Gloss unevenness

An inlget liquid composition has been proposed where a pigment is used with a ratio AmaxIAmin of the maximum absorbance Amax to 

Fluorescein Eosin Erythrosine Rhodamine B Rose Bengal Anthracene Pyrene Perylene Triphenylene Anthraquinone 

Acridine orange Chloroflavine Acriflavine Thionine Methylene blue Toluidine blue 

Further, the liquid composition contains a triblock polymer. The A block in the triblock polymer is highly hydrophobic, and the C block is highly hydrophilic. The B block in between is medium hydrophilic. 

The blocks may be formed by homopol5nnerizing only one type of the unsaturated compoimds or may be formed by random copolymerizing at least two types thereof. Styrene and benzyl(meth)acryl-ate exhibit a small steric hindrance and association occurs easily. 

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Nonplastication This condition produces uneven stress distribution, with consequent lumpiness. The product could appear ugly or have a fine matt finish. With a wide MWD their could be a lack of gloss. 

As an example of good practice in these respects when moulding acrylate-styrene acrylonitrile (which gives poor gloss at low temperatures and uneven colour at high) ... 

The theoretically maximum possible gloss calculated in this way is only rarely achieved in practice. The surfaces are always a little uneven. Also, optical inhomogeneities below the surface, that is, in the medium itself, cause marked light scattering. The relative fraction of light scattered... 

Pressure motting n. The film distortion or uneven pattern that causes a change of gloss and a non-uniform appearance in the coated surface, as opposed to blocking. See pressure marking. 

Figure 4.1 How clarifiers work Conventional homopolymer PP (a) consists of large uneven crystal microstructures that refract hght and increase opacity. Sorhitol clarifiers, (b) generate smaller, highly dispersed crystallites which are smaller than the wavelength of light. The result is a clarified PP in which the haze percentage falls clarity and surface gloss are boosted. (Courtesy Ciba Specialty Chemicals.)...

Other Binders. Unsaturated polyester resins are maleic acid-containing polyesters dissolved in styrene. The resin/styrene solution is cross-linked using free-radical initiators. The polymerization is oxygen inhibited. Inhibition is minimized by incorporating some insoluble semicrystalline paraffin wax. The wax layer results in a relatively uneven, low gloss surface, suitable for some applications. 

Removal of the degraded layer exposes a non-aged layer whose color is close to the initial color, but whose gloss is reduced due to the surface unevenness. The same degradation cycle begins anew on this layer, s. Figure 5.72 [681]. 

Poor gloss finish on one or more faces of the moulded part indicates uneven temperatures of the tool, an insufficient cure time, or by attempting to mould with low moulding pressures. 

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