Process for making PEN/PET blends and transparent articles therefrom

An injection-molded or extrusion-molded article comprising a polyester layer and a solid-stated copolymerized polyethylene naphthalate and polyethylene terephthalate PEN/PET layer, the PEN/PET layer:

• i) having a glass transition temperature Tg at least 15° C. greater than that of the polyester layer;
• and
• ii) a moderate level of transesterification to enable strain orientation and crystallization of both layers while maintaining substantial transparency of both layers.

An injection-molded or extrusion-molded preform comprising a neck finish portion of a solid-stated copolymerized polyethylene naphthalate and polyethylene terephthalate PEN/PET having a transesterification level of greater than 30%, and an adjacent body portion comprising polyester, the PEN/PET being melt compatible with the polyester to maintain substantial transparency of and adhesion between the portions while the polyester portion undergoes strain orientation and crystallization, the neck finish portion remaining substantially unoriented.

An injection-molded or extrusion-molded article comprising a solid-stated copolymerized polyethylene naphthalate and polyethylene terephthalate PEN/PET portion having a transesterification level of at least 30%, and an adjacent portion of polyester, the PEN/PET being melt compatible with the polyester to maintain transparency and adhesion between the portions while the polyester portion undergoes strain orientation and crystallization, the PEN/PET portion remaining substantially unoriented.

A method of copolymerizing polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) comprising:

• providing PEN;
• providing PET;
• reacting the PEN and PET in the presence of alkylene glycol having up to 6 carbon atoms to form a copolymerized PEN/PET product, the alkylene glycol being added in an amount sufficient to increase the Tg at least about 15° C.

A method of copolymerizing polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) comprising:

• providing PEN;
• providing PET;
• reacting the PEN and PET in the presence of alkylene glycol having up to 6 carbon atoms to form a copolymerized PEN/PET product, the alkylene glycol being added in an amount sufficient to achieve a transesterification level of at least about 30% or greater.

A method of copolymerizing polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) comprising:

• providing PEN having an intrinsic viscosity (IV) of about 0.5 dL/g to about 0.8 dL/g;
• providing PET having an IV of about 0.70 dL/g to about 0.75 dL/g, reacting the PEN and PET in the presence of alkylene glycol having up to 6 carbon atoms to form a copolymerized PEN/PET product, the alkylene glycol being added in an amount sufficient to achieve a desired final IV and final level of transesterification in the PEN/PET product.

A method of copolymerizing polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) comprising:

• providing PEN having an intrinsic viscosity (IV) of about 0.5 dL/g to about 0.8 dL/g;
• providing PET having an IV of about 0.70 dL/g to about 0.75 dL/g, reacting the PEN and PET in the presence of alkylene glycol having up to 6 carbon atoms to form a copolymerized PEN/PET product, the alkylene glycol being added in an amount of at least 0.05 weight percent based on the total weight of the PEN and PET.