Ethylenic and Vinylic Based Brighteners

Closely related structurally to stilbenes are a class of compounds containing one or more ethylenic bridges between aromatic or heteroaromatic rings, exemplified by 

Most of the compounds in this group are used for the brightening of synthetic fibres, especially polyester. Application to polyester is either by exhaustion at 125-30 °C, with or without carriers, or by continuous pad bake methods at 160-200 °C with FBAs of a larger molecular size. The benzoxazole group is an important feature of this class, other examples being (3.59) and the bis(benzoxa-zolyl)stilbene (3.60), which is used to produce pre-brightened polyester by adding to the melt prior to extrusion of the fibre. 

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