Plastic and nonmetallic article shaping or treating: processes – Formation of solid particulate material directly from molten... – With subsequent uniting of the particles
Patent
1998-09-08
1999-10-05
Theisen, Mary Lynn
Plastic and nonmetallic article shaping or treating: processes
Formation of solid particulate material directly from molten...
With subsequent uniting of the particles
264 8, 65443, 65455, C03B 3705
Patent
active
059618973
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the manufacture of filled man-made vitreous fibre (MMVF) products. These are products which are made by fiberising mineral melt, collecting the fibres into a web or other structure and incorporating additional particulate material into the product.
It is well known to produce MMVF products by applying mineral melt to a rotating fiberising rotor and thereby throwing the melt from the periphery as fibres and forming a substantially annular cloud of the fibres, spraying binder into the annular cloud of fibres, carrying the fibres axially from the rotor towards a collector surface and collecting the fibres on the collector surface as a web. The binder may be sprayed into the cloud from outside the annular cloud or it can be sprayed radially outwards from inside the annular cloud. When there are several adjacent rotors arranged in a cascade spinner, the individual annular clouds merge into a single substantially annular cloud around the cascade. This annular cloud is carried forward towards a collector and loses its annular configuration as it travels away from the rotor or rotors.
It is known to incorporate filler particles in the web and various ways have been proposed for achieving this. One method involves forming the bonded web in conventional manner and applying the particles to the preformed web. For instance the particles may be scattered onto the web while it is being vibrated, as in U.S. Pat. No. 3,019,127, or the bonded web may be impregnated with an aqueous slurry of the particles. Unfortunately, these methods tend to give non-uniform distribution of the particles, especially when the particles are relatively coarse, with the greatest concentration of particles on the outer surface. Impregnation methods have the disadvantage of needing to dry the impregnated product.
It is known to include the filler in the melt, for instance as described in U.S. Pat. No. 3,953,185, but this severely influences fibre formation and is not suitable for introducing significant amounts of a wide variety of particulate materials.
It is known to add particulate material to the cloud of fibres as it travels towards the collector. For instance in GB 1234075 (DE 1759511) a stream of particles entrained in a gas are projected into the cloud and binder is sprayed onto the fibres or onto the particles or both before they reach the collector. In practice it is difficult to achieve by this technique a uniform distribution of filler particles which are bonded into the web. Thus the bonding of the particles is liable to be non-uniform with the result that a significant proportion of the filler is liable to shake out of the web during handling, and the distribution of the filler may be non-uniform. Particular problems arise when it is desired to introduce rather fine particles, for instance below 100 .mu.m and often below 50 .mu.m. The particles described in GB 1234075 are particles of sand having a size of 0.1 to 0.4 mm, ground glass, pulverised rock, slag, perlite and vermiculite.
In WO 90/15032 the shaft of the rotating fiberising rotor is hollow to allow the blowing of air or other gases, and binder or other additives. It is said that the hollow shaft can also be used for the supply of solid particles such as clay or cement or edge spill fibres. It is stated that air or another gas can carry particles to the front of the rotor, and thus they will be thrown from the stationary outlet orifices in the shaft towards the fibre cloud that is formed around the rotor. It is difficult to achieve the introduction of significant amounts of additive by this technique without loss of properties such as bonding.
In EP-A-530843 particles entrained in a gas stream are injected into a preformed cloud of fibres or are dropped onto binder that is being thrown radially from the centre of the spinning rotor, outwardly into the annular cloud formed from the rotor. Various particulate additives are proposed including MMVF edge trim or scrap and newsprint fibres. It is stated that the fibres should be finely ground, but the di
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Clausen Anders Ulf
Tonder Flemming Weiss
Rockwool International A/S
Theisen Mary Lynn
LandOfFree
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