How to choose high-quality fiberglass mat when manufacturing fiberglass fishing boats?

Choosing the right fiberglass substrate requires understanding its advantages and disadvantages and its suitability. Below are some general selection criteria, but in practice, resin wetting properties also play a role. Therefore, the best approach is to conduct a wetting test at a fiberglass shipyard to confirm its suitability.

First, for fiberglass chopped strand mat used in shipbuilding, the most basic requirement is certification from the China Classification Society (CCS) (mainland China) and Lloyd's Register and Det Norske Veritas (DNV) (internationally recognized). Having several certifications simultaneously is the best proof.

Second, fiberglass mat is mainly used for manual lamination molding. Generally, a good product should meet the following conditions: ① Uniform weight per unit area. This condition is crucial, as it affects both thickness and strength. It's easier to identify under light; severely uneven products are visible to the naked eye. Regarding thickness uniformity, uniform weight per unit area does not necessarily guarantee uniform thickness; this is directly related to the uniformity of the cold press roller gap. Uneven mat thickness leads to uneven resin content in FRP products, and a fluffy mat absorbs more resin. The standard testing method for the uniformity of felt sheet mass per unit area is to cut 300mm x 300mm felt sheets along the width of the felt, number them sequentially, weigh them separately, and calculate the weight deviation of each felt sheet sample.

② Uniform yarn distribution, without excessive local accumulation. The chopped and dispersed nature of the raw yarn is an important indicator in raw yarn production, affecting the uniformity of felt mass per unit area and the distribution of raw yarn on the felt. After the raw yarn bundles on the yarn bobbin (cake) are chopped, each bundle of raw yarn should be fully dispersed. If some raw yarn bundles are not fully dispersed, they are prone to forming sheet-like coarse stripes on the felt.

③ No yarn shedding or separation between the inner and outer layers. The mechanical tensile strength of the felt sheet. Low mechanical tensile strength of the felt indicates poor adhesion between the raw yarn bundles.

④ Free from dirt.

⑤ Thoroughly dried. If damp, it will fall apart when spread out and picked up again. The moisture content of the felt sheet is <0.2%, which is generally acceptable for normal production processes.

⑥ The resin is fully impregnated. Styrene solubility. Ideally, the solubility of the felt in polyester resin should be tested, but this is time-consuming and difficult to quantify. Using styrene instead of polyester resin to test the solubility of the felt can indirectly reflect the solubility of the fiberglass felt in polyester, and this method is accepted worldwide and has been standardized.

⑦ No loosening of the yarn after resin impregnation.

⑧ Easy defoaming.