Take you to understand the production process and characteristics of hydrophilic non-woven fabrics

Polypropylene (pp) nonwovens are widely used due to their excellent properties, simple processing methods and low prices. Especially in recent years, its applications in medical and health, clothing, packaging materials, wiping materials, agricultural covering materials, geotextiles, industrial filter materials and other fields have become more and more extensive, and there is a trend to replace its traditional materials.
Because pp has a non-polar structure and basically does not contain hydrophilic groups, PP non-woven fabrics have basically no water absorption properties. The manufacture of hydrophilic pp non-woven fabrics must be hydrophilically modified or hydrophilically finished.
1. Method of making hydrophilic non-woven fabric
To improve the hydrophilicity of pp non-woven fabrics, generally by improving its surface wettability, there are mainly two methods of physical modification and chemical modification.
a. Chemical modification mainly changes the molecular structure of PP, adds hydrophilic groups to the macromolecular chain, and then changes its hygroscopicity. The main methods include copolymerization, grafting, crosslinking, and chlorination.
b. Physical modification mainly changes the higher-order structure of molecules to achieve the purpose of improving the hydrophilic effect, mainly blending modification (i.e. before spinning) and surface modification (i.e. after spinning).
Youyu non-woven fabric manufacturers now mainly use its physical modification to make PP hydrophilic non-woven fabrics.

2. Blending modification (modification before spinning)
According to the different time period of adding modified additives, it can be divided into master batch method, full granulation method, and pre-spinning injection method.

(1) Ordinary masterbatch method
This is an important method of hydrophilic non-woven fabric produced by non-woven fabric manufacturers.
First, the wood manufacturer will make the hydrophilic masterbatch from the common hydrophilic additives, and then blend it with pp to spunmelt and spun into the fabric.
Advantages: It is easy to produce, does not need to add any equipment, and is suitable for small batch cattle production. In addition, its hydrophilic durability is strong.
Disadvantages: the hydrophilic effect is slow to take effect, the processing performance is not good, and the fabric is often not spun out. The cost is high, and the cost is 2 to 3 times that of the surface modification finishing method.
The spinnability is poor, and the process needs to be adjusted. There is an example of a customer using two masterbatch plants to waste five tons of cloth without producing a finished product.

(2) Full granulation method
Mix the modifier, pp chips, and additives together uniformly, and granulate them under the screw to make hydrophilic PP particles, which are then melt-spun into cloth.
Advantages: Good processability, long-lasting effect, and the cloth can be used repeatedly.
Disadvantages: Need to increase the screw extruder equipment, the cost per ton is higher, the hydrophilic effect is slow, and it is only suitable for mass production.

(3) Pre-spinning injection method
The hydrophilic agent, that is, the hydrophilic base polymer is directly added to the main screw of the non-woven fabric, and it is mixed with the pp melt and spun directly.
Advantages: The effect is lasting, and the cloth can be used repeatedly.
Disadvantages: Due to the inability to mix uniformly, spinning is often difficult and the operability is not strong.
3. Hydrophilic surface finishing (post-spinning treatment)
Hydrophilic finishing is a simple, effective and low-cost method for making hydrophilic non-woven fabrics. Most non-woven fabric manufacturers mainly use this method.
The main process flow is as follows:
On-line spunbond hot-rolled non-woven fabric roll coating or spray water hydrophilic agent one infrared or hot air. Dryer one winder one hydrophilic finishing non-woven fabric coil
Advantages: There is no spinnability problem, the non-woven fabric has fast hydrophilic effect, high efficiency and low price, which is 1/21/3 of the cost of ordinary masterbatch method. Suitable for mass production;
Disadvantages: Post-processing equipment needs to be purchased separately, which is expensive. The washing resistance is poor, and the washing resistance test shows that the water penetration time is increased by about a factor of about three times after washing with water for 3 times. Can not meet the requirements of multiple use; mass production;
The advantages and disadvantages of this method determine that it is mainly used in disposable products with high requirements for water permeability and hydrophilicity, such as sanitary materials, diapers, sanitary napkins, etc.

Four, use the composite hydrophilic masterbatch PPS03 method
Aiming at the advantages and disadvantages of () and (two) methods, the composite hydrophilic masterbatch PPS030 is now developed
The hydrophilic masterbatch has a moderate amount of people (equivalent to ordinary hydrophilic masterbatch), has a fast onset, and has an effect immediately after the cloth is released. The effect will be better over time, with a long-lasting effect and good washing resistance , But the cost is slightly higher (equal to the cost of ordinary hydrophilic masterbatch).
The spinnability is very good, no need to adjust the production process.
It is suitable for small batch production and products that require high washing durability, and are used repeatedly, such as forestry cloth and agricultural cloth.

5. The main evaluation indicators of hydrophilicity of hydrophilic PP non-woven fabrics are water absorption, contact angle, capillary effect, etc.
(1) Water absorption rate: refers to the amount of water absorbed per unit mass of the hydrophilic non-woven fabric in the standard time or within the time required for the material to be completely wetted. The larger the water absorption, the better the effect.
(2) Contact angle method: Lay the hydrophilic pp non-woven on a clean and smooth glass plate, lay it flat in an oven to melt it, take out the glass plate after melting, cool it naturally to room temperature, and use direct testing Method to measure the equilibrium contact angle. The smaller the contact angle, the better the effect. (The contact angle of PP non-woven fabric without hydrophilic treatment is about 148°).
(3) Capillary effect: The test method is to place a 30cm long and 3cm wide PP hydrophilic cloth sample vertically in the capillary effect instrument, the water temperature is controlled at (27±2)℃, and the sample has a length of 8. 10mm, immediately after 30min, measure the liquid leakage height of each sample strip.

Six. Summary
Because pp hydrophilic nonwovens have high hydrophilicity, good hygroscopicity and lotion rate after modification, they are widely used in medical, sanitation, other disposable products, industry, agriculture and other fields.
Youyu non-woven fabric manufacturers have been working hard to improve the hydrophilic properties of pp non-woven fabrics and pursue low-cost methods! At the same time, for different fields and different new uses, new hydrophilic PP non-woven fabric production methods continue to appear, let us work together to achieve better economic benefits.