In the national compulsory standards GB 18401-2010 and GB 31701-2015, it is clearly pointed out that the pH value of clothing, decorative and household textile products produced and sold in China must be determined and meet the corresponding safety and technical requirements. First, let's look at a set of data:
Standard technology
Requirement
Baby products
Direct contact with skin products
Non-direct contact skin products
Decorative materials
GB 18401-2010
4.0-7.5
4.0-8.5
4.0-9.0
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Oeko-Tex100
4.0-7.5
4.0-7.5
4.0-9.0
4.0-9.0
Next, we will lead you to understand all aspects of pH testing.
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1. What is the pH value?
The pH value is a measure parameter of the acid-base strength of the solution. It is a simple method to express the concentration of hydrogen ion in the solution (pH=-lg[H+]). The value is generally between 1 and 14, and 7 is a neutral value. The stronger the acidity of the solution, the lower the value, the stronger the alkalinity, the greater the value.
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2、pH值测试的意义
The surface of human skin is in a weak acidic environment with a pH value of 5.5-6.0. Acidic environment can inhibit the growth and reproduction of some pathogenic bacteria, prevent the invasion of external pathogens, and protect the skin from infection. If the pH value is too acidic or too alkaline, the weak acidic environment of human body will be destroyed, which will cause skin itching or allergy.
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3. Principle of Textile pH Testing
The textiles were extracted by distilled water or deionized water, and the pH value of the extract was determined by a pH meter with a glass electrode.
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4. Reasons for Textile pH Exceeding Standard
The influence of dyestuffs in production: The dyeing of reactive dyes, schlieren dyes and sulfur dyes in common use are all produced under alkaline conditions. Even if the fabric surface can be washed well, it will be affected by the pH value of the water used in production.
Influences of printing and dyeing technology: After cotton, wool, silk, polyester, nylon and acrylic textiles are refined, dyed and printed, alkali, acid chemicals and auxiliaries are left on the fabric, and there are different pH values. After treatment by washing, soaping, acid neutralization and drying, if the amount of chemical auxiliaries is high or after treatment by washing. Inadequate, will make textile pH exceed the standard, affecting the wearability of textiles.
Nbsp; the influence of fabrics: different thickness fabrics affect the fabric surface pH value, thin fabrics are easy to wash after dyeing, and the fabric surface pH value is low; thick fabrics are relatively difficult to wash after dyeing, and the fabric surface pH value is relatively high.
The influence of operating errors of laboratory personnel: the different dryness and humidity, extraction temperature and extraction time of the tested fabrics will affect the determination results of the pH value of the fabrics.
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5. Measures to Improve Textile pH Disqualification
Acid-base neutralization: acidic alkali neutralization, acidic acid neutralization, commonly used acid is acetic acid or citric acid, alkali is soda.
Improvement of dyeing and finishing process: increase washing, etc.
Select high-quality raw materials, dyes and so on, and eliminate them from the source.
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6. How do consumers prevent it?
Consumers should try their best to buy clothes from formal clothing stores, monopoly stores, etc. Textile products produced by formal enterprises will have tags indicating safety technology categories, indicating that the product passes the requirements of national mandatory standards. Newly purchased clothes, especially textile products that are directly in contact with the human body, such as children's, infant products and underwear, should not be directly worn. It can be rinsed with clear water and then worn, which can effectively reduce harmful substances in textile products, so that the pH value does not deviate from the standard range as far as possible.
