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Home / News / Industry News / Baking Temperature Cannot Be Reduced? The Crosslink Reaction Speed May Be Insufficient
Industry News
Industrial Baking Coatings · Amino Baking · DH-7356N
In industrial baking, metal baking, and coil coating systems, baking is an important stage in film formation. After heating, the amino resin and hydroxyl-containing resin crosslink to form a more stable film structure. Whether the crosslink reaction is sufficient directly affects the final film's hardness, water resistance, corrosion resistance, and mechanical performance. But in actual production, baking temperature is not always higher the better — equipment conditions, production pace, and substrate heat resistance all impose constraints on the cure process.
Baking Time Too Long — Affects Efficiency
If system reaction speed is slow, to reach the target performance only the baking time can be extended, easily increasing production cycle time.
Film Performance Declines After Temperature Is Reduced
When baking temperature is limited, crosslinking between resins may be insufficient, ultimately manifesting as inadequate hardness, water resistance, or chemical resistance.
Film Hardness and Durability Difficult to Achieve
When crosslink density is insufficient, the film's internal structure is incomplete, and performance may show noticeable change under moisture, humid environments, or external mechanical action.
Cure Conditions Difficult to Unify Across Different Systems
Waterborne and solventborne coatings have different formulation structures. Different resin combinations require different reaction conditions, and the catalyst system needs to be adjusted for the specific formulation.
Why Increasing Baking Temperature Is Not Always the Good Solution
Increasing baking temperature means higher energy consumption and equipment load; some substrates or composite structures cannot sustain high temperature for long periods. Additionally, if temperature is simply increased without improving the reaction efficiency between resins, actual cure may not improve as expected. The role of an acid catalyst is to accelerate the crosslinking between amino resin and hydroxyl-containing resin from a reaction kinetics perspective, enabling the system to obtain a good cure effect under relatively limited baking conditions. A blocked-type catalyst can deliver catalytic activity triggered by temperature — maintaining relative stability during storage and acting during baking.
DH-7356N: Blocked Sulphonic Acid Catalyst
DH-7356N is a blocked sulphonic acid catalyst, primarily used to promote crosslinking between amino resins and hydroxyl-containing resins. During baking, as temperature reaches the appropriate condition, the catalyst gradually takes effect, helping to improve crosslinking efficiency in the system — thereby reducing the time required to reach the target cure degree, or to some extent reducing the cure temperature requirement.
For film performance, sufficient crosslinking helps the coating obtain better hardness, gloss, and moisture resistance, while also providing some improvement in corrosion resistance and mechanical performance. DH-7356N can be used in waterborne and solventborne baking coatings, suitable for automotive coatings, can coatings, coil coatings, coil aluminium coatings, industrial baking, and metal baking systems. Reference dosage: 1%–5% of total formulation. Actual application should be adjusted based on resin type, amino resin ratio, baking temperature, and baking time.
Slow baking cure speed does not mean the only solution is increasing temperature or extending time. For systems composed of amino resin and hydroxyl-containing resin, a well-designed catalyst can further improve crosslinking efficiency, enabling the formulation to achieve good film performance under limited baking conditions. A blocked sulphonic acid catalyst is better suited to systems that need to balance both storage stability and baking reaction efficiency.
Frequently Asked Questions
How does a blocked acid catalyst differ from a free acid catalyst in a baking coating system?
A free acid catalyst is active at ambient temperature and begins catalysing the crosslink reaction immediately upon mixing — which can significantly shorten pot life and storage stability, and may cause the coating to pre-gel during storage. A blocked catalyst has its acid functionality chemically protected so that it is inactive at ambient temperature, and only releases the active acid species when the formulation is heated to the deblocking temperature during baking. This allows much better storage stability while still providing catalytic activity where it is needed — during cure.
Can DH-7356N be used in single-component waterborne baking systems?
Yes — DH-7356N is specifically noted for use in both waterborne and solventborne baking coating systems. Its blocked structure is designed to provide storage stability in the single-component system while releasing catalytic activity during oven cure. The storage stability should be confirmed by aged-sample testing for the specific waterborne formulation, as system pH and other components can affect the blocking stability over time.
