Low foaming hollow blow molding
DATE：2021/9/25 8:39:24 / READ： / SOURCE：This station
Low foaming hollow blow molding
Low-foaming hollow blow molding is a technology under development. SPE in 199. At the annual meeting, Flambeau Corp. of the United States demonstrated a two-layer foam car dashboard. This is a hollow blown foam plastic part made of PC and HDPE compound. The part is successful in terms of structure and technology, but it cannot be commercialized because of its high cost (compared with corresponding parts of other materials). Now more and more plastic parts manufacturing companies in European and American countries are interested in this technology, because hollow blown foam has potential development advantages in the following aspects.
①As the foam occupies a certain space, the hollow blow molded foam plastic parts can reduce the amount of plastic by 25%-30% compared with the corresponding pure plastic hollow blow molded parts.
②Compared with the same pure plastic hollow blow molding parts, the foam plastic hollow blow molding parts have better rigidity.
③Foam plastic hollow blow molded parts feel soft and safer when made into toys. Since the hollow blow molded foam uses heat-absorbing foaming agent, under the same wall thickness condition, the foam hollow blow molded parts can save 10% The processing cycle.
⑤Because the microbubbles in the foam can better reflect the light, which not only increases the color perception but also reduces the damage of ultraviolet rays to the parts. In addition, the microbubble structure gives people a pearly color. Combining these factors, hollow blow molded parts with micro-bubble structure can save about 25% of the amount of color masterbatch than pure plastic parts.
⑥ Like other foam plastics, hollow blow molded foam plastic parts have better heat preservation, heat insulation and sound insulation properties.
However, foam hollow blow molding has not been widely promoted so far, and it has rarely been commercialized. The reason:
①Foam is not easy to distribute evenly in the whole part.
②The cell is deformed during blow molding. Generally, it is elongated. When the part swells and hits the cavity wall, the cells near the part wall are even squeezed.
③The plastic melt is not strong enough.
In response to the same problem above, many companies are making various efforts to improve the cell control technology of hollow blown foam and reduce the cost of parts. Europe has made advances in this area ahead of the United States, and has applied hollow blow molding foam molding technology to the automotive industry.
The basic process of hollow blow molding of foam plastic is similar to that of ordinary plastic hollow blow molding. The main steps are:
① Use extrusion method or injection method to produce preformed blanks.
②Put the unfoamed or slightly foamed (injection method) or foamed (extrusion method) blanks into the hollow forming mold, and further heat the blanks to soften and complete the foaming.
Author：admin