Polypropylene (PP) non-woven fabric is widely used due to its excellent performance, simple processing methods, and low price. Especially in recent years, it has been widely used in fields such as healthcare, clothing, packaging materials, wiping materials, agricultural covering materials, geotextiles, industrial filtration materials, etc., and has a trend to replace its traditional materials.
Due to the non-polar structure of PP, which basically does not contain hydrophilic groups, PP non-woven fabric has basically no water absorption performance. Hydrophilic modification or finishing is necessary to manufacture hydrophilic PP nonwoven fabrics.
I. Method for preparing hydrophilic non-woven fabrics
In order to improve the hydrophilicity of PP nonwoven fabrics, there are usually two methods to improve their surface wettability: physical modification and chemical modification.
Chemical modification mainly changes the molecular structure of PP and adds hydrophilic groups to the macromolecular chains, thereby changing its hygroscopicity. There are mainly methods such as copolymerization, grafting, cross-linking, and chlorination.
Physical modification mainly changes the higher structure of molecules to improve hydrophilicity, mainly through blending modification (before spinning) and surface modification (after spinning).
II. Mixed modification (spinning pre modification)
According to the different addition times of modified additives, they can be divided into masterbatch method, full granulation method, and spin coating agent injection method.
(1) Ordinary color masterbatch method
This is an important method for producing hydrophilic non-woven fabrics by non-woven fabric manufacturers.
Firstly, ordinary hydrophilic additives are made into jellyfish particles by wood manufacturers, and then blended with PP spinning to form a fabric.
Advantages: Simple production, no need to add any equipment, suitable for small batch production of cattle, in addition to its strong hydrophilic durability.
Disadvantages: Slow hydrophilicity and poor processing performance, often used in spinning fabrics. High cost, 2 to 3 times higher than surface modification.
Poor spinnability requires adjustment of the process. Some customers wasted 5 tons of fabric from two color masterbatch factories without producing finished products.
(2) Full granulation method
Mix the modifier, PP slices, and additives evenly, granulate them under the screw to produce hydrophilic PP particles, then melt and spin them into cloth.
Advantages: Good processability, long-lasting effect, and reusable fabric.
Disadvantages: Additional screw extruder equipment is required, resulting in higher cost per ton and slower hydrophilicity, making it only suitable for large-scale production.
(3) Fangqian Injection
Directly add hydrophilic reagents, i.e. hydrophilic polymers, to the main screw of non-woven fabrics and mix them with PP melt for direct spinning.
Advantages: The effect is long-lasting and the fabric can be reused.
Disadvantages: Due to the inability to mix evenly, spinning is often difficult and lacks mobility.
III. Surface hydrophilic finishing (after spinning treatment)
Hydrophilic finishing is a simple, effective, and low-cost method for producing hydrophilic non-woven fabrics. Most of our non-woven fabric manufacturers mainly use this method. The main process is as follows:
Online spunbond hot-rolled non-woven fabric – roller coating or water spraying hydrophilic agent – infrared or hot air
Advantages: No spinnability issues, fast hydrophilic effect of non-woven fabric, high efficiency, low price, it is 1/2-1/3 of the cost of ordinary color masterbatch. Suitable for large-scale production;
Disadvantage: It requires the purchase of separate post-processing equipment, which is expensive. After washing three times, the water penetration time increases by about 15 times. Unable to meet the requirements for reuse;
Mass production;
The advantages and disadvantages of this method determine that it is mainly used for disposable products that require high permeability and hydrophilicity, such as sanitary materials, diapers, sanitary napkins, etc.
Ⅳ.Using Complex Hydrophilic Particle PPS03 Method
Considering the advantages and disadvantages of (-) and (ii) methods, a composite hydrophilic mother particle PPS030 was developed
This type of jellyfish particle has the characteristics of medium dosage (similar to ordinary jellyfish particles), fast effect, fast spreading effect, good effect, long-lasting effect, good washing resistance, but slightly higher cost (similar to ordinary jellyfish particles).
Good spinnability, no need to adjust production process.
Suitable for small batch production and high washing resistance, reusable products such as forestry and agricultural fabrics.
The main evaluation indicators of hydrophilic PP non-woven fabric include water absorption, contact angle, and capillary effect.
(1) Water absorption rate: refers to the amount of water absorbed per unit mass of hydrophilic nonwoven fabric within a standard time or the time required to fully wet the material. The greater the water absorption, the better the effect.
(2) Contact angle method: Place hydrophilic PP non-woven fabric on a clean and smooth glass plate, lay it flat on the oven, and let it melt. After melting, remove the glass plate and cool it naturally to room temperature. Measure the equilibrium contact angle using direct testing methods. The smaller the contact angle, the better. (PP non-woven fabric without hydrophilic treatment after reaching about 148 ° C).
Post time: Dec-04-2023