Fabricating and finishing

The decoration of injection molded parts and films has gained considerably in importance for the surface finishing of high-quality consumer goods. Whether unmistakable design, unusual shape or indestructible marking by laser - VESTAMID® scores with a wide range of design options because it is easily processed by a variety of methods.

In addition: Whether plastics are to be bonded to each other or to other materials - our high level of expertise in finishing molding compounds ensures that they adhere to metal, for example, and thus protect metal pipes from corrosion, bond inseparably with different rubbers in the plastic-rubber process, or form a secure weld seam in high-pressure gas pipes.

Sawing, turning, milling, drilling, and planning of VESTAMID® parts are possible. We recommend cooling by fluids or compressed air to reduce heating up of the VESTAMID® parts and hence to avoid problems with sticking.

VESTAMID® can easily be printed. Most printing inks can be used for sublimation printing. Screen inks must be adapted for use with VESTAMID® molding compounds. Preparation of the surface by flame treatment, roughening, or corona treatment generally results in improved adhesion of the printing inks. Adhesion can also be improved after printing, by flame treatment or tempering.

PA 12 elastomers of the VESTAMID® E series in particular are excellently suited for decoration by thermal diffusion printing processes. Sublimation printing and cutting-edge digital printing techniques result in brilliantly decorated films with virtually indestructible printed motifs; in the form of highly attractive protective films, these are now dominating the sporting goods and automotive sectors, among others.

Special VESTAMID® molding compounds are available for laser marking, which result in high-contrast lettering that is resistant to wear and chemicals. Even the smallest characters and symbols with very low line thicknesses can be positioned accurately and with clear legibility, on difficultly accessible, smooth, uneven, or structured surfaces as well as through transparent barriers.

The elastomers of the VESTAMID® E series are particularly well suited to overmolding. All VESTAMID® elastomers can be welded to each other and to VESTAMID® L (PA 12). This applies particularly to overmolding of compounds of different hardness or color.

This property is exploited particularly often in the production of multicomponent and multicolored parts of sporting goods such as specialty sports shoe soles and ski boots. A higher melt temperature of up to 300°C, high injection speed, and high holding pressure are recommended for overmolding. Better adhesion between the hard and soft components of the composite can be obtained if the mold temperature is raised up to 100°C. For more transparent overmolding, on the other hand, a lower processing temperature can be useful.

VESTAMID® elastomers can also be bonded to a number of other polymers by overmolding.

VESTAMID® molding compounds can be bonded without problems; however, the bonding surfaces must be clean and free of grease. The use of mold release agents should be avoided in the manufacture of moldings that are subsequently bonded. In addition, the bonding strength can be improved if the surface is pretreated by roughening, priming, corona treatment or flame treatment. In any case, the relevant safety regulations must be observed.

Suitable conventional adhesives are those based on:

  • Epoxide: one- or two-component (gap-filling) adhesives can be used for larger bond areas; the results are often better at higher temperatures.
  • Polyurethane: reactive one- or two-component adhesives and hot-melt adhesives (gap-filling, flexible adhesives, often with fairly long pot lives and cure times); suitable for larger bond areas.
  • Cyanoacrylate: single-component adhesives (with very short cure times); suitable for thin bonded joints and smaller bond areas.
  • Specialty polyamide adhesives are suitable for bonding of VESTAMID® E compounds.

VESTAMID® compounds can be welded by all the conventional techniques. These typically include:

  • Hot plate butt welding: The use of hot plates coated with PTFE prevents adhesion of the molding compound to the hot plate (for hot plate temperatures of up to 270°C).
  • Ultrasonic welding: A weld seam contour such as an energy director or pinch-off weld should be used. Far-field welding of molding compounds with low elastic modulus is possible only with difficulty.
  • Friction welding is possible by rotation or vibration.
  • High-frequency welding