Glass fiber products are widely used in various fields of the national economy, among which electronics, transportation and construction are the three main application fields, and also represents the development trend of the world glass fiber industry in the next few years. 

І. Untwisted Roving

Untwisted roving is made of parallel filaments or parallel monofilament clusters. Untwisted roving can be divided into non-alkali glass untwisted roving and medium-alkali glass untwisted roving according to glass composition. The diameter of glass fiber used in the production of glass roving is from 12~23μm. the number of untwisted roving is from 150 to 9600(tex). Untwisted roving can be directly used in some composite molding methods, such as winding and pultrusion, because of its uniform tension, it can also be woven into untwisted roving fabric. In some applications, the untwisted roving is further cut.

a. The untwisted roving used in FRP injection molding should have the following properties :1 good cutting property, less static electricity produced in continuous high speed cutting, high efficiency of dispersing roving into raw wire after cutting, that is, high splitting rate, usually more than 90%. The raw wire after short cutting has excellent cladding properties and can be covered in every corner of the die. Spray roving is made of multi-strand silk, each silk contains 200 glass fiber monofilament.

b. SMC use untwisted roving SMC i.e. sheet molded plastic, mainly used to press automotive parts, bathtub, water tank plate, purification tank, various seats, etc. SMC untwisted roving should be cut into the length of lin (25mm) and dispersed in resin paste when making SMC sheet. Therefore, the requirements for untwisted roving are good short cut, less wool and good antistatic property. Short cutting wire will not adhere to the cutter roll during cutting. For color SMC, untwisted roving is soaked in resin paste with high pigment content. Usually SMC twistless roving is generally 2400 tex, in a few cases also useful 4800 tex.

c. Twisting roving winding method is used to manufacture glass tubes and storage tanks of various calibres. Winding roving numbers range from 1200 to 9600, Winding large pipes and tanks tend to be direct untwisted roving, Direct untwisted roving such as 4800 tex. The requirements for winding roving are as follows :(1) good banding, Flat banded; The untwisted roving has good receding property, Don't take off the ring when it's coming off the yarn, Do not form a "bird's nest "-like silk; 3 Uniform tension, No drape phenomenon; The line density is uniform, Generally less than 7±; 5. Good penetration of untwisted roving, It is easy to wet and soak the resin when passing through the resin tank.

d. Pultrusion with untwisted roving is used to produce all kinds of profiles with consistent cross section, which is characterized by high glass fiber content and large unidirectional strength. Twisted roving for pultrusion can be multi-strand raw yarn or direct untwisted roving with a linear density range of 1100 to 4400. All kinds of performance requirements are roughly the same as winding untwisted roving.

e. One of the important uses of untwisted roving for weaving is to weave various thicknesses of square or unidirectional untwisted roving fabrics, most of which are used in hand paste FRP molding process. There are the following requirements for strong untwisted roving :1 good wear resistance ,2 good belt forming ,3 weaving untwisted roving need to be forced to dry before weaving, the tension of untwisted roving is uniform, and the drape should meet certain standards.

f.  The preform is made of untwisted roving in the preform process. The untwisted roving is cut short and sprayed on a predetermined shape of the net, while a small amount of resin is sprayed to fix the mesh, and then the formed fiber mesh is transferred into the metal mold and injected into the resin hot-pressing forming. The performance requirements of this process are basically the same as those of spray roving.

П. Untwisted Roving Fabrics (Woven roving)

Square cloth is untwisted roving plain fabric, is the hand paste FRP important substrate. The strength of the square cloth is mainly in the warp and weft direction of the fabric. For the occasions where the warp or weft strength is high, it can also be woven into a one-way square cloth. It can arrange more untwisted roving in the warp or weft direction.

The quality requirements of each other's cloth are as follows:

a. The fabric is uniform, the edge of the cloth is straight, the surface of the cloth is flat, without stains, hair, creases, wrinkles, etc;

b. The warp, weft density, area weight, cloth width and roll length meet the standard;

c. Winding on solid paper core, winding neatly;

Rapid and good resin permeability;

The dry and wet mechanical strength of the laminated fabric shall meet the requirements.

The composite material is characterized by low interlaminar shear strength, poor pressure resistance and fatigue strength.

Ш. Fiberglass Felt　

a. Cut the glass filament (sometimes with untwisted roving) into 50 mm long, lay it randomly but evenly on the mesh, and then apply emulsion binder or powder binder on the cloth to form a short cut filament felt after heating and curing. short cut felt is mainly used in hand paste, continuous plate making and pair-molding and SMC processes. The quality requirements of the short cut raw wire felt are as follows :1. The area along the width direction is uniform and the short cut raw wire is evenly distributed in the felt surface, no large hole formation, and the binder distribution is uniform.

b. The glass filament formed during the drawing process or the continuous filament removed from the filament tube is laid on the continuous moving mesh tape in an 8-shaped shape and bonded by a powder binder. The fiber in continuous glass fiber filament felt is continuous, so its reinforcement effect on composite material is better than that of short cut felt. Mainly used in pultrusion, RTM, pressure bag and glass felt reinforced hot plastics (GMT) and other processes.

c. Surface felt FRP products usually need to form a resin-rich layer, which is generally achieved with medium-alkali glass surface felt. Because this kind of felt is made of medium alkali glass (C), it endows FRP with chemical resistance, especially acid resistance. At the same time, because the felt is thin and the diameter of glass fiber is fine, it can absorb more resin to form resin rich layer, which covers the grain of glass fiber reinforced material (such as grid cloth) and plays the role of surface modification.

d. Needle felt or divided into short cut fiber needle felt and continuous primary wire needle felt. Cut fiber needle felt is to cut glass fiber roving short into 50 mm, randomly spread on the substrate placed on the conveyor belt in advance, then needle with barbed needle, the needle will cut the fiber into the substrate, and crochet will take some fibers up to form a three-dimensional structure. The substrate used can be a thin fabric of glass fiber or other fibers, which has a fluff sense. Its main uses include insulation and sound insulation materials, thermal lining materials, filter materials, also can be used in FRP production, but the strength of FRP is low and the scope of use is limited. Another kind of continuous filament needle felt is the felt that the continuous glass filament is randomly thrown on the continuous mesh belt by the wire throwing device, and the three-dimensional structure of the fiber is formed by the needle plate acupuncture. This kind of felt is mainly used in the production of glass fiber reinforced hot plastic stamping sheet.

Stitching felt short cut glass fiber from 50 mm or even 60 cm length can be stitched into short cut fiber or long fiber felt, the former can replace the traditional binder bonded short cut felt in a number of uses, the latter to some extent replace the continuous filament felt. Their common advantage is that they do not contain binder, avoid the pollution of the production process, at the same time, the soaking performance is good and the price is low.

Ⅳ. Staple And Ground Fibers

a. Short cut primary wire is divided into dry cut primary wire and wet cut primary wire. The former is used in the production of reinforced plastics, while the latter is used in paper making. For glass fiber products reinforced plastic short cut raw wire is divided into reinforced thermosetting resin (BMC) short cut raw wire and reinforced thermoplastic resin short cut raw wire. The requirement of short cut raw wire for reinforced thermoplastic is alkali-free glass fiber with high strength and electrical insulation, good cluster property, good fluidity and high whiteness. The reinforced thermosetting plastic short cut raw wire requires good cluster property, easy to soak in resin quickly, and has good mechanical strength and electrical properties.

b. Grinding fiber grinding fiber system is made by grinding short cut fiber by hammer mill or ball mill. Grinding fiber is mainly used as reinforcing material in reinforcement reaction injection process (RRIM). It is used as filler of resin in manufacturing casting products, molds and other products to improve surface crack phenomenon, reduce molding shrinkage, and can also be used as reinforcing material.

Ⅴ. Fiberglass Fabric

The following is a description of various fiberglass fabrics woven from fiberglass yarns.

a. Glass cloth produced in China is divided into two categories: alkali-free and medium-alkali-free, most of which are alkali-free glass cloth abroad. Glass cloth is mainly used to produce various electrical insulation laminates, printed circuit boards, various vehicle bodies, storage tanks, boats, molds and so on. Alkali glass cloth is mainly used in the production of plastic packaging cloth, as well as corrosion resistance. The characteristics of fabric are determined by fiber properties, warp and weft density, yarn structure and weave pattern. The density of warp and weft is determined by yarn structure and texture. The fabric physical properties, such as weight, thickness and fracture strength, are determined by adding yarn structure. There are five basic weave patterns: flat, twill, satin, rib and mat.

b. The glass belt is divided into two parts: the woven side belt and the non-woven side belt. Glass tape is often used to manufacture parts of electrical equipment with high strength and good dielectric properties.

c. One-way fabric A one-way fabric is a four-pass satin or long-axis satin fabric woven from roving and weft yarns. It is characterized by high strength in the warp main upward.

d. Solid fabric is a solid fabric relative to the plane fabric, its structural characteristics have developed from one-dimensional two-dimensional to three-dimensional, so that the composite with this reinforcement has good integrity and shape imitation, which greatly improves the interlayer shear strength and damage tolerance of the composite. It is developed with the special needs of aerospace, aviation, weapons, ships and other departments. At present, its application has been extended to automobile, sports equipment, medical equipment and other departments. There are five main categories: woven 3D fabrics, knitted 3D fabrics, orthogonal and non-orthogonal nonwoven 3D fabrics ,3D woven fabrics and other forms of 3D fabrics. The shape of solid fabric includes block, columnar, tubular, hollow truncated cone and variable thickness special section.

e. The shape of the special-shaped fabric is very similar to that of the product to be enhanced and must be woven on a special loom. Symmetrical shape of the special-shaped fabric: cover, cone, cap, dumbbell-shaped fabric, can also be made into boxes, hull and other asymmetric shapes.

f. A grooved core fabric is a fabric consisting of two layers of parallel fabric connected by vertical strips, the cross-section of which may be triangular or rectangular.

g. Glass-fiber sewn woven fabric is also called knitted felt or woven felt, which is different from ordinary fabric and felt in common sense. The most typical sewing fabric is a layer of warp yarn and a layer of weft yarn overlap, through sewing warp and weft yarn woven together into a fabric. The advantages of knitted fabrics are as follows:

It can increase the ultimate tensile strength, tensile strength and flexural strength of FRP laminated products;

Reduce the weight of FRP products;

Smooth surface of FRP;

Simplify hand paste operation and improve labor productivity. As a result, the reinforced material can replace continuous wire felt in pultrusion FRP and RTM, and can also replace grid cloth in centrifugal FRP production.

Ⅵ. Composite Glass Fiber Reinforcement

Since the 1970s, there have been the following kinds of reinforcing materials, which have been combined in a certain order:

a. Short cut silk felt + untwisted roving fabric

b. Short-cut raw felt + untwisted roving + short-cut raw felt

c. Short cut raw felt + continuous raw felt + short cut raw felt

d. Stochastic untwisted roving + short cut than felt

e. Unidirectional carbon fiber + short cut raw felt or cloth

f. Short cut wire + surface felt

g. Glass cloth + unidirectional untwisted roving or glass rod + glass cloth

Ⅶ. Glass fibre wet-laid mat

Glass fiber non-woven products originated in Europe, and then introduced into the United States, Japan, China and other countries. China has established several large production lines, the main technology from German technology such as Changzhou Zhongxing Tianma, Shaanxi Walter.

At present, the main classification of domestic glass fiber wet felt:

a. The base material of roofing felt used for waterproof materials such as modified asphalt waterproof roll and colored asphalt tile;

b. Pipe felt is used for coating oil and natural gas pipelines, combined with asphalt to prevent underground pipeline corrosion;

c. Forming and surface polishing of surface felt FRP products;

d. The veneer felt is used for wall and ceiling, which can prevent the cracking of paint, orange peel, and is mostly used to decorate large conference rooms and high-grade hotels;

e. Floor felt used as a substrate for PVC floors;

f. Carpet felt is used as a base material for a square carpet;

g. Copper clad laminate felt attached to copper clad laminate can enhance its punching and drilling performance;

h. Base material for aluminium-acid battery spacer felt;