What is optical brightener?

Let us first understand the fluorescent brightener. It is a type of fluorescent dye, which belongs to a separate category in the Colour Index (C.I.). The molecular structure of fluorescent whitening agent is mainly composed of a continuous conjugated system containing an aromatic ring and one or more substituents. The special chemical structure enables it to absorb ultraviolet rays that are invisible to the naked eye in light, and then excites the visible fluorescence (Usually blue or blue-violet), this kind of fluorescence can make up for the lack of blue light in the reflected light of yellowish white objects, and enhance the reflected light in the blue band, allowing the naked eye to see the whiteness and whiteness of white objects. The brightness has been improved, and the vividness of colored objects is brighter and more eye-catching. This characteristic of fluorescent brightener has achieved its rapid development in the fields of textiles, paper, detergents, plastics, etc., and is considered to be one of the three major achievements in the dye industry in the late 20th century.

At present, there are more than 15 structural types of fluorescent whitening agents produced in the world, and more than 1,000 kinds of commercial fluorescent whitening agents. According to different structures, fluorescent whitening agents can be divided into stilbene type, benzoxazole type, pyrazoline type, coumarin type, naphthalimide type and other types. Among them, the stilbene type fluorescent whitening agent is the most rapidly developing branch.

The safety of fluorescent whitening agent is closely related to its structure and cannot be generalized. Different industrial fields have clear requirements for the use of fluorescent whitening agents, and consumers do not need to hear fluorescent whitening agents as unsafe. For example, "Fluorescent Brighteners for Detergents" (QB/T2953-2008) stipulates that stilbene biphenyls and bistriazine amino stilbene fluorescent brighteners can be added when producing various laundry detergents.

As early as 1999, the European Chemical Industry Committee (CEFIC) and the European Union Detergent Association (AISE) launched the "European Household Cleaning Product Ingredients Human and Environmental Risk Assessment" (HERA) project, and completed the fluorescent brightener 71 etc. The safety evaluation and risk assessment of stilbene fluorescent whitening agents commonly used in laundry detergents concluded that they will not cause adverse effects on the human body and the environment.

Our country's food industry stipulates that artificially adding fluorescent whitening agents is strictly prohibited in the processing of food and related products. However, since some natural plant materials such as bamboo, etc., contain fluorescent substances, trace amounts of fluorescent substances may inevitably be brought into packaging materials, but their residues should be strictly controlled.