Warm Global Customers
With China Plastic Machinery
With China Plastic Machinery
GMT is a glass fiber thermoplastic prepreg, which is a semi-finished sheet made of glass fiber and thermoplastic plastic in advance. GMT is used in transportation and other departments as a container, pier, anti-corrosion, and electrical material.
GMT is actually a glass fiber thermoplastic prepreg, similar to thermosetting SMC, and is a semi-finished sheet made of glass fiber and thermoplastic plastic in advance. It can be softened by heating, then placed in a press, and stamped and cooled to make various products. Since entering industrial production in the 1970s, it has developed rapidly because it is more suitable for the large-scale production of large structural parts of GFRTP. In recent years, the average annual growth rate has been 24%, and the total amount in the world has reached nearly 200,000 tons.
Thermoplastic plastics used for GMT are mainly PP (about 90%), as well as PBT, PET, PA, PC, etc. According to the resin matrix material used, there are currently two types of GMT, namely polypropylene-based GMT and PET (thermoplastic polyester-based). At present, most GMTs are glass fiber reinforced polypropylene, with glass fiber content ranging from 22% to 50%.
According to the glass fiber reinforced substrate used, there are the following types:
1) Continuous glass fiber needle-punched mat. This is a reinforced substrate developed by PPG in the early stage. The glass fiber precursor treated with a special impregnating agent is decomposed and scattered disorderly on the mesh belt to form a felt layer, and then needle-punched by a needle bed to form a three-dimensional glass fiber felt. This continuous felt GMT has a good reinforcement effect because most of the glass fibers are in a continuous shape. The disadvantage is that the fiber fluidity is poor during stamping and cannot flow to every corner of the complex-shaped product, so the local reinforcement is poor. In addition, the fiber is exposed in the appearance of the product, which is not suitable for making automotive parts with high appearance requirements.
2) Chopped fibers are needle-punched or bonded with a binder to form chopped fiber mats. Because the fibers are short, they are suitable for making products with more complex shapes. At present, the proportion of short fiber GMT used is greater than that of continuous fiber GMT.
3) Since some special products require directional mechanical strength, there is also a glass fiber felt reinforced GMT with disordered fiber distribution in all directions.
In addition, there is a wet-formed GMT, which is a suspension of chopped glass fiber, polypropylene powder and additives in water, wet-formed by a paper machine, and then dried and heated by hot air to make the polypropylene reach a plastic melt state, and then cooled to make a sheet. The glass fiber length in this GMT can be relatively long. The brand produced by Azdel Co., Ltd. in the United States is SaperLite. It is said that its advantages are light weight, uniform fiber distribution, high strength-to-weight ratio, recyclability, simple manufacturing process, low investment cost, wide range of product weight and strength, low-pressure processing products, and short product manufacturing cycle.
There are two main production methods for GMT. The continuous fiber mat or needle-punched mat laminated with thermoplastics is mostly made by melt impregnation process (dry process), and the sheet made of randomly distributed medium and long glass fibers (5-50mm) and powdered thermoplastics is made by suspension deposition process (wet process). At present, the latter is more than the former in terms of output.
In comparison, due to the different substrate morphology and process, the dry-process glass fiber is longer and the whole is woven, so the flexural modulus and impact strength of the composite sheet are high, which is more suitable for making large, thick and relatively simple-shaped components. The wet-process glass fiber is shorter but evenly dispersed, so the sheet has good fluidity and is more suitable for components with more complex shapes and less high strength requirements.
In recent years, building formwork made of reinforced thermoplastics has entered the market, which has considerable advantages over steel formwork. In addition, GMT is also used in transportation and other departments as containers, piers, anti-corrosion, and electrical materials.
If you are interested in our company and machine, feel free to contact our sales engineer. We will contact you as soon as possible.