Recycled PET and Our Patent

PET (whether virgin or recycled, in which case it is called rPET) can exist in an AMORPHOUS or SEMI-CRYSTALLINE form. This difference in molecular structure determines its thermal resistance and mechanical strength (in an inversely proportional manner).

To transform a product from an amorphous state to a crystalline state, energy (in the form of heat) must be applied. This can occur either during the molding process or afterward (e.g., by placing it in an oven). Both options involve costs because:

• To achieve crystallization during the production of the piece, a significantly longer cycle time and thermal energy are required to heat the mold.
• To achieve crystallization afterward, the necessary equipment to heat the piece must be acquired, along with the costs of handling and thermal energy expenditure.

In the past, processes were developed to accelerate the transition from an amorphous to a crystalline state (for example, Mitsubishi filed a patent as early as 1970), but none made PET a viable material for injection molding.
In addition to these economic limitations, there are significant technical challenges to using PET in injection molding:

• Difficulty in working with thick articles.
• Difficulty in ensuring the material flows properly within the molds.
• Alteration of the surface aesthetic effect.
• And many others, such as the impossibility of using pinpoint ejectors, etc.

All these limitations have, until now, confined the use of PET to the production of packaging (especially preforms and beverage bottles) through stretch-blow molding or thermoforming technologies..

Our patent allows:

• Precise control, not only of crystallization but also of the speed and temperature of crystallization (which goes far beyond mere acceleration), enabling the right performance in terms of thermal and mechanical resistance depending on the intended use of the product.
• Excellent results in crystallization kinetics, i.e., total control of crystallinity based on cycle time for each individual product
• Significant reduction in cycle time and, consequently, machine costs (in documented tests, cycle time was halved, and it is believed that further efficiency improvements can be achieved).
• Reduction in molding costs (both because no specific equipment is needed and because the energy requirement is significantly reduced).
• The ability to work with thick articles.
• The ability to fill very large surfaces (e.g., for large-diameter bowls), defying the assumption of a 1/60 flow ratio between the thickness of the piece and the spread of the material.
• The ability to control the aesthetic finish even on finely decorated surfaces.
• Numerous other improvements, such as the fact that even the end-of-life of the articles can remain within the PET chain for further uses, etc.

In light of all this, we believe we have given PET (and consequently rPET) value both economically and in terms of technical/mechanical/aesthetic properties, accrediting it as a material worthy of consideration for production through injection molding technology. A status it had not achieved until now.