Gelcoat resin plays an important role in the production of composite materials/glass fiber reinforced plastics. It not only has a decorative effect on the surface of glass fiber reinforced plastic products, but also has the effects of wear resistance, aging resistance and chemical corrosion resistance. Various problems such as cracks and sagging will occur in the actual use process, which can be specifically analyzed from various aspects such as product design, use of gel coat resin and production operations.
1. Wrinkle of gel coat resin
Mainly caused by uneven curing of gel coat resin
1. The gel coat resin is too thin, the thickness is uneven, the gel coat resin is not cured sufficiently, and the reinforcement layer is too early.
2. High ambient humidity and low temperature in the production environment.
3. The flow rate of ambient air is large, which takes away a large amount of styrene.
4. The curing agent has a high water content, and the curing agent and the gel coat resin are mixed unevenly.
5. The gel coat matrix resin has a high content of small molecules, which can bring in water or dirt during the coating process.
2. Pinholes and micropores
The main reason is that the gel coat resin contains gas or small molecules, which are too late to be released during the curing process:
1. The gel time of gel coat is short, and the amount of curing agent added is large.
2. The gel coat resin layer is too thick, the spray flow is too large, and the first spray volume is large.
3. The gel coat resin brings in a large amount of air during stirring without release, and brings in a large amount of air during spraying.
4. Poor atomization during spraying, too close to or too far from the mold.
5 Improper release agent, the surface of the mold is contaminated.
Three, cracks and cracks
1. Cracks on the mold surface.
2. The gel coat resin is too thick and the heat release temperature is high.
3. Impact inside the structural layer.
4. Excessive demoulding, impact of external force on gel coat resin surface.
5. The resin used in the structural layer is too tough and the curing degree is not enough.
Mainly due to the presence of surface tension.
1. There is dirt on the mold, the release agent is not dry, and the release agent is not properly selected.
2. There are impurities in the gel coat resin, and there are impurities in the spray pipe.
3. The gel coat resin is too thin.
1. The thixotropic index of the gel coat resin is low, and the gel time is too long.
2. Excessive spraying of gel coat resin, the facade is too thick, the nozzle direction is wrong or the caliber is small, and the pressure is too large.
3. The release agent applied on the surface of the mold is incorrect.
6. Fiber exposure
1. The gel coat resin is thin, and the gel coat resin is not completely cured, so the reinforcement layer is applied.
2. The fiber rolling is too heavy.
Seven, the product gel coat resin gloss is not good
1. Poor finish of the mold, dust on the surface, etc.
2. Low curing agent content, incomplete curing, low curing degree, and no post-curing.
3. Low ambient temperature and high ambient humidity.
4. The gel coat resin layer is demolded before it is completely cured.
5. The inner filler of gel coat resin is high, and the matrix resin content is low.
8. Local discoloration of gel coat resin
1. The pigment paste is unevenly dispersed and its quality is poor, and the carrier resin of the color paste is of poor quality.
2. The base resin of the gel coat resin has poor weather resistance and corrosion resistance and high styrene content.
3. The thickness of the gel coat resin is uneven, and the gel coat resin is not cured completely.
4. The gel coat resin is too thick, the gel time is long, and the resin and the pigment are separated.