What are the key steps in the mechanical or chemical forming process of nonwoven fabric?

1. Selection and pretreatment of fiber raw materials
The first step in the forming process of nonwoven fabric is to select suitable fiber raw materials. Common fiber raw materials include polyester, polypropylene and vinylon. These fibers will undergo a series of pretreatments during the production process to better adapt to subsequent processing steps.

Polyester fiber has good strength and heat resistance and is often used in nonwoven products that require durability and high strength, such as filter materials and industrial uses.
Polypropylene fiber is often used in the production of sanitary products and disposable consumer goods due to its low density, chemical corrosion resistance and strong air permeability.
Vinylon fiber is suitable for medical and sanitary products due to its good moisture absorption and softness, especially in areas with high comfort requirements, such as baby diapers and sanitary napkins.
After the selection of fibers, the raw fiber needs to be combed, cleaned and other treatments to ensure that the fiber does not carry impurities and can be smoothly formed in subsequent processes.

2. Carding process
The carding process is the first important step in the production of nonwoven fabrics. In this process, the fibers are introduced into the card machine and dispersed into a uniform mesh structure through a series of mechanical devices. Carding can not only break up the fibers, but also effectively remove impurities and ensure the uniformity of the fibers.

In this process, fibers such as polyester, polypropylene and vinylon are combed into a mesh by the card machine and distributed according to a specific thickness and density. The carded fiber mesh can enter the next step of the spinning process.

3. Spinning net forming
Spinning net forming is a key step in further processing the carded fibers into non-woven fabrics. Common spinning net forming methods include dry web forming, wet web forming and air web forming.

Dry web forming: The fiber web is laid into a web through a belt conveyor belt through mechanical action, which is suitable for lighter and higher-strength non-woven fabrics. Dry web forming is generally used for chemical fibers such as polypropylene and polyester, and can produce a uniform mesh structure, which is suitable for disposable products and filter materials, etc.

Wet web forming: The fibers are dispersed in an aqueous solution and then deposited into a web through a filter net, which is suitable for non-woven fabrics with more complex structures and high water absorption requirements. Wet-laid webs are often used for the processing of vinylon fibers, especially for products that require high absorbency and comfort, such as sanitary napkins and diapers.

Air-laid webs: Use airflow to suspend fibers in the air and form them through suction equipment. Air-laid webs are generally used for looser structures, suitable for sanitary products and isolation materials.

These web-forming methods use different technologies and processes to achieve uniform distribution of fibers and the formation of a mesh structure, laying the foundation for subsequent forming processes.

4. Consolidation process
Consolidation is to bond the formed fiber web by mechanical, chemical or hot pressing to form a non-woven fabric with certain strength and stability. According to different application requirements, consolidation methods can be divided into the following types:

Hot-pressed consolidation: Heat is used to melt and bond the fibers. Polypropylene and polyester fibers often use hot-pressed consolidation technology, which can effectively improve the strength and stability of non-woven fabrics. Hot-pressed consolidation is suitable for the production of harder and more durable non-woven fabrics.

Chemical consolidation: The fiber webs are chemically bonded by coating or spraying adhesives. Chemical consolidation is suitable for non-woven products that require specific properties (such as antibacterial and flame retardant). For example, in medical and sanitary products, chemical consolidation can effectively enhance the functionality of non-woven fabrics.

Mechanical consolidation: The fibers are mechanically punctured through a special needle punching device to form an interwoven structure. Mechanical consolidation is often used to produce durable and tear-resistant non-woven fabrics, suitable for carpets, filter materials, etc.

5. Post-processing process
The consolidated non-woven fabric usually needs to undergo a series of post-processing processes to improve its performance or meet specific market needs. Common post-processing processes include:

Antibacterial treatment: Through chemical additives or spraying antibacterial agents, non-woven fabrics are given antibacterial properties, which are widely used in the medical and health fields.
Dyeing and printing: According to market demand, dyeing or printing treatment is carried out to increase the beauty and functionality of non-woven fabrics, which are suitable for home decoration and fashion industries.
Waterproof treatment: Through coating or treatment, non-woven fabrics are made waterproof, which is often used in the manufacture of products such as rain gear and jackets.