Glass fiber yarn is the raw material for various glass fiber products, which is made by twisting continuous glass fiber filaments. Different types of fiberglass yarn have different parameters. The following is a detailed description of several key parameters of fiberglass yarn.
Fiber Density: it refers to the mass per unit length of fibers, single yarns, nets, ropes, etc., and the index describing the degree of yarn thickness. The representation is divided into two types: fixed length and fixed weight system.
- Fixed length system
The parameters indicating the thickness of the yarn, the most common one is the linear density Tex, which is the metric number. This is the current common method of use in the world, which means the weight of the 1000m yarn at the specified moisture regain (unit: g), which is fixed length method. For example, the common 2400 tex means that the weight of the 1000 m yarn is 2400 g. The larger the number, the heavier the weight and the thicker the yarn.
In addition, in a few other countries, fixed-length system will be used. Denier, referred to as Dan, is marked with D. It represents the weight of 9000 meters long fiber under the specified moisture regain, 1D=1g/9000m. Its conversion relationship with tex is: tex=D/9.
- Fixed weight system
Another method for indicating the thickness of the yarn is called the count β, that is, the length (unit: m) of the yarn mass of 1 g, and this is the weight method.
β= fiber length (usually 100m) / fiber weight (mass of 100m original yarn)
The most used to indicate the thickness of glass fiber is Tex, but in some literatures, it will be represented by the count β. In fact, the two can be converted. The conversion formula is: Tex(g/m)=1000/β (m/g).
The twist refers to the number of twists per unit length of the fiber, the Tex system is 10cm; the metric is 1m; the inch is 1inch. According to their different steering, they are divided into S and Z. First, the yarn is suspended, and then the oblique direction of the fibers of the overhanging portion is determined. The tilting direction is Z from left to right from top to bottom, and S from top to bottom in the oblique direction from top to bottom.
The twisting is mainly to improve the cohesion between the fibers, improve the stress of the single fiber, and facilitate the textile. Therefore, twisted yarn is mainly used in some textile products, such as electronic cloth. However, it is not convenient to impregnate the resin after twisting. Generally, the fibers used for the FRP are untwisted yarns. Therefore, according to different needs, it is decided whether to increase the size of the glass fiber and the twist.
- Roving and spun yarn
The roving and spun yarn refer to the monofilament diameter of the fiber. In general, the original yarn with a monofilament diameter of 10 μm or less is called spun yarn, and its main use is as an electronic yarn and an industrial yarn. Raw yarns having a monofilament diameter of 10 μm or more are generally referred to as rovings.
The finer the diameter of the monofilament, the better the tensile strength of the original yarn. Meanwhile, the production process is more complicated and the cost is higher.
- Direct yarn and plied yarn
The direct yarn, also known as the direct roving, is a bundle of parallel monofilaments that are not twisted and joined together, and is directly drawn from the slab to form a continuous fiber. Common products: pultruded yarn, winding yarn and so on.
Plied yarn is a yarn obtained by twisting two or more single yarns. The ply yarn is actually a process of winding the yarn and synthesizing the tex with a low tex into a high-tex product. Common products are spray yarn, SMC yarn, etc.
Since the use of the pool kiln method, the direct yarn production of the major fiberglass plants accounted for a large proportion. As the production process is simplified, the cost is further reduced. There is no need for the winding process, so the yarn has less hairiness.
More: The origin and development history of glass fiber