PP food tray

A PP tray provides a different material choice from a visually similar clear PET food tray.

PP food tray, illustrative image

Material

Polypropylene tray body: PP

Material selection rationale

Low-mass formed shell
A thin wall and shaped rim hold a portion of food with relatively little material.
Grade-dependent heat use
Specified PP packaging can serve hot-fill or heated-food applications, but this capability belongs to the finished tray specification.
Polyolefin backbone
The tray follows propene addition polymerisation, unlike the ester-linked PET and PLA alternatives.

How it becomes a product

  1. Prepare the sheet: A suitable PP compound is extruded as sheet for a representative thermoforming route.
  2. Form and trim: The softened sheet takes the mould shape, then cools and is cut at the rim; a separate lid may be sealed to that rim.

Preparation routes

Propene route

Catalytic addition polymerisation. Propene molecules join into chains. A suitable catalyst controls chain growth and the arrangement of the methyl side groups. Catalyst-controlled arrangement of methyl groups can favour regular packing. The monomer formula alone does not describe this tacticity.

A coordination catalyst system is used; it is not counted as a monomer. A thermoplastic moulding or foam uses already-made PP, not propene reacting inside the final product.

  1. Poly(propene): manufacture and usesChemical Industry Education Centre, University of York

Sources

  1. Polypropylene for food-packaging traysFaerch
  2. Thermoforming food-packaging traysFaerch
  3. Poly(propene): manufacture and usesChemical Industry Education Centre, University of York