Potting adhesive, also known as electronic adhesive, is a broad term mainly used for bonding, sealing, potting and coating protection of electronic components. What are the main components of polyurethane potting adhesives? What is the difference between it and epoxy potting adhesive?
The main components of polyurethane (pu) potting adhesive are polyisocyanate and polyether polyol, which are cross-linked and cured in the presence of catalyst (triethylene-diamine) to form a polymer. Polyurethane potting adhesive has good adhesive performance, insulation performance and weather resistance, and its hardness can be changed by adjusting the ratio of diisocyanate and polyether polyol. It is mainly used in the packaging of various electronic and electrical equipment.
Compared with epoxy resin potting adhesive, polyurethane potting adhesive is more toxic. Epoxy resin adhesive, like polyurethane adhesive, can be made into two-component adhesive. Epoxy resin potting adhesive is generally composed of bisphenol a epoxy resin, curing agent (amine or acid anhydride), reinforcing additives and fillers. It has long curing time at room temperature and can be cured by heating. After curing, the adhesive strength is high and the hardness is generally high, which can be made into transparent potting adhesive for encapsulating electrical modules and diodes.
As for the two-component potting adhesive, the use method is basically the same, the general process is: ingredients – mixing – vacuum – potting – – curing. -Curing. Of course, the process can use two-component potting equipment, which simplifies the whole operation process, saves operation time and reduces the waste of raw materials.
Polyurethane injection molding foam process, how much do you know?
Structural foam injection molding
The structural foam method is a revolution in injection molding technology, which retains many advantages of the traditional injection molding process and avoids some of the problems often encountered in the traditional injection molding process, such as insufficient product strength, too long production cycle and low molding rate.
The most important feature of the structural foam method is that it can be injected without additional equipment and can be produced with ordinary injection molding machines, but the high-pressure structural foam injection molding machine with expanded cavity method adds a secondary clamping device compared with ordinary injection molding machines.
In addition, the use of structural foam technology can also use low-cost molds to mold large and complex products, and can operate multiple cavities at the same time, thereby reducing the production cost of products. The finished product made by the structural foam method is a continuous foam material with a dense surface layer, and its strength and stiffness per unit weight is 3-4 times higher than that of the same unfoamed material.
In recent years, the structural foam injection molding process has been widely developed, and there are many molding methods, but in summary, they can be divided into three types: low-pressure foaming method, high-pressure foaming method (Note: the low pressure and high pressure here refers to the pressure in the mold cavity) and two-component foaming method.
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