A certain amount of foaming agent and water vapor are retained in the beads after the foam mechanical equipment is released. When the machine is released, the liquid is condensed into liquid, and the liquid foaming agent is dissolved in polystyrene again, so that the pressure in the bubble rapidly appears negative pressure (partial vacuum) in the bubble, and the bead is very soft and easy to deform. Therefore, the wind pressure should not be too high, the inner wall of the air duct should be as smooth as possible, the bending radius should be as large as possible (to reduce the collision resistance), the pipeline should be a good electrical conductor, the whole line should be grounded to avoid electrostatic ignition, and the transmission speed should not exceed 8m / s to avoid bead damage.
Just now, the beads of the foam machine are wet. When they come out of the preconditioner, they suddenly freeze because of the absorption of air, resulting in the condensation of foaming agents in the honeycomb bubbles, resulting in the formation of negative pressure in the pores. Therefore, when beads come out, they must be placed for a period of time to dry, and on the other hand, they penetrate into the air to eliminate negative pressure and balance the internal pressure and external pressure in the bubble. So as to avoid the collapse of the bubble hole and make the bead elastic. After a certain period of drying, cooling and stable bubble pressure, the first EPS bead is called ripening. Ripening can improve the further expansion of the preformed beads in the molding process, the melting between the beads and the elasticity of the beads, which is conducive to improving the quality of EPS products.
During the ripening process, the beads are cooled by air, and the foaming agent and water vapor in the pores condense into liquid. When the negative pressure is formed in the pores, the air penetrates into the pores through the stomatal membrane, and the foaming agent and water vapor in the pores balance into liquid. When the negative pressure is formed in the pores, the air penetrates into the pores through the stomatal membrane, The two methods of foaming agent and water vapor balance in stomata can be divided into natural ripening and water vapor ripening. In cool, dry and ventilated conditions, natural aeration is called natural maturity. After natural ripening, the preformed beads are inflated by adding gas (air, nitrogen) into the sealed container, which is called pressurized ripening.