GB1569480A - Methods of making foundry moulds or cores - Google Patents
Methods of making foundry moulds or cores Download PDFInfo
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- GB1569480A GB1569480A GB15239/77A GB1523977A GB1569480A GB 1569480 A GB1569480 A GB 1569480A GB 15239/77 A GB15239/77 A GB 15239/77A GB 1523977 A GB1523977 A GB 1523977A GB 1569480 A GB1569480 A GB 1569480A
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- acid
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- polymeric carboxylic
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- 238000000034 method Methods 0.000 title claims description 39
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 46
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 44
- 239000000203 mixture Substances 0.000 claims description 40
- 150000001735 carboxylic acids Chemical class 0.000 claims description 33
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 claims description 29
- 239000011975 tartaric acid Substances 0.000 claims description 29
- 235000002906 tartaric acid Nutrition 0.000 claims description 29
- 235000011007 phosphoric acid Nutrition 0.000 claims description 25
- 239000011230 binding agent Substances 0.000 claims description 24
- 239000002253 acid Substances 0.000 claims description 23
- 239000000395 magnesium oxide Substances 0.000 claims description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 23
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 21
- 239000011521 glass Substances 0.000 claims description 20
- 229920002125 Sokalan® Polymers 0.000 claims description 12
- 239000004568 cement Substances 0.000 claims description 12
- 239000000243 solution Substances 0.000 claims description 12
- 239000004576 sand Substances 0.000 claims description 11
- 239000003607 modifier Substances 0.000 claims description 10
- 239000004584 polyacrylic acid Substances 0.000 claims description 8
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 claims description 7
- 238000007493 shaping process Methods 0.000 claims description 7
- 239000005354 aluminosilicate glass Substances 0.000 claims description 6
- 239000007864 aqueous solution Substances 0.000 claims description 6
- 150000002500 ions Chemical class 0.000 claims description 6
- 238000002386 leaching Methods 0.000 claims description 5
- 239000011819 refractory material Substances 0.000 claims description 5
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 4
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 4
- 150000007513 acids Chemical class 0.000 claims description 4
- 229920001519 homopolymer Polymers 0.000 claims description 4
- IYXGAVFNZJFSBQ-UHFFFAOYSA-N 2,3-dihydroxybutanedioic acid;phosphoric acid Chemical compound OP(O)(O)=O.OC(=O)C(O)C(O)C(O)=O IYXGAVFNZJFSBQ-UHFFFAOYSA-N 0.000 claims description 2
- 230000000052 comparative effect Effects 0.000 claims description 2
- 230000000694 effects Effects 0.000 claims description 2
- 238000007429 general method Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 150000003016 phosphoric acids Chemical class 0.000 claims description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 13
- 230000006835 compression Effects 0.000 description 6
- 238000007906 compression Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 5
- 238000005266 casting Methods 0.000 description 5
- 150000007519 polyprotic acids Polymers 0.000 description 5
- 239000012467 final product Substances 0.000 description 4
- 239000004615 ingredient Substances 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 239000003479 dental cement Substances 0.000 description 3
- XPFVYQJUAUNWIW-UHFFFAOYSA-N furfuryl alcohol Chemical compound OCC1=CC=CO1 XPFVYQJUAUNWIW-UHFFFAOYSA-N 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 229920001577 copolymer Polymers 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 2
- 239000011236 particulate material Substances 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000011787 zinc oxide Substances 0.000 description 2
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 1
- HEANZWXEJRRYTD-UHFFFAOYSA-M 2-[(6-hexadecanoylnaphthalen-2-yl)-methylamino]ethyl-trimethylazanium;chloride Chemical compound [Cl-].C1=C(N(C)CC[N+](C)(C)C)C=CC2=CC(C(=O)CCCCCCCCCCCCCCC)=CC=C21 HEANZWXEJRRYTD-UHFFFAOYSA-M 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 239000003377 acid catalyst Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 239000013522 chelant Substances 0.000 description 1
- 239000002738 chelating agent Substances 0.000 description 1
- 229910001610 cryolite Inorganic materials 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- 208000002925 dental caries Diseases 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- 230000008570 general process Effects 0.000 description 1
- 239000000383 hazardous chemical Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 239000012633 leachable Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 229910001629 magnesium chloride Inorganic materials 0.000 description 1
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 1
- 239000000347 magnesium hydroxide Substances 0.000 description 1
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 1
- YIXJRHPUWRPCBB-UHFFFAOYSA-N magnesium nitrate Inorganic materials [Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O YIXJRHPUWRPCBB-UHFFFAOYSA-N 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 238000005058 metal casting Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 1
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 229910052609 olivine Inorganic materials 0.000 description 1
- 239000010450 olivine Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- BDHFUVZGWQCTTF-UHFFFAOYSA-N sulfonic acid Chemical compound OS(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-N 0.000 description 1
- 239000001117 sulphuric acid Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- JOXIMZWYDAKGHI-UHFFFAOYSA-N toluene-4-sulfonic acid Chemical compound CC1=CC=C(S(O)(=O)=O)C=C1 JOXIMZWYDAKGHI-UHFFFAOYSA-N 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 230000002110 toxicologic effect Effects 0.000 description 1
- 231100000027 toxicology Toxicity 0.000 description 1
- 210000000689 upper leg Anatomy 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 229910052845 zircon Inorganic materials 0.000 description 1
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- B22C1/18—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 inorganic agents
-
- 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
- B22C1/167—Mixtures of inorganic and organic binding agents
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Inorganic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Description
(54) METHODS OF MAKING FOUNDRY MOULDS OR CORES
(71) We, THE WHITE SEA & BALTIC COMPANY LIMITED, a British Company of
Patman House, George Lane, South Woodford, London, E18 2SA, do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement:
The traditional surgical cements, such as the cements used as dental cements for providing a base and/or lining in a tooth cavity, have often been made by mixing together a zinc oxide powder and a buffered orthophosphoric acid solution immediately prior to use. In British
Patent Specification No. 1,139,430 dental cements are described prepared by mixing together in particular proportions a particular grade of polyacrylic acid with zinc oxide.Zinc oxide can have mixed with it a small amount, 10% in an example, of other oxides such as magnesium oxide. In British Patent Specification No. 1,316,129 surgical cements are described formed by mixing together with polycarboxylic acid, such as polyacrylic acid, of particular molecular weight, with a fluoro aluminosilicate glass powder having particular proportions of silica, alumina and fluorine.
The products according to Patent Specification No. 1,316,129 have commonly become referred to as A.S.P.A. cements and are of increasing importance commercially in surgical applications.
In surgical situations rapid hardening of the cement is essential and according to British
Patent Specification No. 1,422,337 the hardening of cements such as those described in 1,316,129 and 1,139,430 can be accelerated by including up to 20%, based on the weight of polycarboxylic acid, of a chelating agent, preferably citric acid, tartaric acid or a metal chelate.
Metal casting is generally conducted using a foundry sand mould or core. This is made by forming a foundry sand by mixing an inert refractory particulate material, such as sand, with a small amount of a curable binder and then curing the system, preferably at low or room temperature. After casting the mould or core is destroyed. It is preferred that it shall be easy to shatter it and that the residue can easily be recovered for further use and/or dumped without creating a toxicological hazard.Of the two main types of binder system used at present the sodium silicate binders suffer from the disadvantage that the destruction of the mould can be difficult whilst the organic binders, such as synthetic resins based on furfuryl alcohol, urea, and/or phenol condensed with formaldehyde, catalysed with a strong acid, can give environmental hazards and require the use of materials of variable availability and high price.
It is essential that a foundry binder shall cure sufficiently slowly to permit shaping of the mix before curing starts, but sufficiently fast that once the mix is shaped curing is thereafter completed rapidly to give a product having thigh strength.
In British Patent Application No. 14822/75 Serial No. 1546372) a process is described in which a foundary mould or core is made by using as binder an organic polybasic acid and an ion leachable inorganic particulate reactive material, such as the inorganic materials described in British Patent Specifications Nos. 1,139,430 or 1,316,129. It was described therein that the organic polybasic acid could be for example tartaric acid or paratoluenesulphonic acid, a mixture of organic polybasic acids, and mixtures of organic polybasic acids with inorganic acids. The preferred polybasic acid described therein is a polymeric polyacid, preferably a homopolymer or copolymer of acrylic acid.
We have now surprisingly found that very beneficial results are obtained when particular mixtures of ingredients are used as the binder. In particular, a method according to the invention of making a foundry mould or core comprises shaping a mix of a particulate inert refractory material and a binder and allowing the mix to cure, and in this method the binder comprises (a) a water soluble acid component comprising a polymeric carboxylic acid, (b) an alumino silicate glass that can react with the polymeric carboxylic acid by leaching of ions to form a cement, (c) water in an amount of below 5 % the total weight of the mix and (d) at least one modifier selected from tartaric acid, phosphoric acid and particulate fused magnesia, the or each modifier being present in an amount of at least 25%by weight based on the weight of polymeric carboxylic acid.
In one method, at least 25 % tartaric acid (by weight based on polymeric carboxylic acid) is included as modifier. This gives slower setting and improved properties of the final product.
In another method, at least 25 % phosphoric acid (by weight based on polymeric carboxylic acid) is included as modifier. This gives improved properties of the final product, especially improved strength. Preferably at least 25% of each of tartaric acid and phosphoric acid are included. In another method at least 25% fused particulate magnesia is included as modifier.
This gives improved properties in the final product, especially hardness.
The particulate inert refractory material may be selected from any of the inorganic particulate materials conventionally used for making foundry moulds or cores, for example refractory oxides and silicates such as sand, zircon sand, chromite and crushed olivine rock.
The polymeric carboxylic acid used in the invention is preferably a homopolymer of acrylic acid although copolymers of it with other unsaturated carboxylic acids, for example, itaconic acid, can be used if desired. Preferably it is substantially linear and has an average molecular weight from 1000 to 100,000 most preferably 10,000 to 100,000. The amount based on the total weight of the mix is generally 0.3 to 2% and based on the total acid component it is generally at least 10%, preferably 15 to 50% by weight. Normally the acid component consists of the polymeric carboxylic acid alone with tartaric and/or phosphoric acid.
Suitable alumino silicate glasses that will form a cement by leaching of ions from the glass upon contact with the aqueous solution of polymeric carboxylic acid are described in, for example, the aforementioned British Patent Specification 1,316,129. Reference should be made to that specification for a full description of suitable reactive materials. The preferred reactive materials comprise fluoro-aluminosilicate glasses for example, made by fusing mixtures of silica, alumina, cryolite and fluoride in the chosen proportions at temperatures above 950"C. Preferably the glass will pass through a 350 B.S. mesh, although glass in the form of fibres may be used if desired.
The surface hardness of the final product is improved when fused particulate magnesia is included as a modifier that will also react with the polymeric carboxylic acid by leaching of ions to form a cement. The amount is normally at least 50%by weight based on the polymeric carboxylic acid or 10 to 100%, most preferably 25 to 75%, especially 50 to 70% by weight based on the glass. If too much is used the cured product tends to be slightly thermoplastic during casting, while if too little is used the desired improvement in hardness is not obtained.
In order that an optimum rate of curing and improvement in results is obtained it is necessary to use a fused magnesia, as opposed to other forms of magnesia or other metal oxides. The fusion apparently results in a controlled deactivation of the magnesia. Suitable fused magnesia can be made by calcination of materials such as magnesium hydroxide, carbonate, sulphate, nitrate or chloride in one stage, or can be made by calcination to produce magnesium oxide which is then fused to deactivate it. The fusion, either in a single stage or two stage process, preferably comprises heating at a temperature of 800 to 1 5000C, preferably 1200 to 14000C, for 3 to 5 hours. The particle size of the fused magnesia should be from 5 to 50 microns, preferably less than 300 mesh.
When tartaric acid is used, either alone or with phosphoric acid, the amount is preferably at least 50 based on the weight of polymeric carboxylic acid and most preferably is from 100 to 400who, eg. 150 to 250%, normally 200%. The amount based on the total weight of the mix is generally 0.3 to 2%, preferably 0.5 to 1.5%. It will be noted that the amount is very much more than the 20% maximum recommended in British Patent Specification No. 1,422,337.
We find surprisingly that the inclusion of the large amount of tartaric acid leads to a number of advantages that could not have been predicted, for instance, by having a combination of polymeric carboxylic acid and tartaric acid it is possible to slow down the rate of curing in a manner which is highly advantageous for foundry purposes. In British Specification No.
1,422,337 the addition of a small amount of tartaric acid was proposed as a way of accelerating the setting of the cement. While accelerated rates of setting are desirable in dental cements, as described in that specification, in foundry processes it is necessary to control the rate of cure to permit thorough mixing of the very bulky mix and shaping of it into the desired mould or core before setting starts. British Specification No. 1422337 would have suggested that tartaric acid would make the mix set more quickly but in fact we find that the large amounts now proposed make it set more slowly.
Another surprising advantage of the inclusion of a large amount of tartaric acid is that water necessarily has to be included in the binder (generally as the aqueous solution of the polymeric carboxylic acid) and this has a tendency to remain within the cured mix, and this can become serious with very large moulds or cores. However the inclusion of tartaric acid seems to reduce or eliminate this problem in that the water in some way is fixed and evaporation of it during subsequent casting of the metal against the mould or core does not seem to cause such a problem.
Another advantage is that desirable improvement in the strength of the mould is obtained when tartaric acid is used.
When phosphoric acid is included, either along or with tartaric acid, it is preferably included in an amount of at least 33% by weight based on the dry weight of polymeric carboxylic acid, generally 50 to 300% and most preferably 75 or 100%to 200%. The amount based on the total weight of the mix is preferably 0.3 to 2%, usually 0.4 to 0.8%. Surprisingly, we have found that the inclusion of phosphoric acid in this manner causes a very large increase in strength, which increase does not seem to be attainable by any other strong acid addition that we have tested.
The amount of water in the mix must be sufficient for the polymeric carboxylic acid to be in solution and can be introduced as solvent for one or more of the acids or as free water. The polymeric acid can be introduced into the mix either as the desired solution or as a powder, provided extra water is included. Generally the total amount of water included in the mix is sufficient for the polymeric carboxylic acid to be present as a solution of from 15 to 35% based on the total weight of the mix. The phosphoric acid is generally introduced in concentrated form, for example 85%. The tartaric acid may be introduced as powder or solution, but if solution the amount of water should be kept sufficiently low that the total amount of water is still within the preferred range quoted above.Usually the polycarboxylic acid is introduced as a solution and no other significant amount of water is added.
The amount of glass and fused magnesia (if present) is preferably from 1 to 10%, most preferably about 1.2 to 3.5% based on the total weight of mix, or 800 to 200%, eg. about 300% based on the polymeric acid weight. The total amount of binder ingredients is generally from 2 to 20%, by weight of the mix, the remainder being the particulate inert refractory material.
The foundry mould or core is made in the invention by forming the mix by simple mixing, casting it into the desired shape while it retains its plastic properties (generally a period of from 10 to 30 minutes from the beginning of mixing, and then allowing it to cure. Generally it has acquired adequate green strength in 20-30 minutes but is then left to cure further for at least 24 hours before use. Metal may be cast in it in the normal manner and the mould or core shattered to remove the casting. A particular advantage of the bidners of the invention is that the resultant waste foundry sand does not include any toxic ingredients and can be reclaimed, for example by incineration, or dumped without creating a toxicity hazard.
The following are some Examples of the invention.
Examples 1 to 12
In each of these a foundry mix was made using polyacrylic acid having molecular weight 27,000 introduced as a 25% solution in water, tartaric acid powder, 85 % orthophosphoric acid sg 1.7, finely powdered fluoroaluminisilicate glass, which is in accordance with Specification No. 1,316,129 (e.g. the material Glass FLT which is supplied by Pilkington Brothers), in the amounts specified in Table 1 and sufficient Chelford 50 to sand to bring the quantities up to 100. The ingredients were mixed together, standard compression speciments were then rammed and left in the laboratory for 24 hours. The compression figure necessary to break the samples was then measured. Naturally the highest possible compression figure is desirable.
TABLE 1
Example No. 1 2 3 4 5 6 7 8 9 10 11 12
Glass FLT % 4 4 4 4 5 5 5 5 5 5 4 4
Polyacrylic 4 4 2 4 4 4 4 3 3 3 3.6 3.6 acid solution %
Tartaric acid % - - - - - - - 1 1 1 0.4 0.4
Phosphoric acid % - 1 2 2 - 1 2 - 1 2 - 1.0 compression 95 295 315 365 120 480 425 335 425 465 145 870 lb/sq. in The results in Examples 1 and 2 show the massive increase in strength brought about by 1 % phosphoric acid, whilst the results in Examples 5 to 7 show that there seems to be an optimum for the amount of phosphoric acid and above this the strength can decrease. Example 8 shows that there is a significant increase in strength by the use of tartaric acid along, although
Example 9 shows that the addition of phosphoric increased the strength still further.Examination and actual use of the moulds and cores made in Examples 8 to 12 showed that the inclusion of phosphoric acid slowed down the rate of curing substantially, so that the mix remained in the plastic state for 15-20 minutes, whereas in Examples 1 to 7 it was in the plastic state only for 5-10 minutes, which made it difficult to achieve complete mixing.
Examples 13 to 23
The general process described for Examples 1 to 12 was repeated except that a different fluoroaluminosilicate glass was used, glass G 200 supplied by Pilkington Brothers, this being used in an amount of 4%, with 4% of a 25% solution of polyacrylic acid in water and various amounts of various acids. The compression strength of each of the resultant mixes is shown in
Table II.TPX 6 is a commercial sulphonic acid catalyst sold for use in organic foundry binder. TABLE II
Example Added Acid Amount % Compression strength lb/in2 13 none - 135 14 1.7 sg phosphoric acid 0.5 385 15 " 1.0 405 16 77% sulphuric acid 0.5 140 17 " 1.0 200 18 para toluene suphonic acid 0.5 135 19 " 1.0 90 20 concentrated hydrochloric acid 0.5 90 21 " 1.0 70 22 TPX6 0.5 60 23 " 1.0 135 This shows that most of the acids have no effect or weaken the compressive strength whilst phosphoric acids gives a massive improvement.
Example 24
The general method of Example 1 was repeated except that the fluoroaluminosilicate glass used was glass MP 2 supplied by Pilkington Brothers, it was used in an amount of 1 % by weight based on the weight of the mix, and the mix also included % by weight fused magnesia, based on the weight of the mix, 8% of a 25% aqueous solution of polyacrylic acid and 1 % tartaric acid and after mixing and shaping and allowing to cure the cup hardness was determined. The result was 1.5%. In a comparative test in which the fused magnesia was omitted the result was 5.0. In this test the hardness figure is the depth of a scratch test measured in tenths of mm made by a George Fisher instrument the lower the figure the harder being the sand. Thus this Example shows the improvement in hardness obtainable when fused magnesia is used.
Example 25
The method of Example 1 was repeated using a mix of 95 parts sand, 1 part fluoroaluminosilicate glass, 0.5 parts particulate fused magnesia, 1 part tartaric acid, a solution of 0.5 parts polyacrylic acid in 1.5 parts water and, optionally 0.5 parts phosphoric acid.
WHAT WE CLAIM IS:
1. A method of making a foundry mould or core comprising shaping a mix of a particulate inert refractory material and a binder and allowing the mix to cure in which the binder comprises (a) a water soluble acid component comprising a polymeric carboxylic acid (b) an alumino silicate glass that can react with the polymeric carboxylic acid by leaching of ions to form a cement, (c) water in an amount of below 5% the total weight of the mix and (d) at least one modifier selected from tartaric acid phosphoric acid and particulate fused magnesia, the or each modifier being present in an amount of at least 25%by weight based on the weight of polymeric carboxylic acid.
2. A method according to claim 1 in which the polymeric carboxylic acid is an acrylic acid polymer.
3. A method according to claim 1 in which the polymeric carboxylic acid is an acrylic acid polymer.
3. A method according to claim 1 in which the polymeric carboxylic acid is a homopolymer of acrylic acid.
4. A method according to any preceding claim in which the binder includes tartaric acid in an amount of at least 50% by weight based on the weight of polycarboxylic acid.
5. A method according to claim 4 in which the amount of tartaric acid is 100 to 400%.
6. A method according to any of claims 1 to 5 in which the binder includes phosphoric acid in an amount of at least 33% by weight based on the weight of polycarboxylic acid.
7. A method according to claim 6 in which the amount of phosphoric acid is 50 to 300%
8. A method according to any preceding claim in which the binder includes both tartaric acid and phosphoric acid.
9. A method according to any preceding claim in which the glass comprises a fluoroaluminosilicate glass.
10. A method according to any preceding claim in which the binder includes particulate fused magnesia in an amount of 10 to 100% based on the weight of glass.
11. A method according to any preceding claim in which the amount of water is from 0.5 to 3%.
12. A method according to any preceding claim in which the total amount of water included in the mix is sufficient to yield an aqueous solution of polymeric carboxylic acid containing 15 to 35% polymeric carboxylic acid.
13. A method according to claim 1 substantially as herein described.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (13)
1. A method of making a foundry mould or core comprising shaping a mix of a particulate inert refractory material and a binder and allowing the mix to cure in which the binder comprises (a) a water soluble acid component comprising a polymeric carboxylic acid (b) an alumino silicate glass that can react with the polymeric carboxylic acid by leaching of ions to form a cement, (c) water in an amount of below 5% the total weight of the mix and (d) at least one modifier selected from tartaric acid phosphoric acid and particulate fused magnesia, the or each modifier being present in an amount of at least 25%by weight based on the weight of polymeric carboxylic acid.
2. A method according to claim 1 in which the polymeric carboxylic acid is an acrylic acid polymer.
3. A method according to claim 1 in which the polymeric carboxylic acid is an acrylic acid polymer.
3. A method according to claim 1 in which the polymeric carboxylic acid is a homopolymer of acrylic acid.
4. A method according to any preceding claim in which the binder includes tartaric acid in an amount of at least 50% by weight based on the weight of polycarboxylic acid.
5. A method according to claim 4 in which the amount of tartaric acid is 100 to 400%.
6. A method according to any of claims 1 to 5 in which the binder includes phosphoric acid in an amount of at least 33% by weight based on the weight of polycarboxylic acid.
7. A method according to claim 6 in which the amount of phosphoric acid is 50 to 300%
8. A method according to any preceding claim in which the binder includes both tartaric acid and phosphoric acid.
9. A method according to any preceding claim in which the glass comprises a fluoroaluminosilicate glass.
10. A method according to any preceding claim in which the binder includes particulate fused magnesia in an amount of 10 to 100% based on the weight of glass.
11. A method according to any preceding claim in which the amount of water is from 0.5 to 3%.
12. A method according to any preceding claim in which the total amount of water included in the mix is sufficient to yield an aqueous solution of polymeric carboxylic acid containing 15 to 35% polymeric carboxylic acid.
13. A method according to claim 1 substantially as herein described.
Priority Applications (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB15239/77A GB1569480A (en) | 1977-04-13 | 1977-04-13 | Methods of making foundry moulds or cores |
| US05/892,801 US4183759A (en) | 1976-04-09 | 1978-04-03 | Hardenable compositions |
| BR7802205A BR7802205A (en) | 1977-04-13 | 1978-04-10 | PROCESS FOR PREPARING A CASTING MOLD OR MALE |
| AU34928/78A AU517269B2 (en) | 1977-04-13 | 1978-04-10 | Method of making foundry moulds |
| IT48836/78A IT1102584B (en) | 1977-04-13 | 1978-04-11 | PROCEDURE AND COMPOSITION FOR PRO DURING MOLDS OR SOULS FROM FOUNDRY |
| JP4221978A JPS53129121A (en) | 1977-04-13 | 1978-04-12 | Component for casting |
| ES468717A ES468717A1 (en) | 1977-04-13 | 1978-04-12 | Component for casting |
| DE19782815753 DE2815753A1 (en) | 1977-04-13 | 1978-04-12 | METHOD FOR MANUFACTURING A CASTING FORM OR A CASTING CORE |
| FR7810968A FR2387091A1 (en) | 1977-04-13 | 1978-04-13 | Casting mould or core prodn. using cement-forming binder - contg. soluble polymeric carboxylic acid, reactive inorganic powder and modifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB15239/77A GB1569480A (en) | 1977-04-13 | 1977-04-13 | Methods of making foundry moulds or cores |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1569480A true GB1569480A (en) | 1980-06-18 |
Family
ID=10055536
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB15239/77A Expired GB1569480A (en) | 1976-04-09 | 1977-04-13 | Methods of making foundry moulds or cores |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU517269B2 (en) |
| GB (1) | GB1569480A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4775704A (en) * | 1987-04-22 | 1988-10-04 | Teiji Nagahori | Mold material for forming sandmold without requiring mold wash |
-
1977
- 1977-04-13 GB GB15239/77A patent/GB1569480A/en not_active Expired
-
1978
- 1978-04-10 AU AU34928/78A patent/AU517269B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AU517269B2 (en) | 1981-07-16 |
| AU3492878A (en) | 1979-10-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |