Epoxy resin is used as the hot runner manifold heater sealing material, and its formulation and process are not exactly the same. There are basically two kinds.
One is a warming and pressing process, which uses 634# epoxy resin and m-phenylenediamine, double-mixed according to the weight of 5:2, and the mixture is potted and sealed with natural mica sheets at 20kg/cm2. The pressure was formed by drying at a temperature of 120 ° C for 4 hours.
The other is a non-pressurization heating process, which can use 6207 epoxy resin and maleic acid as a hardener to form a sealing material which can be used for a long time in a working environment of 250 °C.
Special epoxy resin sealing materials can also be formulated according to the following ingredients:
Epoxy resin 634# 100 parts
Phthalic anhydride 35 parts
Quartz powder (fumed silica) 270 mesh 150 parts
Dibutyl phthalate 15 parts
This formula is more effective in improving the thermal shock resistance due to the mixing of silica. It is also possible to add no silica in places where the thermal shock is not large.
Epoxy resin is used as the sealing material, and its temperature resistance is generally only about 150~250. The materials prepared during sealing must be used with the equipment. The performance of the electric tubular heater components before sealing must be intact. Otherwise, it is difficult to rework after the epoxy resin seal is hardened.
Expansion technology of hot runner manifold tubular heating element
First, the expansion of the formula, the need for technology transfer
Expanded enamel oil: clay, borax, quartz powder, nitrous acid steel, barium molybdate, barium oxide, melanin, water, etc.;
Second, the porcelain temperature: 830 ~ 850 ° C;
Third, heating time: 15~20 minutes;
Fourth, the supplier phone, the need for technology transfer;
Fifth, the process:
1. The hot runner electric heating element is processed, but it is not sealed, and the electric melting powder is used, and the insulation is >1000mΩ.
2, according to the expansion of the formula, stir well, ball milling for more than 4 hours.
3. The coarse particles in the above slurry were removed using a 100-mesh sieve.
4, the surface of the electric heating pipe is cleaned, one of the methods,
(A) rubbing the surface of the steel pipe with gasoline;
(B) pickling → alkali washing and neutralization → washing the surface of the tube with water;
(C) Decontamination of the surface of the sandblasting electric heating pipe;
(D) Wipe the surface of the polished electric heating tube with a cloth.
5. The surface of the electric heating element is coated with porcelain oil (the slurry treated by 3#), and the method may be any one.
(A) dip coating (specific gravity adjusted as needed);
(B) Spray gun coating.
6, dry for 2 to 4 hours (depending on the humidity and temperature adjustment of the air).
7, oven porcelain: 830 ~ 850, 15 ~ 20 minutes or so.
8. Cool the electric heating tube to about 50 °C;
9. Epoxy resin sealing (see also special instructions for sealing operation)