By analyzing the factors of the pH value of nylon cloth in production, such as bath ratio, acid used in the bath and acid dosage, etc., suitable production conditions are formulated to overcome the shortcomings of sourness, yellowing in storage and unstable pH value of nylon finished cloth. After adopting the improved process conditions, the mass production results show that the nylon cloth can be made without sour taste, non-yellowing, and the pH value is stable within the acceptable range of 5.0~6.0, and the yellowing fastness of the plastic bag can reach above level 4, and the effect is ideal.
The pH value is a chemical indicator used to measure the acidity or alkalinity of a solution. It represents the concentration of hydrogen ions in the solution and is expressed by the negative logarithm of the activity of hydrogen ions. The pH value is sometimes called the hydrogen ion index. Because the value of the hydrogen ion activity is often very small, it is inconvenient to use, so the pH is an index.
The pH value remaining in textiles is one of the indicators of harmful substances that affect human safety and health. The sweat and oil secreted by the sweat glands and sebum of human skin have a pH value, and the pH value of normal human skin is weakly acidic at 5.5 to 7.0. It can inhibit the growth and reproduction of certain bacteria, protect the skin from infection, and is an important barrier for the human body to defend against bacterial invasion. Therefore, the pH value of textiles is between neutral (pH 7.0) and weakly acidic (pH slightly lower than 7.0), which is most beneficial to the skin. If the pH value of the skin surface exceeds the suitable range of human skin, it is easy to cause skin itching, allergies, inflammation and other diseases, and even damage the human sweat glands and nervous system, and affect human health. Therefore, it is very necessary to strictly control the pH value of fabrics. At present, the pH value of large brands of nylon fabrics according to national standards is 4.0~7.5. European and American standards (such as ISO, AATCC, etc.) nylon fabrics require a pH value of 4.0. ~7.0 between.
1 The larger the bath ratio, the more stable the pH value of the nylon fabric. Considering the characteristics and cost factors of the airflow dyeing machine, the bath ratio should be about 1:6.
2 It is advisable to use 0.7g/L HAc and 0.5g/L NaAc buffer solutions for nylon fixation to reduce and stabilize the pH value of the fabric. The finished fabric has very weak sourness and stable pH value.
3 Control the pH value of the nylon fabric cloth at 5.0~6.0, and the finished product will not turn yellow after packaging, which is the best pH control range.