Method for stretching plastic nets and grids apparatus for performing the method
AssigneeTenax S.P.A.
InventorMario Beretta
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Abstract
A method for stretching plastic nets and grids having the peculiarity that it consists in subjecting the product to be stretched to irradiation with electromagnetic waves with a wavelength above the infrared range, so as to heat the product by dielectric loss, and in subjecting the product to traction in order to produce stretching in at least one direction. The method allows to substantially improve the ability of the polymer to absorb the energy in order to profitably perform the stretching process.
Claims13
A method for stretching plastic nets or grids having mutually interconnected strands and nodes with thickness variations comprising thinner regions and thicker regions, and being made of polymeric material with a polyolefin base mix, the method comprising:
- adding additives to the polyolefin base mix of the polymeric material of the plastic nets or grids in order to produce, in the polymeric material, a loss factor of more than 0.01;
- subjecting the plastic nets or grids to be stretched to irradiation with electromagnetic waves with a wavelength above the infrared range, so as to heat said product by dielectric loss, and
- subjecting the plastic nets or grids to traction in order to produce stretching in at least one stretching direction with stretching of all of the layers of the strands and the nodes and uniform and simultaneous elongation of the macromolecules in the stretching direction and simultaneous molecular orientation in the thinner and thicker regions.
Dependencies are inferred from the claim text.