Fabric Accessories About PU Coating Knowledge

We must be familiar with the word "PU coating". So what is PU exactly?

What material is it made of?

How is it coated?

Below I will briefly introduce some common sense in this area and discuss with you all, hoping to help you to have some perceptual knowledge of the concept of PU coating.

PU is actually polyurethane, and its properties are mainly wear-resistant, solvent resistant and low temperature resistant (below 30 degrees Celsius), waterproof and moisture permeable, windproof, soft and so on. In general, it is a milky white emulsion, which can be made into various fabrics or internal fabrics with knitted fabrics, plain woven fabrics, non-woven fabrics and other fabrics. Different kinds of films can be processed by two or three layers.

Our usual contacts are thin coated PU products, which are mainly used for PU coating of outdoor clothing and package fabrics, as well as for example, imitation leather (artificial leather), suede suede and other products are also PU coated products.

Polyurethane PU coating can form many multifunctional and high value-added textile products, widely used in clothing, decoration, military industry and other industries.

PU coating step is divided into its coating form. In short, it can be divided into waterborne and solvent based polyurethane.

The solvent type film has good performance, strong adhesion to fabric, high water resistance, and is more suitable for waterproof and moisture permeable coating.

But the solvent type is toxic and flammable. It is not environmentally friendly. The water-based type is safe, non-toxic and environmentally friendly. However, its adhesion to the fabric is poor and its water pressure resistance is weaker than that of the solvent type.

PU coating agent is a block copolymer consisting of two parts of soft segment and hard segment.

The soft segment makes PU soft and elastic, consisting of polyether or polyester glycol. Its molecular weight can also affect the hardness and hardness of PU. The hard segment makes PU have strength and modulus of elasticity, consisting of various diisocyanate and chain growth agents.

The proportion and structure of raw materials can determine and affect the performance of the product.

The synthesis method is usually made by diisocyanate, polyester glycol or polyether glycol plus chain growth agent and catalyst, through solution polymerization or bulk polymerization.

In general, granular or powdery can be made by bulk polymerization.

Water emulsion can be made by emulsifying agent or introducing hydrophilic groups and self emulsifying in two ways.

The solvent type is made of different organic solvents according to needs.

Coating processes include dry, wet, hot melt, pfer, and bonding methods. Dry process is the most widely used method. Dry method is to evenly coat the coating slurry on the base cloth, and then heat the solvent or water to evaporate. The coating forms a thin film on the surface of the fabric. The PU thin coating is a high-grade product in dry direct coating, mainly used for clothing fabrics.

There are many characteristics and kinds of polyurethane PU coating materials, and other products and uses are not introduced here.

In addition, I recently learned about polytetrafluoroethylene (PTFE) films in a large PU coating material company by using rough knowledge after work. According to the relevant personnel, some (PTFE) films were also made of water-proof and breathable composite membrane after coating a layer of polyurethane (PU) film.

Polyurethane and PTFE thin films were made by dry process.

Using mixed solvents, PU can be well bonded to the surface of PTFE material.

Polyurethane adhesive was coated on PTFE film by scraper technology.

The moisture content of the composite film decreases with the increase of film thickness and vice versa.

The polyurethane used for the composite membrane belongs to the thermoplastic adhesive. After the composite membrane is bonded with the fabric, the waterproof fabric with good water repellency can be obtained.