PH value is a very important quality index of textiles, is the compulsory implementation index of GB18401-2010 "National Technical Specification for Basic Safety of Textiles", PH value is not qualified is also the most common quality problem in the process of textile processing, production and trade, which has attracted more and more attention. This article will discuss with you how to control the pH value of textiles.

1, the definition of pH value:

PH value is pH, human skin is weak acid, in this environmental conditions can prevent the invasion of bacteria, so if the pH value of textiles in a slightly acidic or neutral is conducive to the protection of human health; On the contrary, too high or too low pH value of textiles will destroy the balance and resistance of the skin, resulting in skin allergy or infection leading to the invasion of bacteria.

2, pH value limit requirements:

3. The source of pH anomaly:

The dyeing and finishing processes that can easily cause abnormal pH are mainly alkali dewatering, polyester printing washing, reactive printing washing, cotton desizing, scouring and mercerizing.

4. Comparison of different determination methods of pH value of textiles:

(1) Chinese Standard (GB/T 7573-2009)

Wage 3 portions of 2±0.05g samples, cut them into small pieces of 5×5 mm, put them into a flask containing 100 mL distilled water, shake the flask to make the samples fully wet, put the flask on the oscillator and vibrate for 2 hours ±5 minutes, then directly measure the pH value of the water extract (excluding fabric) with a pH meter at room temperature, and do 3 tests for each sample. The average value of the second and third samples was taken as the final result, and the accuracy was 0.1.

(2) European Standard (EN 1413-1998)

Wage 3 portions of 2±0.05g samples, cut them into small pieces of 5×5 mm, put them into flask containing 100ml potassium chloride solution (0.1mol/L) or 100ml distilled water, shake the flask to make the samples fully wet, put the flask on the oscillator and shake it for 2 hours. The pH value of the water extract (excluding fabric) was directly measured with a pH meter at room temperature. Each sample was tested for 3 times, and the average value of the second and third sample results was taken as the final result, accurate to 0.1.

(3), Japanese Standard (JIS L 1096-1999)

The 5±0.1g sample was weighed and cut into small pieces of 1×1mm, boiled in 50ml distilled water and kept for 2 minutes, then the sample was put in the flask, shaken to make the sample fully wet, stood for 30 minutes at room temperature, then the sample was removed. When the temperature of the water extract reached 25±2℃, the pH value of the water extract was directly measured with a pH meter, accurate to 0.1.

(4), American Standard (AATCC 81-2001)

10±0.1g sample was weighed, cut into small pieces, boiled in 250ml distilled water and kept for 10 minutes, then the sample was put in the flask, shaken to make the sample fully soaked, and continued to boil for 10 minutes. After cooling to room temperature, the sample was removed, and the pH value of the water extraction solution was directly measured with a pH meter, accurate to 0.01.

PH value of water extract of whole cotton fabric under different measurement standards:

5. How to deal with the pH disqualification of textiles?

The PH of the fabric or the garment is found to be unqualified, and the PH of the fabric is generally adjusted by the principle of acid-base neutralization. Alkaline pH unqualified mostly, there are many kinds of, can be used to adjust the acid agent for glacial acetic acid and citric acid are two of the most common, glacial acetic acid volatile and stimulating odour, citric acid to adjust pH is stable, so generally suggest using citric acid to adjust is more appropriate, but should pay attention to control the dosage, too much will affect the handle, also easy to cause yellowing.

For example: if the pH value of the fabric is 9-10, the pH value of the citric acid aqueous solution can be adjusted to 4-5, and then soaked for 10 minutes and dried. Sent to the customer before the formal testing structure test to confirm qualified, reduce the risk of trade.

6. Control method of pH value:

Only by analyzing the reasons for the unqualified pH value and applying the medicine to the case, can we effectively reduce the unqualified rate of the pH value of textiles:

(1) Fabric enterprises should strengthen the quality awareness of relevant quality control personnel and the learning and training of textile standards, and correctly understand the requirements of textile pH. Garment processing enterprises should also choose the appropriate surface and accessories according to their own requirements and safety categories, and provide accurate requirements and standards to fabric suppliers. From the source of attention, quality control, in order to avoid due to PH unqualified trade disputes.

(2) Relevant personnel of dyeing and finishing enterprises should take the initiative to learn the safety knowledge of ecological textiles, be familiar with the standard requirements, take the initiative to pay attention to the internal quality of printing and dyeing products, optimize the production process and improve the technical level.

(3) Inspection institutions or enterprise laboratories should test in strict accordance with the inspection standards to ensure the fairness and accuracy of the test data, avoid errors in the test data caused by improper operation and other human factors, and truly control the quality of the products.