLWTJERLVODH-UHFFFAOYSA-N 4-triethoxysilylbutanoic acid Chemical compound CCO[Si](OCC)(OCC)CCCC(O)=O MLTLWTJERLVODH-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 239000005057 Hexamethylene diisocyanate Substances 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- 235000004443 Ricinus communis Nutrition 0.000 description 1
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Natural products C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 1
- ZJCCRDAZUWHFQH-UHFFFAOYSA-N Trimethylolpropane Chemical compound CCC(CO)(CO)CO ZJCCRDAZUWHFQH-UHFFFAOYSA-N 0.000 description 1
- RPDMQUQDEIOJGO-UHFFFAOYSA-N [diethoxy(methyl)silyl]methanol Chemical compound CCO[Si](C)(CO)OCC RPDMQUQDEIOJGO-UHFFFAOYSA-N 0.000 description 1
- 229920000800 acrylic rubber Polymers 0.000 description 1
- 125000002015 acyclic group Chemical group 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000006136 alcoholysis reaction Methods 0.000 description 1
- 125000002723 alicyclic group Chemical group 0.000 description 1
- 150000008064 anhydrides Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 210000000988 bone and bone Anatomy 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 239000004359 castor oil Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 235000013339 cereals Nutrition 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000002385 cottonseed oil Substances 0.000 description 1
- 235000012343 cottonseed oil Nutrition 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- AYOHIQLKSOJJQH-UHFFFAOYSA-N dibutyltin Chemical compound CCCC[Sn]CCCC AYOHIQLKSOJJQH-UHFFFAOYSA-N 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- 125000000118 dimethyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 125000001301 ethoxy group Chemical group [H]C([H])([H])C([H])([H])O* 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 150000004665 fatty acids Chemical class 0.000 description 1
- 235000021323 fish oil Nutrition 0.000 description 1
- 239000001530 fumaric acid Substances 0.000 description 1
- 125000005456 glyceride group Chemical group 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- RRAMGCGOFNQTLD-UHFFFAOYSA-N hexamethylene diisocyanate Chemical compound O=C=NCCCCCCN=C=O RRAMGCGOFNQTLD-UHFFFAOYSA-N 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 125000001183 hydrocarbyl group Chemical group 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 125000005609 naphthenate group Chemical group 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 150000003022 phthalic acids Chemical class 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 231100000683 possible toxicity Toxicity 0.000 description 1
- 238000010944 pre-mature reactiony Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- FZHAPNGMFPVSLP-UHFFFAOYSA-N silanamine Chemical compound [SiH3]N FZHAPNGMFPVSLP-UHFFFAOYSA-N 0.000 description 1
- 229960001922 sodium perborate Drugs 0.000 description 1
- YKLJGMBLPUQQOI-UHFFFAOYSA-M sodium;oxidooxy(oxo)borane Chemical compound [Na+].[O-]OB=O YKLJGMBLPUQQOI-UHFFFAOYSA-M 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000003549 soybean oil Substances 0.000 description 1
- 235000012424 soybean oil Nutrition 0.000 description 1
- 235000015096 spirit Nutrition 0.000 description 1
- 239000003784 tall oil Substances 0.000 description 1
- 239000012974 tin catalyst Substances 0.000 description 1
- DVKJHBMWWAPEIU-UHFFFAOYSA-N toluene 2,4-diisocyanate Chemical compound CC1=CC=C(N=C=O)C=C1N=C=O DVKJHBMWWAPEIU-UHFFFAOYSA-N 0.000 description 1
- RUELTTOHQODFPA-UHFFFAOYSA-N toluene 2,6-diisocyanate Chemical compound CC1=C(N=C=O)C=CC=C1N=C=O RUELTTOHQODFPA-UHFFFAOYSA-N 0.000 description 1
- 150000003626 triacylglycerols Chemical class 0.000 description 1
- QQQSFSZALRVCSZ-UHFFFAOYSA-N triethoxysilane Chemical compound CCO[SiH](OCC)OCC QQQSFSZALRVCSZ-UHFFFAOYSA-N 0.000 description 1
- 239000002383 tung oil Substances 0.000 description 1
- 150000004670 unsaturated fatty acids Chemical class 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
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
- C08G18/28—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
- C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
- C08G18/4288—Polycondensates having carboxylic or carbonic ester groups in the main chain modified by higher fatty oils or their acids or by resin acids
-
- 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
- B22C1/205—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 organic silicon or metal compounds, other organometallic compounds
-
- 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
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/54—Silicon-containing compounds
Definitions
- This invention relates to sand cores having increased tensile strengths at high temperatures.
- this invention relates to a foundry process for making sand cores using organic core binders containing an isocyanate, which process includes the incorporation into said cores of certain silanes.
- cores for use in making metal castings are usually prepared from mixtures of an aggregate (e.g. sand) which has been mixed with a binding amount of a polymerizable or curable binder.
- a polymerizable or curable binder e.g. sand
- foundry mixes e.g. sand
- the amount of binder used is typically less than by weight based on the weight of the sand, e.g. from 0.5 to 5% on the same basis.
- minor amounts of other materials are also included in foundry mixes, e.g. iron oxide, ground flax fibers and theulike.
- the binder permits a foundry mix to be molded or shaped :into the desired form, usually in a patternbox or mold, and thereafter cured to form a self-supporting structure (e.g. to form a sand core).
- core binders containing polyisocyanates and suitable coreactants. See,, for example, U.S'..S'er. No. 447,513, filed Apr. 12, 1965,,now Patent No.13,255,500.
- Certain binders of this, general type i.e. containing an isocyanate
- One such advantage is their ability to eifectively and rapidly form cured cores at room temperature-without the useof gaseous catalysts.
- cores prepared-with such binders can be baked to accelerate the cure.
- sand cores containing such isocyanate binder compositions can be'substantially increased at elevated temperatures and underhigh humidity conditions by the simple addition of a silane (e.g. 'y-aminopropyl tri-ethoxy silane) to the foundry mix.
- a silane e.g. 'y-aminopropyl tri-ethoxy silane
- one popular commercially-available,isocyanate .binder composition contains both an aromatic polyisocyanate and an oil-modified alkyd resin.
- step 2 (3) Introducing. the resulting foundry mix of step 2 intoa mold or pattern to thereby shape said mix;
- silanes used in this invention have the formula:
- R is a hydrocarbon radical, usually a C -C alkyl radical.
- R is an alkoxy radical, usually a C C alkoxy radical; ethoxy and methoxy radicals are preferred.
- R is a radical selected from the group of aminoalkyl, hydroxyalkyl, sulfhydrylalkyl, carboxyalkyl and N(aminoalkyl)aminoalkyl radicals.
- the alkyl portion(s) of R will usually contain 1-8 carbon atoms, preferably 1-3 carbon atoms, in each uninterrupted carbon chain (ignoring the carbon atom in the carboxyl group).
- Suitable silanes include hydroxypropyl tri-methoxy silane, hydroxymethyl di-ethoxy methyl silane, aminobutyl tri-methoxy silane, N(gamma-aminopropyl)- gamma-aminopropyl tri-methoxy silane, aminobutyl dimethoxymethyl silane, carboxypropyl tri-ethoxy silane, mercaptopropyl tri-methoxy silane, gamma-aminopropyl tri-ethoxy silane, and the like.
- the preferred silanes are the amino and poly-amino tri-alkoxy silanes. N(fl-aminoethyl) gamma aminopropyl tri methoxy silane and gamma-aminopropyl tri-ethoxy silane are the most preferred, with the latter being especially preferred.
- the amount of silane included in the foundry mix will be an effective amount of up to 1% based on the weight of sand. Frequently, the amount of silane will be within the range of 0.002 to 0.1% based on the weight of sand, e.g. from 0.005 to 0.05%.
- binder compositions which can be benefited by the practice of this invention are known to the art and are those which contain a polyisocyanate, usually with a hydroxyl-containing material as a co-reactant. Such isocyanate/hydroxyl binder systems are co-reacted at or about the time of use in th presence of sand.
- the reactive ingredients of such binder compositions are sold, shipped, and stored in separate packages (i.e. a multiple 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 polyisocyanate and its co-reactant.
- cyclic and acyclic polyisocyanates containing from 2-5 isocyanate groups are employed. If desired, mixtures of 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.
- a polyhydric alcohol e.g. a prepolymer of toluene diisocyanate and ethylene glycol
- 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, and diphenyl methane diisocyanate and the dimethyl derivative thereof.
- polyisocyanates are 1,5- naphthalene diisocyanate; triphenyl methane triisocyanate; xylylene diisocyanate and the methyl derivative thereof; polymethylene polyphenyl isocyanate; chlorophenylene-2,4-diisocyanate, and the like. All polyisocyanates do not serve with the same effectiveness. While the aforementioned polyisocyanates are, to a greater or lesser degree, effective in practicing the present invention, there are significant advantages associated with the use of cyclic polyisocyanates, especially the aromatic polyisocyanates, as contrasted to the aliphatic polyisocyanates.
- aromatic polyisocyanates impart more rigidity to cores than do the aliphatic polyisocyanates.
- Polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, and mixtures thereof are preferred because of their high degree of reactivity, desirable core forming properties, and low vapor pressure. The latter minimizes any possible toxicity problems.
- the co-reactant for the polyisocyanate can be hydroxylcontaining material, a natural drying oil, an air-hardenable petroleum polymer, a synthetic drying oil such as a dicyclopentadiene copolymer or a butadiene/styrene copolymer, or the like. Mixtures of such co-rea'ctants can be used. Co-reactants containing free or reactive hydroxyl groups are preferred.
- the hydroxyl-containing material to be co-reacted with the isocyanate can be a polyhydric alcohol (e.g. pentaerythritol).
- a polyhydric alcohol e.g. pentaerythritol
- high molecular weight hydroxyl-containing materials are preferred.
- the hydroxyl-containing co-reactant will be an alkyd resin (e.g. an oil-modified alkyd resin), a hydroxyl-terminated polyester (e.g. alcoholysis products of fatty triglycerides), and polymers and copolymers containing reactive hydroxyl groups (e.g. hydroxy-alkyl acrylate copolymers).
- Hydroxyl-containing materials which can be hardened, at least in part, by air oxidation are particularly preferred.
- drying oil-modified alkyd resins, as well as various unsaturated fatty acid esters and unsaturated fatty acid modified polyesters are preferred.
- oil-modified alkyd resins which have been prepared by co-reacting the following three classes of ingredients:
- polyhydric alcohols having at least three hydroxyl groups e.g. glycerol, pentaerythritol, trimethylol propane and the like. Pentaerythritol is preferred. Mixtures of polyhydric alcohols can be used. While glycols can be used, better results are obtained if such glycols are used in conjunction with the polyhydric alcohols (use a mixture of ethylene glycol and pentaerythritol). Ordinarily only the polyhydric alcohols will be used.
- Polycarboxylic acids such as maleic acid, fumaric acid, phthalic acid, phthalic anhydride, isophthalic acid, chlorendic acid and the like.
- the various phthalic acids are preferred. Mixtures of acids can be used.
- Oil such as soybean oil, linseed oil, cottonseed oil, castor and dehydrated castor oils, tall oil, tung oil, fish oil and the like. Mixtures of oils can be used. Linseed oil is preferred.
- the more preferred oil-modified alkyd resins will contain at least 40 weight percent oil (based on the total weight of the alkyd resin formulation). More desirably, the alkyd resins will contain at least 50 weight percent oil on the same basis (i.e. a long oil alkyd). It should be pointed out that oil-modified alkyd resins can also be prepared (as is known in the resin art) from fatty acids rather than the corresponding oils or glycerides. With alkyd resins, especially the oil-modified alkyd resins, the hydroxyl value should be at least 25 and preferably above 50. The upper limit of hydroxyl value is only limited by practical considerations, e.g. viscosity. For most ordinary applications, oil-modified alkyd resins having hydroxyl values of from 50-250, e.g. 60-150, are desirable.
- Catalysts are optionally and desirably used in conjunction with isocyanate core binders.
- the catalysts which are usually employed are those which accelerate the air oxidation or hardening of the oil-modified alkyd resin, those which accelerate the reaction between the polyisocyanate and the oil-modified alkyd resin, and those which do both.
- the amount of catalyst employed will be a catalytic amount, with the total amount of cata1yst(s) usually ranging from 0.0120%, based on the combined Weight of the polyisocyanate and oil-modified alkyd resin. More frequently, from 01-15%, e.g. 0.25-% catalyst will be 0:4 i used on the same basis.
- Metal naphthenates e.g. cobalt naphthenate
- Sodium perborate can also be used to promote the oxygen cross-linking of the oil-modified alkyd resin.
- Metal ion catalysts such as tetra(hydro-carbyl) tin catalysts are especially desired.
- Particularly preferred catalysts are the dibutyl tin di-hydrocarbyl catalysts. Dibutyl tin dilaurate is a very effective catalyst.
- the isocyanate binder system of the present invention can optionally be used in combination with other known binder systems.
- the foundry mixes of this invention can optionally include other ingredients such as iron oxide, ground flax fibers, wood cereal, pitch, etc.
- the total amount of isocyanate binder employed i.e. the total weight of isocyanate plus co-reactant
- the amount of binder (on the same basis) will be from 0.5 to weight percent, e.g. 13 weight percent.
- silane In mixing the silane, isocyanate, co-reactant, and catalyst with sand, it is advantageous to first mix the co-reactant (e.g. oil-modified alkyd resin or polyester) with the sand (and other optional ingredients), then add the catalyst with mixing, and finally add the polyisocyanate.
- the silane can be added at any point in this sequence of events. No advantages have been noted by, for example, pre-coating the sand with the silane. The resulting foundry mix will typically remain workable or plastic at room temperature for from 20100 minutes. Other variations of this procedure are knownand, under certain conditions, the catalyst can be omitted. However, catalysts are commonly and generally employed.
- This mixture is then molded or shaped into the desired form, usually in a pattern box or mold, and thereafter cured to form a sand core.
- this curing will be accomplished by simply allowing the binder to react at room temperature or by baking, or a combination of both techniques.
- the oilmodified alkyd resin had a hydroxyl number of about and was prepared from about 65% linseed oil, 14% pentaerythritol, and 21% isophthalic acid by conventional alkyd techniques.
- This multiple-package core binder was a commercially-available isocyanate binder (Lino-Cure, a product of Archer Daniels Midland Co.). During the preparation of this foundry mix, 0.01'part of gammaaminophopyl tri-ethoxy silane was added to the foundry IIllX.
- the specimens prepared from both foundry mixes were cured by heating overnight at 125 F. (about hours).
- the silanecontaining cores had an average tensile strength of 70 p.s.i.
- the tensile strengths were determined under identical conditions and the reported values are the actual measured values extrapolated back to zero bench time.
- Example II Two foundry mixes were prepared by repeating the procedure of Example I. Tensile specimens were prepared from both foundry mixes. The tensile specimens were cured for one hour at room temperature, then baked for minutes at 300 F., and then cooled to room tem perature in a desiccator. Tensile strengths were then obtained using a commercial tensile tester. The silane-containing specimens had an average tensile strength of 550 p.s.i. while the specimens without any silane had an average tensile strength of only 435 p.s.i. Again, the reported values are the actual values extrapolated back to zero bench time.
- Example II The procedure of Example II was repeated except that the cooling step was accomplished at 100% relative humidity instead of in a desiccator. The purpose of this was to determine the elfect of humidity, known to have an adverse effect on the tensile strengths of conventional isocyanate bonded sand cores.
- the average tensile strengths thus obtained were 450 p.s.i. for the silane-containing specimens and 360 p.s.i. for the specimens without the silane (strengths extrapolated to zero bench time).
- a further advantage to the inventive system is that the addition of a silane (or mixture thereof) does not adversely effect the performance of the otherwise effective isocyanate core binders.
- x and y are integers, x being zero (0) or one (1) and y being two (2) or three (3) with the sum of x and y being three (3); wherein R is an alkyl radical having 1 to 4 carbon atoms; wherein R is an alkoxy radical having 1 to 5 carbon atoms; and wherein R is an aminoalkyl, hydroxyalkyl, sulfhydrylalkyl, carboxyalkyl, or N(aminoalkyl)aminoalkyl radical having 1 to 8 carbon atoms in each of said alkyl groups.
- said co-reactant comprises oil-modified alkyd resin having a hydroxyl value of at least 25;
- said isocyanate comprises aromatic isocyanate having 2-5 isocyanate groups.
- said isocyanate comprises polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate, or triphenylmethane triisocyanate;
- said alkyd resin is prepared from linseed oil, isophthalic acid and pentaerythritol and contains over 50 weight percent linseed oil based on the total weight of the alkyd resin formulation;
- silane comprises N(;8-aminoethyl)-gamma-aminopropyl tri-methoxy silane or gamma-aminopropyl tri-ethoxy silane.
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Description
United States Patent 'TENSILE STRENGTHS OF CERTAIN SAND CORES Janis Robins, St, Paul, and Robert J. Schafer, Edina,
Minn., 'as'signor's to Ashland Oil & Refining Company,
Ashland, Ky., a corporation of Kentucky No Drawing. Filed June 13, 1966, Ser. No. 556,891
' Claims; (Cl. 164-43) ABSTRACT OF THE DISCLOSURE Process for forming foundry cores comprising sand and an organic binder comprising a hydroxyl-containing material, an isocyanate and a silane.
This invention relates to sand cores having increased tensile strengths at high temperatures. In one aspect, this invention relates to a foundry process for making sand cores using organic core binders containing an isocyanate, which process includes the incorporation into said cores of certain silanes.
In the foundry art, cores for use in making metal castings are usually prepared from mixtures of an aggregate (e.g. sand) which has been mixed with a binding amount of a polymerizable or curable binder. Such mixtures are referred to herein as foundry mixes. The amount of binder used is typically less than by weight based on the weight of the sand, e.g. from 0.5 to 5% on the same basis. Frequently, minor amounts of other materials are also included in foundry mixes, e.g. iron oxide, ground flax fibers and theulike. The binder permits a foundry mix to be molded or shaped :into the desired form, usually in a patternbox or mold, and thereafter cured to form a self-supporting structure (e.g. to form a sand core). I In recent years, the foundry arthas been provided with core binders containing polyisocyanates and suitable coreactants. See,,for example, U.S'..S'er. No. 447,513, filed Apr. 12, 1965,,now Patent No.13,255,500. Certain binders of this, general type (i.e. containing an isocyanate) have a number of outstanding advantages. One such advantage is their ability to eifectively and rapidly form cured cores at room temperature-without the useof gaseous catalysts. Optionally, cores prepared-with such binders can be baked to accelerate the cure. v
It has now been discovered-that the tensile strengths of sand cores containing such isocyanate binder compositions can be'substantially increased at elevated temperatures and underhigh humidity conditions by the simple addition of a silane (e.g. 'y-aminopropyl tri-ethoxy silane) to the foundry mix. For example, one popular commercially-available,isocyanate .binder composition contains both an aromatic polyisocyanate and an oil-modified alkyd resin. When this binder composition was used in the manner recommended by itsmanufacturer and a small amount of an amino-silane was simply added to the foundry mix, sand cores prepared from this foundry mix had tensile strengths at 300 F. which were 40% above the strengths obtained by exactly'the same procedure, omitting only the silane.- A k Thus, in the ordinary practicepf this invention, sand cores (or sand molds) for use in making metal castings will be preparedhy the following steps;
1) Forming a, foundry mix containing sand as the predominanbingredient and an; isocyanate core binder, which binder usually. includes a hydroxyl-containing coreactant and one or more catalystsr,
(2) .Simultaneously or separately mixing a silane with the sand ofstep 1;. r
(3) Introducing. the resulting foundry mix of step 2 intoa mold or pattern to thereby shape said mix; and
3,403,721 Patented Oct. 1, 1968 (4) Thereafter curing the shaped foundry mix to thereby form a sand core (or sand mold).
The silanes used in this invention have the formula:
wherein x and y are integers, x being Zero (0) or one (1) and 1 being two (2) or preferably three (3) with the sum of x and y being three (3). R is a hydrocarbon radical, usually a C -C alkyl radical. R is an alkoxy radical, usually a C C alkoxy radical; ethoxy and methoxy radicals are preferred. R is a radical selected from the group of aminoalkyl, hydroxyalkyl, sulfhydrylalkyl, carboxyalkyl and N(aminoalkyl)aminoalkyl radicals. The alkyl portion(s) of R will usually contain 1-8 carbon atoms, preferably 1-3 carbon atoms, in each uninterrupted carbon chain (ignoring the carbon atom in the carboxyl group).
Suitable silanes include hydroxypropyl tri-methoxy silane, hydroxymethyl di-ethoxy methyl silane, aminobutyl tri-methoxy silane, N(gamma-aminopropyl)- gamma-aminopropyl tri-methoxy silane, aminobutyl dimethoxymethyl silane, carboxypropyl tri-ethoxy silane, mercaptopropyl tri-methoxy silane, gamma-aminopropyl tri-ethoxy silane, and the like. The preferred silanes are the amino and poly-amino tri-alkoxy silanes. N(fl-aminoethyl) gamma aminopropyl tri methoxy silane and gamma-aminopropyl tri-ethoxy silane are the most preferred, with the latter being especially preferred.
The amount of silane included in the foundry mix will be an effective amount of up to 1% based on the weight of sand. Frequently, the amount of silane will be within the range of 0.002 to 0.1% based on the weight of sand, e.g. from 0.005 to 0.05%.
The binder compositions which can be benefited by the practice of this invention are known to the art and are those which contain a polyisocyanate, usually with a hydroxyl-containing material as a co-reactant. Such isocyanate/hydroxyl binder systems are co-reacted at or about the time of use in th presence of sand. Typically, the reactive ingredients of such binder compositions are sold, shipped, and stored in separate packages (i.e. a multiple 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 polyisocyanate and its co-reactant.
Typically, cyclic and acyclic polyisocyanates containing from 2-5 isocyanate groups are employed. If desired, mixtures of 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, and diphenyl methane diisocyanate and the dimethyl derivative thereof. Further examples of suitable polyisocyanates are 1,5- naphthalene diisocyanate; triphenyl methane triisocyanate; xylylene diisocyanate and the methyl derivative thereof; polymethylene polyphenyl isocyanate; chlorophenylene-2,4-diisocyanate, and the like. All polyisocyanates do not serve with the same effectiveness. While the aforementioned polyisocyanates are, to a greater or lesser degree, effective in practicing the present invention, there are significant advantages associated with the use of cyclic polyisocyanates, especially the aromatic polyisocyanates, as contrasted to the aliphatic polyisocyanates. In general, aromatic polyisocyanates impart more rigidity to cores than do the aliphatic polyisocyanates. Polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, and mixtures thereof are preferred because of their high degree of reactivity, desirable core forming properties, and low vapor pressure. The latter minimizes any possible toxicity problems.
The co-reactant for the polyisocyanate can be hydroxylcontaining material, a natural drying oil, an air-hardenable petroleum polymer, a synthetic drying oil such as a dicyclopentadiene copolymer or a butadiene/styrene copolymer, or the like. Mixtures of such co-rea'ctants can be used. Co-reactants containing free or reactive hydroxyl groups are preferred.
The hydroxyl-containing material to be co-reacted with the isocyanate can be a polyhydric alcohol (e.g. pentaerythritol). However, high molecular weight hydroxyl-containing materials are preferred. Preferably, the hydroxyl-containing co-reactant will be an alkyd resin (e.g. an oil-modified alkyd resin), a hydroxyl-terminated polyester (e.g. alcoholysis products of fatty triglycerides), and polymers and copolymers containing reactive hydroxyl groups (e.g. hydroxy-alkyl acrylate copolymers). Hydroxyl-containing materials which can be hardened, at least in part, by air oxidation are particularly preferred. Thus, drying oil-modified alkyd resins, as well as various unsaturated fatty acid esters and unsaturated fatty acid modified polyesters are preferred. Oil-modified alkyd resins are the most preferred hydroxyl-containing reactants.
It is preferred to employ oil-modified alkyd resins which have been prepared by co-reacting the following three classes of ingredients:
(a) Polyhydric alcohols having at least three hydroxyl groups, e.g. glycerol, pentaerythritol, trimethylol propane and the like. Pentaerythritol is preferred. Mixtures of polyhydric alcohols can be used. While glycols can be used, better results are obtained if such glycols are used in conjunction with the polyhydric alcohols (use a mixture of ethylene glycol and pentaerythritol). Ordinarily only the polyhydric alcohols will be used.
(b) Polycarboxylic acids (or their anhydrides) such as maleic acid, fumaric acid, phthalic acid, phthalic anhydride, isophthalic acid, chlorendic acid and the like. The various phthalic acids (particularly isophthalic acid and phthalic anhydride) are preferred. Mixtures of acids can be used.
(c) Oil such as soybean oil, linseed oil, cottonseed oil, castor and dehydrated castor oils, tall oil, tung oil, fish oil and the like. Mixtures of oils can be used. Linseed oil is preferred.
The more preferred oil-modified alkyd resins will contain at least 40 weight percent oil (based on the total weight of the alkyd resin formulation). More desirably, the alkyd resins will contain at least 50 weight percent oil on the same basis (i.e. a long oil alkyd). It should be pointed out that oil-modified alkyd resins can also be prepared (as is known in the resin art) from fatty acids rather than the corresponding oils or glycerides. With alkyd resins, especially the oil-modified alkyd resins, the hydroxyl value should be at least 25 and preferably above 50. The upper limit of hydroxyl value is only limited by practical considerations, e.g. viscosity. For most ordinary applications, oil-modified alkyd resins having hydroxyl values of from 50-250, e.g. 60-150, are desirable.
Catalysts are optionally and desirably used in conjunction with isocyanate core binders. The catalysts which are usually employed are those which accelerate the air oxidation or hardening of the oil-modified alkyd resin, those which accelerate the reaction between the polyisocyanate and the oil-modified alkyd resin, and those which do both. The amount of catalyst employed will be a catalytic amount, with the total amount of cata1yst(s) usually ranging from 0.0120%, based on the combined Weight of the polyisocyanate and oil-modified alkyd resin. More frequently, from 01-15%, e.g. 0.25-% catalyst will be 0:4 i used on the same basis. The choice of catalyst and the amount thereof will aifect the curing rate ofthe sys tem. Metal naphthenates (e.g. cobalt naphthenate) are effective catalysts for both the isocyanate/hydroxyl reaction and the air oxidation of the hydroxyl-containing alkyd resin, the latter being their primary function. Sodium perborate can also be used to promote the oxygen cross-linking of the oil-modified alkyd resin. Metal ion catalysts such as tetra(hydro-carbyl) tin catalysts are especially desired. Particularly preferred catalysts are the dibutyl tin di-hydrocarbyl catalysts. Dibutyl tin dilaurate is a very effective catalyst.
The isocyanate binder system of the present invention can optionally be used in combination with other known binder systems. Also, the foundry mixes of this invention can optionally include other ingredients such as iron oxide, ground flax fibers, wood cereal, pitch, etc.
When combining the isocyanate and its co-reactant (e.g. an oil-modified alkyd resin) with sand at or about the time a sand core is to be made, it is common to use from 5-150 parts by weight of polyisocyanate per parts by weight of the coreactant. More frequently, from 5-90 parts, e.g. from 8-50 parts of polyisocyanate will be used on the same basis. With our preferred embodiment it is common to use from 10-40 parts, e.g. 1030 parts of polyisocyanate on the same basis. I
The total amount of isocyanate binder employed (i.e. the total weight of isocyanate plus co-reactant), based on the weight of sand, will be a binding amount of up to 10%. Generally, the amount of binder (on the same basis) will be from 0.5 to weight percent, e.g. 13 weight percent.
In mixing the silane, isocyanate, co-reactant, and catalyst with sand, it is advantageous to first mix the co-reactant (e.g. oil-modified alkyd resin or polyester) with the sand (and other optional ingredients), then add the catalyst with mixing, and finally add the polyisocyanate. The silane can be added at any point in this sequence of events. No advantages have been noted by, for example, pre-coating the sand with the silane. The resulting foundry mix will typically remain workable or plastic at room temperature for from 20100 minutes. Other variations of this procedure are knownand, under certain conditions, the catalyst can be omitted. However, catalysts are commonly and generally employed.
This mixture is then molded or shaped into the desired form, usually in a pattern box or mold, and thereafter cured to form a sand core. Depending upon the nature of the polyisocyanate, co-reactant, and catalyst, this curing will be accomplished by simply allowing the binder to react at room temperature or by baking, or a combination of both techniques. Q r
The present invention will be further understood by reference to the following specific examples which include the best mode known to the inventors for practicing their invention. Unless otherwise indicated, all parts and percentages are by weights r EXAMPLE I Sand cores were prepared in the conventional dog bone shape used for determining tensile strengths. These specimens were preparedby conventional techniques from a foundry mix containing 100 parts of Lake sand, (1) 1.6 parts of a mixture containing 47% oil-modified alkyd resin, 29% air-hardenable petroleum polymer, and 24% mineral spirits; (2) one part of a solution of cobalt naphthenate and dibutyl tin dilaurate; and (3) k 0.24 part diphenylmethane diisocyanate (Mondur MR). The oilmodified alkyd resin had a hydroxyl number of about and was prepared from about 65% linseed oil, 14% pentaerythritol, and 21% isophthalic acid by conventional alkyd techniques. This multiple-package core binder was a commercially-available isocyanate binder (Lino-Cure, a product of Archer Daniels Midland Co.). During the preparation of this foundry mix, 0.01'part of gammaaminophopyl tri-ethoxy silane was added to the foundry IIllX.
For purposes of comparison, the procedure was repeated exactly, with the sole exception being the omission of the silane.
The specimens prepared from both foundry mixes were cured by heating overnight at 125 F. (about hours).
When the tensile strengths of these specimens were tested at 300 F. using a commercial tensile tester, the silanecontaining cores had an average tensile strength of 70 p.s.i. The other specimens, without any silane, had an average tensile strength of only 50 p.s.i. The tensile strengths were determined under identical conditions and the reported values are the actual measured values extrapolated back to zero bench time.
EXAMPLE II Two foundry mixes were prepared by repeating the procedure of Example I. Tensile specimens were prepared from both foundry mixes. The tensile specimens were cured for one hour at room temperature, then baked for minutes at 300 F., and then cooled to room tem perature in a desiccator. Tensile strengths were then obtained using a commercial tensile tester. The silane-containing specimens had an average tensile strength of 550 p.s.i. while the specimens without any silane had an average tensile strength of only 435 p.s.i. Again, the reported values are the actual values extrapolated back to zero bench time.
EXAMPLE IlII The procedure of Example II was repeated except that the cooling step was accomplished at 100% relative humidity instead of in a desiccator. The purpose of this was to determine the elfect of humidity, known to have an adverse effect on the tensile strengths of conventional isocyanate bonded sand cores.
The average tensile strengths thus obtained were 450 p.s.i. for the silane-containing specimens and 360 p.s.i. for the specimens without the silane (strengths extrapolated to zero bench time).
EXAMPLE IV Results similar to those obtained in Examples I-III will be obtained when N(B-aminoethyl)-gamma-aminopropyl tri-methoxy silane is substituted for the gamma-aminopropyl tri-ethoxy silane of Examples I-III.
EXAMPLE V Results similar to those obtained in Examples I-III will be obtained when a mixture of equal parts by weight of mercaptopropyl tri-methoxy silane and aminobutyl trimethoxy silane is substituted for the gamma-aminopropyl tri-ethoxy silane of Examples I-III.
From the foregoing description and examples, it will be appreciated that a novel procedure'has been developed for increasing the tensile strengths of sand cores at elevated temperatures and under conditions of high humidity, which cores have been prepared using isocyanate binder compositions. By simply adding small amounts, e.g. 0.01% of a silane of the type described herein (based on the weight of sand) to a foundry sand mix highly desirable sand cores and molds can be obatined.
A further advantage to the inventive system is that the addition of a silane (or mixture thereof) does not adversely effect the performance of the otherwise effective isocyanate core binders.
Although the present invention has been described with a certain degree of particularity, it will be realized that numerous minor changes and variations, falling within the spirit and scope of this invention, will become obvious to those skilled in the art. It is not intended that this invention be limited to any of the materials which have been specifically mentioned for the sake of illustration, nor by the specific proportions which have been given for the sake of illustration.
What is claimed is:
1. In a process for preparing sand cores wherein an organic binder containing an isocyanate and a suitable co-reactant for said isocyanate is mixed with sand to form a foundry mix, the foundry mix is shaped and thereafter cured to form a sand core by reacting said isocyanate and said co-reactant in the presence of said sand, the improvement which comprises including in said foundry mix a silane of the formula:
wherein x and y are integers, x being zero (0) or one (1) and y being two (2) or three (3) with the sum of x and y being three (3); wherein R is an alkyl radical having 1 to 4 carbon atoms; wherein R is an alkoxy radical having 1 to 5 carbon atoms; and wherein R is an aminoalkyl, hydroxyalkyl, sulfhydrylalkyl, carboxyalkyl, or N(aminoalkyl)aminoalkyl radical having 1 to 8 carbon atoms in each of said alkyl groups.
2. The process of claim 1 wherein the amount of silane is from 0.005 to 0.05% by weight based on the weight of said sand.
3. The process of claim 2 wherein:
(a) xis zero(0);
(b) the alkyl portions of R each contain 1-3 carbon atoms;
(c) said co-reactant comprises oil-modified alkyd resin having a hydroxyl value of at least 25; and
(d) said isocyanate comprises aromatic isocyanate having 2-5 isocyanate groups.
4. The process of claim 3 wherein:
(a) said isocyanate comprises polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate, or triphenylmethane triisocyanate;
(b) said alkyd resin is prepared from linseed oil, isophthalic acid and pentaerythritol and contains over 50 weight percent linseed oil based on the total weight of the alkyd resin formulation; and
(c) said curing is accomplished at room temperature with the aid of catalyst which has been included in said foundry mix.
5. The process of claim 4 wherein said silane comprises N(;8-aminoethyl)-gamma-aminopropyl tri-methoxy silane or gamma-aminopropyl tri-ethoxy silane.
References Cited UNITED STATES PATENTS 4/1966 Haluska. 6/ 1966 Engel et a1.
U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, 0.6. 20231 UNITED STATES P ATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,403,721 October 1, 1968 Janis Robins et a1.
It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:
Column 4, line 25, "10-30" should'read 15-30 line 31, after "0.5" insert 5 Column 5, line 1, "aminophopyl" should read aminopropyl line 63, "obatined" should read obtained Signed and sealed this 10th day of'March 1970.
(SEAL) Attest:
Edward M. Fletcher, Jr.
Attesting Officer Commissioner of Patents
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US3839265A (en) * | 1972-02-09 | 1974-10-01 | Texaco Ag | Polymeric composition and method |
US3862080A (en) * | 1971-06-29 | 1975-01-21 | Catalin Limited | Foundry binder compositions |
US3875090A (en) * | 1973-05-24 | 1975-04-01 | Nl Industries Inc | Impact and abrasion resistant coating composition |
US4072649A (en) * | 1974-08-23 | 1978-02-07 | Bayer Aktiengesellschaft | Process for the production of foundry cores and molds |
US4086211A (en) * | 1975-03-14 | 1978-04-25 | Bridgestone Tire Company Limited | Method of producing polyurethane products having an improved flex crack resistance |
US4144215A (en) * | 1978-06-21 | 1979-03-13 | International Minerals & Chemical Corp. | Binders for foundry mixes comprising polyisocyanate and styrene-allyl alcohol copolymer or alkylene oxide derivative thereof |
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US4172068A (en) * | 1978-07-24 | 1979-10-23 | International Minerals & Chemical Corporation | Foundry core composition of aggregate and a binder therefor |
US4205987A (en) * | 1978-11-15 | 1980-06-03 | Eastman Kodak Company | Sulfonamido phenol scavenger compounds |
US4209428A (en) * | 1977-07-21 | 1980-06-24 | Fordath Limited | Foundry binders |
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US4268425A (en) * | 1979-05-14 | 1981-05-19 | Ashland Oil, Inc. | Phenolic resin-polyisocyanate binder systems containing a drying oil and use thereof |
US4318840A (en) * | 1980-12-17 | 1982-03-09 | The Quaker Oats Company | Binders for foundry core sands |
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US4320043A (en) * | 1981-01-12 | 1982-03-16 | The Quaker Oats Company | Furfuryl alcohol-dialdehyde foundry binders |
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US5190993A (en) * | 1988-04-08 | 1993-03-02 | Borden, Inc. | Process to enhance the tensile strength of reclaimed sand bonded with ester cured alkaline phenolic resin using an aminosilane solution |
US5234973A (en) * | 1988-04-08 | 1993-08-10 | Acme Resin Corporation | Compositions for foundry molding processes utilizing reclaimed sand |
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US3246048A (en) * | 1962-09-14 | 1966-04-12 | Dow Corning | Organosiloxane-polyether urethanes |
US3255500A (en) * | 1965-02-01 | 1966-06-14 | Archer Daniels Midland Co | Foundry composition comprising sand, drying oil and polyisocyanate |
Cited By (26)
Publication number | Priority date | Publication date | Assignee | Title |
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US3720642A (en) * | 1969-10-02 | 1973-03-13 | Dynamit Nobel Ag | Use of modified resins as binding agents for mineral substances |
US3862080A (en) * | 1971-06-29 | 1975-01-21 | Catalin Limited | Foundry binder compositions |
US3839265A (en) * | 1972-02-09 | 1974-10-01 | Texaco Ag | Polymeric composition and method |
US3875090A (en) * | 1973-05-24 | 1975-04-01 | Nl Industries Inc | Impact and abrasion resistant coating composition |
US4072649A (en) * | 1974-08-23 | 1978-02-07 | Bayer Aktiengesellschaft | Process for the production of foundry cores and molds |
US4086211A (en) * | 1975-03-14 | 1978-04-25 | Bridgestone Tire Company Limited | Method of producing polyurethane products having an improved flex crack resistance |
US4148777A (en) * | 1977-05-09 | 1979-04-10 | Delta Oil Products Corporation | Binder for foundry process |
US4209428A (en) * | 1977-07-21 | 1980-06-24 | Fordath Limited | Foundry binders |
US4224201A (en) * | 1977-07-21 | 1980-09-23 | Fordath Limited | Foundry binders |
US4144215A (en) * | 1978-06-21 | 1979-03-13 | International Minerals & Chemical Corp. | Binders for foundry mixes comprising polyisocyanate and styrene-allyl alcohol copolymer or alkylene oxide derivative thereof |
US4256623A (en) * | 1978-07-06 | 1981-03-17 | Dynamit Nobel Aktiengesellschaft | Binding agents prepared from resins containing adhesivizing agents of long shelf life |
US4172068A (en) * | 1978-07-24 | 1979-10-23 | International Minerals & Chemical Corporation | Foundry core composition of aggregate and a binder therefor |
US4205987A (en) * | 1978-11-15 | 1980-06-03 | Eastman Kodak Company | Sulfonamido phenol scavenger compounds |
US4268425A (en) * | 1979-05-14 | 1981-05-19 | Ashland Oil, Inc. | Phenolic resin-polyisocyanate binder systems containing a drying oil and use thereof |
US4318840A (en) * | 1980-12-17 | 1982-03-09 | The Quaker Oats Company | Binders for foundry core sands |
US4320042A (en) * | 1980-12-17 | 1982-03-16 | The Quaker Oats Company | Binder compositions and process for preparing said compositions |
US4320043A (en) * | 1981-01-12 | 1982-03-16 | The Quaker Oats Company | Furfuryl alcohol-dialdehyde foundry binders |
US4782102A (en) * | 1982-12-27 | 1988-11-01 | Union Carbide Corporation | Novel organofunctional silanes containing hindered group |
US4645817A (en) * | 1984-04-26 | 1987-02-24 | Bayer Aktiengesellschaft | Preparation of hydroxyl group-containing alkoxylation products of organic carboxylic acids |
US5082876A (en) * | 1988-04-08 | 1992-01-21 | Borden, Inc. | Compositions for foundry molding processes utilizing reclaimed sand |
US5190993A (en) * | 1988-04-08 | 1993-03-02 | Borden, Inc. | Process to enhance the tensile strength of reclaimed sand bonded with ester cured alkaline phenolic resin using an aminosilane solution |
US5234973A (en) * | 1988-04-08 | 1993-08-10 | Acme Resin Corporation | Compositions for foundry molding processes utilizing reclaimed sand |
US5238976A (en) * | 1990-06-15 | 1993-08-24 | Borden, Inc. | Process to enhance the tensile strength of reclaimed sand bonded with ester cured alkaline phenolic resin |
WO1997041876A1 (en) * | 1996-05-07 | 1997-11-13 | Emory University | Water-stabilized organosilanes and methods for use |
US5959014A (en) * | 1996-05-07 | 1999-09-28 | Emory University | Water-stabilized organosilane compounds and methods for using the same |
US6221944B1 (en) | 1996-05-07 | 2001-04-24 | Emory University | Water-stabilized organosilane compounds and methods for using the same |
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