There are many varieties of knitting products in our country, and different varieties have different characteristics. The industry standard of "Knitted thermal underwear flakes" has made normative requirements for flake-type thermal underwear.
The flake layer is a non-woven flake layer of wool, silk and various chemical fibers, which is made by needle punching and combing.
Insulation rate Breathability rate The moisture permeability is based on the characteristics of "Knitted Thermal Underwear". The "Knitting Thermal Underwear Flakes" industry standard specifies 11 internal quality indicators, including insulation rate, square meter dry weight, air permeability and moisture permeability. , pilling, marble breaking strength, washing dimensional change rate, tensile elasticity, formaldehyde content, fiber content, color fastness. Among them, the heat preservation rate, air permeability and moisture permeability are important indicators reflecting the comfort of thermal underwear. At present, the flake layer knitted thermal underwear has a considerable proportion in the market. The structure of the product is a thermal layer composed of a composite of flakes, which is the fastest growing type of development. The intermediate flakes can be made of synthetic fiber composite fiber, polyester polypropylene staple fiber, functional fiber, silk, wool, and the like. The fabric structure generally adopts a knitted single-sided structure, and the fiber raw materials generally adopt fibers such as pure cotton, polyester-cotton blend, and modified polypropylene. According to expert arguments, a comfortable underwear is the result of the best combination of three indicators, that is, the insulation rate is more than 50%, the air permeability is controlled between 300 and 600 mm/s, and the moisture permeability is greater than 3000 g/m2/day. .
In addition, in order to ensure the wearing performance of knitted thermal underwear, the standard also specifies the pilling, washing dimensional change rate, tensile elasticity, formaldehyde content, dyeing rate and other indicators. Among them, the pilling, washing dimensional change rate, and color fastness are directly felt by the consumer after wearing. For example, the pilling index is that after the product is rubbed, the fiber ends protrude from the surface to form fluff or small spherical protrusions. The quality of this indicator is related to the cotton used. Products made from low-cotton or polyester-cotton are easy to pilling, and cotton products are not easy to pilling.
Washing Dimensional Changes The dimensional change rate of the washing wash specifies the method for determining the dimensional change of the textile after it has been treated by a suitable washing and drying combination procedure. This program tests the washing temperature to 40 ° C, reminding consumers to master the temperature during the process of washing thermal underwear, preferably washing at 40 ° C water temperature, otherwise it will cause poor washing results.
The color fastness test of dyeing fastness is to comprehensively evaluate the degree of discoloration of textiles from three aspects: acid resistance, alkali resistance and friction resistance. The color fastness is low and the product is badly colored.
The content of formaldehyde in the formaldehyde content is also strictly required for the formaldehyde content. According to analysis, formaldehyde is generally present in some finishing agents, while knitted thermal underwear uses adhesives during processing, which is one of the factors leading to the presence of formaldehyde. After a lot of testing, we finally set the formaldehyde content index to ≤50mg/kg.
Invited Expert: Xing Zhigui, Executive Deputy Director of National Knitting Product Quality Supervision and Inspection Center
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