Process for producing cellulose/plastic composites and product of the process
OwnerLothar Thiele, Hans-Peter Kohlstadt +1inventors
InventorsLothar Thiele, Hans-Peter Kohlstadt, Hans Reinhard Striewski
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Abstract
The invention is a process for producing a particulate cellulose containing composite and the product of the process. The composite is formed by mixing a cellulose containing material with a polyol and water to form a first mixture. The first mixture is mixed with an equivalent excess of a polyisocyanate to form a second mixture which is reacted under pressure of 1 Kg/cm2 to 100 Kg/cm2 at a temperature of 10° C. to 30° C. for from 5 minutes to 30 minutes to form the composite.
Claims19
Wood-plastic composites based on wood particles and/or cellulose-containing material and at least one binder, the binder being a carbon-dioxide-eliminating two-component polyurethane binder of a polyol, water and a polyisocyanate, characterized in that the binder is present in a quantity of 10 to 200 parts by weight, based on 100 parts by weight of the wood particles and/or the cellulose-containing material, the composite being obtainable by reaction of the wood particles and/or the cellulose-containing material and the binder under a pressure of at least 1 kp/cm2 and, more particularly, in the range from 50 to 100 kp/cm2.
Composites as claimed in at least one of the preceding claims, characterized in that vegetable fibers, such as cotton, jute, flax, hemp, or chemically modified fibers, such as rayon staple, are used as the cellulose-containing material.
Composites as claimed in at least one of the preceding claims, characterized in that the wood particles are used in the form of wood chips or wood powder with particle sizes of at most 1 mm (thickness)×20 mm (width)×50 mm (length).
Composites as claimed in at least one of the preceding claims, characterized in that the moisture content of the wood particles and/or the cellulose-containing material is between 5 and 2% by weight.
Composites as claimed in at least one of the preceding claims, characterized in that they additionally contain inserts or strengtheners, for example in the form of wires, cables, wire nets or rods.
Composites as claimed in at least one of the preceding claims, characterized in that the polyisocyanate is a diisocyanate or triisocyanate, more particularly diphenylmethane-2,2′-diisocyanate (as the crude product).
Composites as claimed in at least one of the preceding claims, characterized in that the polyol is a diol/triol mixture of polyether and polyester polyols with water.
Composites as claimed in at least one of the preceding claims, characterized in that they have a density of 0.40 g/cm3 to 0.65 g/cm3.
A process for the production of the composites claimed in the preceding claims, characterized in that
- a) the wood particles and/or the cellulose-containing material are/is first mixed with the polyol component,
- b) the other component(s), more particularly the polyisocyanate in excess, is/are added to the resulting mixture and the mixture is homogenized,
- c) the mixture is introduced into a closable pressure-tight mold optionally coated with release agents and the reaction mixture is reacted under a pressure of at least 1 kg/cm3 and
- d) the molding is removed from or freed from the mold.
Dependencies are inferred from the claim text.