Oxazoline coating crosslinking agent
Oxazoline coating crosslinking agent
There are 1, 3 or 1, 4 - benzene dioxazoline in the representative varieties of oxazoline coatings.
The aromatic dioxazoline (PBOX) is widely used in liquid coatings as a synergistic crosslinking agent.Under the influence of nucleophilic and electrophilic reagent oxazoline ring can be open loop under about 150 ℃ and bonus.The nucleophilic reagent mainly attacks the slightly electropositive 4-bit C atoms connected with O, while the electrophilic reagent mainly attacks the 2-bit naked N atom.
Can use it to the properties of PBOX and polyester resin, epoxy resin, phenolic resin, anhydride and 1.1.2 introduction of phenolic reactions such as crosslinking agent constitute a class of fast crosslinking performance of coating systems.Since there are only two functional groups, PBOX is generally not used as the main crosslinking agent, for example as a combination of auxiliary components and epoxy resin.
DSM developed an economic PBOX method to make this expensive compound widely available.
PBOX and carboxyl polyesters were produced by the following open-loop addition reaction, which produced the ester-amide crosslinking structure, so the reaction was not released by the byproducts.The ester-amide structure has no strong H bond, thus providing low viscosity and high flow performance.
It has been found that PBOX as crosslinking agent in polyester powder coating presents a very good flow, excellent chemical resistance, high anti-scratch and mechanical properties.In addition, this kind of powder coating also shows excellent storage stability, color retention and excellent weathering ability.
Recently, the four oxazoline - N, N, N 'n'-4 [2 - (2 - oxazoline-base) -hexanamide - as a crosslinking agent for new weather-resistant polyester powder coatings.It is reported that this new compound has focused almost all the advantages of existing products: such as no volatiles release can be thick coating, excellent crosslinking performance, appearance and excellent resistance to yellowing, it completely eliminates the HAA class the defect of crosslinking agent, is a kind of ideal TGIC alternatives.
Like HAA, the crosslinking agent can be crosslinked at low temperature, reaction by about 130 ℃, without catalyst.If Solutia can bring it to market in time, it will undoubtedly be a revolutionary contribution to the powder coating industry.
Chinese name: Diethyl toluene diamine(DETDA)
Domestic in gas baking yellowing resistant additives have new results, K7003, for example, although the structure is different, the product with HP - 136 gas baking yellowing resistance but also have a good effect, also has excellent heat-resistant yellowing effect.
In practical application, the choice of suitable antioxidant is often required to consider the factors such as discoloration, volatility, solubility, thermal stability, synergistic/antagonistic effect.In addition, antioxidants have a maximum effective dose (usually between 0.2 and 0.8% of the total), and more than that will not help.Sometimes an overdose of antioxidants can even cause discoloration, so trial evaluation is needed first.
Operation time (also working time or use period) is a part of crosslinking time. After mixing, the mixture of resin/crosslinking agent is still liquid and can work and suitable for application.In order to ensure reliable adhesion, all construction and positioning should be done within the time of delivery.
The mixture begins to enter the crosslinking phase (also known as the maturation phase) when it begins to gel or "mutate".The epoxy does not have long working hours, and it will lose its viscosity.There is no interference at this stage.It will become a hard rubber-like soft gel that you can press with your thumb.
Since the mixture is only locally crosslinked, the newly used epoxy resin can still be linked to it, so the unprocessed surface can still be glued or reactive.In any case, the ability to approach the crosslinking mixture is diminishing.
The epoxy mixture reaches a solid stage when the crosslinking is turned into a solid phase.His thumb at this time you have fixed it, about 90% of the final when epoxy resin reaction intensity, thus removing the clamp, it continues to put it in room temperature to maintain several angel crosslinking.
The newly used epoxy resin cannot be chemically linked with it, since the surface of the epoxy must be properly pretreated to be polished to obtain good adhesion mechanical strength.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Spanish
French
Italian
Portuguese
Japanese
Korean
Arabic
Russian