(1) Chopped strand mats. Glass strands (sometimes also rovings) are cut into 50 mm lengths, randomly but evenly laid on a mesh belt, followed by application of an emulsion binder or dusting with a powdered binder. After heating and curing, they are bound into chopped strand mats. Chopped strand mats are mainly used in hand lay-up, continuous board and die molding and SMC processes. The quality requirements for chopped strand mats are as follows: 1 The area in the width direction is of uniform quality; 2 The chopped strands are evenly distributed in the mat, no large holes are formed, and the binder is evenly distributed; 3 has a moderate dry felt strength; 4 excellent Resin infiltration and permeability.
(2) Continuous strand mats The raw glass strands formed during the drawing process or the continuous strands withdrawn from the original bobbins are laid in a figure 8 shape on a continuous moving mesh belt and bonded with a powder binder. The fiber in the continuous fiberglass mat is continuous, so its reinforcing effect on the composite material is shorter and the mat is better. Mainly used in pultrusion, RTM method, pressure bag method and glass mat reinforced thermal plastic (GMT) and other processes.
(3) Surface mats Glass fiber reinforced plastic products usually need to form a rich resin layer, which is generally achieved with alkali glass surface mats. This kind of felt is made of alkali glass (C), so it gives chemical resistance and especially acid resistance to glass steel. At the same time, because the felt is thin and the diameter of glass fiber is fine, it can absorb more resin to form a rich resin layer. Lived glass fiber reinforced material (such as gingham cloth) lines, play a surface modification.
(4) Needling felt Needling felt is divided into chopped fiber needled felt and continuous strand needle felt. Chopped-fiber needled felts are short-cut glass fiber rovings to 50 mm, randomly placed on a substrate previously placed on a conveyor belt, and then needled with a barbed needle, and the needles pierce the short-cut fibers into the substrate. In the middle, the crochet hook brings some fibers up to form a three-dimensional structure. The substrate used can be a thin fabric of glass fibers or other fibers, and this needle felt has a fluffy feel. Its main uses include thermal insulating materials, thermal insulation materials, and filter materials. It can also be used in the production of fiberglass, but its strength is low and its use is limited. Another type of continuous strand needled felt consists of randomly throwing continuous glass strands onto a continuous belt with a wire- throwing device and needle-punching through a needle board to form a three-dimensional structure felt with fibers interlinked. This kind of felt is mainly used for the production of glass fiber reinforced thermoplastics stampable sheets.
(5) Stitched felt chopped glass fibers can be sewn into chopped fibers or long fiber mats from 50 mm to 60 cm long by a stitching machine. The former can be used in place of conventional binder bonded chopped strand mats in several applications. The latter replaces the continuous strand mat to some extent. Their common advantage is that they do not contain binders, which avoids the pollution of the production process. At the same time, they have good soaking, bonding, and low prices.