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Dealer providing black PU foam
PU Foam (PU Foam) is a common product in daily life and industrial production today. Most people use products containing Polyurethane, but few know much about it. Here's a look at this popular type of foam and its uses.
What is PU foam?
PU Foam (PU Foam) is a common product in daily life and industrial production today. Most people use products containing Polyurethane, but few know much about it. Here's a look at this popular type of foam and its uses.
Dealer providing black PU foam
PU foam production process:
1. Mix the ingredients and stir the sponge. The chemical ingredients are prepared (usually by calibrated equipment) in appropriate amounts and proportions and are mixed together (in the mixing head of the machine (mixing head) or in the container in case of hand mixing ( hand-mixing)). During mixing, a small amount of air bubbles form in the liquid mass. In the case of a foam filling machine, a small amount of air is injected into the mixing chamber.
2. Creamtime. After a short period of time, the blooming gases (CO2 or other blooming aids) begin to diffuse in and increase the amount of small air bubbles in the mass, a phenomenon similar to ice cream. The time from starting to mix until the mass turns into ice cream is called the ice cream creation time, usually about 6 - 15 seconds for soft sponges (hard sponges usually take longer to create ice cream).
3. Rising. As more blowing air is generated, the foam mixture continues to expand and become more viscous as long as the polymerization process occurs in the liquid phase. The total number of air bubbles remains constant during the foam expansion process. Reducing surface tension with surface-active silicone makes the foam more stable and prevents air bubbles from clumping together.
4. Full rise. About 100 - 200 seconds after mixing, the blowing reaction stops and the gelation reaction continues. The architecture of gas-filled cells gradually becomes more solid, their thin walls may not be able to hold gas pressure for longer. When fully expanded, these thin walls burst and gases are released (deflated) and the foam finally gels properly and is strong enough to hold the mass stable. The time from start to complete expansion (to deflation) is called rise time.
5. Gelling. The gelation (or polymerization) reaction continues until a time called gelation time (usually 20 - 120 seconds after swelling time) is reached when the foam mass has gelled. To check whether the foam block has gelled or not, use a wooden stick to dip it about 2 - 4 cm deep into the foam block until you feel elasticity. When the skin on the outside of the foam block is not sticky when touched by the fingertip, it means the tack free time has been reached.
Although the gelation time usually occurs after the bloom time when producing soft foams, it can be the opposite for hard foams.
6. Curing. The foam block is then transferred to the vulcanization zone for at least 24 hours to allow the gelation (or polymerization) reaction to completely occur.
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