FAQ

• Q1: Why do plastic products sometimes show dye migration to the surface after dyeing?

  Reason: The migration of solvent dyes typically stems from their insufficient solubility in the plastic matrix or a poor affinity with the matrix, leading dye molecules to gradually migrate to the surface over time.

  Solution:

  • Select solvent dyes with high affinity and compatible solubility with the plastic substrate (e.g., Solvent Red 135 for PMMA).
  • Control the dye concentration (recommended range: 0.1%-2%) to avoid exceeding the substrate's saturation solubility.
  • Add anti-migration agents (such as low molecular weight polymers) to enhance the dye's stability within the substrate.
• Q2: How can the lightfastness of dyed plastics be improved to prevent fading?

  Reason: Insufficient dye lightfastness allows UV irradiation to damage the dye's molecular structure, which is more pronounced in ABS or PMMA products used outdoors.

  Solution:

  • Choose solvent dyes with high lightfastness (e.g., anthraquinone-based Solvent Blue 104, lightfastness rating of 6-7).
  • Incorporate UV absorbers (such as benzotriazoles) or hindered amine light stabilizers (HALS) into the formulation.
  • Enhance the UV protection layer on the product surface to reduce direct UV exposure.
• Q3: Why do solvent dyes sometimes dissolve incompletely in plastic films, resulting in color streaks?

  Reason: Low dye solubility or incompatibility with the plastic substrate may be due to the selection of an inappropriate dye type or uneven mixing.

  Solution:

  • Choose solvent dyes with good compatibility with the substrate (e.g., Solvent Yellow 163 for PC and PMMA).
  • Use a premixing technique: first dissolve the dye in a small amount of a compatible solvent (such as xylene), and then mix it with plastic pellets.
  • Utilize high-speed mixing equipment to ensure uniform dye dispersion.
• Q4: How can I determine whether a dye's migration will affect product quality?

  Reason: Highly migratory dyes may cause color transfer upon contact with other materials or precipitate out under high-temperature, high-humidity conditions.

  Solution:

  • Conduct migration tests before use (e.g., press a dyed sample against white cloth at 60°C and 95% humidity for 24 hours and observe the results).
  • Select low-migration dyes (such as anthraquinone dyes) and avoid using volatile solvent carriers.
  • Increase the processing temperature (e.g., process PC at 280°C) to promote the integration of the dye with the substrate.
• Q5: Can dyes with poor lightfastness not be used at all for outdoor products?

  Reason: Dyes with low lightfastness (e.g., certain azo dyes, lightfastness ratings of only 3-4) fade rapidly under prolonged outdoor exposure.

  Solution:

  • Select dyes with higher lightfastness ratings according to requirements (e.g., single or complex dyes with lightfastness ratings of 6 or higher).
  • If dyes with poor lightfastness must be used, combine them with UV absorbers and restrict usage scenarios (e.g., short-term displays).
  • Test color stability under outdoor exposure conditions (e.g., according to ISO 4892 standards) to confirm compliance with requirements.
• Q6: What problems can arise from insufficient solvent dye solubility?

  Reason: Insufficient solubility can cause dye crystals to precipitate out, affecting the product's appearance (e.g., PMMA light boxes) or surface gloss.

  Solution:

  • Consult the dye's technical data to select products with high solubility (e.g., Solvent Green 3 has good solubility in PC).
  • Adjust the dye concentration to avoid exceeding the substrate's solubility limit (typically not exceeding 2%).
  • Add a solvent aid (such as a small amount of ester solvent) to the mixture to improve dye solubility.
• Q7: How can I prevent dye migration from affecting the connection with other components?

  Reason: Dye migration can cause color transfer to adjacent plastics or packaging materials, affecting overall product quality.

  Solution:

  • Select low-migration dyes and test their stability in actual application environments.
  • Coat the product surface with a protective layer (such as clear lacquer) to isolate the dye from external contact.
  • Avoid direct contact between dyed parts and materials with high oil absorption (such as soft PVC).
• Q8: Does lightfastness and migration resistance change due to processing conditions?

  Reason: Excessively high processing temperatures (e.g., PC exceeding 320°C) can damage the dye structure, affecting lightfastness; excessively low temperatures can lead to incomplete dissolution, increasing migration risk.

  Solution:

  • Adjust the processing temperature according to the dye's thermal tolerance range (e.g., anthraquinone dyes are suitable for 260-300°C).
  • Maintain stable screw speed and pressure to ensure the dye melts fully and disperses evenly.
  • Record lightfastness and migration resistance performance under different conditions during trial production to optimize processing parameters.
• Q9: How can solubility be guaranteed while controlling costs?

  Reason: Dyes with high solubility (such as certain specific anthraquinones) are more costly, which can increase production expenses.

  Solution:

  • Select cost-effective dyes based on product requirements (e.g., Solvent Orange 60 is suitable for ABS).
  • Reduce the dye concentration and achieve the target color through color matching techniques (e.g., using a small amount of complementary color dye).
  • Negotiate with suppliers to bulk purchase specific dyes to reduce unit price.
• Q10: How are the migration resistance, lightfastness, and solubility of solvent dyes tested?

  Reason: Without testing, it may not be possible to predict the dye's performance in actual applications, affecting product longevity.

  Solution:

  • Migration resistance test: Press the dyed sample against wet paper or white cloth under high-temperature conditions (60°C, 95%RH, 24 hours) and observe the color transfer.
  • Lightfastness test: Test the degree of fading using a xenon lamp according to the ISO 105-B02 standard.
  • Solubility test: Gradually increase the dye concentration in a small sample, observe whether there is precipitation or color streaks, and determine the concentration limit.