Highly transparent polypropylene (PP) sheet without nucleating agents
PURETHEMO is highly transparent and easily thermo-formable PP sheet produced by a unique processing process and material design. PURETHEMO is widely used for food packages, lids and medical packages.
2001 AOKI-KATASHI AWARD
2011 James L. White Innovation AWARD
A newly developed technology to control PP crystallization has made it possible to produce clear, transparent PP sheet.
Generally, PP develops large crystal structures . If the spherulite has a comparable size of visible light wave length (ca.400-800nm), visible light cannot go straight through the PP sheet. PURETHERMO has no such spherulite structures.
Transparent sheet with nucleating agent has high melting temperature so that precise temperature control is necessary in thermoforming process. PURETHERMO softens in lower temperature than such general PP sheet. It means broad thermo-formable temperature range can be obtained.
Thermoforming process brings about crystallization in PURETHERMO and the sheet crystallinity increases. But PURETHERMO can maintain its fine structure. The high crystallinity and fine structure make PURETHERMO transparent and rigid.
PURETHERMO has a comparable rigidity of general PP.
PURETHEMO is resistant to oily food or heat in common with general PP.
Heating up in microwave oven sometimes causes package deformation, especially if the package contains oily foods. The temperature sometimes becomes over 100 degree Celsius so that packages for this application need to be resistant to heat. PURETHEMO has been shown good performance for this application.
Medical packages are often sterilized by ethylene oxide gas or autoclave. They also need see-through appearance.
Polypropylene is not polar material in nature so that generally used inks cannot be cohesive to it, which means PP is not printable. This non-polar nature prevents from using PP sheet for decorative parts. Idemitsu Unitech has developed new PURETHERMO grades with polar surface. General inks for printable BOPET or PVC can be used for this PURETHERMO grades. This printable (enhanced ink adhesion) PURETHEMO grades widen their use for decorative parts without using expensive non-polar PP dedicated inks. PURETHERMO is showing a good performance in the applications.