The present thesis work was entirely developed at IMA – Fillshape, which is a division of the IMA Group located in Vicofertile (PR). It aimed at selecting the most adequate mono-polyethylene multilayer film expected to constitute a spouted stand-up pouch, among the ones provided by the supplier, and defining an operating process window – intended as the set of process parameters combinations leading to a satisfactory heat-seal – to be adopted on the actual packaging lines, which was the primary objective for the division. Fillshape is currently pursuing modern logics of sustainability and the major step towards such logics is surely represented by the introduction of recyclable films, as valid sustainable alternatives to conventional multilayer plastic films. Seven diverse mono-polyethylene pouches were analysed based on a qualitative analysis of the associated datasheets and test results provided by the supplier, with the intention of selecting two candidate materials. Thereafter, the selected ones were thoroughly examined from a mechanical, thermal and sealability point of view, in order to objectively determine a process window within which they could be sealed ensuring an adequate and leak-free sealing along with a superior aesthetic appearance. In particular, a differential scanning calorimeter was employed to assess the thermal response of the involved materials highlighting the melting points distribution and an optical microscope was required to verify the material stratification. Furthermore, preliminary tensile tests were performed on materials strips along both machine and transverse direction and heat-sealed samples were tested in order to evaluate the heat-seal strength. In particular, the fin heat-seal between film and spout was assessed, as it represents the most critical region of the pouch. On the other hand, the seal appearance of the lateral film-film regions was taken into account to determine the upper thermal limit in terms of shrinkage. The effect of set temperature, dwell time and sealing pressure was examined and diverse failure modes of the film-spout heat-seal were itemized. Eventually, an additional integrity assessment was made by performing burst and leak tests. As an auxiliary analysis, the heat-sealing jaws were analyzed via finite element analyses to assess their actual thermal behaviour, identify possible criticalities to overcome, and improve the aesthetics of the sealed pouch by acting on the bar temperature profile. In conclusion, the feasibility of introducing mono-polyethylene recyclable films in industrial automatic packaging lines was effectively demonstrated. Nonetheless, few limiting aspects were observed during the experimental campaign from a heat-sealing perspective, which must be undoubtedly accounted for when processing mono-material spouted stand-up pouches on packaging automatic machines.
Il presente lavoro di tesi è stato interamente sviluppato presso IMA - Fillshape, divisione del Gruppo IMA con sede a Vicofertile (PR). Gli obiettivi primari di tale progetto sono stati la selezione del film multistrato, tra quelli messi a disposizione dal fornitore, in mono-polietilene più adeguato ed idoneo alla realizzazione industriale di buste in formato Doypack con beccuccio, e la definizione di una finestra di processo - intesa come l'insieme delle combinazioni dei parametri di processo che garantiscano una soddisfacente saldatura - da adottarsi sulle vere e proprie linee di confezionamento, obiettivo primario della divisione. Fillshape sta attualmente perseguendo logiche moderne di sostenibilità ed il passo più importante è sicuramente rappresentato dall'introduzione di film riciclabili, come valide alternative ai film plastici tradizionali. Sono state analizzate sette diverse buste in mono-polietilene sulla base di un'analisi qualitativa delle schede tecniche associate e di risultati sperimentali preliminari messi a disposizione dal fornitore, con l'intenzione di selezionarne due. Successivamente, queste sono state esaminate nel dettaglio dal punto di vista meccanico, termico e di saldabilità, al fine di determinare in modo oggettivo una finestra di processo, all'interno della quale essi possano essere saldati garantendo un'adeguata tenuta, completa assenza di perdite dalla busta ed un aspetto estetico accettabile. In particolare, sono stati utilizzati un calorimetro a scansione differenziale per valutare la risposta termica dei materiali coinvolti, evidenziandone la distribuzione dei punti di fusione, ed un microscopio ottico per verificarne la stratificazione. Inoltre, sono state eseguite prove di trazione preliminari su campioni di materiale sia in direzione macchina che in direzione trasversale, e sono stati testati campioni saldati per valutarne la resistenza meccanica. In particolare, è stata valutata la saldatura tra film e beccuccio, in quanto essa rappresenta la regione più critica della saldatura stessa. Le zone laterali di saldatura sono state invece considerate per valutare globalmente l’estetica della busta e per determinare il limite termico superiore in termini di deformazione dovuta all’apporto termico. È stato esaminato l'effetto della temperatura, del tempo e della pressione di saldatura, e sono state definite le diverse modalità di “fallimento” delle saldature in oggetto. Infine, è stata effettuata un'ulteriore valutazione dell'integrità della confezione eseguendo test di scoppio e di perdite. In parallelo, sono state analizzate le pinze saldanti tramite analisi agli elementi finiti per valutarne l'effettiva risposta termica, identificare possibili criticità da risolvere e migliorare globalmente l'estetica della busta sigillata, agendo sui profili di temperatura delle due pinze. In conclusione, è stata dimostrata in modo efficace la fattibilità dell'introduzione di tali film riciclabili in mono-polietilene nelle linee automatiche di confezionamento a livello industriale. Tuttavia, durante la campagna sperimentale, sono stati osservati taluni fattori ed aspetti limitanti dal punto di vista della saldatura, di cui è necessario tener conto ai fini di una corretta introduzione di buste in mono-materiale sulle linee automatiche di confezionamento.
Characterization and validation of mono-polyethylene spouted stand-up pouches for industrial purposes
SETTI, CARLO
2019/2020
Abstract
The present thesis work was entirely developed at IMA – Fillshape, which is a division of the IMA Group located in Vicofertile (PR). It aimed at selecting the most adequate mono-polyethylene multilayer film expected to constitute a spouted stand-up pouch, among the ones provided by the supplier, and defining an operating process window – intended as the set of process parameters combinations leading to a satisfactory heat-seal – to be adopted on the actual packaging lines, which was the primary objective for the division. Fillshape is currently pursuing modern logics of sustainability and the major step towards such logics is surely represented by the introduction of recyclable films, as valid sustainable alternatives to conventional multilayer plastic films. Seven diverse mono-polyethylene pouches were analysed based on a qualitative analysis of the associated datasheets and test results provided by the supplier, with the intention of selecting two candidate materials. Thereafter, the selected ones were thoroughly examined from a mechanical, thermal and sealability point of view, in order to objectively determine a process window within which they could be sealed ensuring an adequate and leak-free sealing along with a superior aesthetic appearance. In particular, a differential scanning calorimeter was employed to assess the thermal response of the involved materials highlighting the melting points distribution and an optical microscope was required to verify the material stratification. Furthermore, preliminary tensile tests were performed on materials strips along both machine and transverse direction and heat-sealed samples were tested in order to evaluate the heat-seal strength. In particular, the fin heat-seal between film and spout was assessed, as it represents the most critical region of the pouch. On the other hand, the seal appearance of the lateral film-film regions was taken into account to determine the upper thermal limit in terms of shrinkage. The effect of set temperature, dwell time and sealing pressure was examined and diverse failure modes of the film-spout heat-seal were itemized. Eventually, an additional integrity assessment was made by performing burst and leak tests. As an auxiliary analysis, the heat-sealing jaws were analyzed via finite element analyses to assess their actual thermal behaviour, identify possible criticalities to overcome, and improve the aesthetics of the sealed pouch by acting on the bar temperature profile. In conclusion, the feasibility of introducing mono-polyethylene recyclable films in industrial automatic packaging lines was effectively demonstrated. Nonetheless, few limiting aspects were observed during the experimental campaign from a heat-sealing perspective, which must be undoubtedly accounted for when processing mono-material spouted stand-up pouches on packaging automatic machines.| File | Dimensione | Formato | |
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2021_04_Setti.pdf
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Descrizione: Testo integrale della tesi
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https://hdl.handle.net/10589/175344