by marc dan
Article by jekky
HC coating Network News: Polyurethane coating to protect because of its excellent performance, excellent decorative properties, easy workability and widely used in furniture and interior decoration, however, the phenomenon of white paint as paint companies, furniture companies, enterprises must be long-term surface decoration on the quality problems of the white paper on the mechanism of polyurethane film discussed, and corresponding preventive measures for paint companies, furniture and decoration business enterprise reference.
White film of the mechanism of formation from the beginning of film. After construction paint, resin and curing agent form a film by crosslinking reaction. Paint film components, including film-forming substances (such as resins and curing agent), efficiency of material (such as leveling agents, dispersants, defoamers, extinction etc), fill material (such as Titanium dioxide, etc.). With time and environmental conditions, this relative stability may be broken to form a film of phase change. Phase the changes are for the formation of tiny air sacs, not shape the formation of ceramics, the formation of small liquid capsule, etc., these phase changes can not be fully reversible recovery, the specific performance of white hair for the film made fog. Another white paint for the reaction of water and air to form compounds that are incompatible with the paint.
Film whitish reasons: 1, construction ambient air humidity, high temperature and relative humidity over 80%. Performance in wet weather for the construction of large chance of white paint, the precautionary approach to cool the interior dehumidifier to improve the dehydration effect of compressed air, or by adding appropriate amount of white water.
2, paint drying too fast, low boiling point diluent. Volatile thinner fast water vapor condensation in the air when the surface of incompatible and white paint. Preventive measures is to improve the speed of paint drying, evaporation rate under moderate temperature conditions of the diluent used.
3, substrate moisture content is too high, more than 14%. Substrate moisture content is too high, formed in the film, substrate moisture in the slow precipitation, in the film or coating and the substrate form a small sac between Er Shi white film. Specific performance of the substrate in the construction of water and local water content than the average high in water-based adhesive for stickers, veneer, spliced, Bottom water mill, the water did not spray volatile entirely on the immediate construction. Prevention is the control of solid wood and plywood substrate moisture of 8% to 12%, with a water-based adhesive for stickers, veneer, spliced at least 24 hours before they were spray drying construction, the bottom water mill for at least 12 hours before they were dried painting construction.
4, primer filler too much, too thick brush off. Primer filler material over the film-forming insufficient, resulting in membrane packing material can not be wrapped and precipitation, resulting in white paint; a one-time construction too thick layer of lead paint inside and outside the inconsistency caused by solvent evaporation speed of uneven paint film The paint white poor transparency. Prevention method is to use filler primer moderate, thin brush multiple times to follow the principles of construction.
5, contains a low melting point resin component, at low temperatures with no shape or tiny sac microcrystalline precipitate. Phenomenon in all white, because this item causes white film is the longest incubation period, the largest losses, rework measures to the most complex and most difficult to prevent one. Therefore, the paint manufacturers in the raw material control, formulation control, product delivery inspection control factors should be included; furniture manufacturers, decorative coatings companies in product selection and purchase inspection should also be taken into account.
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