This article systematically introduces the concept, characteristics, functions, application fields, selection considerations, and solutions to common problems of TGIC powder coatings. It focuses particularly on the functions of TGIC powder coatings to help readers better understand what TGIC powder coatings are, their characteristics, and their specific application areas.
What Is TGIC Powder Coating?
TGIC powder coating, also known as Triglycidyl Isocyanurate (TGIC) powder coating, is a type of thermosetting powder coating. Its core system consists of two main components:(1) Base resin:
A carboxyl group (-COOH) containing saturated polyester resin, which acts as the structural backbone of the coating film.
(2) Curing agent:
Triglycidyl isocyanurate (TGIC), a heterocyclic compound containing three epoxy groups (-CH(O)CH₂).
Characteristics of TGIC Powder Coating
The main characteristics of TGIC powder coatings are as follows:(1) Superior Outdoor Durability
Because TGIC molecules contain stable triazine rings, the coating film has extremely strong UV resistance. After long-term outdoor exposure, its gloss retention and color retention are significantly better than those of ordinary indoor coatings. Therefore, TGIC powder coatings are the preferred choice for outdoor components such as architectural aluminum profiles and automotive wheels.
(2) Balanced Physical and Mechanical Properties
With a high cross-linking density, the coating film combines high hardness (scratch resistance) with excellent flexibility (impact resistance and crack resistance). It provides strong adhesion and can adapt to thermal expansion and contraction of substrates.
(3) Wide Processing Tolerance
TGIC powder coatings have a wide curing window (commonly 180–200°C for 10–20 minutes). During curing, no by-products are released, minimizing pinhole formation. They can be applied in a single thick coating layer (80–120 μm) while maintaining excellent leveling performance and decorative appearance.
(4) Environmental-Friendly Coating Advantages
The entire coating process produces almost zero VOC (Volatile Organic Compound) emissions. Overspray powder can be recycled and reused, meeting the requirements of green manufacturing.
Functions of TGIC Powder Coating
The main functions of TGIC powder coatings are reflected in the following aspects:
1. Physical Protection Function
After curing, TGIC powder coating forms a dense and hard protective layer that effectively resists scratches, impacts, and abrasion. It also provides good flexibility, allowing slight bending of the substrate without cracking, thereby creating a strong physical barrier for outdoor metal components.
2. Chemical Protection Function
The coating film provides excellent resistance to acids, alkalis, and salt spray. It isolates moisture and corrosive media, preventing metal substrates from rusting, oxidation, and chemical corrosion. It is especially suitable for architectural aluminum profiles and outdoor equipment.
3. Weather Protection Function
The triazine ring structure in its molecular composition provides outstanding UV resistance. It can withstand long-term exposure to sunlight and rain, significantly delaying coating chalking, fading, and gloss loss, thereby ensuring a long service life in outdoor applications (which can reach more than 10–20 years).
4. Decorative Enhancement Function
TGIC powder coatings can be formulated into various colors and gloss levels (high gloss/matte). With excellent leveling performance, the coating surface is smooth and uniform, improving the product appearance, texture, and commercial value.
Application Fields of TGIC Powder Coating
The specific application fields of TGIC powder coatings are as follows:1. Architectural and Building Materials Field
Applications include aluminum alloy doors and windows, curtain walls, railings, ceilings, and other building components.
This is the core application field with the largest consumption of TGIC powder coatings. Due to its excellent weather resistance, it can ensure that building surfaces maintain their appearance for decades without fading or chalking.
2. Transportation Equipment Field
Applications include automotive wheels, vehicle frames, agricultural machinery, bicycle and motorcycle components.
TGIC powder coatings are used to resist gravel impact during operation, salt spray corrosion, and UV aging, providing long-lasting protection for transportation equipment.
3. Power and Communication Facilities Field
Applications include outdoor electrical cabinets, communication enclosures, street lamp poles, and transformer housings.
TGIC powder coatings provide insulation, corrosion resistance, and weather protection, ensuring the long-term stable operation of equipment under harsh outdoor environmental conditions.
4. Household Appliances and General Industrial Applications
Applications include outdoor air-conditioning unit housings, outdoor furniture, sports equipment, valves, and pipelines.
TGIC powder coatings provide both corrosion protection and decorative appearance, improving product durability and commercial value.
How to Select TGIC Powder Coating
When selecting TGIC powder coatings, users may face difficulties in determining the most suitable product. Based on our industry experience, we recommend paying attention to the following aspects when choosing TGIC powder coatings.1. Consider Weather Resistance Grade
(1) Extreme Outdoor Applications (More than 10 Years)
For applications such as architectural aluminum profiles, roof systems, and curtain walls, high-weather-resistance TGIC systems must be selected.
High-purity TGIC and high-quality polyester resin should be used to ensure a gloss retention rate of ≥90% (QUV 1000 hours).
(2) General Outdoor Applications (3–5 Years)
For applications such as agricultural machinery and outdoor furniture, standard weather-resistant grades can be selected to achieve a balance between performance and cost.
2. Consider Mechanical Properties
(1) High Hardness / Wear Resistance
For applications such as automotive wheels and road barriers, formulations with high cross-linking density should be selected.
The pencil hardness can reach 2H–3H.
(2) High Flexibility / Impact Resistance
For applications such as coils, thin metal sheets, or workpieces requiring stamping and forming processes, flexible formulations should be selected.
The coating should pass reverse impact testing (≥50 kg·cm) without cracking.
3. Consider Appearance and Color Requirements
(1) High Leveling Performance / High Gloss
For applications requiring a mirror-like appearance, such as high-end household appliances and automotive decorative components, specialized leveling agents and high-quality polyester resins should be used.
(2) Sand Texture / Wrinkle Texture / Matte Finish
These finishes are suitable for covering substrate defects or achieving low-reflection surfaces, such as electrical cabinets and instrument housings.
Special additives or fillers should be added to achieve the desired appearance.
(3) Light Colors / Bright Colors
These applications require high-performance pigments with excellent heat resistance and light resistance to prevent color changes during curing.
High-performance inorganic or organic pigments should be selected.
4. Consider Compliance Requirements and Cost
(1) Export to Europe
TGIC should generally be avoided for European markets. Alternative curing systems such as HAA (β-hydroxyalkylamide) or other TGIC-free systems should be used because TGIC is classified as a Category 1B sensitizer.
(2) Domestic Applications
TGIC remains a mainstream choice due to its high cost-performance ratio.
However, attention should be paid to TGIC purity (recommended ≥99%) and the quality control capability of the manufacturer.
(3) Curing Conditions
Confirm whether the baking temperature (normally 180–200°C) matches the existing coating production line.
For heat-sensitive substrates such as plastics and wood, low-temperature curing formulations may need to be considered. However, achieving low-temperature curing in TGIC systems is relatively difficult.
Common Problems and Solutions of TGIC Powder Coating
During the application of TGIC powder coatings, the most common problems mainly include the following aspects.Based on our industry experience, we provide corresponding solutions to help effectively solve powder coating application issues.
1. Pinhole Problems
Phenomenon:
Dense or scattered small volcano-shaped holes appear on the coating surface.
Causes:
The coating film is too thick, causing internal air or small molecular volatile substances to be unable to escape during curing.
Incorrect dosage or poor quality of degassing agents (such as benzoin).
Solutions:
Control coating thickness (recommended 80–120 μm).
Select high-quality degassing agents and adjust the dosage to the optimal level.
Appropriately reduce the heating rate and extend the leveling time.
2. Cratering / Fish Eye Problems
Phenomenon:
Circular depressions appear on the coating surface, often with foreign particles or contaminants at the center.
Causes:
Contamination of the coating system by low surface tension substances such as silicone oil, grease, or dust.
Poor dispersion of pigments or fillers.
Solutions:
Strictly clean production equipment and spraying environments to prevent contamination sources.
Optimize the formulation and add suitable wetting and dispersing agents to improve pigment dispersion.
3. Orange Peel / Poor Leveling Problems
Phenomenon:
The coating surface shows rough textures similar to orange peel and lacks smooth gloss.
Causes:
Excessively high melt viscosity resulting in insufficient leveling.
Excessively fast reaction between resin and curing agent or poor compatibility.
Insufficient curing temperature or curing time.
Solutions:
Adjust the formulation, add leveling agents, or reduce cross-linking density to lower melt viscosity.
Select resin/TGIC systems with better matched reaction rates.
Ensure curing temperature and curing time meet requirements.
4. Poor Adhesion / Delamination Problems
Phenomenon:
The coating film easily peels off from the substrate, or separation occurs between coating layers (during recoating).
Causes:
Insufficient substrate pretreatment (residual oil contamination, rust, or oxide scale).
Over-curing or under-curing of the coating.
Poor interlayer wetting during recoating.
Solutions:
Strictly implement chemical pretreatment processes or sandblasting/phosphating processes.
Precisely control the curing oven temperature profile to ensure the workpiece reaches the required effective curing temperature.
Before recoating, sand and roughen the existing coating surface with sandpaper to improve interlayer adhesion.
5. Yellowing Problems
Phenomenon:
The coating film turns yellow, especially noticeable in light-colored or white coatings.
Causes:
Excessively high curing temperature or prolonged baking time (over-baking).
Color change caused by conventional benzoin decomposition at high temperatures.
Insufficient heat resistance of resin or additives.
Solutions:
Strictly control the curing window and avoid over-baking.
Select specialized anti-yellowing benzoin.
Use high heat-resistant polyester resins and add antioxidants/light stabilizers.
6. Low Gloss / Matte Appearance Problems
Phenomenon:
The gloss level of high-gloss formulations fails to reach the expected value.
Causes:
Incorrect curing curve (temperature or time does not reach the optimal range).
Improper proportion of matting fillers or additives in the formulation.
Uneven dispersion of pigments or fillers.
Solutions:
Check and calibrate the temperature profile of the curing oven.
Precisely adjust the dosage of matting agents according to the formulation type (physical matting or chemical matting).
Improve the uniformity of premixing and extrusion processes.
7. Powder Agglomeration / Poor Storage Stability Problems
Phenomenon:
The powder coating forms hard lumps during packaging or storage and cannot be used normally.
Causes:
The glass transition temperature (Tg) of the formulation is too low.
Storage environment temperature is too high or affected by moisture.
Poor extrusion or grinding process control results in excessive fine powder particles.
Solutions:
Adjust the ratio of resin and curing agent to increase Tg.
Store in a cool and dry environment (recommended temperature ≤30°C).
Control powder particle size distribution and avoid excessive fine powder content.
If you encounter difficult problems during the use of TGIC powder coatings, please feel free to contact us at any time. We will provide professional technical support, discuss solutions together, and contribute to the continuous development of the powder coating industry.
We hope this article can provide you with a professional and reliable reference in the powder coating industry.
We sincerely welcome your inquiries regarding powder coating product performance, industry standards, application methods, precautions, or any other related questions.
Please feel free to leave a message or contact us directly. We look forward to providing you with more detailed product information, demonstration videos, or customized solutions, helping you gain a comprehensive understanding of the product’s functions and advantages.
