Plastic and nonmetallic article shaping or treating: processes – Forming articles by uniting randomly associated particles
Reexamination Certificate
2000-08-24
2003-07-29
Staicovici, Stefan (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Forming articles by uniting randomly associated particles
C264S116000, C264S122000, C264S123000, C264S128000
Reexamination Certificate
active
06599454
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a method for producing a building material.
Building materials based oh synthetic and mineral raw materials or synthetic and mineral semifinished materials are known. It is also known that these materials may include natural fiber materials. Such materials are for example used for the interior trim of automobile doors. Moldings are produced based both, on duroplastics and on thermoplastics as a matrix. These moldings are reinforced by glass fibers, bast fibers, sisal and the like. The matrix may be foamed in order to reduce the weight. Fibers from bast fiber plants, which are completely or substantially free of shives, are used for this purpose. A higher shive fraction is acceptable in the case of flax and oil linen than in the case of hemp and jute, since they are finer.
Wood fragments from bast fiber plants, which are formed when the bast fibers are separated from the ligneous core, are called shives. For this purpose, the stalks are fed in full length or in portions of the stalk to corresponding apparatuses. The apparatuses break up the brittle wood core into fragments and at the same time separate the bast fiber from the wood. By “scutching” or “tangle fiber hackling” and subsequently using machines for cutting off residual shives from the fibers, either an almost shive-free long fiber or a tow with a certain residual shive fraction is then produced.
Depending on the structure of the production plant, short fibers with a relatively high shive fraction and relatively low-fiber shives are produced as a byproduct. The short fibers, of a length of between two and thirty millimeters, are freed of the residual shives in further process steps and are sold mainly to the paper industry, in particular the cigarette paper industry. The substantially fiber-free shives have to be disposed of. According to most recent developments, decortication, i.e. removing the wooden materials, is already, carried out in the field, so that the shives, for which there is hardly any use at the present time, can be left directly as waste in the field. In earlier decades, the fibers from bast fiber plants were used predominantly for the production of clothing textiles and industrial textiles (ship's sails, ropes, tarpaulins, tents and the like). These textiles have since been largely replaced by synthetic fibers. With growing ecological awareness, attempts are being made, throughout the world, to reintroduce bast fibers. The main field of use is nonwovens for the production of interior fittings and equipment of passenger vehicles and for insulating purposes in the building industry.
After being decorticated, the fibers have to undergo a number of costly cleaning and opening operations. These operations inevitably shorten the fibers and they become pliable and soft. However, nonwovens made from soft fibers will collapse. Since they become too dense when they collapse, they are difficult to impregnate with thermoplastic melts or are difficult to impregnate evenly. This also applies to the spray-coating or cast-coating of thermosets or duroplastics of a synthetic or a biological type. Due to the collapsing, these materials lose some of their insulating value, when used as fleeces for insulating materials. Synthetic fibers, which prevent collapse due to their brittleness, therefore have to be admixed.
Shives are, in principle, extremely light wood, almost as light as balsa wood. They are rigid and brittle and possess a fibrous structure. Their density is in the range of between 250 and 350 kg/m
3
. After breaking, they do not have a very high degree of fineness. In contrast to shives, fibers from bast fiber plants, also short fibers, have a very high strength and a very high degree of fineness. Customarily, bast fibers and shives are always thoroughly separated, since, for further processing operations with the currently available machines and technologies for the production of fleeces, mats and balls, as well as for spinning and for currently known products, shives have a disruptive effect and oftentimes even make processing impossible.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method for producing a building material and the structural parts, which economically utilize shives.
With the foregoing and other objects in view there is provided, in accordance with the invention, a building material, comprising:
shives of bast fiber plants;
first multiplicity of bast fibers separate from the shives;
a second multiplicity of bast fibers in a natural bond with some of the shives, partially detached from some of the shives and irregularly projecting laterally from some of the shives; and
a binder for binding the shives and the first and second multiplicity of bast fibers to form the building material.
In accordance with a further feature of the invention, the shives have lengths of between 2 and 50 mm and the second multiplicity of bast fibers have lengths of between 2 and 100 mm.
In accordance with another feature of the invention, the first multiplicity of bast fibers have lengths of between and 2 and 80 mm.
In accordance with another feature of the invention, the first and the second multiplicity of bast fibers have a crimped shape.
In accordance with a further feature of the invention, the shives and the first and second multiplicity of bast fibers form a loose structure having contact points, the binder fixing the loose structure at the contact points.
In accordance with yet a further feature of the invention, a matrix formed from a material selected from the group consisting of synthetic plastic, biogenous plastic, mineral materials, and foam is provided, the shives and the the first and second multiplicity of bast fibers are introduced into the matrix.
In accordance with another feature of the invention, the shives are shives separated in a fiber direction for increasing a degree of fineness and homogeneity.
With the object of the invention in view there is also provided, a method of producing a building material, the method which comprises:
providing bast fibers and shives of bast fiber plants;
loosening the bast fibers and the shives of bast fiber plants;
metering the bast fibers and the shives of bast fiber plants;
subsequently feeding the bast fibers and the shives of bast fiber plants to at least one of an applicator device for liquid additives and a spreading system for solid additives; and
subsequently spreading the bast fibers and the shives of bast fiber plants in the form of one of a fleece and a cake.
In accordance with another mode of the invention, at least one of the liquid additives and the solid additives are homogeneously incorporated into the bast fibers and the shives of bast fiber plants.
In accordance with yet another mode of the invention, the bast fibers and the shives of bast fiber plants in the form of one of the fleece and the cake are mechanically felted by an air flow.
In accordance with a further mode of the invention, the bast fibers and the shives of bast fiber plants, mixed with at least one of the liquid additives and the solid additives, are provided in the form of a loose layer and the bast fibers and the shives of bast fiber plants in the form of the loose layer are combed off, swirled and homogenized with a spiked stripping and mixing roller.
With the object of the invention in view there is furthermore provided, an apparatus for producing a building material, comprising:
an upper rotating mechanical supply conveyor for feeding bast fibers and shives of bast fiber plants;
a hopper feeder downstream of the upper rotating mechanical supply conveyor receiving the bast fibers and the shives of bast fiber plants from the upper rotating mechanical supply conveyor;
a rotating floor belt downstream of the hopper feeder, the rotating floor belt receiving the bast fibers and the shives of bast fiber plants from the hopper feeder and having a carding device for premetering.
In accordance with another feature of the invention, there is provided a layer-height lim
Moeller Plast GmbH
Staicovici Stefan
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