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Problem4_RotationalMoulding_Workshop_Question4

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Ian Hansen
Ian Hansen

The document discusses the phenomenon of "orange peel" defects that can occur in rotomoulded parts with stone effect colors. Orange peel is characterized by an irregular pitted internal surface texture resembling an orange peel. It can range from mild to severe. The main causes of orange peel identified are: 1. Small density differences between colored polymer particles that shrink differently during molding. Different pigments result in different particle densities. 2. The effect of pigments, as different colors create different crystal structures during molding. Dry blending colors makes orange peel more severe. 3. Particle size effects, as higher percentages of coarse particles make orange peel defects easier to observe, but particle size itself is not the cause

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Rotomould Workshop Problem 4 What is the cause of Orange peel in stone effect colours Materials, by Ian Hansen, Rotoconsult
Orange Peel [OP] defined Ian Hansen Consult 1: STUDY OF ORANGE PEEL PHENOMENA IN ROTATIONAL MOLDING, E. Soos Takacs, M. Emami, D. DAgostin and J. Vlachopoulos, Department of Chemical Engineering, McMaster University, Canada The term orange peel describes an inside surface defect that is characterized by irregular grooves and pittingmuch like the topography of the outer skin of an orange.1
Orange Peel [OP] effect Ian Hansen Consult Rough internal surface. Seen in varying levels from mild to severe Found thru whole batch of parts of a batch of powder Source : Orange Peel in Rotomoulded Parts; Bloys Rijkmans ICO Polymers ARMA Rotomould Conference 2009 Sydney Intermittent Difficult to predict Occurs Natural & Colour Not well understood
Orange Peel [OP] effect in Colours Ian Hansen Consult Example of same base polymer, same green colour, same Particle Size but different pigment formulation, in 50/50 blend of 2 batches. Pigment can act as a nucleating agent and affect the crystallization process.1 Density has stronger effect on OP than MI - Differential shrinkage Particles RAISED Particles SUNKEN 1.Theeffectofcolourcompoundingoncrystalgrowthduringrotomoulding M.P.McCourt,MarkP.Kearns,G.M.McNally,PolymerProcessingResearchCentre,Queen'sUniversityBelfast, andR.J.Crawford,UniversityofWaikato Source : Test This : Materials Guide Ian Hansen ARMA Rotomould, Penang 2011ianhansenconsult.com
Crystal Structure affected by pigment Homogeneous crystal structure. Some air bubbles are observed. Dissimilar crystal structure. Indicating two different materials. This was a mixture of Batch 1 and Batch 2 Homogeneous crystal structure. Change in crystal size. Some air bubbles are observed. Batch 1 Batch 2 Batch 1 +2 50/50 Source : Test This : Materials Guide Ian Hansen ARMA Rotomould, Penang 2011
Cause of Orange Peel effect in Stone Effect Ian Hansen Consult 1. Small DENSITY differences of coloured polymer particles shrink differently. Different colours, are different pigments, are different densities Independent of degree of cure or additive depletion.
Cause of Orange Peel effect in Stone Effect Ian Hansen Consult 2. Effect of Pigment Different colours create different crystal structure. Dry blending of colours results in more severe OP 3. Effect of Particle Size Higher % coarse particles increases ease at which you can observe OP but PS is not the cause.
Ian Hansen Consult

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Problem4_RotationalMoulding_Workshop_Question4

  • 1. Rotomould Workshop Problem 4 What is the cause of Orange peel in stone effect colours Materials, by Ian Hansen, Rotoconsult
  • 2. Orange Peel [OP] defined Ian Hansen Consult 1: STUDY OF ORANGE PEEL PHENOMENA IN ROTATIONAL MOLDING, E. Soos Takacs, M. Emami, D. DAgostin and J. Vlachopoulos, Department of Chemical Engineering, McMaster University, Canada The term orange peel describes an inside surface defect that is characterized by irregular grooves and pittingmuch like the topography of the outer skin of an orange.1
  • 3. Orange Peel [OP] effect Ian Hansen Consult Rough internal surface. Seen in varying levels from mild to severe Found thru whole batch of parts of a batch of powder Source : Orange Peel in Rotomoulded Parts; Bloys Rijkmans ICO Polymers ARMA Rotomould Conference 2009 Sydney Intermittent Difficult to predict Occurs Natural & Colour Not well understood
  • 4. Orange Peel [OP] effect in Colours Ian Hansen Consult Example of same base polymer, same green colour, same Particle Size but different pigment formulation, in 50/50 blend of 2 batches. Pigment can act as a nucleating agent and affect the crystallization process.1 Density has stronger effect on OP than MI - Differential shrinkage Particles RAISED Particles SUNKEN 1.Theeffectofcolourcompoundingoncrystalgrowthduringrotomoulding M.P.McCourt,MarkP.Kearns,G.M.McNally,PolymerProcessingResearchCentre,Queen'sUniversityBelfast, andR.J.Crawford,UniversityofWaikato Source : Test This : Materials Guide Ian Hansen ARMA Rotomould, Penang 2011ianhansenconsult.com
  • 5. Crystal Structure affected by pigment Homogeneous crystal structure. Some air bubbles are observed. Dissimilar crystal structure. Indicating two different materials. This was a mixture of Batch 1 and Batch 2 Homogeneous crystal structure. Change in crystal size. Some air bubbles are observed. Batch 1 Batch 2 Batch 1 +2 50/50 Source : Test This : Materials Guide Ian Hansen ARMA Rotomould, Penang 2011
  • 6. Cause of Orange Peel effect in Stone Effect Ian Hansen Consult 1. Small DENSITY differences of coloured polymer particles shrink differently. Different colours, are different pigments, are different densities Independent of degree of cure or additive depletion.
  • 7. Cause of Orange Peel effect in Stone Effect Ian Hansen Consult 2. Effect of Pigment Different colours create different crystal structure. Dry blending of colours results in more severe OP 3. Effect of Particle Size Higher % coarse particles increases ease at which you can observe OP but PS is not the cause.