Method and apparatus for producing porous plastic profiles
A method is disclosed for manufacturing connectable or non-connectable elongate porous plastic profiles 12 from substantially continuous randomised extruded plastic strands made of recycled thermoplastics. Current manufacturing processes can manufacture similar products, comprising short partially melted plastic particles melded together forming planks. These planks, however, are inherently friable, easily broken and not readily connectable. These shortcomings are caused by the manufacturing method used, being friction plate agglomeration. This invention utilises an extrusion process, which produces substantially endless random strands of thermoplastic 13 which drop and are welded together to form a porous mass, which is then compressed into boards or planks by pulling the mass through a forming tool 6 and 7 . The profile can be adjusted to form edge recesses allowing the planks to be fitted together, for instance to form area coverings, or they can simply be laid end to end to form drainage channels.
1. A method of forming porous thermoplastic profiles, comprising:
extruding molten strands of thermoplastic material of a diameter between about 3-12 mm to a length of at least 1 m;
letting the molten extruded strands of thermoplastic material drop at least 15 cm onto a horizontal forming base where the molten extruded strands of thermoplastic material contact each other and agglomerate to form a porous molten strand mass;
shaping the molten strand mass to form a profile;
transporting the profile along the base;
cooling the profile by means of a water spray or bath; and
separating the cooled profile into lengths.
2. A method according to claim 1 , wherein separating the cooled profile into lengths comprises cross cutting the cooled profile into the lengths once sufficiently cooled.
3. A method according to claim 1 , further comprising dividing the porous molten strand mass by one or more vertically orientated plates causing more than one profile to be produced simultaneously.
4. A method according to claim 1 , further comprising shaping the profile by horizontally mounted inserts within the porous molten strand mass creating longitudinal recesses allowing lateral connection together of numerous profiles.
5. A method according to claim 1 , further comprising adding non-melting particles to the thermoplastic material before the extruding.
6. A method according to claim 1 , wherein the strands of thermoplastic material include recycled thermoplastic material.