Nonwovens made of "somewhat different fibers"
The constantly growing synthetic fiber industry also generates constantly increasing amounts of plastic waste and microplastic particles in the world's oceans. Some 4.8 to 12.7 million tons of plastic waste get into the ocean every year. Between 15 and 31 percent of that consists of very small plastic particles. One cause of this pollution is the improper disposal of waste.
In the meantime, the first companies have begun working intensively on this topic, producing the first products made from recycled materials, for example from discarded fishing nets that are normally made from polypropylene (PP), polyamide (PA), or polyester (PET). These are processed back into fibers and introduced back into the textile supply chain.
Process optimizations and production innovations help to make the topic of sustainability viable for the future. Some approaches also focus on by-products from production within other industries, such as the food industry.
Banana fibers are a by-product of banana harvesting, for example. As you probably assumed from the beginning, this does not refer to fruit fibers, but rather to parts of the palm trunk. Since banana trees only produce fruit once in their lives, the entire parent plant is cut down during harvest. The trunks are then cut open and separated into individual layers. These individual layers are processed via machine into separate fiber bundles by squeezing out the fluid components of the fibers. Finally, the fibers are hung up to dry.
In addition to using banana fibers in clothing fabrics, tea bags, and Japanese yen notes, they are also processed into nonwoven mats for use in the geotextile industry as erosion or weed protection, for instance.
Because of their resistance to moisture, coconut fibers are also used for erosion protection and in gardens and landscaping. Coconuts consist of an outer solid shell, a layer of fiber about 8 centimeters thick underneath, the rock-hard inner shell, and the inner white core (nut meat) with the milk contained within. The fiber layer makes up approx. 30 to 35 percent of the total weight. It is composed of short fibers and fiber bundles that are up to 30 centimeters long. The latter is machined into individual fibers.
Coconut fiber mats are used as nonwoven material for heat insulation but also as mattress pads, carpet backings, or reinforcement elements for natural fiber reinforced plastics (NFRP). Car interior linings are just one of many applications.
The car manufacturer Ford is one of the companies focusing on the topic of sustainability and new resources. In cooperation with the tequila producer Jose Cuervo, Ford is researching the use of agave fibers for possible applications in vehicle interiors or as a light-weight vehicle part.
Agave fibers, commonly known as sisal, are a by-product of tequila production and are harvested from cut leaves of the agave plant. The share of fibers in agave leaves is about five percent, and these fibers are removed from the meat of the plant through a mechanical process similar to the one used to acquire banana fibers.
In addition to being used in the automotive industry, agave fibers, like banana and coconut fibers, are also used as mats and geotextiles.
The pineapple fiber is another example of a by-product of the food industry. Similar to agave harvesting, the plant leaves are cut off during harvest and separated into fibers. Pineapple leaves have, however, less pulp, which makes it easier to acquire fibers and increases the share of fiber.
Instead of polyester or polyamide, equivalent pineapple fibers can be used to create synthetic leather substrates, which an European company was able to prove lately. To do so, the fibers are needled into a nonwoven, alternating on both sides. This is then coated with a polymer and treated chemically. This vegan leather is used in shoes, clothing, and accessories, as well as interior furnishings such as furniture or automotive interiors.
Fibers and felting needles in harmony
GEBECON® felting needle
The fiber cross-section of natural fibers is not uniform, which makes needling difficult, in principle. This means that conical felting needles or vario barb needles with varying vario barb sizes are used, thus ensuring increased stability and leading to less needle breakage creating a longer product life. This plays an important role, even in abrasive natural fibers such as coconut fibers.
GEBECON® felting needles from Groz-Beckert distinguish themselves with their conical working part and a continuous conical geomerty to the shaft. This results in a reduced penetration force at the beginning of the penetration process, which also reduces the strain on the needling machine. In addition, the slim working part results in smaller penetration holes in the end product, thereby improving the surface appearance. Compared to standard felting needles with intermediate reductions, GEBECON® felting needles show more even deflection during stress tests. Overload points are absorbed by the improved dynamic behavior, thus minimizing the danger of needle breakage. In addition, the more uniform bending strength ensures reduced draft for higher flexibility and allows for faster line speeds.
Product processes must be harmonized in order to meet the requirements of the end product. Choosing the correct needle is essential for this. A suitable felting needle with optimized product life also ensures an economic production process.
Needling example application: natural fiber mat
- Fiber: natural fibers (with additions of synthetic fibers as needed)
- Product weight: 300–2.000 g/m²
- Production requirement: one-sided needling - Possible use of scrim to improve dimensional stability
- Needle gauge:18–32 gg (e.g. 15x25x32x3½ M332 G 530P7 – 621971)
- Penetration depth:11–15 mm
- Stitch density:30–110 S/cm²
Nonwovens made of natural fibers lie in a fabric weight range of 500 to 3.000 g/m². For large weights, primary needling of both sides is essential.
To reduce needle breakage in the entrance zone of the machine, shorter (3 inch) needles can be used in the first rows of the needle board. These provide stabilization and can counteract a chain reaction.
Would you like to get more involved in the needling of natural fibers, or do you need advice on optimizing production of nonwovens based on natural fibers? The Groz-Beckert experts are happy to share with you how to perfectly design your production process.