(1) Chopped strand mats Glass strands (sometimes also with rovings) are cut to a length of 50 mm, which are randomly but evenly laid on a mesh belt, followed by application of an emulsion binder or powder coating on the fabric. After heat curing, it is bonded into a chopped strand mat. Chopped mat is mainly used in hand lay-up, continuous board and counter-molding and SMC processes. The quality requirements for the chopped strand mat are as follows: 1 the area quality is uniform in the width direction; 2 the chopped strands are evenly distributed in the felt surface, no large holes are formed, the binder is evenly distributed; 3 has moderate dry felt strength; 4 excellent Resin impregnation and permeability.
(2) Continuous strand mat The glass strand formed during the drawing process or the continuous strand retracted from the original strand is laid in a figure-eight shape on a continuous moving web belt and bonded by a powder binder. The fibers in the continuous glass fiber mat are continuous, so the reinforcing effect on the composite material is shorter. Mainly used in pultrusion, RTM, pressure bag method and glass felt reinforced thermoplastic (GMT) and other processes.
(3) Surface felt FRP products usually need to form a resin-rich layer, which is generally achieved by using a medium alkali glass surface felt. This kind of felt is made of medium alkali glass (C), so it gives chemical resistance to glass fiber reinforced plastic, especially acid resistance. At the same time, because the thin felt and the diameter of the glass fiber are fine, more resin can be absorbed to form a resin-rich layer. The texture of the glass fiber reinforced material (such as gingham) is used to modify the surface.
(4) Needle felt The needle felt is divided into a chopped fiber needle felt and a continuous strand needle felt. The chopped fiber needle felt is a short cut of 50 mm roving, placed on a substrate placed on a conveyor belt, and then needled with a barbed needle. The needle pierces the chopped fiber into the substrate. In the middle, the crochet pulls some fibers up to form a three-dimensional structure. The substrate used may be a woven fabric of glass fibers or other fibers which have a fluffy feel. Its main uses include thermal insulation materials, heat-insulating materials, filter materials, and can also be used in the production of FRP, but the made FRP has low strength and limited use. Another type of continuous strand needle felt is a felt in which a continuous glass strand is randomly thrown on a continuous web belt by a spinnering device and needle-punched by a needle plate to form a three-dimensional structure in which fibers are hooked to each other. This type of felt is mainly used in the production of glass fiber reinforced thermoplastic stampable sheets.