In recent years, everyone's love for outdoor nature has become stronger.
Picnics and camping have also become a new social activity.
But the weather is changing, and the rainstorm often hits at some unknown time.
Therefore, the waterproof "equipment" for outdoor activities cannot be less-
Umbrellas, waterproof jackets, rain boots, tents...
▇ How can textile fabrics be waterproof?
Waterproof finishing can make textiles waterproof. Fabric waterproof finishing is divided into water repellent finishing and hydrostatic pressure resistant finishing.
■ Water repellent finishing
After the water repellent finishing, the surface tension of the fabric changes, and the fabric changes from hydrophilic to hydrophobic. The water droplets on it, like dripping on a lotus leaf, can roll but cannot be wetted.
■ Hydrostatic pressure resistant finishing
The surface of the fabric is coated with a layer of impermeable continuous film, which blocks the voids of the fabric tissue and prevents the passage of water droplets. This method is also called coating finishing.
is divided from the moisture permeability of the fabric after waterproof finishing, and can be divided into moisture-permeable waterproof finishing and moisture-impermeable waterproof finishing.
■ Moisture-permeable and waterproof finishing
The hydrophobic substance forms a continuous film on the surface of the fabric, which can prevent the penetration of water, and can withstand long-term rain and certain water pressure. Clothing is usually made of moisture-permeable and waterproof finishing, so that it has a certain degree of waterproof performance without reducing the moisture permeability of the fabric, and it is comfortable to wear and not stuffy.
■ Impermeable and waterproof finishing
Impermeable waterproof processing fabrics are usually used for waterproof canvas, tents and packaging.
▇ How to evaluate the waterproof performance of textiles?
Principle: According to different product uses, the current main evaluation indicators are wetness level, water penetration, and hydrostatic pressure resistance level.
1. Water dip test (spray method)
Principle: Install the sample on the ring holder, keep the holder at 45° from the horizontal, and the center of the sample is at a certain distance from the nozzle. Spray the sample with a certain amount of distilled or deionized water. After spraying, by comparing the appearance of the sample with the description of the wetness phenomenon and the picture, the wetness level of the fabric is determined, and the waterproof performance of the fabric is evaluated.
Commonly used standards:
GB/T 4745 "Testing and Evaluation of Textile Waterproof Performance-Wetting Method"
ISO 4920 "Test method for surface moisture resistance of textile fabrics: Water dip test"
AATCC 22 "Water repellency spray test"
Evaluation method:
Take GB/T 4745-2012 "Testing and Evaluation of Textile Waterproof Performance: Wetting Method" as an example: Wetting level ≥3, with anti-wetting performance.
2. Rain test
Principle: Place a piece of absorbent paper of known weight on the back of the test sample, and after continuous spraying for a certain period of time, weigh the change in the weight of the absorbent paper to measure the water permeability. The test methods are divided into horizontal spray rain test and top-to-bottom impact penetration test.
Commonly used standards:
- Horizontal spray rain test
AATCC 35 "Water repellency performance and rain test"
ISO 22958 "Textile Waterproofness Horizontal Spray Rain Test"
GB/T 23321 "Textile Waterproofness Horizontal Spray Rain Test"
- Impact penetration test
ISO 18695 "Determination of impermeability of textiles, impact penetration test"
GB/T 33732 "Determination of impermeability of textiles, impact penetration test"
AATCC 42 "Waterproof, Impact Penetration Test"
3. Hydrostatic pressure test
Principle: One side of the sample bears the rising water pressure until three water seepages appear on the other side, and the water pressure data is recorded.
Commonly used standards:
GB/T 4744 "Textile Waterproof Performance Testing and Evaluation: Hydrostatic Pressure Method"
ISO 811 "Determination of the impermeability of textile fabrics: Hydrostatic pressure method"
AATCC 127 "Waterproof Hydrostatic Pressure Test"
Evaluation method:
Take GB/T 4744 "Textile Waterproof Performance Testing and Evaluation Hydrostatic Pressure Method" as an example:
The anti-static water pressure of textiles is ≥1 grade, and it has anti-static water pressure performance. The higher the grade, the better the hydrostatic pressure resistance.
National standard textile products that have requirements for waterproof performance are mainly concentrated in outdoor products
E.g:
GB/T 21980-2017 "General technical specifications for professional sportswear and protective equipment"
GB/T 32614-2016 "Outdoor Sportswear Jackets"
GB/T 21294-2014 "Methods for testing physical and chemical properties of clothing"
GB/T 21295-2014 "Inspection methods and technical requirements for physical and chemical properties of clothing"
▇ Warm reminder
1. According to the use of the product and the desired effect, choose an appropriate method to test the waterproof performance.
2. In recent years, the application of fluorine-containing compounds in fabric water-repellent, oil-repellent, and anti-fouling finishing has developed rapidly. Perfluorinated compounds represented by PFOA & PFOS are reproductively toxic and difficult to degrade, and have been included in the EU POPs regulation and control category , Waterproof products exported to the EU should ensure material safety.
