4.6.3 Gel-forming adhesives

Gel-forming adhesives: Plastisols

General description:

  • Two-phase system: polymer particles (usually PVC) as a solid phase suspended in a viscous plasticiser; Hardening: the plasticiser penetrates into the PVC particles on supplying suitable heat
  • After hardening one has a soluble, meltable plastic or plastigel
  • Resulting adhesive film: plastified polymer

Physical properties in the as-supplied state:

  • Paste-like to firm

Processing:

  • Manual, semi-automated or fully automated processing
  • For preferred equipment contact the adhesive manufacturer
  • Processing temperature: room temperature
  • Normal contact pressure
  • Adhesive film thickness: 0.2 – 2 mm
  • Hardening via the sol-gel process whereby the supply of heat causes the plasticiser to penetrate into the polymer particles; then harden at 160 – 180°C
  • Secure in position during the entire oven process
  • Special products suitable for bonding oiled metal sheets
  • If overheated (e.g. spot welding work): liberation of hydrochloric acid; resulting risk of corrosion which can weaken the adhesive bond; reduction of the joint strength
  • Take relevant measures for health and safety at work and environmental protection (General: see Section 7; Details: see safety data sheet)

Typical properties of the hardened adhesives:

  • Ratio of polymer to plasticiser 1:1 to 1:4
  • Low strength
  • Relative high flexibility; medium elongation at fracture
  • Temperature for continuous use: up to 120°C

Points to heed:

  • The substrates must be acclimatised prior to bonding
  • Check the thermal stability of the substrates prior to hardening the adhesive (in an oven)
  • Take into account the heating-up time and cooling-down time for the substrates; this time must be added to the curing time for the adhesive
    → Take special care with thick substrates
  • The heating temperature refers to the temperature in the joint
    → Take special care with thick substrates
  • Stress can develop in the joint on heating and cooling

If you have questions about the product then see the technical data sheet or contact the adhesive manufacturer.