The national mandatory standards GB 18401-2010 and GB 31701-2015 clearly state that in Clothing, decorative and household textile products produced and sold in my country must have pH values measured and comply with corresponding safety technical requirements.
First, let’s look at a set of data:
Below, The editor will lead everyone to learn about the pH test of textiles.
1. What is pH value?
The pH value is a measurement parameter of the acid-base strength of a solution. It is a simple way to express the hydrogen ion concentration in the solution (pH=-lg[H+]). The value is generally 1 Between -14, 7 is a neutral value. The more acidic the solution, the lower the value, and the more alkaline the solution, the higher the value.
2. The significance of pH value testing
The surface of human skin is a weakly acidic environment with a pH value of 5.5 to 6.0. An acidic environment can inhibit the growth and reproduction of certain pathogenic bacteria, prevent the invasion of external bacteria, and protect the skin from infection. If the pH value exceeds the standard, is too acidic or too alkaline, the weakly acidic environment of the human body will be destroyed, causing skin itching or allergies.
3. Principle of textile pH testing
After the textile is extracted with distilled or deionized water, use a pH meter with a glass electrode to measure the pH value of the extract.
4. Reasons for excessive pH of textiles
The influence of dyes in production: Commonly used reactive dyes, Shilin dyes, and sulfur dyes are all produced under alkaline conditions. Even if the cloth surface can be washed, it will be affected by the production water. The influence of pH value.
Influence of printing and dyeing processes: After refining, dyeing, printing and other processing of cotton, wool, silk, polyester, nylon, acrylic and other textiles, alkali and acid chemicals remain on the fabrics Products and additives, and there are different pH values, after washing, soaping, acid neutralization, drying and other post-processing processes, if the dosage of chemical additives is high or the post-washing treatment is insufficient, the pH value of the textiles will exceed the standard. Affect the wearing properties of textiles.
Influence of fabrics: Fabrics of different thicknesses affect the pH value of the cloth surface. Thin fabrics are easy to wash after dyeing, and the pH value of the cloth surface is low; thick fabrics are relatively difficult to wash after dyeing, and the cloth surface The pH value is relatively high.
The impact of laboratory personnel’s operating errors: Different dry humidity, extraction temperature, extraction time, etc. of the test fabric will affect the measurement results of the pH value of the cloth surface.
5. Improvement measures for unqualified textile pH
Acid-base neutralization: add alkali to neutralize the acidic ones, add acid to neutralize the alkaline ones. The commonly used acid is acetic acid or citric acid, and the alkali is soda ash. Improvement of dyeing and finishing process: increase washing, etc. Choose high-quality raw materials, dyes, etc. to eliminate them from the source. </p
