How can polyester be flame-retardant?

The flame retardant modification of polyester has two methods: blending modification and copolymerization modification. Blending modification is to add a blended flame retardant during the synthesis of polyester chips to prepare flame-retardant chips or to add flame retardants to blend with polyester melt during spinning to form flame-retardant fibers; copolymerization modification is to synthesize polyester In the process, a copolymerized flame retardant is added as a monomer to prepare a flame retardant polyester through a copolymerization method.

The flame retardant methods are classified according to the production process, which can be summarized into the following 5 types:

(1) In the transesterification or polycondensation stage, a reactive flame retardant is added for co-condensation;

(2) Add an additive flame retardant to the melt before melt spinning;

(3) Ordinary polyester and polyester containing flame-retardant components are combined spinning;

(4) Graft copolymerization with reactive flame retardant on polyester fiber or fabric;

(5) Perform flame retardant post-treatment on polyester fiber fabric.

There are many additional flame retardants that can be used for polyester fibers, and adding flame retardants is also the initial flame retardant modification method for polyester fibers. Flame retardants mainly include halogen flame retardants and phosphorus flame retardants. Among the halogen flame retardants, bromine flame retardants have the best flame retardant effect, and can be used with antimony compounds (such as antimony trioxide) to form a synergistic effect with them to improve their flame retardant effects. Among the phosphorus flame retardants, various organic phosphate, inorganic phosphate and phosphorus oxide flame retardants can be used for flame retardant modification of polyester fibers. Among them, the aromatic phosphate ester has good thermal decomposition stability, and its addition to the polyester melt has little effect on the thermal degradation of the polyester, so that it will not affect the spinning process and the performance of the fiber. At present, additive flame retardants have been widely used in some small polyester fiber manufacturers. Reactive flame retardant for polyester fiber refers to a small molecule flame retardant containing flame retardant elements (phosphorus, chlorine, bromine, fluorine) and active groups (carboxyl, hydroxyl, acid anhydride, etc.) in the molecule. Reactive flame retardants will gradually replace additive flame retardants. Usually adding a lower content (3% to 8%) of flame retardant can make the fiber have a good flame retardant effect. Reactive flame retardants that can be used for polyester fibers include halogen and phosphorus flame retardants. At present, the most commonly used in the world is the phosphorus-based copolymer flame retardant. Phosphorus flame retardants have a good flame retardant effect on polyester fibers, and no toxic gas is generated during the combustion process. It belongs to an environmentally friendly flame retardant system.

In the transesterification or polycondensation stage, a reactive flame retardant is added for co-polycondensation. Because the co-fire-retardant monomer is fixed on the copolyester chain through co-polycondensation reaction and becomes a component of the macromolecular chain, this method is suitable for PET spinning performance has little effect, and represents the mainstream of the development of flame-retardant polyester for fibers. For example, when synthesizing flame-retardant polyester, adding 4wt% to 5wt% 2-carboxyethyl phenyl phosphinic acid (CEPPA) flame retardant made of polyester fiber chips, the oxygen index can reach 32% to 33%; reaction Good activity, can obtain high molecular weight non-toxic, tasteless, high thermal stability, oxidation stability and water resistance polyester chips.