Thermoplastic Prepreg Systems

Litzler has extensive experience building thermoplastic prepregging equipment.

• The two simplest and most efficient methods of achieving uniform resin distribution are the water-slurry method and the solution method.
  • In the water-slurry method, thermoplastic resin powder is suspended in water.
  • In the solution method, the thermoplastic resin is dissolved in a compatible solvent.
  • In both cases, the fiber web is saturated with the slurry or solution.  Then the liquid is evaporated, leaving the resin behind, evenly distributed on the fiber.
• With some resin and fiber combinations, it is possible to achieve good resin distribution by applying the resin powder directly.
• After resin is applied (and liquid is removed), the web is preheated to the resin’s melt temperature and pulled through a heated die.  This stabilizes the resin distribution and forces the resin to penetrate and wet the fiber web.

Thermoplastic machines incorporate many of the same subsystems and components as Solution and Hot Melt thermoset prepreg machines:

• Creels
• Fiber management and spreading systems
• Unwinds and rewinds
• Litzler Automation control systems
• Edge trim and trim rewinds

There are several features and components unique to thermoplastic prepreg machines:

• Fiber Saturation and Impregnation
  • Stainless steel, recirculating slurry dip tanks
  • Mixing and distribution manifolds
  • Submerged rollers to encourage wetting
• Water/solvent removal and resin pre-heating
  • Infrared ovens are used because they do not disturb the resin distribution
• Heated Die
  • Precision machined to maintain/improve resin distribution
  • Uniform temperature distribution across and along the web for uniform penetration and wetting