d) Color fastness
Color fastness is the quality requirement for dyeing and printing fabrics. Because dyed fabrics can be worn or stored, they can be discolored or discolored due to light, sweat, friction, washing, ironing, etc., thereby affecting the aesthetic appearance of fabrics or garments. The nature or degree of variation in the staining state can be expressed in terms of color fastness. The color fastness of fabrics is related to the type of fiber, yarn structure, fabric organization, printing and dyeing methods, dye type and external force. It can be divided into light fastness, washing or soaping fastness, rubbing fastness, perspiration fastness, ironing fastness and sublimation fastness.
1. Light fastness
The light fastness refers to the degree of discoloration of a colored fabric by sunlight. The test method can be used either in the sun or in the sunlight. The fading degree of the sample after the sun exposure is compared with the standard color sample. The sample is classified into 8 grades, 8 grades best and 1 grade worst. Fabrics with poor light fastness should not be exposed to sunlight for a long time and should be dried in a ventilated place.
2. Wash fastness
Washing or soaping fastness refers to the degree of color change after the dyed fabric is washed with the washing solution. Gray graded sample cards are usually used as the evaluation criteria, that is, the color difference between the original sample and the sample after fading is used for evaluation. Washing fastness is divided into 5 levels, 5 is the best and 1 is the worst. Fabrics with poor washing fastness should be dry-cleaned, and if wet cleaning is performed, care must be taken to wash conditions, such as washing temperature not too high and time not too long.
3. Friction fastness
Rubbing fastness refers to the degree of discoloration of dyed fabrics after rubbing, which can be classified as dry rubbing and wet rubbing. The rubbing fastness is evaluated on the basis of the degree of white cloth staining, and is divided into 5 levels (1 to 5). The larger the value, the better the rubbing fastness. Fabrics with poor rubbing fastness have limited service life.
4. Perspiration fastness
Perspiration fastness refers to the degree of discoloration of a dyed fabric after it is impregnated with sweat. Perspiration fastness Due to the different composition of artificially formulated perspiration, it is generally combined with other color fastnesses in addition to individual measurements. Perspiration is divided into 1 to 5 grades, the larger the value, the better.
5. Ironing fastness
Ironing fastness refers to the degree of discoloration or discoloration of a dyed fabric when it is ironed. This degree of discoloration and fading is assessed by the coloring of the iron to other fabrics at the same time. Ironing fastness is divided into 1 to 5 grades, 5 is the best, and 1 is the worst. When testing the ironing fastness of different fabrics, the test iron temperature should be selected.
6. Sublimation fastness
Sublimation fastness refers to the degree of sublimation that occurs in dyed fabrics during storage. Sublimation Fastness The grey graded sample cards were used to assess the degree of discoloration, discoloration, and white-cloth staining of the fabrics after dry hot embossing. The scores were divided into 5 grades, with grade 1 being the worst and grade 5 being the best.
The color fastness of normal fabrics is generally required to reach 3 to 4 levels to meet the wearing needs.
Third, health care performance Health care performance is one of the important performance of clothing materials. It includes the weather nature of clothing when the human body wears clothing - comfort and protective nature of clothing - safety protection. The performance related to the comfort of the garment is hygroscopicity, heat preservation, gas-bearing, breathability, thermal conductivity, etc., and the performance related to safety protection is the skin's anti-injury, anti-moth-eaten, anti-mildew, and anti-bacterial properties. Antistatic and antifouling properties.
(a) gas-bearing
Most of the garment materials are fiber products. Since the yarns constituting the fabric are elastic, there are many weaving eyes in the weave of the fabric. Air is usually present in the weaving eyes, and air is contained inside the yarn and between the fiber assemblies. This property is called the gas-bearing nature of the fabric. These eyes and spaces are called air holes. The size and presence of pores are related to the breathability, thermal conductivity, and wettability of garment materials. The factors affecting the fabric's gas content include fiber type, yarn thickness, fiber direction, tissue type, thickness, square meter weight, post-processing, and sewing.
1. Fiber properties
Different types of fibers contain different shapes and sizes of pores, so their gas-bearing properties will also be different. Reflected on fabrics, there will be differences in the degree of warmth and ventilation. In general, natural fibers have good gas-bearing properties and synthetic fibers have poor gas-bearing properties, and the gas-containing properties of wool fibers are the best.
2. Fabric properties
The gas-bearing property is a superior property of the textile, and the general woolen fabric has good gas-bearing properties. This is because the wool fibers have good gas-containing properties, and the yarns can be woven into a multi-void fabric structure, which greatly increases the air content in the fabrics, reduces the heat transfer rate, and improves the warmth and cold resistance. This is also a warm winter clothing. the reason.
3. Detection method
The gas content of the garment material can be expressed as a percentage of the volume of air in the volume.
Gas content (%) = (SP) / S X 100
In the formula, S - the volumetric mass of the fiber (g/cm3)
P—apparent bulk mass of material (g/cm3), P=FW/d (g/cm3)
FW - square meter weight (g/cm2), d - thickness (cm)
From the above formula, we can obtain the gas content as long as the weight, thickness and fiber specific gravity of the fabric are measured.
(B) Hygroscopicity, moisture permeability (water permeability)
Hygroscopicity and moisture permeability are important health indicators for apparel materials. The ability of garment materials to absorb moisture in the atmosphere is called hygroscopicity.
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