In addition to the quality of the product, finishing materials now pay more attention to whether it is toxic. Epoxy resin is a new type of material. What kind of material is epoxy resin? Is epoxy toxic? see Bar.
What is epoxy resin?
Epoxy resin is a general term for a class of polymers containing more than two epoxy groups per molecule. It is a polycondensation product of epichlorohydrin and bisphenol A or a polyol. Due to the reactivity of the epoxy group, various compounds containing active hydrogen can be used to open the ring, cure and crosslink to form a network structure, so it is a thermoset resin.
Epoxy resins have secondary hydroxyl groups and epoxy groups, and the secondary hydroxyl groups can react with isocyanates. The epoxy resin is directly added to the hydroxyl-containing polyurethane adhesive component in the form of a polyol. With this method, only the hydroxyl group is involved in the reaction, and the epoxy group does not react.
Use the carboxyl group of the acid resin to open the epoxy ring and then react with the isocyanate in the polyurethane adhesive. It is also possible to dissolve epoxy resin in ethyl acetate, add phosphoric acid to heat the reaction, and add its adduct to polyurethane adhesive, and the initial viscosity of the adhesive, heat resistance and hydrolysis resistance can be improved. or amines react to form polyols, and the presence of tertiary nitrogen atoms in the adducts can accelerate the NCO reaction.
The use of epoxy resin as a polyhydroxy component combines the advantages of polyurethane and epoxy resin, and has good adhesive strength and chemical resistance. The epoxy resin used in the production of polyurethane adhesives generally uses EP-12, EP-13, EP-16 and EP -20 and other varieties.
Is epoxy toxic?
Epoxy and epoxy-based adhesives are non-toxic on their own, but due to the addition of solvents and other toxic substances during the preparation process, many epoxy resins are "toxic". In recent years, the domestic epoxy resin industry water-based modification In order to maintain the "non-toxic" epoxy resin, avoiding the addition of other methods.
Currently, most epoxy resin coatings are solvent-based coatings that contain large amounts of volatile organic compounds (VOCs), which are toxic and flammable, which are harmful to the environment and the human body.
Epoxy resins are commonly used in conjunction with additives to improve application performance. Additives can be selected according to different purposes. Commonly used additives include the following categories: (1) hardener, (2) modifier, (3) filler, (4) thinner, (5) others.
Whether used as an adhesive, coating or casting, a hardener must be added, otherwise the epoxy cannot be cured. These epoxy hardeners are carcinogenic and toxic. Epoxies must be cured with epoxy hardeners, but these epoxy hardeners are toxic, such as MDA and TD1, are carcinogens, and they remain in the epoxy floor and slowly volatilize.
The above is a detailed content of "what is epoxy and is epoxy poisonous", I hope this can be used as a reference for everyone!