Textile seals preserve formaldehyde content or increase

Recently, the reporter learned from the National Key Laboratory of Textile Testing (Shishi) that the laboratory has found through extensive research that when the textile is exposed to the air, the measured formaldehyde content gradually decreases with the increase of the standing time; when the textile is sealed When stored, the formaldehyde content of some samples increased gradually with the increase of the standing time, and the formaldehyde content of the other samples did not change significantly with the increase of the standing time.

Formaldehyde is widely used as a reactant in textile printing. Its purpose is mainly to improve the durability of the auxiliaries on fabrics. The scope of use includes resin finishing agents, fixing agents, waterproofing agents, softeners, adhesives, etc. Very broad, such as cellulose fiber-based fabric shrink-proof, anti-wrinkle finishing cross-linking agent is the main source of free formaldehyde. Formaldehyde is a volatile organic substance. Formaldehyde in textiles will gradually be released during the wearing process. Lightness will irritate the eyes, skin and mucous membranes, causing intense itching, causing skin irritation, inflammation of the respiratory tract, and severe cancer. Therefore, in the National Technical Specifications for Basic Textile Products GB 18401-2010, the detection values ​​of formaldehyde for infant products, products that are in direct contact with the skin, and products that are not directly in contact with the skin are limited to 20 mg/kg, 75 mg/ Kg and 300 mg/kg.

It is understood that the release of formaldehyde in textiles is mainly divided into three stages: free release, barrier release and chemical release. Free release means that the formaldehyde concentration on the textile surface is higher at the initial stage of release, free formaldehyde is freely volatilized as a gas, and the volatilization rate is faster; the release release is that the formaldehyde concentration on the textile surface gradually decreases with the release time, physicality Formaldehyde deposited in textiles or combined with fiber macromolecules gradually overcomes resistance and spreads outward. However, due to the influence of textile resistance and force, the diffusion rate is slower and the amount of volatilization is gradually reduced. The chemical release is mainly The finishing agent which is crosslinked by the fiber and fixed to the fiber undergoes a reversible reaction under certain conditions, and the formaldehyde is released to a limited extent until equilibrium.

The relevant person in charge of the National Key Laboratory of Textile Testing (Shishi) said that free formaldehyde is mainly determined by formaldehyde on the surface of textiles. When the textile is exposed to the air, the free-release and barrier-released formaldehyde volatilizes into the air, resulting in a gradual decrease in the measured formaldehyde content as the time of standing increases. When the textile is sealed, the formaldehyde on the surface of the textile fails to volatilize through the polyethylene bag and the aluminum foil, and the formaldehyde released by the barrier gradually diffuses to the surface of the sample. As the standing time increases, the formaldehyde content measured by some samples gradually increases. .

To this end, the National Key Laboratory of Textile Testing (Shishi) reminds the majority of garment enterprises to be cautious when using samples with formaldehyde detected. After the samples are stored for a period of time, the detection value does not fall and rises, reducing unnecessary economy. loss.