Polyurethane molded high resilience foam cushion sticky skin, peeling how to do?
Polyurethane soft foam is mostly open-hole structure, with low density, good elastic recovery, sound absorption, breathability, heat preservation and other properties, mainly used as furniture cushioning materials, mattresses, transportation seat cushions and other cushioning materials. Molded soft foam is a foam product that is mixed with raw materials and injected into the mold to form the required shape through the gap method process.
Today to talk about the molded soft foam crust easy to bond, peeling problem, according to my work experience and the master’s guidance to write down my experience.
First of all, it should be clear that the skin is related to these processes.
1) the configuration of the material and its liquidity: including raw materials, water, additives, any improper configuration will not work;
2) mold temperature, material temperature: should not be too low;
3) mold structure, design and placement;
4) the choice and amount of release agent, of which the amount of more will defoam, less will be peeling;
5)Control the time of product maturation, insufficient maturation (too high proportion of B material) or too long maturation can cause peeling;
6) other complex factors.
Then you can start from these points to adjust.
First, find the reason in the formula, if the B material T / M system, should consider the ratio, appropriate to improve MDI; recommended to remove T-9 plus some DMEA (dimethylethanolamine); grasp the fluidity of the material.
Second, the amount of water and silicone oil, the amount of water should be moderate, generally controlled at about 2.8 – 3.5, or it will sticky skin; silicone oil should not use too much, otherwise it will peel.
Third, check the mold, whether clean, whether air leakage, the placement is balanced, or collapse bubble on the sticky film.
Fourth, the mold temperature and material temperature, the two temperature gap is easy to peel and sticky skin. Mold temperature is generally 30 to 50 degrees, the material temperature is 21 to 25 degrees, the season must be adjusted to the temperature.
After all, polyurethane is also a chemical industry, these problems actually involve each raw material problems. Where to participate in the chemical reaction of each raw material is very important, whether it is the main material or small materials have its unique effect, so if one of the raw materials in the chemical reaction of the change, then it will naturally be reflected in the foaming process from the sponge bubble body, which is the most basic principle, the reflected problem if not a disease, then it is a revelation; if it is a disease, then If it is a pathology, then we should consider what to do to solve it; if it is a revelation to us, then we should consider how to use it or perfect it, to know that many evolution and invention are developed in the revelation.
For example: we all know that the current domestic slow rebound polyether manufacturers have Shanghai High Bridge’s 2000, Nanjing Jinpu’s 1070, the two slow rebound polyether, although its hydroxyl value is 240, but in the actual production of their chemical activity is very different from each other, a few years ago, 2000 and 1070 without adjusting other raw materials can be used in place of each other, however A few years ago, 2000 and 1070 can be used in place of each other without making adjustments in other raw materials, but today, a few years later, they have formed their own characteristics, and can no longer be used in place of each other.
Of course, the current domestic production of slow rebound polyether is far more than these two manufacturers, so each slow rebound sponge manufacturers use raw materials is difficult to unify, which also includes a variety of small materials. This has formed each enterprise has its own formula, in terms of slow rebound polyether has a better open-hole and stability. The slow rebound polyether with better openness is a little less in the production process, and the amount of silicone oil (stabilizer) compared to its dosage should be increased appropriately; conversely, if you use the slow rebound polyether more stable or more closed gas type, then the amount of openness in the production process should be a little more, and the amount of silicone oil should be slightly lower.
