Compression-moulded tray and method of producing a fibre tray
A compression-molded tray of fiber material, said tray being formed of fiber material in a compression method, from a suspension of mechanical pulp of cellulose. The formed tray has been formed by press-drying using heat to a dry content of 80-95%, preferably 90-95%, and the fiber material of the formed tray has a density in the order of 400-650 kg/m3. The inside of the tray is provided with a protective barrier.
1. A method of producing a fibre tray, comprising the steps of:
a. forming a fibre tray by immersing a dewatering tray having the shape of the tray to be produced into a bath of a suspension of mechanical pulp and dewatering the suspension in the dewatering tray, the mechanical pulp comprising at least 75% virgin fibre-based mechanical pulp from the group, CMP, CTMP, cTMP, HTCTMP and mixtures thereof;
b. press-drying using a suitably smooth pressing tool and heating the formed tray to a dry content of 80-95% and a density of 400-650 kg/m3; and
c. coating the dried fibre material with a protective barrier having a thickness of 50 μm or less producing a coated press-dried fibre tray, wherein the coating is free of pin-holes.
2. The method according to claim 1 , wherein said press-drying is performed at 250-280° C.
3. The method according to claim 1 , wherein said protective barrier is applied by coating a surface of the formed fibre material with a plastic emulsion that is polymerised to a film by the addition of an initiator, or dries to a film, on the tray.
4. The tray according to any of claim 1 , wherein said protective barrier is constituted by a film of PET, PA, PP, PE, PBT, EVOH or combinations thereof.
5. The method according to any of claim 1 , wherein said film or protective barrier is secured to the formed tray by heat-lamination.
6. The method according to claim 1 , wherein the tray is formed from a suspension of fibre material having a pH between 6 and 8.5, preferably between 7 and 8.
7. A method of laminating a film or a protective barrier on a fibre material comprising at least 75% virgin fibre-based mechanical pulp from the group CMP, CTMP, cTMP, HTCTMP and mixtures thereof, comprising the steps of:
a. press-drying using a suitably smooth pressing tool and heating the fibre material to a dry content of 80-95% and a density of 400-650 kg/m3;
b. applying said film or protective barrier on said fibre material; and
c. laminating said film or protective barrier on said fibre material producing a protected fibre material having a protective barrier having a thickness of 50 μm or less and free of pin-holes in the protective barrier.
8. The method according to claim 7 , wherein said protective barrier is applied by coating a surface of the formed fibre material with a plastic emulsion that is polymerised to a film by the addition of an initiator, or dries to a film, on the tray.
9. The method according to claim 7 , wherein said film or protective barrier is secured to the formed tray by heat-lamination.
10. The method of according to any of claim 7 , wherein the applied film is PA, PP, PE, PBT, EVOH, APET, or combinations thereof.
11. The method of according to any of claim 7 , wherein the applied film is a film exhibiting increased E-modulus when stretched.