Timeless popularity – the tradition of leather
Leather is supple, hard-wearing, relatively rigid, long-lasting and highly versatile in application. It is waterproof yet simultaneously breathable, so it enables sufficient penetration of air and steam. These properties have made leather into a highly desirable traditional product. Today the leather industry generates annual worldwide sales that are well in excess of 30 billion Euro. The amount of leather produced each year is estimated at around 450,000 tons, equivalent to one billion square meters. By far the largest producer of leather in the world is China, followed by the US and Brazil. For many years now there has been a steady shift in leather production from industrialized countries to developing and emerging ones. Finished leather goods also show an interesting distribution: 55 percent of them are footwear, equivalent to an astonishing annual production figure of 4.5 billion shoes. Automotive and furniture leather account for 20 percent, and gloves for 15 percent.
The leather production process has been around for millennia: indeed, the famous "Ötzi" gave us quite an insight into just how varied it was during the Stone Age. The shoes, hat and clothing of this 5,300-year-old mummified corpse found in a glacier were made of several different types of leather that had been tanned and smoked using various fats - always depending on their precise use. Paintings from Ancient Egypt dating from around 3500 BC also show animal hides being tanned. For the Roman Empire, too, trade in leather was absolutely essential. Vast amounts of it were required for army uniforms, and a steady supply was crucial. Indeed, the trade in leather was one of the reasons for the outbreak of the Punic Wars from 246 - 146 BC.
Imitation leather – sometimes better than the original
Leather production has always been an elaborate and expensive process - so the prospect of imitating leather with less expensive materials is an attractive one. The so-called artificial leather familiar to us today has been around for many decades. Artificial leather manufacturers have succeeded in producing a perfect imitation of the look and feel of a leather surface - indeed, numerous imitation-leather products cannot be told apart from genuine leather. Most of these artificial leather products can be clearly recognized, however, by their textile backing - unless, of course, the attachment of leather fibers has produced a natural-leather look here as well. In such cases even experts have problems in differentiating imitation leather from the genuine article.
Today, regardless of what it looks like, imitation leather does actually offer clear advantages in numerous applications. Used for outdoor coverings, for instance, it is impressively weatherproof and easier to clean, and is also frequently employed for seat and couch coverings in the medical sector.
High-quality types of artificial leather are more hard-wearing and lighter, and also have more breathability than natural leather. They are odorless, absorbent, UV-resistant and non-creasing; they retain their shape, and are also non-slip, tear-proof and abrasion-resistant.
All in all, these properties make them ideal for applications in the footwear, handbag, apparel and furniture industries, as well as for seat coverings and interior paneling in the automotive sector.
The production process
Essentially, imitation leather is an uncoated material - that is, a composite nonwoven made from microfibers, based on natural chamois leather. A major component in the production of imitation natural leather is industrial flat needling. This is followed by a very elaborate and energy-intensive refinishing process, during which the material surface is given its characteristic look and feel. These properties are achieved by filtering out polystyrol and replacing it with polyurethane. Further refinement processes such as grinding, sanding and cleaning also play their part.
Sample application – imitation leather for apparel
- Fiber fineness: 1,7- 3,3 dtex
- Fiber type: PES, PA
- Product weight: 350 g/m²
Needle type: 15x18x38x3 1/2 R222 G 3027 (614071)
Penetration depth: 12 mm
Penetration density: 50 P/cm²
- Needle type: 15x18x40x3 R222 G 3037 (603721)
- Penetration depth: 10 mm
- Penetration density: 200 P/cm²
- 15x18x40x3 R222 G 3037 (603721) (entry zone)
- 15x18x40x3 C222 G 3037 (609901) (exit zone)
- Penetration depth: 9 mm
- Penetration density: 200 P/cm²
- 15x18x40x3 C222 G 3037 (609901) (entry zone)
- 15x18x40x3 R222 G 3037 (603721) (exit zone)
- Penetration depth: 8 mm
- Penetration density: 200 P/cm²
- Needle type: 15x18x42x3 R222 G 3037 (615451)
- Penetration depth: 7 mm
- Penetration density: 250 P/cm²
- Needle type: 15x18x42x3 R222 G 3027 (609921)
- Penetration depth: 5 mm
- Penetration density: 350 P/cm²
Alcantara®, Ecsaine® and Ultrasuede®
Examples of innovative types of artificial leather include Alcantara®, Ecsaine® und Ultrasuede®.
The more valuable imitation buckskin is manufactured on the basis of 4 dtex PES bicomponent fibers, whereby the thickness of the individual filaments varies from 0.001 to 0.2 dtex. To give a comparison: a human hair is roughly 40 to 50 times thicker than the individual filaments used for this product.
The rigidity of the product is created by mechanical needling. With the aid of thermal or chemical treatment, the outer sheath of the polyester fibers is dissolved in order to loosen and detach the matrix fiber. This process activates the individual filaments and an enclosed surface is created.
To copy the surface and the textile properties of artificial leather in a way that is as close to nature as possible, the fibers have to be very powerfully integrated into the nonwoven. Up to 3.000 P/cm² are required. For this reason preneedling, intermediate needling and finish needling take place using a row of up to 11 multiboard machines, which needle from both sides alternately.
Imitation leather production: Alcantara®
Fine-gauge needles from Groz-Beckert
The production of imitation leather is a special application that involves very high standards. Fine-gauge needles from Groz-Beckert in the 38 - 42 gg range with very low fiber transport per individual stroke are ideally suitable here. To keep surface marking to an absolute minimum, the penetration depth of the needles has to be continuously reduced from one machine to the next.
To bring the required product density into line with the desired needling effect, a combination of needles with broad barb spacing for maximum surface quality and needles with narrow barb spacing for a good density effect is employed. Needles with RF barb style are primarily used here, because they facilitate gentle and defined fiber transport. To achieve a very high surface quality needles with only one barb are used.