Acrylic processing technology
Poly (methyl methacrylate) can be used casting, injection molding, extrusion, thermoforming and other processes.
Casting molding for the molding of plexiglass sheet, bar and other profiles, that is, with bulk polymerization method of molding profiles. After casting molding products need to be post-processing, post-treatment conditions are 60 ℃ under heat 2h, 120 ℃ for 2h.
Injection molding Suspension polymerization of the obtained pellets, molding in the ordinary plunger or screw-type injection molding machine on. Table 1 shows the typical process conditions for polymethylmethacrylate injection molding.
Injection molding products also need to eliminate the stress after treatment to deal with in the 70-80 ℃ hot air circulation drying oven for processing time depending on the product thickness, usually about 4h.
Poly (methyl methacrylate) can also be used extrusion molding, the suspension polymerization of particles produced plexiglass sheet, rod, pipe, sheet, etc., but the profiles, especially the plate, the polymer molecular weight, Mechanical properties, heat resistance, solvent resistance are not and casting molding of the profile, the advantage of high production efficiency, especially for the pipe and other casting method with the mold. Difficult to manufacture profiles. Extrusion can be single or two-stage exhaust extruder, screw diameter to diameter ratio is generally 20-25. Table 2 shows the typical process conditions for extrusion molding.
Thermoforming is to plexiglass sheet or sheet made of various sizes of products(acrylic box, acrylic display stand, acrylic holder) in the process, will be cut into the required size of the blank clamped in the mold frame, heated to soften, and then press it close to the mold surface , Get the same shape with the shape, the shape of the cooling after finishing the edge of the finished product. Pressurization may be by vacuum drawing or by direct pressing with a punch having a molding. Refer to Table 3 for the recommended temperature range for thermoforming temperatures. When using vacuum low drawing products, it is advisable to adopt the temperature close to the lower limit, and to adopt the normal temperature when the depth of the product is complex.