GB2131789A - Binder for calcined dolomite refractory compositions - Google Patents
Binder for calcined dolomite refractory compositions Download PDFInfo
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- GB2131789A GB2131789A GB08332571A GB8332571A GB2131789A GB 2131789 A GB2131789 A GB 2131789A GB 08332571 A GB08332571 A GB 08332571A GB 8332571 A GB8332571 A GB 8332571A GB 2131789 A GB2131789 A GB 2131789A
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- phenol
- resin
- molar ratio
- formaldehyde
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- 239000000203 mixture Substances 0.000 title claims abstract description 47
- 239000010459 dolomite Substances 0.000 title claims abstract description 29
- 229910000514 dolomite Inorganic materials 0.000 title claims abstract description 29
- 239000011230 binding agent Substances 0.000 title claims abstract description 16
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims abstract description 62
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 claims abstract description 49
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 26
- 229920001568 phenolic resin Polymers 0.000 claims abstract description 15
- 150000008044 alkali metal hydroxides Chemical class 0.000 claims abstract description 12
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229920005989 resin Polymers 0.000 claims description 40
- 239000011347 resin Substances 0.000 claims description 40
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 32
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 28
- 239000007788 liquid Substances 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 19
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 claims description 17
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 15
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 229920003986 novolac Polymers 0.000 description 15
- 229920003987 resole Polymers 0.000 description 13
- 239000003795 chemical substances by application Substances 0.000 description 9
- 239000000243 solution Substances 0.000 description 9
- 235000011121 sodium hydroxide Nutrition 0.000 description 8
- 239000005011 phenolic resin Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 4
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- 239000003513 alkali Substances 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 239000004312 hexamethylene tetramine Substances 0.000 description 3
- 235000010299 hexamethylene tetramine Nutrition 0.000 description 3
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 229920001187 thermosetting polymer Polymers 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- -1 alkali metal salt Chemical class 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000011449 brick Substances 0.000 description 2
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 2
- 239000000920 calcium hydroxide Substances 0.000 description 2
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- SLGWESQGEUXWJQ-UHFFFAOYSA-N formaldehyde;phenol Chemical compound O=C.OC1=CC=CC=C1 SLGWESQGEUXWJQ-UHFFFAOYSA-N 0.000 description 2
- 230000036571 hydration Effects 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 239000001095 magnesium carbonate Substances 0.000 description 2
- 235000014380 magnesium carbonate Nutrition 0.000 description 2
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 2
- 239000011295 pitch Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- GHMLBKRAJCXXBS-UHFFFAOYSA-N resorcinol Chemical compound OC1=CC=CC(O)=C1 GHMLBKRAJCXXBS-UHFFFAOYSA-N 0.000 description 2
- URAYPUMNDPQOKB-UHFFFAOYSA-N triacetin Chemical compound CC(=O)OCC(OC(C)=O)COC(C)=O URAYPUMNDPQOKB-UHFFFAOYSA-N 0.000 description 2
- 238000005292 vacuum distillation Methods 0.000 description 2
- HMUNWXXNJPVALC-UHFFFAOYSA-N 1-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]-2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethanone Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)C(CN1CC2=C(CC1)NN=N2)=O HMUNWXXNJPVALC-UHFFFAOYSA-N 0.000 description 1
- VGVRPFIJEJYOFN-UHFFFAOYSA-N 2,3,4,6-tetrachlorophenol Chemical class OC1=C(Cl)C=C(Cl)C(Cl)=C1Cl VGVRPFIJEJYOFN-UHFFFAOYSA-N 0.000 description 1
- KMZHZAAOEWVPSE-UHFFFAOYSA-N 2,3-dihydroxypropyl acetate Chemical compound CC(=O)OCC(O)CO KMZHZAAOEWVPSE-UHFFFAOYSA-N 0.000 description 1
- VZSRBBMJRBPUNF-UHFFFAOYSA-N 2-(2,3-dihydro-1H-inden-2-ylamino)-N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]pyrimidine-5-carboxamide Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C(=O)NCCC(N1CC2=C(CC1)NN=N2)=O VZSRBBMJRBPUNF-UHFFFAOYSA-N 0.000 description 1
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000012769 bulk production Methods 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000011294 coal tar pitch Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 150000001896 cresols Chemical class 0.000 description 1
- 230000006735 deficit Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 239000008098 formaldehyde solution Substances 0.000 description 1
- 239000001087 glyceryl triacetate Substances 0.000 description 1
- 235000013773 glyceryl triacetate Nutrition 0.000 description 1
- 150000002334 glycols Chemical class 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 239000000383 hazardous chemical Substances 0.000 description 1
- 231100000206 health hazard Toxicity 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 229920002866 paraformaldehyde Polymers 0.000 description 1
- 150000002989 phenols Chemical class 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 150000003839 salts Chemical group 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 230000009974 thixotropic effect Effects 0.000 description 1
- 229960002622 triacetin Drugs 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
- 150000003739 xylenols Chemical class 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/013—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics containing carbon
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/03—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite
- C04B35/06—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite based on oxide mixtures derived from dolomite
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Ceramic Products (AREA)
- Compositions Of Oxide Ceramics (AREA)
Abstract
Calcined dolomite refractory compositions comprise a major proportion of calcined dolomite and, as binder therefore, a phenolformaldehyde resin which has a phenol; formaldehyde molar ratio of from 1:0.7 to 1:4.0, and alkali metal hydroxide:phenol molar ratio of from 0.2:1 to 1.5:1 and a water content of less than 20%, preferably not greater than 5%, by weight. Refractory articles are made by forming the composition into the desired shape and then curing at an elevated temperature.
Description
SPECIFICATION
Calcined dolomite refractory compositions
Coal tar pitch has been traditionally used to bond dolomite and magnesite refractory articles.
However, because of the potential health hazards in the handling of pitch and the evolution hazards of pyrolysis products, there is a tendency to use polymers to replace pitch. Phenolic resins, both novolaks and resoles, are favoured because they are thermosetting, have a high carbon yield and, under some conditions, can be pyrolysed during service.
Calcined magnesite (MgO) can be easily bonded with both:- (1) phenol-formaldehyde novolaks, either in solution or as powders, with hexamine added to
provide thermosetting characteristics; and
(2) resoles, as high solids solutions in water or in alcohol/water mixtures.
However, when bonding calcined dolomite the mix exotherms rapidly and the resin tends to gel.
The mix quickly dried up and is difficult to form into the bricks after only a few minutes. If the mix has sufficient life to enable bricks to be made, then the are very weak and tend to crack up on standing and even further on attempting to cure at 1 500 C.
There are two problems in using calcined dolomite as a refractory binder with phenolic resins.
(1) reaction of the CaO fraction of the calcined dolomite with the phenolic hydroxy group. This
reaction is exothermic so that the mix heats up, the molecular weight of the phenolic novolak
or resole increases as a result of polymerisation and water tends to evaporate. The bivalent
calcium ion, CA++, crosslinks the polymer chains. The overall effect is that the mix appears
to dry out and can no longer be formed into the required article.
(2) the presence of water in the resin causes rapid hydration to calcium hydroxide. This reaction
is also exothermic and expansion occurs for two reasons; (a) because of the temperature rise
and (b) because the volume of the calcium hydroxide molecule is larger than that of the oxide.
The expansion of the inside of the compressed calcined dolomite article breaks resin bonds
and causes surface cracking.
Heating of calcined dolomite in air accelerates hydration due to absorption of water from the air.
(It is important to carry out bonding of calcined dolomite in as dry an atmosphere as possible).
We have now found that the above problems may be circumvented by employing, as binder for the calcined dolomite, a phenolic resin in which at least some of the phenolicOH groups are blocked by forming the alkali metal salt and which has a low water content.
The present invention provides a composition comprising a major proportion of calcined dolomite and, as binder therefore, a phenol-formaldehyde resin having a phenol:formaldehyde molar ratio of from 1:0.7 to 1:4.0, an alkali metal hydroxide:phenol molar ratio of from 0.2:1 to 1.5:1 and a water content of less than 20% by weight.
The present invention also provides a process for producing refractory articles which process comprises mixing calcined dolomite with, as binder, a phenol-formaldehyde resin having a phenol:formaldehyde molar ratio of from 1:0.7, to 1:4.0, an alkali metal hydroxide:phenol molar ratio of from 0.2:1 to 1.5:1 and a water content of less than 20% by weight, forming the mixture and curing the formed mixture at elevated temperature.
It is known to employ phenolic novolak resins to bond refractory granules, for example, sand, in the manufacture of foundry moulds and cores. It would, in theory, be possible to employ phenolic novolak resins, in which the phenolicOH groups have been converted to the salt form using an alkali metal hydroxide, as binders for calcined dolomite. However, in practice, the hexamethylenetetramine, commonly employed to make up the deficit of formaldehyde in order to render the novolak resin thermosetting, is destroyed by the alkali, with the liberation of ammonia. It is, nevertheless, possible to employ a phenolic novolak resin in conjunction with a phenolic resole resin as a curing agent therefore, both the phenolic novolak and the phenolic resole having a proportion of their phenolicOH groups blocked by alkali.Alternatively, the novolak could be a normal novolak containing no alkali.
It may be necessary, particularly when using novolak resole combinations, to employ an accelerator to speed up the reaction. Examples of such accelerators include dihydrophenols, for example, resorcinol, amines and esters such as monoacetin or triacetin.
Where, in the above, reference is made to a phenol:formaldehyde molar ratio and to an alkalimetal hydroxide:phenol molar ratio, it is to be understood that these ratios relate the the overall molar ratios, so that, where a mixture of phenolic resins is employed, for example, a phenolic novolak resin together with a phenolic resole resin as curing agent therefore, it is the ratio of the combined weights of phenol and formaldehyde and of phenol and alkali-metal hydroxide used which is of relevance.
Typically, the resin will be used in an amount of from 2 to 10%, preferably from 3 to 8%, by weight based on the weight of the mixture with calcined dolomite.
In order to create a mixture which can be formed to the desired shape it is desirable that the binder should be in the liquid state or contain sufficient liquid to enable it to adhere to the calcined dolomite particles and to flow under heat and pressure. Consequently, because it is necessary to minimise the water content of the resin, it is desirable to incorporate, as pick up agent, an amount of a non-aqueous liquid to permit the composition to be formed to shape. To prevent drying out during use, the non-aqueous liquid should preferably be of low volatility, although it is within the scope of the invention to employ a mixture of non-aqueous liquids for this purpose and such a mixture may include some volatile liquid.
It is not essential that any or all of the non-aqueous liquids employed to render the compositions formable should be solvents for the resin. Suitable non-aqueous liquids for this purpose include glycols, such as ethylene glycol or diethylene glycol. Examples of volatile liquid which may be used in combination with non-volatile non-aqueous liquids include lower alcohols, such as methanol or ethanol.
The pick up agent, when used, will typically be present in an amount of up to 10% by weight of the composition. Preferably, however it is used in an amount of from 1.5 to 5% by weight of the composition.
As indicated above, however, the presence of water is generally undesirable, since it reacts with the calcined dolomite to produce heat, as well as resulting in expansion of the composition. It is, nevertheless, not essential to eliminate all of the water and satisfactory results may be achieved with a phenolic resole containing water up to 20%.
To reduce to a minimum the heating and expansion effect of the binder, however, it is preferred that the phenolic resole should have a water content no greater than 5.0% by weight.
In this connection, it should be noted that commercially available spray-dried phenolic resole resins may typically exhibit water contents of from 10 to 14% by weight based on the weight of the resin.
In one embodiment of the invention, the binder is a phenolic resole prepared by condensing a phenol and formaldehyde in the presence of sodium hydroxide, distilling under vacuum to reduce the water content to below 5.0% by weight and adding a high-boiling liquid, such as a glycol, and, optionally, a volatile solvent, such as methanol to reduce viscosity. This approach is best achieved with low molecular weight resoles or novolaks since the amount of high boiling solvent is kept to a minimum and solubility is increased.
In a further embodiment of the invention, a phenol and formaldehyde are condensed in the presence of sodium hydroxide and spray-dried prior to mixing with a pick-up agent, such as ethylene glycol, and employment as a binder for the calcined dolomite particles.
This technique is only applicable to resins which form powders on dehydration (i.e. these which are sufficiently high in molecular weight). However, we have found that such resins do act as adequate bonds for calcined dolomite when used with a high boiling solvent as a pick up agent as described in the examples.
The phenol employed in preparing the resins of the present invention is preferably phenol itself, but all or part of the phenol may be replaced by any one (or more) of the many phenols well known for the manufacture of phenolic resins, such as, for examle, the various cresols, xylenols and chlorophenols.
For reasons of convenience and availability, the formaldehyde employed will normaily be in the form of an aqueous solution, such as, for example, a 50% w/w aqueous solution. Since much of the water present in the mixture of reactants must be removed prior to use, however, it may prove to be advantageous to replace all or part of the aqueous formaldehyde solution by paraform, or by one of the commercially available high strength flake or block forms of formaldehyde.
The compositions of the invention may be prepared in any convenient manner which will ensure substantially uniform and intimate mixing of the binder with the particles of calcined dolomite. After the binder and calcined dolomite have been mixed, the resultant composition is formed to the desired shape under pressure and finally cured at elevated temperature.
The following examples illustrate the invention:
Example 1 1) Preparation of powdered resin
30 g of caustic soda flake was dissolved in 30 g of water and the solution allowed to cool to 200C.
94 g of phenol was charged to a flask and the caustic soda solution added slowly. The solution produced was cooled to 400C and 86 g of 52% formalin added, raised to reflux and reacted for 1 hour 30 minutes, then cooled to 250 C.
The resin solution was spray dried to produce a powdered resin having the following characteristics:
Approximate water content 1 1.6% NaOH:phenol 0.75:1
P:F 1:1.5 2) Bonding of calcined dolomite with powdered resin
750 g of fresh coarse ground calcined dolomite was mixed with 250 g fresh fine ground material powdered resin of Example 1 and ethylene or diethylene glycol pickup agents added. The temperature of the mix before and after mixing was measured. 2x2 cyclinder specimens were made at 1 tonne/in2 pressure and baked in an oven at 1 600C for 1 hour. The attached table describes the mixed made. All specimens were extremely strong and showed no signs of surface cracking, even after baking for 1 hour at 3000C.
Resin content 5% 4% 3% 3%
Pickup agent EG EG EG DEG % Pickup agent 3.75% 3% 2.25% 2.25%
Temperature after mixing* 300C 280C 280C 280C
Cure 1 hr1600C 1 hr1600C 1 hr1600C 1 hr1600C +1 hr 3000C +1 hr 3000C *Initial aggregate temperature 1 70C.
EG=Ethylene glycol.
DEG=Diethylene glycol.
All mixes remained sticky for above 24 hours although they had stiffened up after about 1 hour.
All specimens were so strong it was impossible to break them using a laboratory Houndsfield tensometer (above 20 KN).
This example shows that adequate bonding can be obtained with a resin which does not have complete salt-like character but contains some free hydroxy groups. However, the mix does exotherm slightly which tends to advance the resin and could result in loss of bench life in bulk production
mixers.
Example 2 1) Preparation of liquid resin
40 g of caustic soda flake was dissolved in 85 g of water and the solution cooled to 200 C.
94 g of phenol was charged to a flask and the caustic soda solution added slowly.
The solution produced was cooled to 200C and 69.2 g of 52% formalin added slowly over 1 hour maintaining cooling to keep the temperature down to 4045 C. After a further 2 hours at 40-450C the free formaldehyde fell to 0.2%. The resin was vacuum distilled under full vacuum until the temperature rose to 650C under full vacuum (28 mmHg). 25 g of ethylene glycol were added and vacuum distillation continued until the temperature rose to 800 C, whereupon 10 g of ethylene glycol were added and vacuum distillation continued until the temperature rose to 800 C. 20 g of ethylene glycol and 35 g methanol were then added and the resin, which had a viscosity of 10.4 poises at 250C, was cooled to 250C.
The product, which was opaque in appearance and tended to be thixotropic, had the following characteristics:
Approximate water content 3.2% Mo ratio NaOH:Phenol 1:1
P:F 1:1.2 2) Bonding of calcined dolomite with liquid phenolic resin
A similar procedure was adopted as for Example 1 except that 8% of the above-described liquid resin was used. No wetting agent was required in this case. The mix showed no temperature rise and remained in a formable state for at least 3 days at room temperature. Again the specimens exhibited strengths in excess of 20 KN after curing for 1 hour at 1600 C.
Example 3 1) Preparation of a higher phenol-formaldehyde molar ratio liquid resole resin
The procedure of Example 2 was foliowed except that the molar ratio of phenol to formaldehyde' used was 1:2.5 by increasing the amount of 52% formalin used to 144.2 g. The product had the following characteristics:
Approximate water content 2.0%
Molar ratio of NaOH to phenol 1:1
Phenol:formaldehyde 1:2.5 2) Bonding of calcined dolomite with powdered resin
750 g of coarse ground Doloma and 250 g of fine ground Doloma were mixed with 6% of powdered resin as prepared in step 1) above and 3% of a powdered novolak resin made by condensing phenol and formaldehyde in a molar ratio of 1:0.8 in the presence of oxalic acid, as catalyst, and then dehydrated by heating up to 1 500 C. This novolak did not contain caustic soda or hexamine. The mix remained formable for at least one day at room temperature. Specimens compressed at 1 tonne/in2 and cured for 1 hour at 1 600C again showed strengths in excess of 20 KN and no signs of surface cracking.
Claims (23)
1. A composition comprising a major proportion of calcined dolomite and, as binder therefore, a phenol-formaldehyde resin having a phenol:formaldehyde molar ratio in the range of from 1:0.7 to 1 :4.0, an alkali metal hydroxide:phenol molar ratio in the range of from 0.2:1 to 1.5:1 and a water content of less than 20% by weight.
2. A composition according to claim 1 , wherein the phenol-formaldehyde resin has a water content not greater than 5.0% by weight.
3. A composition according to either claim 1 or claim 2, wherein the molar ratio of the phenol to formaldehyde in the resin is in the range of from 1:1 to 1 :2.5.
4. A composition according to any one of claims 1 to 3, wherein the molar ratio of alkali metal hydroxide to the phenol in the resin is in the range of from 0.75:1 to 1:1.
5. A composition according to any one of claims 1 to 4, wherein the phenol component of the resin is phenol.
6. A composition according to any one of claims 1 to 5, wherein the alkali metal hydroxide is sodium hydroxide.
7. A composition according to any one of claims 1 to 6, which additionally comprises a nonaqueous liquid.
8. A composition according to claim 7, wherein the non-aqueous liquid is selected from ethylene glycol, diethylene glycol and mixtures thereof.
9. A composition according to either claim 7 or claim 8, wherein the non-aqueous liquid contains a minor amount of a volatile liquid.
10. A composition according to claim 9, wherein the volatile liquid is selected from methanol, ethanol and mixtures thereof.
11. A process for the production of refractory articles which process comprises mixing calcined dolomite with, as binder therefor, a phenol-formaldehyde resin having a phenol:formaldehyde molar ratio in the range of from 1:0.7 to 1 :4.0, an alkali metal hydroxide:phenol molar ratio in the range of from 0.2:1 to 1.5:1 and a water content of less than 20% by weight, forming the mixture and curing the formed mixture at elevated temperature.
12. A process according to claim 11, wherein the phenol-formaldehyde resin has a water content not greater than 5.0% by weight.
1 3. A process according to either claim 11 or claim 12, wherein the molar ratio of the phenol to formaldehyde in the resin is in the range of from 1:1 to 1 :2.5.
14. A process according to any one of claims 11 to 13, wherein the molar ratio of alkali metal hydroxide to the phenol in the resin is in the range of from 0.75 to 1:1.
15. A process according to any one of claims 11 to 14, wherein the phenol component of the resin is phenol.
1 6. A process according to any one of claims 11 to 1 5, wherein the alkali metal hydroxide is sodium hydroxide.
17. A process according to any one of claims 11 to 16, wherein the calcined dolomite and the binder are mixed with a non-aqueous liquid.
1 8. Process according to claim 17, wherein the non-aqueous liquid is selected from ethylene glycol, diethylene glycol and mixtures thereof.
1 9. A process according to either claim 1 7 or claim 18, wherein the non-aqueous liquid contains a minor amount of a volatile liquid.
20. A process according to claim 19, wherein the volatile liquid is selected from methanol, ethanol and mixtures thereof.
21. A process according to any one of claims 11 to 20, wherein the mixture, after being formed to the desired shape, is cured by heating at a temperature of from 100 to 3500C for from 15 minutes to 48 hours.
22. A process for producing a refractory article substantially as hereinbefore described in the
Examples.
23. Refractory articles made by the process according to any one of claims 11 to 22.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08332571A GB2131789A (en) | 1982-12-08 | 1983-12-07 | Binder for calcined dolomite refractory compositions |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8235017 | 1982-12-08 | ||
| GB08332571A GB2131789A (en) | 1982-12-08 | 1983-12-07 | Binder for calcined dolomite refractory compositions |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8332571D0 GB8332571D0 (en) | 1984-01-11 |
| GB2131789A true GB2131789A (en) | 1984-06-27 |
Family
ID=26284632
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08332571A Withdrawn GB2131789A (en) | 1982-12-08 | 1983-12-07 | Binder for calcined dolomite refractory compositions |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2131789A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0164139A1 (en) * | 1984-04-26 | 1985-12-11 | Hoogovens Groep B.V. | Method for the manufacture of refractory bricks containing CaO |
| US5686506A (en) * | 1995-04-04 | 1997-11-11 | Borden Chemical, Inc. | Mixtures of phenolic novolaks for use with refractory aggregate and methods for making same |
| EP4499333A4 (en) * | 2022-03-28 | 2025-09-10 | Harbisonwalker Int Holdings Inc | PHENOLIC RESIN COMPOSITIONS AS BINDERS IN FIRE-RESISTANT ARTICLES |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2088845A (en) * | 1980-12-05 | 1982-06-16 | Eltra Corp | Binder for refractory compositions |
-
1983
- 1983-12-07 GB GB08332571A patent/GB2131789A/en not_active Withdrawn
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2088845A (en) * | 1980-12-05 | 1982-06-16 | Eltra Corp | Binder for refractory compositions |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0164139A1 (en) * | 1984-04-26 | 1985-12-11 | Hoogovens Groep B.V. | Method for the manufacture of refractory bricks containing CaO |
| US5686506A (en) * | 1995-04-04 | 1997-11-11 | Borden Chemical, Inc. | Mixtures of phenolic novolaks for use with refractory aggregate and methods for making same |
| US5760104A (en) * | 1995-04-04 | 1998-06-02 | Borden Chemical, Inc. | Mixtures of phenolic novolaks for use with refractory aggregate and methods for making same |
| EP0736502A3 (en) * | 1995-04-04 | 1999-02-03 | Borden Chemical, Inc. | Mixtures of phenolic novolaks for use with refractory aggregate and methods for making same |
| EP4499333A4 (en) * | 2022-03-28 | 2025-09-10 | Harbisonwalker Int Holdings Inc | PHENOLIC RESIN COMPOSITIONS AS BINDERS IN FIRE-RESISTANT ARTICLES |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8332571D0 (en) | 1984-01-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |