Whether it's a standard ship deck or an aircraft carrier deck, due to the deck's direct contact with the atmosphere, it tends to accumulate water and condensation, and is subject to erosion from wind and rain, sun exposure, and the alternating effects of saltwater moisture. Moreover, the movement of personnel and mechanical operations on the deck often lead to wear and tear from foot traffic and friction. Additionally, decks are prone to contamination by various acidic, alkaline, and oily substances, necessitating frequent cleaning. Therefore, deck coatings must possess excellent properties: 1. Chemical properties: corrosion resistance, oil resistance, and alkaline resistance; 2. Mechanical properties: good wear resistance, washability, impact resistance, strong adhesion, and slip resistance; 3. Physical properties: water resistance, weather resistance, and flame retardancy. Achieving these functionalities is inseparable from good application techniques.
Composition of Anti-Slip Deck Coating
Due to the cost of coatings, the anti-slip coating on the decks of ordinary warships is typically just a single layer. However, for the decks of aircraft carriers and flight decks, where higher performance requirements are placed on the anti-slip coatings, traditional single-layer coatings and single-component paints are no longer sufficient. Therefore, significant improvements have been made in composition. Currently, double-component coatings are used, primarily consisting of resin and hardener components. In terms of composition, the anti-slip coating layers on the decks are mainly composed of four parts: primer, elastic intermediate layer paint, topcoat, and anti-slip aggregates.
The performance of the primer, elastic intermediate coating, and topcoat each emphasizes different aspects: The primer should have good adhesion to the substrate, requiring a strong bond between them to prevent flaking of the coating. Additionally, the primer should possess excellent anti-rust and corrosion resistance. The intermediate coating should offer good elasticity and flexibility to protect the coating from cracking and withstand significant impact forces. The topcoat should have excellent corrosion resistance, oil resistance, weather resistance, abrasion resistance, and decorative properties. The combined effect of these three layers contributes to the exceptional performance of the anti-slip deck coating.
Primer
Base materials commonly chosen for their excellent weather resistance and mechanical properties include alkyd resins, chlorinated rubber, phenolic resins, epoxy resins, or polyurethane resins. Due to the material's coefficient of friction and wear resistance, epoxy resins or polyurethane resins are typically used as the base. In the application of anti-slip deck bottom paints, considering the adhesion of the primer to the steel substrate, epoxy-modified polyurethane is generally selected as the base material. This ensures the primer's superior impact resistance, deformation adaptability, and compatibility with the topcoat, while also guaranteeing effective corrosion and rust prevention in marine environments. Another advantage of epoxy-modified polyurethane is its strong adhesion to old steel plates and those with slight corrosion, making it commonly used in construction and maintenance.
Zhongtu Paint
Zhongtu paint is a solvent-free, high-elastic thick-film coating, with a single application thickness that can reach several millimeters, even up to a dozen or more. In contrast, the anti-slip coating on ordinary ship decks typically ranges from 1 to 5 millimeters thick, which is one of the significant characteristics of anti-slip deck coatings. The intermediate coating greatly enhances the abrasion resistance, crack resistance, impact resistance, water resistance, and rust prevention of the coating, extending its service life, improving the protective performance of the layer, and enhancing the comfort of stepping on it.
Surface Paint
The surface paint is predominantly made with polyurethane coatings known for their weather resistance, elasticity, and flexibility, with colors that can be adjusted according to the application. After curing, the surface paint layer exhibits excellent aging resistance and possesses strong adhesion to anti-slip aggregates.
Anti-slip aggregate
Anti-slip granular materials can significantly enhance the frictional properties of coatings, increase their wear resistance, and prolong the service life of the coatings. Elastic granular materials not only improve the anti-slip performance of coatings but also enhance the comfort of stepping and touching. Hard anti-slip granular materials such as quartz sand, aluminum oxide particles, silicon carbide, carbon black, and ore particles can significantly increase the friction coefficient of anti-slip coatings in dry conditions, as well as greatly improve the friction resistance in wet and lubricated states. For flight decks, the use of anti-slip granular materials like silicon carbide, aluminum oxide, nepheline syenite, and amorphous glass, while reducing the use of silicon dioxide crystals, is particularly important, especially in the landing areas of aircraft. This is because the high-temperature exhaust gases produced during landing cause the crystallization of silicon dioxide in the coatings, posing a threat to human health.
In summary, the undercoat, intermediate coat, and topcoat of the anti-slip deck coating should adopt a similar polyurethane coating system to ensure good overall compatibility and good adhesion between layers. Additionally, various additives must be included in the anti-slip coating, such as wetting agents, defoamers, flame retardants, toughening agents, leveling agents, thixotropes, anti-aging agents, light stabilizers, and various colored fillers. Due to the different functional focuses of each coating layer, these factors should be thoroughly considered when developing the coating formula. Moreover, the compatibility of the construction techniques must be ensured, with strict control over the construction process and quality to achieve complementary advantages in the formed coating, significantly enhancing the overall performance.
Issues Identified During Construction
Common issues during the application of anti-slip deck coatings include cracks, inadequate drying, wrinkling, sagging, stickiness, peeling, and whitening. The main reasons for these problems are primarily two-fold: the improper mixing of the coating and the construction process not meeting quality requirements.
Bubble in Coating
During the curing and aging process of coatings, blistering is a common issue, manifested between the primer and the base material interface, among multiple coating layers, and particularly evident in the intermediate layers. The main causes of blisters include: improper surface treatment of the base material, which may result in residual moisture or oil; coating absorption of water; release of gases dissolved in the paint with increasing temperature; osmotic pressure; residual gases in porous base materials; electroosmotic action; cathodic protection blistering; adsorption of gases or liquids on the surface of pigments or fillers; phase separation in the coating, etc.
Poor adhesion between anti-slip granular material and coating
Slip-resistant aggregates endow the coating with excellent anti-slip properties. However, several common issues often arise during application, leading to the loss of the aggregates' original function: 1. Uneven distribution of slip-resistant aggregates. The rolling of the base paint and the application of the aggregates should be done simultaneously. Due to climate, temperature, and construction techniques, the base paint often cures quickly at high temperatures, but the aggregates may not be applied in time or unevenly, resulting in poor adhesion between the aggregates and the base paint, making it prone to fall off and significantly reducing the anti-slip performance. 2. The content of slip-resistant aggregates is not calculated meticulously. In actual construction, it is common to encounter situations where the content of the aggregates is either too low or excessive. The former leads to most of the aggregates being encapsulated within the base paint, failing to form protrusions on the surface, resulting in a low coefficient of friction that does not meet the usage requirements; while the latter causes an excessive number of protrusions in the base paint, with each protrusion experiencing reduced pressure. Experimental research proves that an ideal content of slip-resistant aggregates in the coating is around 40%, and attention should be given to the proportion of large particle aggregates.
Surface coating color is uneven
The large deck coating area, as a decorative finish paint, requires even and consistent color as an intuitive quality indicator. However, in actual construction, it is common to encounter issues such as局部 discoloration or lightening of the finish paint, severely affecting aesthetics and progress. The main reasons for these problems are as follows: a large deck requires a significant amount of finish paint, inevitably involving multiple batches. Different batches of finish paint will result in varying colors, so it is crucial to calculate the paint quantity based on the coating area and pre-mix paints from different batches to ensure color consistency. Neglecting weather changes during the application process can lead to insufficient drying time under humid conditions, resulting in a whitened appearance or even bleaching effects. In roller coating applications, unavoidable overlap areas will dry with a deeper color compared to other parts. During application, the finish paint should be rolled in one direction with moderate pressure to prevent paint build-up and ensure even application.
To prevent color changes after painting in direct sunlight, the non-slip coating system currently used on naval ship decks contains UV blockers. Not only do these blockers maintain the finish's color and luster, but they also reduce the deck's heat absorption.
Processing Measures
In response to issues encountered during construction, adhere to the principles of pre-emptive prevention, on-site control during construction, and timely handling post-construction. Strengthen construction management by deploying professional technical personnel for on-site technical guidance.
In summary, the requirements for the application of anti-slip coatings are becoming increasingly stringent, with the painting techniques for various new types of coatings demanding higher standards. However, issues arise frequently during the application process due to poor working environments, high labor intensity, and varying skill levels among workers. Therefore, it is particularly important to strengthen technical training for workers and manage the construction process effectively. This includes reasonably avoiding and properly handling numerous issues that may arise during the painting process, thereby enhancing the quality of the anti-slip coating application on decks.
