What is the significance of the main technical indicators of exterior wall latex paint?
Indices of Coating Performance
state in container
The national standard stipulates that "no hard lumps, and it will be in a uniform state after stirring". This is the most basic requirement. If it is possible to open the tank to check that there is no layering, no floating color, no unpleasant smell, the material is uniform, and it seems to be uniform without stirring, and the stirring can be inserted into the paint to the end, and it is very easy to stir, then It will surely occupy a greater advantage in the product market competition.
Construction
In general engineering construction, at least two coats are painted on the surface, so it is required to paint two coats without obstacles. Coating workability is a qualitative index, and the subjective factors for evaluating its quality are relatively heavy. It feels effortless when brushing and roller mixing; there is no splashing, no wire drawing, no sagging when the roller is mixed, and the tool does not fall to the ground after the paint is dipped until it is applied; it does not block the nozzle of the Spray Gun when spraying; unsatisfactory parts are easy to Repainting and so on are the performances that please the construction workers. The construction conditions of the external cultivation are relatively difficult, and the construction performance of the exterior wall latex paint needs to be particularly good.
It is generally stipulated that the surface should be dry within 2 hours. Because of the long drying time of the paint, the time required for coating maintenance is long, and the interval between construction roads is also long; the dry operation time is short, the coating is prone to lap marks, the leveling of the paint is deteriorated, the surface of the paint is easy to peel, and the coating Not easy to level. Therefore, it should be adjusted appropriately. Extra latex paint should not dry too fast.
low temperature stability
Investigate the ability of the original performance of the coating after being subjected to freezing (the test condition is -5°C/l8h) and subsequent melting (the test condition is 23°C/6h). It is generally stipulated that after 3 cycles, the coating will not deteriorate. Indicators are needed for areas where the temperature is below 0°C.
Indices of Coating Performance
Coating color and appearance
The color is within the color difference range of the standard color, uniform, and free from defects such as sagging, knotholes, and air bubbles.
contrast ratio
It reflects the ability of the dry coating film to cover the substrate and is related to the consumption of coatings. The higher the contrast ratio, the more area the coating can cover the substrate. This is the basic performance of exterior wall latex paint. Therefore, the contrast ratio index is stipulated.
water resistance
Water resistance of exterior wall latex paint is very important. Water, together with sunlight and atmospheric oxygen, constitute the three major factors of coating aging. Early morbidity of the coating is also almost always related to water erosion.
Magnetic resistance
The construction objects of latex paint for exterior walls are cement mortar and concrete, which have strong alkalinity, so latex paint should have excellent alkali resistance.
Scrub resistance is an index to investigate the ability of the coating film to withstand the scrubbing of the brush under pressure without being brushed off in dilute detergent solution. As far as the index value stipulated in GB/T9755-2001 is concerned, any exterior wall latex paint that can pass the artificial weather aging resistance and stain resistance index will not fail this index, and it can be ignored. It's just that the scrub resistance test method is much simpler and more convenient than the artificial weather aging and stain resistance tests, so it is often used as an index for frequent control in production.
Stain resistance
Stain resistance reflects the ease with which the coating film can be removed after it is contaminated by pollutants such as dust and suspended solids in the air. This is a very useful and important technical indicator.
Weather-resistant exterior wall latex makes important technical indicators.
It reflects the ability of the coating to maintain its use value (decorative and protective functions) in typical use environments. Two test methods are used to evaluate: a natural weather aging test, that is, natural sun exposure test. b Artificial weathering test. The test results of the former are more in line with the actual situation, and the test time is longer. The latter is an artificial aging test that artificially simulates natural climate conditions and is a common method for evaluating aging resistance. The quality grade of exterior wall latex paint is mainly classified according to the pros and cons of weather resistance.
Coating resistance to temperature denaturation
It reflects the ability of the coating to resist severe temperature changes. This is an important indicator for regions with severe weather conditions.
