Binder mixture

Details Binder mixture Binder mixture

1991-10-25

1994-04-19

Klemanski, Helene

Abrasive tool making process, material, or composition

With synthetic resin

524541, 524841, C09K 314

Patent

active

053042255

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a carbon-forming binder mixture for the production of thermostable molding materials such as refractory products and carbon materials, grinding wheels and friction linings.
Refractory products can be classified according to their chemical composition, their form, and according to manufacturing processes. According to ISO Standard 1109/78, refractory products are divided chemically into high-alumina products, fireclay products, dinas clay products, silica products, basic products and special products, e.g. carbon materials, zirconium silicate, nitrides, borides, spinels. For their further classification, refractory materials are distinguished as shaped, e.g. bricks, or unshaped products, e.g. mortar, tamming mixes, sunning materials.
ISO Standard 2246 describes a classification by manufacturing methods, with which types of bond are associated. At temperatures below 150.degree. C. there can be used as binders e.g. clay, waterglass, cement or organic binders, such as molasses, lignin sulfonate, tar and pitch, or synthetic resins. The bonding for products which are heat-treated at 150.degree. to 800.degree. C. can also be inorganic-chemical (phosphates, sulfates), hydraulic (cement) or organic carbon-forming (e.g. tar, pitch, synthetic resin).
Hot-pressed grinding wheels have heretofore been made with the use of furfurol or other liquid substances as abrasive grain wetting agents, which are able only incompletely to absorb the high proportion of filler that is to be bound to the abrasive grain, and therefore highly dust-creating and unstable molding mixtures were obtained. What is wanted are ways to produce stable, storable molding material mixtures as granulates.
Friction lining mixtures are produced either by a dry method by mixing binder powders into a filler-fiber mixture, or by a wet process using aqueous liquid resin or solvent-containing resin solutions with subsequent drying. Adequate fiber and filler wetting and adhesion is often insufficient, in particular when processing asbestos-free lining mixtures.. Besides, severe dust problems arise in the dry mixing process.
While in the past mainly tars or pitches were used as starting material for proper carbon formation in the sector of carbon forming binders, e.g. for obtaining an especially good slagging resistance, at present attention is being directed to the use of hardenable synthetic resins, specifically furane and phenolic resins, as raw materials which at high temperatures lead to very little or no development of smoke and soot and at the same time improve the quality and processibility of the refractory compositions, but are rather expensive.
From EP 248 980 Al are known binders for thermostable molding materials, consisting of such a phenolic resin with a molar ratio of phenol and formaldehyde of 1:0.2 to 1:0.55.
According to DE-PS 27 23 792, DE-OS 36 20 473 and EP 249 959 Al, also phenol-derived binders are known, for which 3 to 30% by wt residues from dimethyl terephthalate production can be used.
A disadvantage of these products, however, is their high viscosity. It can indeed be lowered by addition of solvents or oils, so that the binder can be processed in a favorable temperature range below 100.degree. C. During heating, however, these volatile, odorous components are in part released again, whereby smoke and soot formation may be caused.
It is, therefore, the object of the invention to make available cost-effective binders equally suitable for the production of shaped and unshaped thermostable molding materials as well as for the production of carbon materials and usable under the usual conditions, which due to their property profile, without addition of solvents or oil, show on the one hand good processibility but are, on the other hand, good carbon formers even at high temperatures.
The problem is solved by the production and use of binders of the invention according to claims 1 to 19.
It has been found, surprisingly, that cost-effective binders with improved properties for thermostable molding materials can be p

REFERENCES:
patent: 3510283 (1970-05-01), McGurran
patent: 4251408 (1981-02-01), Hesse et al.
patent: 4298356 (1981-11-01), Teschner et al.
patent: 4364746 (1982-12-01), Bitzer et al.
patent: 4690692 (1987-09-01), Hesse et al.
Copy of European Response-translation-Encyclopedia of Polymer Science & Engineering (2 pages).

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