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Green Technology for Home Wood Products—LED UV Coating

Release time:

2024-03-20 17:24

Green Technology for Home Wood Products—LED UV Coating

As people’s pursuit of a higher quality of life continues to grow, the use of furniture and wood products is also on the rise. However, traditional wood coatings often contain significant amounts of harmful substances, which not only pose health risks to humans but also cause environmental pollution. In today’s society, we are advocating for a low-carbon, eco-friendly economy and placing increasing emphasis on environmental protection and sustainable development. Consequently, LED UV coating has emerged as an ideal choice for wood product finishing.

In the production process of solid wood furniture, painting is an essential step. For wooden products, the paint layer acts like armor, effectively protecting the wood from external environmental factors and enhancing its resistance to wear and tear. Moreover, the painted surface significantly improves the aesthetic appeal of the wood product, making its surface smoother and more refined, with richer and more diverse colors, thereby elevating the overall texture and serving as a crucial factor in boosting the value of the furniture—making it of great importance to the furniture itself.

I. Comparison Between Traditional Coating and UV Coating

In traditional manufacturing processes, the finishing coats applied to wood products and furniture are typically applied by spray coating. The coatings used in this process are mostly conventional ones such as nitrocellulose lacquers and polyurethane paints. These paints generally suffer from drawbacks including high costs, low efficiency, poor performance, and significant environmental pollution.

Compared to traditional paints, UV coating is more in line with today’s low-carbon and environmentally friendly policies. UV coating works by using UV lamps to emit ultraviolet light, which triggers chemical polymerization and cross-linking reactions, causing the paint film to cure in an extremely short period of time. The composition of UV coatings does not contain toxic or harmful substances such as benzene, toluene, or xylene, nor do they produce irritating odors, thereby reducing potential hazards to both the environment and human health.

II. Process of UV Coating

UV coating can be applied using methods such as spray coating, roll coating, or dip coating. In practical applications, the appropriate coating method and coating material should be selected based on specific conditions to achieve the best coating results.

The UV coating process typically includes the following steps: (1) Pre-treatment; (2) Primer application; (3) Topcoat application; (4) UV curing; (5) Surface finishing.

1. Pre-treatment: Before starting the painting process, sand the product surface to remove dirt and impurities, ensuring that the surface is smooth, even, and free of scratches. This provides a good foundation for painting, guaranteeing that the coating will adhere evenly and achieve the desired finish.

2. Primer Coating: After completing the pre-treatment, you can proceed with applying the primer. UV primers are typically applied using a roller coating process. The primer is required to provide excellent leveling and sealing performance on the substrate. Its primary functions include enhancing adhesion between the coating and the substrate, providing a uniform base color for subsequent topcoat application, and preventing substrates such as wood from absorbing excessive paint, which could otherwise compromise the final finish.

3. Topcoat Application: UV topcoats are most commonly applied by flow coating, but they can also be applied by spray coating or roller coating. Flow coating allows for a high coating thickness and easily achieves a high-gloss, full-bodied finish. During the application process, it’s important to maintain an appropriate spraying speed and distance to avoid uneven coating thickness or inconsistent color.

4. UV Curing: After the topcoat has been applied, the product needs to be placed under a UV lamp for curing, forming a durable and abrasion-resistant coating. Typically, this process takes only a few seconds to a few minutes; the exact duration depends on the coating thickness and the power of the UV lamp.

5. Surface Treatment: After curing is complete, further treatments such as dust removal and polishing are required.

III. LED UV Coating

With the advancement of science and technology, UV coating technology has continued to evolve, giving rise to LED UV coating technology. This technology has developed from traditional UV coating. While conventional UV coatings use mercury lamps as their light source, LED UV coatings employ LED lights. Compared to traditional UV coating technologies, LED UV coating offers numerous advantages.

1. Low energy consumption: LED light-curing equipment consumes electricity only during the curing process, and its power consumption during standby mode is virtually zero, making it more energy-efficient.

2. Long lifespan: LED lights have high light concentration, uniform illumination, and low energy loss; in contrast, traditional UV mercury lamps have a broad wavelength range, generate significant heat, and have a shorter lifespan than LED lights.

3. High Efficiency: The effective luminous efficiency of LEDs is significantly higher than that of mercury lamps. LEDs can be switched on and off instantaneously, offering rapid irradiation and thereby boosting coating efficiency. The adhesives cured by LEDs exhibit high transparency, strong adhesive strength, and fast curing speed.

4. Excellent Performance: In terms of coating results, LED UV curing machines exhibit outstanding film-forming properties. After curing, the coating boasts high gloss, a smooth and even surface, and exceptional resistance to abrasion, heat, and solvents. Since LED UV systems utilize a cold light source, products won't deform due to heat, allowing even materials with low heat resistance to be processed effectively.

5. More environmentally friendly: LED lights emit virtually no volatile organic compounds during use, resulting in minimal environmental pollution. They also do not produce ozone, thus avoiding environmental damage.

IV. Common Problem Phenomena in UV Coating

1. Orange peel phenomenon

This is usually caused by excessive viscosity of the UV ink or uneven application.

The solutions include replacing the low-viscosity UV ink, adjusting or replacing the leveling rollers, and adjusting the working pressure to ensure uniformity.

2. Insufficient glossiness

This may be due to the low viscosity of the UV varnish and the excessively thin coating layer.

Consider increasing the viscosity of the UV varnish, adjusting the coating thickness, and improving its uniformity.

3. Strong aftertaste

This could be caused by insufficient drying or excessive use of paint thinner.

To solve this problem, it is necessary to ensure that the drying process is thorough and to use diluents in appropriate amounts.

4. Bottom exposure phenomenon

The phenomenon of show-through is often caused by an excessive resin content and a low pigment content in the coating, which reduces the coating's opacity.

To address this issue, the paint formulation can be adjusted by increasing the pigment content to enhance the paint’s opacity.

5. White film formation on the coating

After curing, the paint film may turn white; in severe cases, it may even crack or chalk. This could be caused by factors such as incomplete solvent evaporation, the presence of other unrelated impurities in the coating, or applying too much coating material in a single application.

Ensure that the solvent fully evaporates during the coating process, strictly control the production process to prevent the introduction of impurities, and make reasonable adjustments to the coating amount.

Disclaimer: The above content is sourced from the internet and is for reference only. If any infringement occurs, please contact us, and we will remove it promptly.

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