日本研制成一种新型钢板,其比重比普通钢板小得多,而强度和刚性则相等,生产成本也降低。这种钢板是夹层式的复合钢板,即两块钢板之间夹以聚丙烯树脂层,树脂层厚度占总厚度的一半。其生产工艺是,将熔融树脂涂满钢板的一面,或是把薄膜状树脂粘合在 Japan developed a new type of steel, the proportion is much smaller than ordinary steel, but the strength and rigidity are equal, the production cost is also reduced. This kind of steel plate is a sandwich type composite steel plate, that is, a polypropylene resin layer is sandwiched between two steel plates, and the resin layer thickness accounts for half of the total thickness. The production process is, the molten resin coated steel side, or film-like resin bonded to