Talking about the preparation and detailed evaluation of polypropylene hydrophilic nonwoven fabric (2017 latest finishing)

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. The method of making hydrophilic non-woven fabrics 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. 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. Physical modification mainly changes the high-order structure of molecules to achieve the purpose of improving the hydrophilic effect, mainly blending modification (that is, before spinning) and surface modification (that is, after spinning). We now mainly use its physical modification to make pp hydrophilic non-woven fabrics. 2. Blending modification (modification before spinning) According to the time period of adding modified additives, it can be divided into master batch method, full granulation method, and injection method before spinning. (1) Ordinary masterbatch method This is an important method for hydrophilic non-woven fabrics produced by non-woven fabric manufacturers. The wood manufacturer first prepares the hydrophilic masterbatch from ordinary hydrophilic additives, and then blends it with pp to spunmelt spun into fabric. Advantages: simple production, no need to add any equipment, and 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. 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 slices, 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 screw extruder equipment, higher cost per ton, slow onset of hydrophilic effect, 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, 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. Surface hydrophilic finishing (post-spinning treatment) Hydrophilic finishing is a simple, effective and low-cost method for making hydrophilic non-woven fabrics. Most of our 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 water spraying hydrophilic agent-infrared or hot air. Dryer-rewinding machine-hydrophilic finishing non-woven coil Advantages: no available Spinnability problems, non-woven fabrics have fast hydrophilic effect, high efficiency and low price, which is 1/21/3 of the cost of ordinary masterbatch method. Suitable for mass production; Disadvantage: Need to purchase post-processing equipment separately, which is expensive. The washing resistance is poor, and the washing resistance test shows that the water penetration time has increased by about a factor of three after three washings. 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. 4. Using the composite hydrophilic masterbatch PPS03 method to address the advantages and disadvantages of the () and (two) methods, the composite hydrophilic masterbatch PPS030 is now developed. The hydrophilic masterbatch has a moderate addition amount (and ordinary hydrophilic masterbatch). Equivalent), the effect is quick, the effect is immediately after the cloth, and the effect will be better over time, with the characteristics of long-lasting effect and good washing resistance, but the cost is slightly higher (the cost is equivalent to that of ordinary hydrophilic masterbatch). The spinnability is very good, no need to adjust the production process. It is suitable for small batch production and high washing durability requirements, products that are used repeatedly, such as forestry cloth and agricultural cloth. 5. The main evaluation indexes of hydrophilicity of hydrophilic PP non-woven fabric are water absorption, contact angle, capillary effect, etc. (1) Water absorption rate: refers to the amount of water absorbed per unit mass of hydrophilic non-woven fabric in the standard time or within the time required for the material to be fully wetted. (2) Contact angle method: Lay the hydrophilic pp nonwoven 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 measure the balance by direct test method 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 length is 8-10mm, 30min Immediately measure the liquid penetration height of each sample strip. 6. Summary Because pp hydrophilic nonwovens have high hydrophilicity, good hygroscopicity and lotion rate after modification, they are widely used in medical, sanitary, other disposable products, industry, agriculture and other fields. The hydrophilic properties of pp non-woven fabrics have been improved, and the pursuit of cheap methods has also attracted more and more attention. 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.