Process and installation for manufacturing a preform, implementing improved drying means, and plastic receipient obtained from the preform

• Main Author: HAESENDONCKX FRANK
• Format: Patent
• Language: English
• Published: 08.06.2004
• Edition: 7
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; MAKING GRANULES OR PREFORMS; PERFORMING OPERATIONS; PREPARATION OR PRETREATMENT OF THE MATERIAL TO BESHAPED; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIALCONTAINING PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

The process for manufacturing a preform from at least one thermoplastic resin in the form of granules (A) and in a substantially crystalline state, comprises following successive operations are carried out:drying the thermoplastic resin in the form of granules;melting the dried granules of resins;injecting the melted resin into a mould and removing the preform from the mould;The drying operation is carried out in at least two successive separate steps:in a first step (first hopper 5), the granules of resin substantially in a crystalline state are dried for a predetermined duration (t1) at a predetermined drying temperature (T1);in a second step (second hopper 5'), the drying of the granules from the first step is continued at a drying temperature (T2) that is markedly higher than the drying temperature (T1) of the first stage, and for a duration (t2) that is markedly shorter than the period (t1) of the first step.