PMMA commonly known as organic glass, acrylic etc.. Poly methyl methacrylate. As the PMMA surface hardness is not high, easy to rub hair, low impact resistance, poor molding flow performance and other shortcomings, PMMA has emerged. Such as the copolymerization of methyl methacrylate and styrene, butadiene, PMMA and PC blends, etc.. 372 organic glass is methyl methacrylate and styrene copolymerization. If the nitrile rubber added in the 372 organic glass in small (about 50%) can be made into 373 organic glass. PMMA flow ratio of PS, ABS is poor, melt viscosity is more sensitive to changes in temperature, in the molding process, mainly from the injection temperature to change the melt viscosity. PMMA is an amorphous polymer, the melting temperature is greater than 160, and the decomposition temperature is 270.
PMMA
1, plastic processing
PMMA has a certain water absorption, its water absorption rate of 0.3-0.4%, while the injection molding is required to be below 0.1% of the temperature, usually 0.04%. The presence of water makes the melt appear bubbles, gas lines, transparency and so on. So to carry out the drying process. Drying temperature 80-90 degrees, the time is more than 3 hours.
Recycled materials in some cases can be 100% of the use of the actual weight to the quality requirements of the set, usually over 30%, recycled materials to avoid pollution, otherwise it will affect the transparency and the nature of the finished product.
2, injection molding machine ion
PMMA no special requirements for injection molding machines. Because the melt viscosity of the melt is large, it needs deeper screw groove and larger diameter nozzle hole. If the strength of the product requirements are higher, it is to use a large - diameter ratio of the screw to implement low - temperature plastic. In addition, PMMA must be stored in a dry hopper.
3, mold and gate design
Die temperature is 60 DEG C to -80 DEG C, the sprue diameter should be combined with internal taper, the best angle is 5 to 7, if the injection of 4mm or above products, angle should be 7, the sprue diameter of 8 to 10mm, the overall length of the gate do not exceed 50mm.
For products with a wall thickness less than 4mm, the runner diameter shall be 6-8mm
For products with a wall thickness greater than 4mm, the runner diameter shall be 8-12mm
The depth of the side shape, fan shape and the vertical piece gate shall be 0.7 to 0.9t (t for the thickness of the wall), the diameter of the pin should be 0.8 to 2mm; the low viscosity should be ed with a smaller size.
The exhaust hole 0.05 common to 0.07mm deep and 6mm wide
The draft for the 30 '-1 35' -130 cavity part.
4, melt temperature
Can be used for the measurement of air injection method: from 210 to -270 degrees Celsius, depending on the information provided by the supplier.
5, injection temperature
Can be fast injection, but to avoid a high degree of internal stress, should use a multi-stage injection, such as slow - Fast - slow, etc., when the injection of thick parts, the use of slow.
6, the retention time
If the temperature is 260 degrees Celsius, the retention time of up to no more than 10 minutes, if the temperature is 270 degrees Celsius, the retention time can not be more than 8 minutes.
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Xintai bottle blowing machineHuangyan Zhejiang Plastic Machinery Factory
