Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D1/00—Casings; Linings; Walls; Roofs
  • F27D1/16—Making or repairing linings ; Increasing the durability of linings; Breaking away linings
• • 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
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/24—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing alkyl, ammonium or metal silicates; containing silica sols
• • 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
  • C04B30/00—Compositions for artificial stone, not containing binders
  • C04B30/02—Compositions for artificial stone, not containing binders containing fibrous materials
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/34—Filling pastes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
  • C09K3/1025—Materials in mouldable or extrudable form for sealing or packing joints or covers characterised by non-chemical features of one or more of its constituents
  • C09K3/1028—Fibres
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D1/00—Casings; Linings; Walls; Roofs
  • F27D1/0003—Linings or walls
  • F27D1/0006—Linings or walls formed from bricks or layers with a particular composition or specific characteristics
  • F27D1/0009—Comprising ceramic fibre elements
• • 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
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
  • C04B2111/00663—Uses not provided for elsewhere in C04B2111/00 as filling material for cavities or the like

Definitions

• This invention relates to refractory mastics and is particularly applicable to mastics comprising saline soluble fibres bonded with a binder comprising colloidal silica.
• Refractory ceramic fibres are well known materials and typically comprise an alumino- silicate inorganic fibre formed from an oxide melt which is spun, blown, drawn, or otherwise formed into fibres. Such RCF fibres are used in the manufacture of various industrial and domestic articles. Typical uses of RCF are for applications in which resistance to temperatures in excess of 800°C is required.
• RCF fibre is used in the form of needled blankets of fibre in which structural integrity is provided by the fibres that are tangled together in the needling process. (Such products are known as "blanket"). Sometimes a binder is used to lock the fibres together subsequent to exposure to high temperature. Blanket can be processed further to form cut shapes or folded to form insulating modules.
• RCF fibre is also used in the production of so-called "Converted Products".
• Converted products comprise materials in which the RCF is processed further to provide materials in which the RCF is present as either a minor or major constituent.
• Typical converted products include the following:- "Board” - substantially rigid flat sheets containing inorganic and/or organic binders produced by a wet process (for example made by dehydrating a suspension of RCF and binders); "Paper” - a flexible fibrous insulating material with a thickness of less than or equal to
• Shapes substantially rigid shapes made of ceramic fibre with the addition of inorganic and/or organic binder, fired or unfired (for example,RCF formed by vacuum fo ⁇ riing into a variety of shapes);
• 'Tire shapes - RCF formed by a vacuum forrning route and used for domestic and industrial fires either as radiant bodies or for decorative appearance;
• Ceramics - ceramic fibre with inorganic and/or organic binder which may be cast (for example, RCF in the form of cements, concretes and mortars);
• Plastics - A mouldable material containing RCF with binders and which may be trowelled, hand moulded, or dispensed from a pressure gun and which sets upon drying/heating;
• Textiles - ceramic fibre which has been woven with or without the addition of other filaments, wires, or yarns (for example, RCF formed into rope, yam, mats and the like by textile technology).
• binders are used. There are two broad classes of binders:- "Organic binders” - which serve to improve the handling characteristics of the product concerned at low temperatures but which bum off at higher temperatures.
• Organic binders include, for example, such materials as starch.
• “Inorganic binders” which may be effective to improve the handling characteristics of the product concerned at low temperatures, but which also give integrity to the product after exposure to high temperatures.
• Inorganic binders include, for example, such materials as colloidal silicas, aluminas, and clays.
• RCF is an inorganic fibrous material.
• Inorganic fibrous materials can be either glassy or crystalline.
• Asbestos is an inorganic fibrous material one form of which has been strongly implicated in respiratory disease.
• Such fibres comprise alkaline earth silicates (e.g. WO87/05007, WO89/12032, WO93/15028, WO94/15883, WO96/02478, and WO97/49643) which are soluble to varying extent in body fluids.
• alkaline earth silicates e.g. WO87/05007, WO89/12032, WO93/15028, WO94/15883, WO96/02478, and WO97/49643
• a problem with saline soluble fibres is that by their nature they are more reactive than RCF and therefore cannot always be used as a dire t replacement for RCF. Mastics are required to have a reasonable shelf life, which for RCF containing mastics is generally about 6 months. Mastics made using alkaline earth metal silicates have had such a short shelf life as to be unusable. The applicants have realised that this is due to the reactivity of the fibres with the binders. Calcium ions released from the alkaline earth metal silicate fibres set the organic and inorganic constituents of the mastic.
• the present invention provides a mastic comprising:- a) inorganic refractory fibres; and, b) colloidal silica characterised in that the inorganic refractory fibres are alkaline earth metal silicates and the colloidal silica has a pH of below 8.
• the pH is below 7 and may usefully lie in the range 4 to 7.
• Fig. 1 is a schematic view of a penetrometer used in measuring the characteristics of mastics
• Figs. 2 to 5 are graphs showing penetrometer readings for various mastic compositions.
• the invention is exemplified in the following with reference to the alkaline earth silicate fibres SUPERWOOL 607TM and SUPERWOOL 612TM (both available from Thermal Ceramics Limited of Bromborough, England).
• SUPERWOOL 607TM has a nominal composition (by weight) of SiO 2 65%, CaO 29.5%, MgO 5.5%, and Al 2 O ⁇ 1% and is usable at temperatures up to 1050°C.
• SUPERWOOL 612TM has a nominal composition (by weight) of SiO 2 64%, CaO 17%, MgO 13.5%, ZrO 2 5%, impurities 0.5% and is usable at temperatures up to 1260°C.
• Fibre mastics or mouldables are used to repair fibre linings of kilns.
• SUPERWOOL 612TM has been used to replace refractory ceramic fibre in many applications but when used in current mastic formulations as a replacement for RCF the shelf life is not satisfactory and certainly will not be useable 6 months after manufacture.
• the applicants have shown that by using certain types of colloidal silica and/or a different viscosity modifier and/or calcium scavenging multi- dentate ligands then the shelf life can be much extended over the standard formulation.
• the fibres used in experiments of mastic compositions were SUPERWOOL 612TM and SUPERWOOL 607TM.
• the latter fibre was used in an attempt to predict the long-term effects on the SUPERWOOL 612TM fibre.
• a standard mastic mix with SUPERWOOL 612TM as a one for one replacement of RCF will be useable up to about three weeks compared to only 1-2 days with the SUPERWOOL 607TM fibre which is much more reactive.
• a standard RCF fibre (HY20TM (46%Al 2 O 3 /54%SiO 2 ) ob t ainable from Thermal Ceramics Limited, Bromborough, England) was used as a comparison.
• the standard procedure for producing a mastic in these experiments was to first combine the ingredients of colloidal silica, water, biocide and dye (if appropriate) with a paddle-type stirrer. Then the viscosity modifier was slowly added to this liquid which was allowed to thicken on standing (3 - 5 minutes). A Hobart-type mixer was used to break down the bulk fibre for 10-15 seconds on low speed before the thickened liquor was added. After about 1 minute the speed was then increased to its maximum for 4 minutes to obtain a homogenous mixture that had a consistency that was stiff/creamy. The mastic would then be ready for use or for storage in airtight containers.
• a penetrometer (Fig. 1).
• the penetrometer had two rams 1 (one aluminium and the other steel of respective masses 109 g and 336g) which gave the ability to measure quite different consistencies due to the different weights involved.
• the lever 2 on top of the penetrometer was used to release the ram to drop down and penetrate the mastic.
• Indicator mark 3 was viewed through window 4 and compared with scale 5 (in mm). Higher penetration readings represented mastic of lower viscosity.
• the penetrometer tests show that the stability of the SUPERWOOL 612TM mastic, as measured using the steel ram, can be extended from approximately 20 days to over 120 days. This was achieved by substituting the standard colloidal silica used in such mastics (NyacolTM 1430 - a colloidal silica with a pH of 10.2) by an acidic colloidal silica (LudoxTM TMA - a colloidal silica with a pH of 4-7), a different viscosity modifier (Magnafloc 351), or a combination of both (Ludox SKTM - a colloidal silica with a pH of 4-7 & Magnafloc 351). The results of the tests are shown in Figures 4 & 5.
• Formulations using SUPERWOOL 607TM fibre were used as accelerated tests of the SUPERWOOL 612TM fibre. Values for the standard formulation (using Nyacol colloidal silica) had bottomed out after only 1-2 days.
• the Ludox TMA gave about 14 days before it plummeted within a day to its lowest level. This mastic gave very high readings to start with and could not be measured with the steel ram until day 10.
• the Ludox SKTM with Magnafloc 351 produced fairly linear values at least up to 50 days; if this difference were to be reproduced with the SUPERWOOL 612TM fibre then a shelf life of at least 6 months could be expected. Magnafloc 351 substituted in the standard SUPERWOOL 607TM mix alone did not make such a large difference, reaching the same value in 2 days as the standard and then continued to drop below this.
• EDTA As an alternative to the acidic colloidal silicas or the Magnafloc 351, EDTA has also proven to be reasonably effective extending the normal life of the standard mix by adding only 0.4% EDTA. The mix thickened very quickly over the first few hours but then remained stable. Extra initial water may achieve the required viscosity without altering other properties.
• a production formulation for a mastic comprises approximately :- Ludox TMA silica 42.2wt%
• an acidic colloidal silica reduces liberation of calcium ions from the fibre; use of the non-ionic viscosity modifier reduces the risk of setting reactions with the calcium ions released; and provision of multi-dentate ligands such as ethylene glycol and EDTA scavenges and locks up the calcium produced by the fibres.
• the present invention is not limited to the particular viscosity modifiers and multi-dentate ligands disclosed however.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Structural Engineering (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Nonwoven Fabrics (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Sealing Material Composition (AREA)
• Furnace Housings, Linings, Walls, And Ceilings (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)
• Agricultural Chemicals And Associated Chemicals (AREA)
• Ceramic Products (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 1998
  • 1998-09-15 GB GB9820123A patent/GB2337993B/en not_active Expired - Fee Related
• 1999
  • 1999-09-14 EP EP99946345A patent/EP1115672A1/en not_active Withdrawn
  • 1999-09-14 AU AU58759/99A patent/AU5875999A/en not_active Abandoned
  • 1999-09-14 MX MXPA01002622A patent/MXPA01002622A/es not_active Application Discontinuation
  • 1999-09-14 CA CA002336974A patent/CA2336974A1/en not_active Abandoned
  • 1999-09-14 CN CN99810824A patent/CN1316981A/zh active Pending
  • 1999-09-14 KR KR1020017003334A patent/KR20010079828A/ko not_active Withdrawn
  • 1999-09-14 ID IDW20010606A patent/ID27836A/id unknown
  • 1999-09-14 WO PCT/GB1999/003062 patent/WO2000015573A1/en not_active Ceased
  • 1999-09-14 BR BR9912238-3A patent/BR9912238A/pt not_active Application Discontinuation
  • 1999-09-14 JP JP2000570118A patent/JP4319355B2/ja not_active Expired - Fee Related
  • 1999-09-14 PL PL99346610A patent/PL346610A1/xx unknown
  • 1999-09-14 CZ CZ2001948A patent/CZ2001948A3/cs unknown

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