- Natural leather materials
(1) Classified by raw materials: pig leather, cow leather, sheep leather, horse leather, ostrich leather, etc.
(2) Classified by tanning methods: chrome tanned leather (the most common), vegetable tanned leather, aluminum tanned leather, aldehyde tanned leather, oil tanned leather, etc.
(3) Classified by the number of leather layers: first layer leather, second layer leather.
(4) According to the surface condition of leather, it can be classified as: front painted leather, light frosted leather, suede leather, embossed leather, color printed leather, cracked leather, etc.
(5) Classified by usage function: water-resistant leather, three proof leather, anti-static leather, etc.
- Artificial leather and synthetic leather
Early artificial leather was coated with polyvinyl chloride (PVC) on the surface of fabrics, which had poor appearance and practical performance.
In recent years, polyurethane (PU) synthetic leather has been widely used. The base is made of non-woven fabric, and the surface layer is made of porous polyurethane material, imitating the structure and composition of natural leather, with good practical performance. People are accustomed to referring to synthetic leather produced using PVC resin as PVC synthetic leather (abbreviated as synthetic leather); The artificial leather produced using PU resin is called PU artificial leather (abbreviated as PU leather); The artificial leather produced using PU resin and non-woven fabric is called PU synthetic leather (abbreviated as synthetic leather). At present, there is no unified and accurate naming for PU synthetic leather and PU synthetic leather in the industry, but these three types of leather are usually collectively referred to as synthetic leather.
PVC synthetic leather is mainly divided into the following three categories of products:
Ordinary synthetic leather, also known as non foaming synthetic leather. Usually, flat cloth, canvas, and recycled cloth are used as substrates and made by direct coating method. Due to the dense coating and the ability of the paste to penetrate into the pores of the base fabric, the finished product has a hard and wear-resistant feel, and is mainly used to make wear-resistant packaging bags, construction and industrial accessories, etc.
Foamed synthetic leather. Usually, the knitted fabric is used as the substrate, and the surface paste contains foaming agents and additives, which forms a microporous structure during the gel process. Therefore, the finished product is light, full and soft, and is mostly produced by transfer coating. Mainly used for making gloves, bags, pouches, clothing, and furniture.
Suede synthetic leather: commonly known as synthetic suede, has a wide variety of varieties and various production methods. The gelatinized microporous surface layer of artificial leather can be grinded by sanding rollers to produce ground suede leather; After the coating layer is raised and stretched by a fuzzing roller, curled suede leather can be produced. This material is suitable for use as a toe cap and border material for sports shoes. Add soluble salts (such as table salt) into the coating paste, dissolve the salt with water after gel, and make the surface layer appear microporous, so as to have a texture. In addition, by using electrostatic flocking method, synthetic fiber short fibers with a length of 0.5 to 1 millimeter can be planted on polyvinyl chloride synthetic leather coated with adhesive to produce flocking surface leather, which is suitable for making packaging bags and decorations.
In the manufacturing process of PVC leather, plastic particles are first melted and stirred into a paste, then evenly coated on the T/C knitted fabric base according to the specified thickness, and then sent to the foaming furnace for foaming treatment to make it flexible to meet the needs of different products. Surface treatment such as dyeing, embossing, polishing, extinction, and surface fuzzing should be carried out at the same time as baking. The specific treatment method depends on the product requirements. In contrast, the manufacturing process of PU leather is more complex. Due to the fact that the base fabric of PU is a canvas PU material with good tensile strength, PU leather can not only be coated on top of the base fabric, but also contain the base fabric in the middle, making the appearance of the base fabric invisible.
The physical properties of PU leather are superior to PVC leather, with better resistance to bending, softness, tensile strength, and breathability (PVC leather does not have breathability). Due to differences in craftsmanship and raw materials, the price of PU leather is usually more than twice that of PVC leather, and for some special requirements, the price of PU leather can even reach 2 to 3 times that of PVC leather. Therefore, many domestic manufacturers adopt the method of partially replacing PU with PVC, that is, coating PVC synthetic leather on the fabric first, and then applying PU coating. Although this approach reduces costs, the plasticizers in PVC will migrate out in less than a year, causing synthetic leather (actually “synthetic leather”) to become hard and brittle. Therefore, some consumers purchase PU leather products that become brittle and crack within a year, and these products are called semi synthetic leather or semi PU leather.
- Artificial fur. With the development of textile technology, artificial fur not only looks similar to natural fur, but also has a low price and similar performance to natural fur. Usage: Commonly used for decorative materials and children’s fun bag products.
- Fiber cloth (fabric). Fabric can be used as both fabric and lining in bags and suitcases. Polyvinyl chloride coating: This type of fabric is coated with transparent or opaque polyvinyl chloride film on the front or back, such as Scottish checkered cloth, printed cloth, synthetic fiber cloth, etc., which has waterproof and wear-resistant properties and is suitable for travel bags, sports bags, student bags, etc;
Ordinary fabrics: including canvas, flannel, twill fabric, etc. According to their sources, they can be divided into natural fiber fabrics (such as cotton, wool, silk, linen) and chemical fiber fabrics (such as artificial cotton, acrylic fiber, polyester fiber, etc.).