Audited Supplier
FS7350
ISO9001
Product Description
Product introduction
Self-adhesive coating FS7350
1,Product features
FS7350 is composed of special waterborne epoxy resin, special curing agent, water, etc. It is a one-component waterborne epoxy emulsion coating. The product has low odor, low VOC content and long storage life. It can be fast curing from 130 ° C to 250 ° C, and has strong adhesion and high adhesion strength.For the dry adhesively bonding of magnet core sheets. The coated sheets or punchings may be bonded together under heat and pressure. Therefore, a rivet joint or a welding of the magnetic cores is not necessary, which reduces inter-lamellar loss. The bonded cores show optimal thermal conductivity, no hum noise, and do not breathe at temperature changes. Thus interlaminar corrosion is avoided. In addition to the bonding function, FS7350 also has the role of interlayer insulation.
2,Composition
| No. | Name | Percent(%) | Note |
| 1 | BPA Epoxy | 35-38 | |
| 2 | Modified epoxy resin | 8-10 | |
| 3 | Emulsifier | 6-8 | |
| 4 | Curing agent | 5-8 | |
| 5 | 1 methoxy 2-propanol 2-2 | 5-10 | |
| 6 | Water | 30-35 |
3,Technical indexes
| No | Items | Indicators | Test Standard |
| 1 | viscosity at 23ºC | 60±20s | DIN 53211 |
| 2 | solids content (1g/2h/130ºC) | 50±3% | DIN 53216 |
| 3 | density at 23ºC | 1.08±0.05 g/ml | EN ISO 2811-2 |
| 4 | single side coating | 0.6 kg/t·µm | yield per metric ton coreplate (gauge 0,5mm) on single side coating |
| 5 | single side coating | 2.2 g/m²·µm | yield per 1m² coreplate surface on single side coating |
| 6 | Shelf life(0~25 ºC) | 6 months | No performance degradation |
| No. | Items | Indicators | Test Standard |
| 1 | Shelf life | 6 months | Store in a dry environment below 40ºC |
| 2 | colour | clear | visual |
| 3 | density of the coating | 1.2 g/cm³ | calculated |
| 4 | surface resistivity | >1000 ·cm²/lam. | ASTM A717(Franklin) |
| 5 | bending over cylindrical mandrel Ø3mm | crack-free | ISO 1519 |
| 6 | cross cut test | GT 0B | DIN 53151 |
| 7 | pencil hardness | >5H | EN 13523-4 |
| 8 | enhancement of punchability | yes | compared to bare steel |
| 9 | bonding strength, T-peel test | >3.0 N/mm | YB/T 4732-2019 |
5,Processing
5.1 ApplicationSingle-sided coating: thickness of 5~10um; Double-sided coating:3~5um, depending on the roughness of the steel plate surface. It can be applied by light roller or grooving roller.
5.2 Curing
It's hot curing and comprises two stages of curing. They can be controlled by means of curing oven adjustments. In case of moderate curing temperature a dry, flexible and still reactive coating ("B-stage") can be achieved. It is suitable for the processing of core plate steel, like slitting and punching. Under further heat treatment the still reactive B-stage chemically reacts to a final cured C- stage. Within this process the coating intermediately becomes soft. Thus core plates which are pressed together while heating, bond to a stiff stack unit.
The optimum curing temperature to achieve the active B-stage depends on the dwell time in the furnace and must be determined for each oven separately and corresponds to those used for other core plate varnishes.
The opposite table shows guide numbers for the strip temperature (PMT) which has to be achieved for the corresponding dwell time in the curing furnace.
The B-stage is defined by its capability to bond.
| Dwell time | PMT |
| 30-50s | 200-240ºC |
| 60-80s | 180-230ºC |
5.3Alcohol test
Check the coating by rubbing with a wad moistened with alcohol (ethanol). The coating is cured properly to B-stage, if it can be totally or partially washed away.5.4 Bonding
The coated sheet is punched without additional lubrica- tion. The varnish has a lubricating effect and extends the service life of the punching tools. The punchings are stacked one upon the other. By application of pressure and heat the bonding takes place by intermediate softening and curing of the coating. The pressure required depends on steel flatness and coating thickness and should not much lower than 300 N/cm2.
The optimum bonding temperature depends on core size and heat-up rate. On big-sized cores with several hours heat-up time good bonding results can be obtained yet with 2.5h at 180°C .
Very small-sized cores can be heated-up in shortest time by means of induction heating. The table can be used as a reference when the bonding pressure is 300N/cm2.
| Workpiece heating temperature | Dwell time |
| 180ºC | 2.5h |
- Storage tank, circulation tank, pipeline should be made of stainless steel material, so as not to appear water rust.
- Before coating, the steel plate should be clean and dry, and the plate temperature should be <40ºC.
- The coating is best used between 15~25ºC, stirring when state. After shutdown, the recycled coating should stored at 0~25ºC.
- Pay attention to the control of baking temperature and holding time in the curing process. Under the recommended baking temperature and time, if the result cannot be reached, increasing baking temperature or extending baking time can be adopted to solve the problem.
- The outlet of the curing furnace should be unobstructed to facilitate the evaporation of water vapor, so as not to affect the curing speed.
