“Poly(ethylene terephthalate) resins are commonly referred to in the industry as "PET" even through they may and often do contain minor amounts of additional components. PET is widely used to manufacture containers for juice, water, carbonated soft drinks ("CSD") and the like. PET is used for these purposes due to its generally excellent combination of mechanical and gas barrier properties. “

“PET containers must conform to fairly rigid specifications, especially when used to contain and store carbonated beverages in warm climates and/or in the summer months. Under such conditions, the containers often undergo thermal expansion, commonly referred to in the industry as "creep", caused by the high pressure in the container at high temperature. The expansion increases the space between the PET molecules in the side wall of the container thus allowing for CO2 to escape through the side wall faster than under normal conditions. Expansion also increases the head space of the container, which allows carbonation to escape from the beverage into the headspace area. Regardless of how carbonation is released from the beverage while enclosed in a container, loss of carbonation is undesirable because the beverage will taste "flat" when this occurs. Creep increases the interior space in the container which, in turn, reduces the height of the beverage in the container. This reduced height can translate into a perception by the consumer that the container is not completely full and, as such, perception of product quality is reduced. “

“PET container performance is also relevant in regards to sidewall strength. In storage and transport, filled PET containers are normally stacked with several layers of filled containers on top of each other. This causes significant vertical stress on the container which is manifested in large part against the sidewalls. If there is not sufficient sidewall strength or top load in the PET container, the bottle can collapse in storage or in use. “

“Moreover, consumer perception of container quality is manifested in the feel of the container when it is being held. When consumer hold a container and squeeze the container, the contain sidewall will deform. If sidewall deflection is too high, the container will feel too soft;, and consumers relate this to a poor quality of products, even though the products are of the same quality as compared

“It is desirable to reduce the amount of PET used in the preparation of PET containers for cost reduction. Lower weight PET containers result in lower material costs, less energy usage during the manufacturing process and lower transport costs. Lighter weighted containers also provide less solid waste and have less negative environmental impact. However, with reducing the amount of PET per container the desired properties mentioned above are also sacrificed, thus achieving a balance between source reduction and performance is difficult to achieve.”

“Prior art methods of reducing the weight of PET containers generally focus on reduction of the amount of polymer used to prepare the container. The weight of the container can be reduced to an amount that is shown through performance testing to not dramatically sacrifice performance of the containers in use, although some deterioration in container performance are seen with prior art methods of lightweighting where no barrier coating is used. Generally, the above-described container properties are directly related to the amount of PET resin used to prepare the container. In prior art methods of light weighting containers, lower amounts of PET resin used will result in thinner-walled finished containers and will consequently result in lower barrier and strength properties in the finished container. Thus, the tension between maximizing the performance of PET containers while attempting to reduce the weight of PET containers remains a concern, especially in warmer climates.”
(Kjorlaug et al, US Patent 7,820,257; 10/26/2010)

Blow Molding   
Blow Molding Applications    
Blow Molding Containers    
Polyethylene Terephthalate (PET)    
Stretch Blow Molding
Processing    

Recent US Patents

Comments