Surface tension studies of levelling additives in powder coatings

Wulf, M.; Uhlmann, Petra; Michel, Stefan; Grundke, Karina

doi:10.1016/s0300-9440(00)00082-5

Cited by 26 publications

(13 citation statements)

References 9 publications

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“…In thermoplastic epoxy melts, it has likewise been found elsewhere [3] that flow agents do not alter the viscosity. The viscosity for all three powders approaches a plateau value (listed in Table 1 This result can be used to an indication of a change in the surface energy of the melt with the addition of flow agent.…”

Section: Resultsmentioning

confidence: 63%

“…In work reported elsewhere [3], accurate measurements of the surface tension of melts of epoxy resins were obtained 4c). When the concentration of flow agent is higher (5%), these spots emerge at a temperature as low as 130 C.…”

Section: Resultsmentioning

confidence: 99%

“…STGs have been proposed as a possible cause of poor levelling in powder coatings [3,10], but there has been limited experimental or theoretical work on this topic reported in the literature. We suggest that the basic concepts of the STG models should also apply to powder coatings, in which there is an analogy between flow agents at the surface of a polymer melt and surfactants at the surface of water.…”

Section: Published In Journal Of Materials Science (2002) 37(22):4759mentioning

confidence: 99%

“…One tactic to create smoother, defect-free surfaces is to incorporate levelling aids in the formulation [3]. This type of additive encourages the flattening out of surface undulations by increasing the surface tension to enhance the driving force for the process [4].…”

Section: Introductionmentioning

confidence: 99%

“…Flow agents usually lower the surface tension. As noted by Wulf et al [3], these terms are rather arbitrary, and the classification cannot usually be made unambiguously. Powder formulations usually have a balance of levelling aids and flow agents with the intention of their acting independently and at different stages during the film formation [4].…”

Section: Introductionmentioning

confidence: 99%

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Zhao

Carey

Knoops

et al. 2002

Journal of Materials Science

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Previous theoretical and experimental work has shown that surface tension gradients in liquid layers create surface defects and inhibit the levelling of an uneven surface. In coatings deposited from thermosetting polyester powders, which are studied here, small amounts of a low molecular-weight acrylate are incorporated to act as a "flow agent". We find that this additive lowers the surface tension of the polymer melt and has a minor effect on the melt viscosity. A slower rate of levelling results from the decreased surface tension. We provide experimental evidence that lateral gradients in the surface tension of the polymer melt, resulting from the nonuniform distribution of the flow agent, inhibit the levelling of the surface.Specifically, the surface roughness of a powder coating is up to three times greater when a steep surface tension gradient is purposely created through powder blending.Surface tension gradients might also be responsible for the greater surface roughness (observed with atomic force microscopy on lateral length scales of 100 m) that is found in coatings that contain flow agent.

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Section: Resultsmentioning

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Section: Published In Journal Of Materials Science (2002) 37(22):4759mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Untitled

Zhao

Carey

Knoops

et al. 2002

Journal of Materials Science

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Coating Processes, Powder Technology

Richart¹

2001

Kirk-Othmer Encyclopedia of Chemical Technology

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Methods for applying decorative and protective coatings utilizing finely divided powders followed by heat fusion of the powder particles to form a continuous film are gaining in popularity and commercial acceptance. Since there are no volatile organic compounds present, powder coating is an environmentally friendly, nonpolluting coating process, providing coatings with improved performance as well. Powder coatings can be found on many common items including lawn and garden equipment, outdoor metal furniture, display racks, architectural aluminum panels and trim, and many automotive compounds including the exterior clear coat. The chemistry and composition of powders used in coatings and their properties are described, as well as their method of manufacture, processes used to apply them, their applications and a review of health, safety and environmental considerations. Over 100 references are supplied to provide more detailed technical information.

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Coating Methods, Powder Technology

Richart¹

2001

Encyclopedia of Polymer Science and Technology

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Methods for applying decorative and protective coatings utilizing finely divided powders followed by heat fusion of the powder particles to form a continuous film are gaining in popularity and commercial acceptance. Since there are no volatile organic compounds present, powder coating is an environmentally friendly, nonpolluting coating process, providing coatings with improved performance as well. Powder coatings can be found on many common items including lawn and garden equipment, outdoor metal furniture, display racks, architectural aluminum panels and trim, and many automotive components including the exterior clear coat. The chemistry and composition of powders used in coatings and their properties are described, as well as their method of manufacture, processes used to apply them, their applications, and a review of health, safety, and environmental considerations. Over 100 references are supplied to provide more detailed technical information.

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Surface tension studies of levelling additives in powder coatings

Cited by 26 publications

References 9 publications

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Coating Processes, Powder Technology

Coating Methods, Powder Technology

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