Phenomenon 3: PVC film/foil vacuuming process has a side suction or shrinkage phenomenon
Cause analysis:
1. When vacuuming, the side temperature is low or vacuum degree is not enough;
2. The temperature resistance of glue is not enough;
3. After vaccum press molding, in the case of temperature has not come down, the pressure is withdrawn.
Solutions:
1. Increase the temperature or vacuum degree;
2. Use of curing agent;
3. After vacuum press forming, the temperature is cooled to room temperature or slightly higher before withdrawing from the vacuum.
Phenomenon 4: PVC film/foil vacuum press out of the product surface pitting
Cause analysis:
1. The size of glue is large, and the use of thin PVC film is easy to produce pitting, which is characterized by uniform dispersion;
2. When the curing agent is used, the curing agent is not completely dispersed;
3. The surface of the plate is not treated clean, or after spraying glue, the dust in the workshop is big and stuck on, and the pitting is dispersed very uneven, and the size is different;
4. The viscosity of glue is too large and uneven;
5. The viscosity of the glue is too small or the solid content is low, resulting in the plate fuzz, such pitting generally appears in the corner of the groove, into a block.
6. The air pressure of spray gun is not enough, and the atomization is not good.
7. Glue is not filtered (this situation refers to: when a bucket of glue is used at the end, if there is stolen material or conjunctiva in it, it should be filtered with a filter).
Solutions:
1. Choose glue with small particle size;
2. With curing agent, prolong the stirring time, so that the curing agent can be completely dispersed;
3. Clean the surface of the plate before spraying, and separate the spraying workshop;
4. Choose glue with appropriate viscosity or high solid content;
5. After the glue is dried, polish it with fine sandpaper.
6. Increase vacuum degree and adjust atomization effect;
7. When in use, filter with a strainer.
Phenomenon 5: orange peel is produced locally in PVC film/foil vacuum press process
Cause analysis:
1. Excessive spraying of local glue;
2. The surface of the plate is greasy, so that the glue produces shrinkage;
3. The curing agent is not completely dispersed, resulting in shrinkage cavity.
Solutions:
1. Spray glue evenly;
2. Keep the surface of the plate clean;
3. Stir the hardener well to disperse it evenly.