Page 66 - Handbook of Surface Improvement and Modification

4.3 Application data 61

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with either triglycidyl isocyanurate or hydroxyethyl adipamide. They are processed
together forming a microscopically irregular surface, distracting visual light, to produce a
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gloss reduction due to different rates of curing. A chemically resistant powder coating
composition is composed of a urethane-polyester powder coating resin, a styrene-free
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hydroxyl functional acrylic resin, and a hardener (e.g., tetramethoxy glycoluril). The
composition provides low gloss without using matte agents or fillers such as barium and
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calcium sulfates. Matte fillers are not necessary because the composition, when cured,
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meets low gloss military specifications.
Three dental composites were formulated using silica having particle sizes of 7, 12,
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and 16 nm at 45.5 wt% loading in an epoxy matrix. Filler size influenced optical and sur-
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face properties of the composites. Materials containing filler having smaller particles had
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improved optical stability and surface properties that require less maintenance.
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A cosmetic composition imparts a matte finish to lip cosmetics. The lip composition
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comprises a mattifying powder containing polyethylene, calcium silicate, and silica. It
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has a gloss value of less than 50. Matt-effect composition comprises hydrophobic aerogel
particles, silica particles, and particles that absorbs sebum (shiny skin is associated with a
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substantial secretion of sebum). The hydrophobic aerogel particles have a specific surface
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area per unit of mass ranging from 600 to 1200 m /g, particle size in the range of 5-20 μm,
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and a tapped density ranging from 0.03 to 0.08 g/cm . The hydrophobic aerogel particles
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are trimethyl silica aerogel particles. The silica particles different than the aerogel parti-
cles are chosen from porous silica microspheres, polydimethylsiloxane-coated amorphous
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silica microspheres, or precipitated silica microspheres, coated with inorganic wax. The
sebum absorbing particles can be chosen from polyamide powders, acrylic polymers, sili-
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cone elastomers, talc, boron nitride, or clays.
A multi-layer biaxially oriented polypropylene, BOPP, film exhibits matte appear-
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ance. The formulation comprises a blend of high density polyethylene, medium density
polyethylene, low density polyethylene or linear low density polyethylene with polypro-
pylene used in the core layer to achieve a matte appearance of film that exhibits typical
properties of BOPP films with significantly lower haze than conventional matte films. 6
When polyolefin resin core layer comprising a resin blend of crystalline propylene and
HDPE, MDPE, LDPE or LLDPE is biaxially oriented, particularly during the transverse
orientation process, the incompatibility between the high density polyethylene (or medium
density or low density polyethylene or linear low density polyethylene) and polypropylene
domains in the film matrix causes formation of discrete domains in the core layer that
affect the uniformity of the layer interface between the core layer and adjacent layers, thus
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imparting the matte appearance of the film. This effect is amplified when higher stretch-
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ing rates are used. These non-uniformities do not significantly increase light scattering,
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therefore the matte appearance is obtained without a significant increase in film haze. The
non-uniformities do not cause increase in the coefficient of friction, as commonly
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observed in traditional matte films. Also, the mechanical properties of the matte film are
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substantially increased.
A powder coating composition comprises a resin component, a polyisocyanate-con-
taining uretdione crosslinking agent, catalyst, and flattening agent (blend of synthetic par-
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affin and polytetrafluoroethylene). The resin component may comprise a hydroxyl-
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containing resin and a hydroxyl-containing halogenated copolymer resin. Catalyzed