Dynamic wetting in metering and pre-metered forward roll coating

Benkreira, Hadj

doi:10.1016/s0009-2509(02)00175-6

Cited by 8 publications

(2 citation statements)

References 20 publications

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“…Thus, the hydrodynamic force resulting from the impact of the falling liquid can reduce the contact angle, assist the dynamic wetting, and postpone the onset of air entrainment to higher surface speeds. Such a hydrodynamic assist of dynamic wetting has also been observed in curtain coating (Blake et al, 1999), forward roll coating (Benkreira, 2002b) and reverse roll coating (Benkreira, 2002a).…”

Section: Introductionmentioning

confidence: 64%

Particle-assisted dynamic wetting in a suspension liquid jet impinged onto a moving solid at different flow rates

Yamamura

Matsunaga

Mawatari

et al. 2006

Chemical Engineering Science

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Section: Introductionmentioning

confidence: 64%

Particle-assisted dynamic wetting in a suspension liquid jet impinged onto a moving solid at different flow rates

Yamamura

Matsunaga

Mawatari

et al. 2006

Chemical Engineering Science

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“…They also confirmed that having the dynamic wetting line not perpendicular to the substrate motion was an effective way to delay air entrainment in slide coating flows. Benkreira 23 examined the dynamic wetting in forward roll coating and found that, as forward roll coating switches from metered to premetered with changes in the operation conditions, the dynamic wetting line moves near to the minimum gap position, just as in reverse roll coating. Ikin et al 24 studied the coating windows in the slide coating process and found that increasing the slide angle maintains the direction of flow down the slide normal to the web at the dynamic wetting line.…”

Section: Introductionmentioning

confidence: 99%

Improved Coating Window for Slot Coating

Chin

Wang

2010

Ind. Eng. Chem. Res.

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Slot die is a premetered coating operation in which the coating solution is extruded from a feed slot onto the surface of a substrate passing through. The defect-free region of operation is known as the “coating window”, and the wider it is, the more versatile the operation will be. The slot-coating experiments reported here were carried out with two types of coating solutions, a hard coating solution with low viscosity and a polysilica solution with high viscosity. The coating windows were measured as flow rates q versus minimum and maximum coating speeds, V min and V max, respectively. Therefore, at a given flow rate of the coating solution, there exists a minimum speed and a maximum speed that border the corresponding coating window, outside which coating defects occur. Also, in our experiments, the coating windows shifted to higher coating speed and obtained thinner coating film thicknesses through different settings of the die angle to the substrate and different geometries of die lips. The data showed that the coating windows shifted to higher speed and thinner film thicknesses when the die angle and the geometry of the die lips were varied appropriately. These results have important practical implications. The fundamental principles involved here are also applicable to other premetered coating processes.

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