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raw · articles · ingested 2026-10-27

Lysis Technologies In-Mould Spray System for Two-Color Rotational Molding

confidence: medium

Source: https://interplasinsights.com/plastics-materials/lysis-tech-and-polymer-developments-use-in-mould-spray-syste/

Source

Interplas Insights (trade publication for UK plastics industry). Report on collaboration between Lysis Technologies (ink system) and Polymer Developments (rotomolding). Date approximate; article undated but technology described as current.

Process Description

  1. Half of the rotomolding tool is coated with colour-matched in-mould sprayed ink using a spray gun
  2. The tool is then charged with PE powder
  3. Standard rotational moulding cycle is carried out as normal
  4. The in-mould ink transfers to the part surface during the moulding cycle
  5. Result: well-defined line between the coloured and non-coloured areas

Materials

  • Part material: polyethylene (PE) powder — standard rotomolding grade
  • Ink system: colour-matched in-mould sprayed ink from Lysis Technologies
  • The ink bonds to the PE during the moulding cycle

Demonstrated Product

  • Dimensions: 1.7 m x 0.5 m x 0.2 m
  • Configuration: grey top section, white bottom section
  • Well-defined colour boundary between sections

Performance Claims

  • Durable against solvents, UV, and weather
  • Easy to apply
  • Reduces overall cost compared to alternatives
  • Sharp colour boundary (contrasted with coloured powder approaches that give no clear distinction)

Alternative Two-Color Rotomolding Methods (from patent literature)

  • Separation sheet (US 7754133): Physical barrier placed in mould to divide compartments; resins fuse to opposite sides or sheet melts while maintaining colour boundary
  • Barrier plastic partition (US 5932161): Two mould chambers separated by partition wall with barrier plastic in access opening
  • Module swapping (US 4331626): Different colour materials supplied from separate modules
  • Traditional approach: Mold single-colour parts separately, then fasten together

Limitations

  • No spray specifications given (ink viscosity, coat thickness, application rate, gun settings)
  • Single demonstration example; no data on tanks or large cylindrical items
  • Colour powder approaches described as inaccurate for large products
  • BPF (British Plastics Federation) notes that multi-colour rotomolding has limitations especially for large items and “very rarely the final outcome can be predicted”

Relevance to Tank Application

For a Duxberry-style HDPE/PP tank molded black on one side and white on the other:

  1. In-mould spray is the most promising technique — it can produce a sharp colour boundary on PE parts
  2. The demonstrated part size (1.7m) suggests feasibility for medium tanks
  3. Key question: can a cylindrical tank mould be sprayed on one hemisphere only with sufficient precision?
  4. Alternative: separation sheet technique may work for a tank split into hemispheres
  5. Carbon black loading for the dark side could provide both color and UV stabilization
  6. The ink system’s UV and weather durability is relevant for outdoor tank use