PET Preforms

The production of PET preforms presents a constant challenge: maintaining excellent product quality while keeping manufacturing costs under control. One of the key quality parameters is the concentration of acetaldehyde (AA), a naturally occurring by-product formed during PET processing.
Although acetaldehyde occurs naturally in products such as citrus fruits, even very low concentrations can affect taste and odor, particularly in bottled water. For PET preform manufacturers, excessive AA levels are therefore highly undesirable and can lead to product quality concerns.

The challenge of Acetaldehyde formation

The formation of AA during PET processing is primarily influenced by:

  • Melt temperature
  • Residence time of the material
  • Processing conditions
  • Material formulation

Due to the laminar flow characteristics of molten PET, residence time is not uniform throughout the melt stream. As a result, localized AA concentrations can develop and reach individual mold cavities. In multi-cavity systems, this can lead to occasional preforms with elevated AA levels despite otherwise stable production conditions.

To address this issue, many processors rely on AA scavengers or blockers. While effective, these additives increase production costs and can migrate into packaged products, requiring compliance with regulatory limits.

PET preforms (picture: Depositphotos)

Eliminate AA Peaks with the Promix PET Mixing Nozzle

The Promix PET Mixing Nozzle was specifically developed to solve this challenge by homogenizing the PET melt before it enters the mold cavities.

By uniformly distributing localized AA concentrations within the melt flow, the nozzle significantly reduces concentration peaks and prevents individual outliers. In many applications, peak AA levels can be reduced by 20-30%, helping all cavities remain below critical AA thresholds.

When AA blockers are used, their effectiveness is improved through better additive distribution. This often allows processors to significantly reduce additive consumption and, in some cases, eliminate AA blockers entirely.

The result is:

  • Lower additive costs
  • More consistent preform quality
  • Reduced risk of off-taste in bottled products
  • Improved process reliability

Promix PET Mixing Nozzle

Supporting higher rPET content

As sustainability requirements continue to increase, PET bottle manufacturers are incorporating growing percentages of recycled PET (rPET) into their products. Today, PET bottles commonly contain 30-40% recycled content, with higher percentages becoming increasingly common.

The Promix PET Mixing Nozzle supports this transition by improving the homogenization of lower-viscosity rPET flakes within the melt stream. This enables more stable processing and facilitates higher recycled content without compromising quality.

Superior color and temperature homogeneity

In addition to AA reduction and enhanced rPET processing, the Promix PET Mixing Nozzle provides outstanding melt homogenization benefits:

  • Excellent color distribution in colored preforms
  • Uniform temperature distribution throughout the melt
  • Improved cavity-to-cavity consistency
  • More balanced filling of all mold cavities

The homogeneous temperature profile within the preform contributes to more consistent wall thickness in the final bottle, resulting in better quality and improved process stability.

Designed for PET Preform Production

The Promix PET Mixing Nozzle has been specifically engineered for the demanding conditions of PET preform manufacturing, including high injection pressures and extremely fast injection times.

Its compact design allows for easy retrofitting of existing systems, while its robust construction ensures long-term reliability. The technology has been successfully implemented by numerous PET processors and machine manufacturers worldwide.

Key Benefits at a Glance

  • Reduction of local acetaldehyde (AA) concentrations
  • Significant savings in AA blockers and additives
  • Improved product taste neutrality
  • Excellent color distribution in colored preforms
  • Better incorporation of recycled PET (rPET)
  • Supports higher rPET content
  • Homogeneous melt temperature distribution
  • Improved bottle wall thickness consistency
  • Better cavity balance and filling behavior
  • Easy retrofit and rapid return on investment

Promix PET Mixing Nozzle: Delivering higher-quality PET preforms, lower production costs, and greater sustainability in a single solution.

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