Saudi Basic Industries Corporation

Anthony Paul Unwin

Ian MacMillan Ward

Zahir Bashir

Glen Peter Thompson

The invention relates to a process for making an opaque and glossy film from a thermoplastic polyester composition, comprising the steps of a) extruding the polyester composition through a slot die, and quenching to form a substantially amorphous film having a crystallinity of at most 5%; b) rapidly heating the amorphous film to a drawing temperature in the range from Tto (T+50)&#xb0; C. while applying a draw ratio in the range of from &#x3bb;to &#x3bb;in longitudinal direction, and a drawing rate of at least 1 m/min to form an oriented film showing stress-whitening, wherein &#x3bb;is the draw ratio at which a transfer from a transparent product to a stress-whitened product occurs and &#x3bb;is the draw ratio at which failure of the stress whitened film occurs; and c) heat-setting the oriented stress-whitened film; the thermoplastic polyester composition substantially consisting of at least one crystallizable polyester derived from at least one aliphatic diol and at least one aromatic dicarboxylic acid. With this process it is possible to make a unitary, glossy, opaque film from a polyester composition that does not contain void-forming additives like high amounts of fine pigment particles or dispersed non-miscible polymer particles. The film obtained also has very good mechanical properties. It is a further advantage that the process can be performed continuously on conventional extrusion and stretching equipment used for making transparent film from polyesters. The invention also relates to an opaque polyester film obtainable by said process.

Process for making opaque polyester film

The invention relates to a Flexible Intermediate Bulk Container (FIBC) having a body made of flexible woven fabric, and integral handling devices, wherein the fabric is woven from opaque oriented polyethylene terephthalate (PET) strips having a density of from 500 to 1300 kg/mand a tensile strength of at least 250 MPa. Advantages of said FIBC include directly printability with the usual type of inks, giving excellent contrast and good adhesion, without pre-treatment like a corona- or flame-treatment. The FIBC based on the PET fabric also shows higher gloss; better UV resistance; better mechanical properties, like high tensile strength and creep resistance; favorable abrasion resistance; and higher temperature resistance than a conventional big bag based on polypropylene strips. The invention further relates to such a FIBC based on stress-whitened PET tapes obtained by a special drawing process.

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Leeds, United Kingdom

Anthony Paul Unwin