The fire resistance and flame retardancy grade of acrylic solid surfaces needs to be evaluated in combination with specific formulas and testing standards. Its performance is significantly affected by the design of the flame retardant system, the selection of base materials and process conditions. The following analysis is carried out from three aspects: flame retardant mechanism, formula design and testing standards:
The flame retardant mechanism is related to the grade
Acrylic resin itself has relatively weak flame retardant performance, and the fire resistance rating needs to be improved by adding flame retardants. For instance, an intumescent flame retardant system that uses ammonium polyphosphate as the dehydration catalyst, pentaerythritol as the carbonizing agent, and melamine as the foaming agent can enable the coating to form a 20-30mm thick foam protective layer when exposed to fire, thereby isolating the fire source. This system can enable the coating to meet the UL94 V-0 or GB 8624 B1 grade standards, and the specific grade depends on the type and proportion of flame retardants in the formula.
The influence of formula design on grades
The compounding scheme of flame retardants directly affects the fire protection grade. For instance, the formula with acrylic resin as the base material and the addition of ammonium dihydrogen phosphate, pentaerythritol and melamine can achieve a fire resistance time of up to 106 minutes under the condition of a coating thickness of 1.30mm. If inorganic flame retardants such as nano-Mg (OH)₂ are introduced, the thermal stability of the coating and the density of the carbonized layer can be further improved, thereby enhancing the fire resistance grade.
Test standards and grade determination
The determination of fire resistance grades should be based on specific testing standards. For example, the GB/T 15442.2-1995 standard stipulates that the flame resistance time of grade 1 fireproof coating should be ≥20 minutes, the flame spread ratio ≤25, the weight loss <5.0g, and the carbonization volume ≤25cm³. Acrylic fireproof coatings must pass such standard tests before their fire resistance grades can be determined. Furthermore, international standards such as the ISO5659-2 method and the Japanese JIS A 1321 method can also be used to evaluate parameters such as the smoke density and combustion rate of the coating.
Grade performance in practical applications
In practical applications, the grade performance of acrylic fireproof coatings is affected by environmental factors. For instance, in high-temperature and high-humidity environments, phosphorus/nitrogen-containing flame retardants may affect the water resistance of the coating film and need to be compensated by crosslinking agents. In addition, the mechanical properties such as adhesion and flexibility of the coating also need to be matched with the fire resistance rating to ensure its reliability under complex working conditions.
