EVA films, which stand out for their excellent elasticity, are often produced by extrusion blow molding. The properties of this film are closely related to the content of vinyl acetate (VA). VA sisalduse suurenedes paraneb kile elastsuse, stressi pragude takistuse, madala temperatuuri takistuse ja soojuse tihendamise osas. When the VA content reaches 15%~20%, its performance is even comparable to that of flexible PVC film. Conversely, when the VA content is lower, the film performance is closer to that of LDPE film. Generally, the content of VA in EVA film is controlled in the range of 10%~20%.
EVA films are known for their transparency, softness, and self-adhesiveness to the comfortable feel. Its excellent stress crack resistance and high elasticity make the elongation as high as 59%~80%, making it an ideal spiral wound film. Pakendi valdkonnas kasutatakse seda laialdaselt kastide ja kottidega kaupade kogumisel ja pakkimisel, samuti kaubaaluste venitamispakke. Samal ajal sobib EVA kile ka raskete materjalide, näiteks väetiste ja keemiliste toorainete jaoks pakendikottide tootmiseks. In addition, it has excellent low-temperature heat sealing and inclusion sealing, and is often used as a heat sealing layer for composite films.
The production methods of PVA films include solution casting and extrusion blow molding. PVA kõrge sulamistemperatuuri ja lagunemistemperatuuri läheduse tõttu on otsene sulamise väljapressimine keeruline, seetõttu kasutatakse töötlemistemperatuuri vähendamiseks sageli vee plastistamist. In this way, the film needs to be dried and dehydrated after molding to obtain a practical PVA film. In the field of packaging, the industry prefers to use the cast method to produce PVA films.
PVA films can be divided into water-resistant films and water-soluble films. Veekindlad kiled on valmistatud PVA-st, mille polümerisatsioon on üle 1000 ja täielikult seenestatud, samas kui vees lahustuvad kiled on valmistatud osaliselt sabiseeritud PVA-st madala polümerisatsiooniga. In packaging applications, we mainly use water-resistant PVA films.
PVA -kile, mis paistab silma suurepärase läbipaistvuse ja läike tõttu, pole mitte ainult vähem kalduvus elektri staatilisele kogunemisele ja tolmu imendumisele, vaid sellel on ka hea printimisvõime. In the dry state, it exhibits excellent airtightness and fragrance retention, as well as excellent oil resistance. In addition, PVA films have good mechanical strength, toughness, and resistance to stress cracking, and can be heat-sealed. However, due to its high moisture permeability and strong water absorption, the dimensional stability needs to be improved. Selle probleemi lahendamiseks kasutatakse polüvinülideenkloriidi katte, st K kattekihti, tavaliselt selle õhukindluse, lõhnapeetuse ja niiskusekindluse suurendamiseks. This specially treated PVA film is ideal for food packaging.
PVA -kilet kasutatakse sageli komposiitkilede tõkkekihina ja seda kasutatakse laialdaselt kiirtoidu, lihatoodete, kreemikatoodete ja muude toitude pakendamisel. At the same time, its single film is also widely used in the packaging of textiles and clothing. Lisaks on vees lahustuvatel PVA-kiledel suurepärase jõudluse ka keemiatoodete, näiteks desinfitseerimisvahendite, pesuvahendite, pleegitajate, värvainete, pestitsiidide jms mõõtmisel ja pakendamisel, samuti patsientide riiete pesukotid.
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Postiaeg: 18. märts2025