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HAA Hardener RC559 is a beta-hydroxyalkylamide (HAA) curing agent from Hangzhou Right Chemical Co., Ltd., supplied as a white granular solid and used to crosslink carboxyl-functional polyester resins in TGIC-free powder coatings for architectural, appliance, furniture and general industrial applications.
The RC559 HAA curing agent is chosen when powder coating producers want a TGIC-free polyester system with good outdoor durability, good mechanical properties and good colour stability, together with a more favourable labelling and handling profile than triglycidyl isocyanurate (TGIC).
The RC559 beta-hydroxyalkylamide hardener works by esterification: during the bake, its beta-hydroxyalkylamide groups react with the carboxyl groups of the polyester to form ester crosslinks, and water is released as the by-product of this condensation reaction.
Chemical type: Beta-hydroxyalkylamide (HAA) hardener for carboxyl polyester powder coatings
Manufacturer: Hangzhou Right Chemical Co., Ltd.
Appearance: White granular solid
Solubility in water: Poorly soluble to insoluble in the coating, reacts in the polyester melt
Curing reaction: Esterification with carboxyl groups, water is released
Storage: Dry, tightly closed, approx. 15–30 °C
COMMON PRODUCT & CHEMICAL NAMES OF HAA HARDENER RC559:
HAA Hardener RC559, RC559, HAA RC559, RC559 HAA Hardener, RC559 Hardener, RC559 Curing Agent, Hydroxyalkylamide Hardener RC559, Hydroxyalkyl Amide Hardener RC559, Beta-Hydroxyalkylamide Hardener RC559, β-Hydroxyalkylamide Curing Agent RC559, HAA Curing Agent RC559, HAA Crosslinker RC559, TGIC-Free Hardener RC559, Polyester Powder Coating Hardener RC559, Carboxyl Polyester Hardener RC559, Primid-Type HAA Hardener, Beta-Hydroxyalkylamide, Hydroxyalkylamide, HAA
RC559 is the manufacturer's product code, "HAA" stands for hydroxyalkylamide, more precisely beta-hydroxyalkylamide, the chemical family of the hardener. Products of this family are sometimes called "Primid-type" hardeners after Primid, the best-known brand of HAA crosslinkers, RC559 is a separate product and not identical with any Primid grade.
The RC559 HAA crosslinker is listed by its manufacturer alongside HAA Hardener RC552, a tetra-functional beta-hydroxyalkylamide offered as a TGIC substitute. The two codes are different products, so data for RC552 or for other HAA hardeners should not be transferred to RC559 without confirmation. The chemical identity, CAS number and composition of HAA Hardener RC559 are given in the manufacturer's SDS, available on request from Ataman Kimya.
WHAT IS HAA HARDENER RC559?
Beta-hydroxyalkylamides are amides in which the nitrogen atom carries hydroxyethyl or hydroxypropyl groups, so that each hydroxyl group sits on the carbon two positions away from the amide nitrogen (beta position). This arrangement makes the hydroxyl groups unusually reactive towards carboxylic acids at baking temperatures, much more reactive than ordinary alcohols, without the need for a catalyst. A typical member of the family is N,N,N',N'-tetrakis(2-hydroxyethyl)adipamide, a tetra-functional HAA.
The RC559 beta-hydroxyalkylamide hardener is described by its manufacturer as a hydroxyalkyl amide hardener supplied as a white granular solid for curing carboxyl-functional polyesters. Data such as hydroxyl value or hydroxyl equivalent weight, melting range and functionality of HAA Hardener RC559 determine the mixing ratio and are given in the TDS of the product, available on request from Ataman Kimya.
Polyester powder coatings for outdoor use need a hardener that does not turn yellow in sunlight and that builds a dense, flexible network. For many years TGIC was the standard choice. Because TGIC carries serious health hazard classifications, many producers moved to beta-hydroxyalkylamide hardeners, and HAA–polyester systems are now one of the main technologies for exterior powder coatings, especially in Europe.
The RC559 HAA curing agent belongs to this group. It is used with carboxyl-functional polyester resins designed for HAA cure. These resins differ from TGIC-grade polyesters in acid value and reactivity, so the resin and HAA Hardener RC559 must be matched.
HAA Hardener RC559 can contribute to:
- good weather resistance and gloss retention with exterior-grade polyesters
- good colour stability in white and light shades
- hardness, flexibility and impact resistance
- good adhesion to properly pretreated metal
- formulations in high-gloss, satin, matt and textured finishes, depending on the resin and additive system
Typical coated products: aluminium profiles, façade elements, window frames and doors, metal furniture, garden furniture and equipment, lighting fixtures, appliance housings, electrical cabinets, shelving and racks, bicycles and sports equipment, machinery parts and general steel structures.
HOW HAA HARDENER RC559 CURES POLYESTER POWDER COATINGS
1. Extrusion: HAA Hardener RC559 is premixed with the carboxyl polyester, pigments, fillers and additives and melt-extruded, usually at around 100–120 °C, which is below the temperature where significant reaction starts.
2. Application: the ground powder is applied electrostatically to the pretreated substrate.
3. Bake: in the oven, the powder melts, flows and levels. At cure temperature the beta-hydroxyalkylamide groups of HAA Hardener RC559 react with the carboxyl groups of the polyester and form ester bonds. The network builds up and the film hardens.
4. By-product: each ester bond formed releases one molecule of water. This water must leave the film during the bake, if it is trapped, pinholes or bubbles can form, especially in thick films.
Typical HAA–polyester systems are cured at oven temperatures of about 160–200 °C for about 10–20 minutes, depending on the resin. The exact cure window for a system with HAA Hardener RC559 is set by the resin manufacturer's recommendation and must be confirmed by tests.
Mixing ratio: the amount of HAA Hardener RC559 is calculated from the acid value of the polyester and the hydroxyl equivalent weight of the hardener, usually aiming at about stoichiometric balance. Typical HAA polyester systems are formulated at polyester-to-HAA ratios in the range of about 93:7 to 97:3. The correct ratio for HAA Hardener RC559 depends on its equivalent weight and the chosen resin.
TGIC VS HAA: WHERE HAA HARDENER RC559 FITS
TGIC (triglycidyl isocyanurate): epoxy-type crosslinker, addition reaction without volatile by-product, so thick films are easier, carries health hazard classifications that require strict handling and labelling.
HAA (such as HAA Hardener RC559): condensation reaction releasing water, more favourable labelling and handling profile, good exterior durability and mechanical properties, film thickness and degassing need more attention.
For many exterior architectural and general industrial applications, HAA systems now replace TGIC. Where very high film builds, edge coverage or specific approvals are required, the choice should be checked with the resin supplier and by testing.
WHICH PROBLEMS DOES HAA HARDENER RC559 SOLVE?
- A TGIC-free exterior polyester powder is required → HAA Hardener RC559 provides a TGIC-free curing route.
- Light colours yellow with other curing agents → HAA–polyester systems give good colour stability with suitable resins.
- Coatings must combine hardness and flexibility → HAA Hardener RC559 builds an ester network with good mechanical balance.
- Labelling and workplace exposure concerns with TGIC → HAA hardeners generally have a more favourable profile, check the SDS of RC559.
THINGS TO CONSIDER WHEN USING HAA HARDENER RC559
- Use resins designed for HAA cure, TGIC-grade polyesters are not automatically suitable.
- Calculate the ratio from the actual acid value of the resin lot and the equivalent weight of HAA Hardener RC559.
- Water release: limit film thickness, use a degassing agent such as benzoin or other degassing additives, and choose a bake profile that allows water to escape before the surface closes.
- Dispersion: ensure good premixing and extrusion, because poor distribution of HAA Hardener RC559 leads to incomplete cure, gloss differences and weak mechanical properties.
- Overbake: test colour and gloss stability under overbake conditions, especially in white and light colours.
- Additives and fillers: some acidic or basic additives can influence reactivity and storage stability of the powder, check compatibility.
- Moisture: keep HAA Hardener RC559 and finished powder dry, moisture causes caking and can affect feeding and film appearance.
INITIAL FORMULATION APPROACHES WITH HAA HARDENER RC559
The compositions below are illustrative starting mixtures (% w/w), not validated commercial recipes or confirmed RC559 dosage recommendations. Each totals 100 %. A polyester:HAA binder ratio of 95:5 is used only for illustration, calculate the actual RC559 level from the selected resin acid value and the confirmed hardener equivalent weight, then rebalance the formulation to 100 %.
1. WHITE EXTERIOR GLOSS POWDER
Carboxyl polyester for HAA cure (around 93–96 parts of the binder), HAA Hardener RC559 (about 4–7 parts of the binder, adjusted to stoichiometry), rutile titanium dioxide, barium sulphate filler, a flow agent (for example an acrylic flow modifier on silica carrier) and a degassing agent (for example benzoin). Premix, extrude, grind and sieve. Cure according to the resin recommendation and test gloss, impact, cupping, adhesion, colour and pinhole-free film thickness.
Illustrative initial components (% w/w of total powder):
Carboxyl-functional polyester for HAA cure: 57 %
HAA Hardener RC559: 3 %
Rutile titanium dioxide: 25 %
Barium sulphate: 14 %
Flow agent: 0.8 %
Degassing agent (for example benzoin): 0.2 %
Total: 100 %
2. SATIN OR MATT FINISH
Use a matting system compatible with HAA cure (dry-blend of two resins with different reactivity, or a dedicated matting additive) with HAA Hardener RC559 at the calculated ratio. Measure gloss at 60° and adjust the matting system.
Illustrative initial components for the dedicated matting-additive route (% w/w of total powder):
Carboxyl-functional polyester for HAA cure: 55.1 %
HAA Hardener RC559: 2.9 %
Rutile titanium dioxide: 25 %
Barium sulphate: 13 %
HAA-compatible matting additive: 3 %
Flow agent: 0.8 %
Degassing agent (for example benzoin): 0.2 %
Total: 100 %
3. TEXTURED FINISH FOR FURNITURE OR CABINETS
Combine the HAA polyester base with HAA Hardener RC559, fillers and a texture agent, adjust film thickness and texture level, and check that the water released during cure does not cause defects in the texture.
Illustrative initial components (% w/w of total powder):
Carboxyl-functional polyester for HAA cure: 57 %
HAA Hardener RC559: 3 %
Rutile titanium dioxide: 15 %
Barium sulphate: 23.5 %
Flow agent: 0.8 %
Degassing agent (for example benzoin): 0.2 %
Texture agent: 0.5 %
Total: 100 %
These are starting points only. The resin supplier's formulation guide and practical tests are required for every system with HAA Hardener RC559.
ALTERNATIVES TO HAA HARDENER RC559
Other beta-hydroxyalkylamide hardeners (for example tetra-functional HAA grades such as HAA Hardener RC552, or Primid-type products): similar chemistry, different equivalent weights and reactivity.
TGIC: epoxy-functional crosslinker for polyester powders, no water release, stricter health classification.
TGIC substitutes based on glycidyl esters (such as PT 910/912 types): epoxy-functional alternatives.
Epoxy resins: crosslinker in epoxy–polyester hybrid powders for interior use.
Blocked isocyanates and uretdiones: crosslinkers for hydroxyl-functional polyester (polyurethane) powders.
Glycoluril-based crosslinkers (such as tetramethoxymethyl glycoluril): for hydroxyl polyester powders.
HOW DOES HAA HARDENER RC559 WORK AT THE MOLECULAR LEVEL?
HAA Hardener RC559 belongs to the β-hydroxyalkylamide family of curing agents used with carboxyl-functional polyester resins in powder coatings. Hardeners of this type are typically based on molecules such as N,N,N′,N′-tetrakis(2-hydroxyethyl)adipamide, in which several hydroxyethyl groups sit on amide nitrogen atoms. The key feature is the position of each hydroxyl group: it is located two carbons away from the amide nitrogen, and this β-position makes the hydroxyl far more reactive toward carboxylic acids than an ordinary alcohol.
Why the β-hydroxyl is special: In a normal alcohol, esterification with a carboxylic acid is slow without a catalyst. In a β-hydroxyalkylamide, the neighbouring amide group takes part in the reaction. When the coating is heated, the amide oxygen or nitrogen assists in activating the hydroxyethyl group, and an oxazolinium-type intermediate is formed. This neighbouring-group assistance lowers the energy barrier, so the hydroxyalkylamide can react quickly with carboxyl groups at typical powder coating stoving temperatures without an added catalyst.
Crosslinking reaction: The activated intermediate is attacked by a carboxyl group of the polyester resin, forming an ester bond and releasing one molecule of water. Because each hardener molecule carries several reactive hydroxyethyl groups and each resin chain carries several carboxyl groups, repeated esterification links chains together into a three-dimensional polyester network. As the network grows, the film loses its ability to flow and turns into a hard, insoluble coating with good mechanical strength.
Stoichiometry: The final network depends on the ratio between hydroxyl groups of the β-hydroxyalkylamide and carboxyl groups of the resin. A balanced ratio leaves few unreacted ends and gives the best combination of hardness, flexibility and chemical resistance. Excess hardener or excess resin leaves free hydroxyl or carboxyl groups, which can reduce resistance to water, chemicals and weathering.
Condensation water and film thickness: Since every crosslink releases water, a curing film must allow this vapour to escape before the surface closes. In thin and medium films, water diffuses out without trouble. In very thick films, or when heating is too fast, trapped vapour can form pinholes or blisters. This outgassing behaviour is a direct consequence of the condensation mechanism and is why film build and oven profile are planned together for HAA-cured powders.
Flow and levelling: Before the network forms, the melted polyester and the hydroxyalkylamide pass through a low-viscosity phase in which the film flows and levels. The speed of the esterification reaction sets how long this window lasts. A reactive system closes the window quickly, while a slower one allows smoother levelling. Matting systems take advantage of this by combining resins of different reactivity, so that separate network domains form at different times and create a fine surface texture that scatters light.
Weathering performance: When used with saturated polyester resins, the resulting ester network contains no aromatic amine or epoxy-derived structures that absorb strongly in the UV range. This gives HAA-cured coatings good gloss and colour retention outdoors, which is why β-hydroxyalkylamides are widely used as an alternative to triglycidyl isocyanurate (TGIC) in architectural and outdoor powder coatings.
Handling and moisture: The many hydroxyl and amide groups make β-hydroxyalkylamides polar and able to absorb moisture from the air. Absorbed water can affect powder flow and storage stability, so hardener and finished powder are kept dry and well sealed.
The final properties of a coating cured with HAA Hardener RC559 depend on the resin acid value, the hardener-to-resin ratio, film thickness, stoving temperature and time, and the pigments and additives used. HAA Hardener RC559 dosage and process conditions should therefore be confirmed through laboratory trials.
QUALITY CONTROL AND PURCHASING CRITERIA FOR HAA HARDENER RC559
- product code and manufacturer (HAA Hardener RC559, Hangzhou Right Chemical Co., Ltd.)
- appearance: white granules, free from lumps and foreign particles
- hydroxyl value or equivalent weight
- melting range
- volatile content / moisture
- particle size or granule size
- COA for each batch, TDS and SDS
- recommended resin types and mixing ratio
Technical data, the recommended mixing ratio and documents for HAA Hardener RC559 are available on request from Ataman Kimya.
STORAGE AND HANDLING OF HAA HARDENER RC559
Store HAA Hardener RC559 in tightly closed original packaging in a cool, dry, well-ventilated place, typically at about 15–30 °C, protected from moisture, heat, direct sunlight and contamination. Close opened bags immediately. Use clean, dry equipment for weighing and premixing, and rotate stock on a first-in, first-out basis. Avoid dust generation during weighing, mixing and feeding the extruder, fine organic dust can form explosive mixtures with air, so keep powder processing areas clean and grounded. Shelf life of the supplied lot is available on request from Ataman Kimya.
SAFETY OF HAA HARDENER RC559
The RC559 HAA crosslinker should be handled with normal industrial hygiene practice for chemical powders. Wear safety glasses, gloves and suitable dust protection during bulk handling, and use local exhaust where dust is generated.
First aid: after inhalation of dust, move to fresh air and seek medical advice if symptoms persist, after skin contact, wash with soap and water, after eye contact, rinse cautiously with water for several minutes, removing contact lenses if present, after swallowing, rinse the mouth with water and seek medical advice if discomfort occurs.
Spills: sweep or vacuum up without raising dust and collect for reuse or disposal according to local rules.
The hazard classification of HAA Hardener RC559 depends on its exact composition and is given in its SDS, available on request from Ataman Kimya.
BUYING HAA HARDENER RC559
The RC559 HAA curing agent is supplied as granules in bags or cartons. When requesting an offer, please describe the polyester resin used (or its acid value), the application (architectural, appliance, furniture, general industrial), the finish (gloss, matt, texture) and the quantity. Packaging and lead times for HAA Hardener RC559 are available on request from Ataman Kimya.
SUPPLY OF HAA HARDENER RC559 FROM ATAMAN KIMYA
Ataman Kimya supplies HAA Hardener RC559 to powder coating manufacturers. Ataman Kimya provides TDS, SDS and COA documents, helps customers calculate the polyester-to-hardener ratio and compare HAA Hardener RC559 with other HAA and TGIC-free hardeners, and supports logistics. For prices and technical support, please contact Ataman Kimya.
FREQUENTLY ASKED QUESTIONS ABOUT HAA HARDENER RC559
CAN HAA HARDENER RC559 BE USED IN EPOXY COATINGS?
No. The RC559 beta-hydroxyalkylamide hardener is designed to cure carboxyl-functional polyester resins in powder coatings, it is not an epoxy hardener.
IS HAA HARDENER RC559 THE SAME AS RC552?
No. Both are HAA hardeners from the same manufacturer, but they are separate products with their own specifications.
WHY DO HAA POWDERS SOMETIMES SHOW PINHOLES?
Because the curing reaction releases water. Film thickness, degassing additives and the bake profile must be adapted.
WHAT RESIN SHOULD BE USED WITH HAA HARDENER RC559?
A carboxyl-functional polyester designed for HAA cure, the resin supplier's recommendation should be followed.
HOW MUCH HAA HARDENER RC559 SHOULD BE ADDED?
The amount depends on the polyester acid value and the equivalent weight of RC559, HAA systems are typically in the range of about 93:7 to 97:3 polyester to hardener.
IS HAA HARDENER RC559 SUITABLE FOR OUTDOOR COATINGS?
Yes, together with exterior-durable polyester resins, HAA Hardener RC559 is used for architectural and other outdoor powder coatings.
DOES HAA HARDENER RC559 NEED A CATALYST?
Beta-hydroxyalkylamide cure normally proceeds without added catalyst, the reactivity is controlled mainly by the resin and the bake schedule.
HAA HARDENER RC559 – TECHNICAL SUMMARY
Product name: HAA Hardener RC559
Manufacturer: Hangzhou Right Chemical Co., Ltd.
Chemical type: Beta-hydroxyalkylamide (HAA) curing agent
Appearance: White granular solid
Reaction partner: Carboxyl-functional polyester resins for HAA cure
Reaction type: Esterification (condensation), water released
Typical polyester : HAA ratio range: approx. 93:7 to 97:3 (calculate from acid value and equivalent weight)
Main uses: TGIC-free exterior and interior polyester powder coatings for aluminium profiles, façades, furniture, appliances, general industry
Key points: Control film thickness and degassing, keep dry
Storage: Tightly closed, dry, approx. 15–30 °C
The RC559 HAA crosslinker can be sourced from ATAMAN KİMYA. For further information and supply inquiries about HAA Hardener RC559, please contact ATAMAN KİMYA.
