How to avoid pinhole problems in FRP molds

First of all, choose high-quality FRP mold gel coat.

As the surface layer of the mold, the mold gel coat requires a dense surface after curing, a certain strength and hardness. However, due to the influence of the resin matrix of the gel coat, the added auxiliary materials, and the quality control, the final product quality indicators such as leveling, defoaming, viscosity, and thixotropy of the gel coat are very different. Layers produce different defects. Such gel coats have higher requirements on the skills of the operators during construction, which is reflected in the fact that the on-site personnel must make corresponding adjustments according to the actual situation during construction. A high-quality FRP mold gel coat should be a spray type gel coat, with low viscosity, high thixotropy, good defoaming and leveling properties, and stable curing characteristics. In order to achieve the above purpose, in addition to the use of excellent matrix resin in the gel coat, it is also necessary to add leveling and defoaming substances to improve the leveling and defoaming properties of the gel coat, but note that these substances are small molecules and not Participate in the reaction, and because of the presence of solvents, it may lead to the appearance of pinholes. Therefore, it is necessary to choose high-efficiency leveling and defoaming additives to avoid the introduction of excessive small molecules by using a large amount of addition. Therefore, high-quality FRP mold gel coat should be selected, and spraying method should be used, which can effectively reduce the pinholes in the mold gel coat layer.

Secondly, the curing system of the gel coat is also one of the factors prone to pinholes.

Disproportionate accelerators and initiators will remain in the gel coat after the gel coat is cured, and appear on the surface of the gel coat to form pinholes after demolding. Excessive curing system or high temperature will easily shorten the gel time of the gel coat too much, so that the air brought in during the application process of the gel coat cannot escape in time, resulting in the existence of a large number of micro-bubbles in the gel coat. Pinholes are formed on the surface. When the amount of gel coat is small, it is easy to cause disproportion or excessive addition due to metering errors. Therefore, it is recommended to use a pre-accelerated gel coat. The addition ratio of the accelerator is more accurate, the gel time is relatively stable, and the stirring promotion is reduced. The number of bubbles introduced during the preparation. The gel time can also be controlled easily. After spraying a thick gel coat at a time, the bubbles brought in during the operation of the highly thixotropic gel coat will not easily escape, and often form pinholes in the gel coat. Proper amount of initiator and accelerator, reasonable gel time, and uniform gel coat thickness can effectively reduce pinholes. The quality of the initiator will also affect the quality of the gel coat. A high-quality initiator contains less hydrogen peroxide, and less water molecules are generated when the resin polymerization reaction is initiated. This improves the degree of curing of the gel coat and reduces the probability of defects such as pinholes. Thereby effectively improving the surface quality such as surface hardness and surface density.

Hebei Yuniu Fiberglass Manufacturing Company Limited is a fiberglass material manufacturer with over 10-year experience, 7- year exporting experience.

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